Updated software for Guide 6.0

This page will only help if you have a Guide 6 CD; click here for updates to Guide 5.

The following downloads contain files that will add some features to your Guide 6.0 software, such as RealSky South use, artificial satellites, eclipse display, and more. They will also eliminate a few small bugs people reported on the first batch of CD-ROMs.

It's recommended that you return to this page from time to time. There is a long list of possible improvements to Guide that will be worked on in the coming months, and they will be reflected on this page.

Windows software (GUIDE6.ZIP) (about 630K)
32-bit DOS software (WGUIDE.ZIP) (about 615K)
16-bit DOS software (GUIDE.ZIP) (about 408K)
Additional ZIP file for RealSky South (REALSKY.ZIP) (about 260K)

Important safety tip: GUIDE.ZIP was last updated in March 1998. The problem is that the 16-bit DOS software is restricted to 640K. With all the recent wonders added, this had become increasingly hard to manage. For the last few months, Guide has pushed that limit so hard that, if you did something requiring a few extra KBytes (zoomed in on a star-rich area, for example), the 16-bit DOS software would exit with an "out of memory" error message. So GUIDE.EXE has reached an end; future updates will involve only the Windows and 32-bit DOS software.

Improvements so far, in reverse chronological order:

  • (24 Sep 98) Russian-language version
  • (24 Sep 98) Tables of solar eclipses
  • (28 Aug 98) Triton and Charon shown
  • (28 Aug 98) Display of guider chip for ST7, ST8
  • (28 Aug 98) Display of constellations in ephemerides
  • (29 Jul 98) Constellation lines show proper motion
  • (29 Jul 98) Control over the ground color
  • (29 Jul 98) A1.0 stars show an inferred visual magnitude
  • (5 Jul 98) Ability to show more 'realistic' stars
  • (5 Jul 98) Updated Spanish, French, and Italian files
  • (5 Jul 98) Ability to (often) compute magnitudes for satellites, even if the elements lack the necessary data
  • (25 May 98) Higher-precision planetary positions
  • (25 May 98) Ability to reset background color
  • (25 May 98) Ability to run from a hard drive
  • (29 Apr 98) High-precision lunar positions
  • (29 Apr 98) Central line data for eclipses, occultations
  • (29 Apr 98) Extra options for RealSky images
  • (29 Apr 98) Visual magnitude limit in Quick Info
  • (29 Apr 98) Location dialog also includes temperature, pressure, humidity data
  • (29 Apr 98) Lat/lon formats and English vs. metric units
  • (29 Apr 98) Display of RA/dec offsets
  • (10 Apr 98) Eclipse and horizon object bugs in 5 Apr version fixed
  • (5 Apr 98) Lat/lon/altitude and home planet in one "Location Dialog"
  • (5 Apr 98) Ability to get views from the surfaces of objects other than the Earth
  • (5 Apr 98) Fix to lunar tables handling
  • (5 Apr 98) More logical order of menus
  • (14 Mar 98) Better handling of A1.0 data
  • (14 Mar 98) More logical way to find user-added asteroids
  • (12 Mar 98) Johnson B-V magnitudes for Tycho stars
  • (12 Mar 98) Ability to import the new MPEC single-line orbital elements
  • (12 Mar 98) Improved Dutch menus
  • (4 Mar 98) Text in Dutch and Japanese
  • (25 Feb 98) Constellations in German, all text in Italian
  • (21 Feb 98) Better ability to right-click on objects in crowded areas
  • (21 Feb 98) Ability to set the limiting magnitude for stars directly
  • (21 Feb 98) Ability to get contact times for eclipses/occultations/transits
  • (21 Feb 98) Ability to find "locally visible" and/or "total only" eclipses/occultations/transits
  • (21 Feb 98) Buttons to put ecliptic or galactic north at the top of the chart
  • (22 Jan 98) Considerably improved eclipse handling
  • (22 Jan 98) Updated Spanish text
  • (14 Jan 98) Missing file for eclipses put back in place
  • (13 Jan 98) Paths of eclipses, occultations, and transits
  • (13 Jan 98) Ultima 2000 control
  • (22 Dec 97) "Recent Changes" option in Help menu
  • (20 Dec 97) Background menu
  • (20 Dec 97) Objects on the horizon
  • (20 Dec 97) Fields of view of less than one arcsecond
  • (25 Nov 97) Version number (date) in 'About Guide'
  • (25 Nov 97) Hotkey for 'full sky view'
  • (25 Nov 97) New option to show hour angle in the Legend area
  • (25 Nov 97) Updated French and German-language files
  • (25 Nov 97) New dialog box to define ephemeris format
  • (25 Nov 97) Check-box in Measurements dialog for the center cross-hair
  • (12 Nov 97) Ability to use the RealSky South CDs
  • (1 Nov 97) Ability to get trails and ephemerides for artificial satellites
  • (1 Nov 97) Better prompting for RealSky and A1.0 CDs
  • (1 Nov 97) Labelling of buttons in languages other than English fixed
  • (20 Oct 97) Ability to show DSS images downloaded from Web servers
  • (20 Oct 97) Ability to "go to" a satellite
  • (14 Oct 97) Better ability to add languages
  • (13 Oct 97) Non-bitmapped planets
  • (12 Oct 97) Artificial satellite features
  • (9 Oct 97) New animation features
  • (5 Oct 97) A RealSky problem fixed
  • (4 Oct 97) Two small bugs fixed
  • Display of "more info" for RealSky images
  • Help/glossary/"more info" data in a scrolled window
  • Display of a crosshair at the center of the screen
  • Display of HD, HIP, Yale numbers and common names
  • Dialog to control the RA/dec format
  • A way to get exact angular distance/PA between two objects
  • Transparent text (Windows only)
  • Better "automatic mode" for ticks, grids, etc.
  • (24 Sep 98) Tables of solar eclipses: The Tables menu now contains, in addition to the "table of lunar eclipses" feature, a "table of solar eclipses" feature. The current table is a short one; you can generate lists running from 1900 to 2100. (A complete table will be provided in Guide 7; it runs from -2000 to +3000, and is quite large!) The data involved came directly from this Catalog of Solar Eclipses. (By storing the catalog in this manner, Guide evades the need to actually compute the eclipse data each time you use the option; so it tends to run very fast.)

    (28 Aug 98) Triton and Charon shown: For some time, the most glaring omission in Guide's display of objects in the solar system has been Triton, the largest moon of Neptune. Of considerably lesser importance, the only moon of Pluto was omitted. Using formulae from the Explanatory Supplement to the Astronomical Almanac, both objects have been added to Guide. Zoom in far enough on Neptune or Pluto, and you will see these satellites.

    I am not entirely happy with the display of Triton, though. Its positions are definitely good enough for visual and CCD use, and its occultation of a magnitude 13.9 star on 18 July 1997 is shown correctly. Its series of occultation/shadow/transit events in 1951 is shown. And the positions match closely those from the JPL Horizons Web site. But in the Explanatory Supplement, J2000 and B1950 are "mixed and matched" at one point, while later, it is made apparent that the same reference frame should be used throughout. I'm still tracking this issue down. But the difference should be nearly undetectable in most situations.

    (28 Aug 98) Display of guider chip for ST7, ST8: Users of the "CCD Frame" option in Guide have sometimes asked for this. I have some thoughts for a very nice user interface, where one would select a type of CCD camera and a focal length, and Guide would do all the math for you. In the meantime, though, the following will at least get the guiding chip on the screen for you:

    In Windows Guide, hit Alt-J. When prompted to "Enter a test flag", type "f1" (as in an "f" and a "1", not the F1 function key!) and hit Enter. If the camera frame is currently shown on screen, Guide will redraw it with an ST7 guiding chip drawn next to it.

    Use of "f2" will get you an ST8 guiding chip. Use of "f0" will put you back into the normal mode where no guiding chip is drawn.

    (28 Aug 98) Display of constellations in ephemerides: If you look in the "ephemeris items" dialog, you'll see a new "constellation" checkbox. Setting this box will mean that, when you create an ephemeris, the three-letter abbreviation for that constellation will be given at each step.

    (29 Jul 98) Constellation lines show proper motion: Setting Guide's date to thousands of years in the future will result in an oddly distorted view of the sky, as the proper motions of stars such as Arcturus destroy the patterns we're all used to. Previously, doing this just moved the stars, leaving constellation lines unaffected... obviously, not an ideal solution. That problem is now fixed.

    (29 Jul 98) Control over the ground color: In the past, one could set a solid-fill ground, but only in a certain reddish color. This is now fixed. In the Backgrounds dialog, the "Show Ground" check-box is followed by a small button you can click to choose the ground color (much as you can use the other two small color buttons to set the background color in "normal" and "chart" modes.)

    (29 Jul 98) A1.0 stars show an inferred visual magnitude: The A1.0 star catalog provides only B and R magnitudes (and even these are not of wonderful quality; it's hoped that the A2.0 star catalog will provide more accurate magnitudes and positions.) Bob Leitner asked if I had heard of a way to compute a "guesstimated" V magnitude from these; when I confessed ignorance, he supplied the following formula, due to T. Kato:

    Vmag = .375 * B + .625 * R

    I've added this to Guide; when you click on an A1.0 star now, you'll get the B, R, and "computed V" magnitudes. And you'll get the same data when making lists of A1.0 stars in a given area.

    (5 Jul 98) Ability to show more 'realistic' stars: From time to time, people have asked about having Guide show stars as single pixels of varying intensities. Many other programs, such as Dance of the Planets and Starry Night, do this; and now Guide also can do it, as follows: Enter the Star Display dialog, and you will see a "max star size" and "min star size". By default, this runs from .5 pixels (radius of dimmest stars) up to 30 pixels (radius of brightest stars).

    If you set this to be, say, .1 pixel to 1 pixel, then the brightest stars would be shown as single pixels of full intensity; the dimmest would be shown at 1/100 intensity. In general, such low intensities are not really visible. In a darkened room, I personally find that a range of .2 pixels to 12 pixels looks about right; with this setting, the dimmer stars are shown as single pixels, and multiple pixels are still used for very bright stars. Your preferred settings will vary according to monitor brightness and taste.

    The "in a darkened room" statement is very important. Using a single pixel does not allow for much variation in intensity. Since one can't get a pixel brighter than 'full intensity', we have to work at the dim end of the scale; in daylight, a .2-pixel star is (on my monitor) invisible. If one is truly devoted to single-pixel stars, one can set (for example) a range of .2 to 1, recognizing that one cannot then display a range of ten magnitudes (the default value). Guide does allow you to reset the "magnitude range" accordingly, in the same Star Display dialog box.

    (5 Jul 98) Updated Spanish, French, and Italian files: Fortunately, a bit before this update was posted, I received new files for these languages from Alberto Romero, Jean-Noël Moreau, and Giuliano Pinto, respectively. These bring the menus for those languages completely up-to-date, and also update some of the 'comments' given for some objects to reflect the selected language.

    (5 Jul 98) Ability to (often) compute magnitudes for satellites, even if the elements lack the necessary data: Previously, Guide could only compute satellite magnitudes if the elements ("two-line elements", or "TLEs") were in the special "Molczan" form, distributed by Ted Molczan at this site. With any other elements, you were out of luck.

    But now, if a satellite has a Molczan-determined magnitude, then Guide will use this even if you're using a non-Molczan element set. The result is that, for about 1300 of the brighter satellites, Guide can now determine magnitudes, no matter what the source of the .TLEs. (Yes, this does include all the Iridium satellites... but unfortunately, the 'flares' resulting from reflections off the antennae are not included. Yet.)

    (25 May 98) Higher-precision planetary positions: The difference will, in general, be a small fraction of an arcsecond... but, if you download and unZIP this file (about 116 KBytes) , and use the current Guide software, and set "Full Precision" for planets in the Data Shown menu, then you will be using an improved theory.

    In this case, Guide will switch from its "usual" use of the VSOP planetary theory, to the more recent "Planetary Series 1996" of J. Chapront. (Everything pertinent to this new theory is posted on the Astronomical Data Center (ADC) Web site. Click here to get full source code, coefficients, and descriptions of this new planetary theory. You don't need that for use with Guide; I mention it just because people are often curious as to how Guide does what it does.)

    The PS-1996 has two advantages over the older VSOP theory. First, the way it's put together is more computationally convenient, leading to better speed than was possible with the VSOP theory. (Computing a "full precision" VSOP position involves a lot of floating-point math.) Second, it was based on the JPL numerical integration DE403. You may recall that, once upon a time, one argument for the existence of a tenth planet was the slight irregularities in the motions of Neptune and Uranus; no planetary theory completely accounted for their motions at the time. The Voyager flyby in 1989 revealed the reason for the discrepancy: the mass of Neptune had been miscomputed, by about one part in 200.

    DE403 (and, hence, PS-1996) is based on the revised mass for Neptune, while VSOP87 predates this adjustment. As a result, use of PS-1996 results in better positions (by about .5 arcsecond!) for Neptune. Other planets are also affected, but none by much more than about .01 arcsecond.

    (25 May 98) Ability to reset background color (Windows only) If you look in the Backgrounds dialog (under the Display menu), you'll see that two new colored buttons have been added, next to "Normal Mode" and "Chart Mode". By default, these show black and white, respectively. Click on either, and you can reset the background color in either mode to be something "close to black" (for Normal Colors) or "close to white" (for Chart Mode).

    This is admittedly not a big deal. I added it, in part, because I have seen star charts with a dark blue background (close to, but not quite equal to, black). They seemed a little easier on the eyes to me. It came to mind when I ran in "realistic mode" in deep twilight, which happens to be represented with that color. I now run Guide with this sort of dark blue background all the time.

    The one drawback to this is that animation in "RA/dec" mode can result in garbage on the screen. I have yet to work out a way around that unpleasant reality.

    (25 May 98) Ability to run from a hard drive This is in a bit of an "experimental" mode. I have determined that Guide can indeed be run with a mere 11 MBytes of files, copied from the CD-ROM to the hard drive. At some point, I will endeavor to make this a painless, click-a-few-buttons process. Right now, though, it's slightly more involved than this; click here for details.

    (1 May 98) High-precision lunar position fix: Several people reported very strange positions from the new "high-precision" lunar position function. You do not need to download the software again to fix this problem. The error comes about because some browsers interpreted the data file, ELP82.DAT, as text, even though it's really binary data. If that happens, you get a corrupted file.

    The solution is to click here for the PKZipped ELP82.DAT file (about 28 KBytes), and unZIP it in your Guide directory. All browsers I know of are bright enough to download such a file properly.

    (29 Apr 98) High-precision lunar positions: Previously, the precision of lunar positions in Guide has been somewhat embarrassing. While asteroids and planets are shown to a fraction of an arcsecond, and star positions from Hipparcos are given with sigmas (error measurements) in the thousandths of an arcsecond, the Moon has been no better than about ten arcseconds! This is particularly unfortunate when dealing with eclipses and occultations.

    The reason was that Guide used a lower-precision formula; but it now instead uses the ELP 2000-82B (Ephemerides Lunaires Parisiennes) when "Full Precision" is checked in the Planets section of the "Data Shown" dialog box. To use this, though, you'll have to click here for the PKZipped ELP data file (about 28 KBytes) and decompress the file in your Guide directory.

    ELP 2000-82B is an extremely precise series expansion of lunar motion created at the Bureau des Longitudes by Michelle Chapront-Touzé and Jean Chapront. Some of the terms are as small as a few centimeters, meaning that the ultimate level of precision is being reached for. Guide does truncate the series, resulting in a loss of precision of about ten meters.

    It's not yet clear, though, that the actual precision is even close to this. Solar eclipses computed using "full precision" are off by about one kilometer; it appears that this error is in the lunar motion, but more investigation is needed. (In any case, this is much better than the previous level of error. Once the source of this discrepancy is found, it is assumed that the lunar position will indeed be determined to within meters, and solar eclipse results should be exact.)

    (29 Apr 98) Central line data for eclipses, occultations: When in 'eclipse' mode, you can now click on "Quick Info" to get latitude/longitude data along the central line of the eclipse. You'll also get the duration of the total (or annular) phase at that point. Eventually, this will be expanded to include data such as the limits of the eclipse (both partial and umbral), Saros number (for solar eclipses), path width, and so on... a full discussion of the event will be provided.

    It should be noted that not all events have a central line. Partial solar eclipses never do, and some total and annular eclipses lack one.

    (29 Apr 98) Extra options for RealSky images: A way has been added to fine-tune the actions of the RealSky image extraction software, GETIMAGE. The way this is done is to add a few options when you're entering the image size. For example, if instead of entering a size of "20x30" (twenty arcminutes wide by 30 high), you enter "20x30 -s2", GETIMAGE will "subsample" the image twofold. The resulting image will have every second pixel from every second line, so it will be four times smaller. (It will also draw quite a bit faster; at present, RealSky images can be very slow when you zoom out to cover a few square degrees.) You can reduce the image size (and resolution) still further by using -s4 or -s5 (every fourth or fifth pixel and line) instead of -s2. In fact, any value that evenly divides 500 can be used; so we have -s10, -s20, -s25, -s50 as well (though these are not really as useful.)

    These are not the only new options added. RealSky South and North overlap in the declination zone 0 to -16. By default, GETIMAGE looks for the RS North data in this zone. You can use the '-b2' option to override this behavior, forcing GETIMAGE to use RS South instead. (This is particularly important if you have only RS South!)

    Also: In some cases, you may want to force GETIMAGE to use a particular plate. By default, GETIMAGE selects the "best" plate, defined as the one where your image would be farthest from a plate edge. (The plate edges are sometimes quite dodgy, so this selection method makes some sense.) But the plates do overlap a bit, and in some cases, you may decide you would really prefer to use a different plate. Adding, for example, "-pxe241" would tell Guide to use RealSky plate XE241.

    To find out which plates cover a given area, go into "Toggle User Datasets" (in the Extras menu) and toggle either "RealSky North" or "RealSky South" (or both) on. At wider fields of view, you'll see the rectangles defining the plates, each labelled with a plate number. (You can also click on the rectangle corner, to get some data about that plate.)

    (29 Apr 98) Visual magnitude limit in Quick Info: The May 1998 issue of Sky & Telescope has a very interesting article by Bradley E. Schaefer, describing a way to compute the visual magnitude limit and sky brightness for a given place and time. It includes most of the important effects, such as scattering of light from the sky and moon, skyglow, extinction of light, and so forth. It's an impressive piece of work, and it is now used in Quick Info. When you click on the Quick Info option, Guide will compute the magnitude limit at the screen center and list it among the other data.

    Schaefer also provides ways to compute sky brightness in five photometric bands (U, B, V, R, I) and CCD magnitude limits. I expect to add this at some point; I'd also like to use the sky brightness data to produce a really "realistic" Realistic Mode. (The current Realistic Mode, available in the Backgrounds dialog in the Display menu, gives decent results; but I think a system based on Schaefer's formulae could be spectacular.)

    Schaefer's system also takes the local temperature and humidity into account, so the following section will be of interest.

    (29 Apr 98) Location dialog also includes temperature, pressure, humidity data: For certain calculations, such as refraction and the aforementioned visual magnitude limit calculations , these three items can be quite important. Previously, Guide assumed default values for all of them; but to get the best results, it was felt best to make them all user-settable values in the Locations dialog.

    (29 Apr 98) Lat/lon formats and English vs. metric units: The RA/Dec format dialog box has been expanded into a general-purpose "formats" box. The main reason was that people wanted display of latitude/longitude values in something other than the simple "compass sign and decimal degrees" notation. This dialog box now allows one to set the use of + and - in place of the usual N, E, W, S. The subject of whether East longitudes are positive or West longitudes are positive has been in dispute for a long time (see, for example, page 89 of Jean Meeus' Astronomical Algorithms), so Guide allows you to select either convention.

    In general, Guide uses metric units almost everywhere. But the US and Burma have yet to make this conversion; in recognition of this fact, there are now "Metric" and "English" radio buttons in this dialog box. Not every function in Guide recognizes these switches yet, though. But you'll notice that (for example) the Locations dialog shows lat/lon in the correct format, with altitude in meters or feet as appropriate (and pressure in millimeters or inches of mercury, and temperature in centigrade or Fahrenheit.) As time allows, all portions of Guide will be modified to reflect choices in units and format.

    (29 Apr 98) Display of RA/dec offsets: Previously, dragging a line between two points with the right mouse button rewarded you with the distance and position angle between those two points. This has been enhanced a bit; for distances of less than one degree, Guide will now also show the "deltas" in right ascension and declination, a feature several people have requested lately.

    Also, if you're in "geographic" (eclipse) mode, the distance in angular measurement was not always helpful, and the suggestion that one multiply degrees by 111 to get kilometers was not always well-received. So now, geographic distances are shown in miles or kilometers (depending on which radio button is selected in the formats dialog box .)

    (10 Apr 98) Eclipse and horizon object bugs in 5 Apr version fixed: Adding the views from the surfaces of other planets turned out to have side effects. Two of them count as bugs. The display of eclipse and occultation paths were sometimes ruined, and the objects on the horizon (such as houses, trees, etc.) were rotated by 180 degrees. Both are now fixed.

    Lat/lon/altitude and home planet in one "Location Dialog": (Windows only) As part of a further effort to tidy up an awkward point in the user interface, these functions have been combined into one "location dialog", accessed through the Settings menu. You can select the home planet from a drop-down combo box; edit boxes are provided for the altitude, latitude, and longitude. There is also a check-box for setting a geocentric viewpoint. (Pedants may object to the use of this term when applied to planets other than the earth, but I expected that "planetocentric" would confuse people.) This box will be a nice starting point for the long-awaited "set your position as a city name or as a US postal code" (the databases for this are already on your Guide 6 CD-ROM).

    Ability to get views from the surfaces of objects other than the Earth: In the past, views from the earth were uniformly done from its surface (possibly modified slightly with the "altitude" parameter). Views from all other planets were done from the center of that object.

    The current version correctly supports views from other planets. You can set a lat/lon value and see what the sky looks like from them. This is admittedly not particularly useful, though it can be quite educational ( click here for two interesting examples using this new feature).

    There are some very small things that still need to be done before this feature can be considered complete; click here for details.

    Fix to lunar tables handling: Gary Seronik pointed out that the "lunar tables", giving rise/set times and libration data, were a bit odd when run in a local time zone. A bit of experimenting revealed the cause: the rise/set times given for a day such as (for example) 4 Apr 1998 were the times the moon rose and set between 0h UT and 24h UT on that day, with the times expressed in your local time zone.

    A bit of re-coding fixed this. The rise and set times will now be the times when the moon did these things, between 0h and 24h local time of the day in question. The mix-and-match of local and UT is now gone.

    More logical order of menus: Quite a few items have been added to the menus in Guide over the last few months, and there is no really logical pattern to most of them. But I've re-ordered the "Go To", "Settings", and "Extras" menus, and added separators, in a manner that I hope will seem more logical to people.

    The "Go To" menu still has Messier, NGC, and IC options at the top. Below this is a section for objects within the solar system, at progressively greater distances: horizon points, artificial satellites, planets, comets, asteroids. Next is a section for objects outside the solar system: stars, nebulae, open clusters, globulars, constellations, galaxies. Finally, there are two "uncategorized" items: coordinates and .TDF (user-added dataset) objects.

    In the "Extras" menu, RealSky related items are in a section at the top of the menu. Eclipse and conjunction items are in a section at the bottom of the menu.

    Better handling of A1.0 data: (14 Mar 98) Some people reported problems with extracting A1.0 data that crossed multiple CDs. This was probably due to errors in recognizing swapped CD-ROMs, and has now been fixed. Also, when multiple CDs are required, the software will be bright enough to first check to see if one of the needed CDs is already in the drive; if so, it will extract that data first, and then move on to requesting the remaining CD(s), thereby saving you one "swap".

    More logical way to find user-added asteroids: (14 Mar 98) This is perhaps better considered a bug fix. Normally, one can find an asteroid by clicking on the "Go to Asteroid" option and entering its name. But user-added asteroids (added with either the "Add MPC Comets/Asteroids" or "Edit Comet Data" options) caused a problem; you couldn't "find" them in this manner. Instead, they appeared in the "Go to Comet" list!

    With the current version, one can instead find them in the more "logical" manner of using the Go to Asteroid function. (There are still some "logic" problems to be fixed, though. If you add an asteroid already in Guide's internal database, both the precomputed version and your new version are displayed, because Guide isn't bright enough to recognize them as one and the same. This is pretty high on the list of "things to work on".)

    Improved Dutch menus: (12 Mar 98) Guus Gilein has just sent an updated version of the STRINGS.DAB file used by Guide to display menus in Dutch. He has pointed out that this file is still not completely translated; please contact him if you are willing to help complete the translation.

    Ability to import the new MPEC single-line orbital elements: (12 Mar 98) Recently, subscribers to the Minor Planet Center Electronic Circulars have been receiving "daily orbit updates", giving low-precision orbital data for dozens of asteroids each day. These data are given with one line per object, in a new format. The 80-character restriction is the reason for the poor precision; it limits the MPC to rounding angular data to .001 degree (3.6 arcsecond). So positions generated from these elements will not be really wonderful!

    Still, these elements either new objects, or orbits from more recent data not available when Guide was made. In either case, they're improvements, and you may want to import them into Guide. And you can now do so in exactly the same manner you would import other orbital elements from the MPC: you click on "Add MPC comets/asteroids", select the text file containing the new orbital data, and click OK.

    Johnson B-V data for Tycho stars: (12 Mar 98) Stars from the Hipparcos catalog have B-V ("blue minus visual") magnitudes given, often from ground-based observations. Such data isn't given for Tycho stars, but it can be computed fairly well from Tycho B and V ("BT" and "VT") magnitudes, using formulae from the printed guide to the Hipparcos/Tycho catalogs. These have been added to Guide; so now, when you ask for "more info" on a Tycho star, you'll get a computed Johnson B-V magnitude. This was added at the suggestion of Richard Miles, who pointed out that it would be helpful to people doing photometric work.

    Text in Japanese and Dutch: (4 Mar 98) (Windows only) Two Guide users, Masaki Kouda and Guus Gilein, have provided files to allow Guide to display text in Japanese and Dutch. You'll see "Japanese" and "Dutch" options added to the Language menu, inside the Settings menu.

    Click here for more information about the Japanese version .

    Constellations in German, all text in Italian: (25 Feb 98) Philipp Kordowich noticed that, when running Guide in the German-language mode, the names of constellations were not translated. These names are given in CONSTELL.NAM; to repair the situation, he wrote a CONSTELL.NAD (the 'D' indicates a 'Deutsch' version), which has been added to the ZIP file.

    Also, Giuliano Pinto supplied an updated STRINGS.ITA, so that the user interface is once more available in a completely Italian form.

    Better ability to right-click on objects in crowded areas: (21 Feb 98) This change addresses a common frustration encountered when trying to right-click on an object to get information about it. Often, that object is close to (or exactly on top of) another object, and you have to fiddle with the mouse to get the one you want. This usually happens when one object is listed twice (say, as an NGC galaxy and as a GSC "non-star", or as a Tycho/Hipparcos star and as a GCVS variable star).

    To fix this, an extra button has been added to the "short info" box. In addition to "OK" and "More Info", there is a "Next" button; click on this, and Guide finds the second-closest object to the point you selected, and brings up a short-info box for it. And you can then click "Next" again, in the (admittedly unlikely) event that the second-closest object wasn't what you wanted, either... each time you click "Next", Guide tries again with the next nearest object.

    This problem has been annoying people since Guide 1.0 came out, so I'm quite pleased that I can now mark it "done"!

    Ability to set the limiting magnitude for stars directly: (21 Feb 98) It's been pointed out that you can set the limiting magnitude for most objects (planets, asteroids, variable stars, etc.) quite readily in the Data Shown menu, but that no similar control exists for stars. You have to hit '+' to get more stars, and '-' to dim them and drop out fainter ones. Some people have been rather exasperated with this omission.

    The Star Display dialog now has a "Limiting Magnitude" option at the very top of the box.

    Ability to get contact times for eclipses/occultations/transits: (21 Feb 98) When in Eclipse mode, you can now right-click with the mouse on the chart. Guide will show the lat/lon of that point, plus contact times for the event. These follow the usual convention that "first contact" is when object A first reaches object B; "second contact" is when object A totally eclipses (or annularly eclipses) object B; "third contact" is the end of annularity/totality; and "fourth contact" is when the objects no longer overlap at all.

    In the case where one object is a star, it only makes sense to speak of a first and second contact (beginning and end of occultation). Also, it's pretty common for some contacts to be omitted because they occur when the object is below the horizon. (For example, the 11 Aug 1999 total solar eclipse will be visible as a deep partial event from my position in the northeastern US; but first contact will occur before dawn, so Guide would only give me a "second contact" time for that event.)

    Ability to find "locally visible" and/or "total only" eclipses/occultations/transits: (21 Feb 98) When you're in Eclipse mode, you'll notice two new items in the Extras menu: "Local Events only" (defaults to Off) and "Partial events" (defaults to Checked.)

    They work as follows. Suppose you've set up Guide to show solar eclipses, and have a solar eclipse chart on your screen. And suppose you would like to know when the next solar eclipse will be visible from your location (or when the last one came through.) You would zoom in on that location, putting it at the center of the chart. You would then turn the "Local Events only" option to On. Now, when you use the "Next" and "Previous" options, Guide will skip any event that isn't visible from your position.

    Next, try shutting off the "Partial Events". Guide will now disregard any partial eclipses in its search (total and annular events only). When you click on "Next" or "Previous", be prepared for a wait; Guide may have to hunt through two or three centuries worth of events before finding one visible from your location. Even on a Pentium, this can take a respectable number of seconds.

    Buttons to put ecliptic or galactic north at the top of the chart: (21 Feb 98) In the past, one could readily switch between having celestial north at the top of the chart, and having the zenith be at the top of the chart. This was controlled by a check-box in the Inversion dialog. Now, there are instead four radio buttons for this setting, and one can now put ecliptic north or galactic north at the top of the chart.

    These may seem to be somewhat useless items, but there are cases where they can be pretty helpful. For a case in point, try the following. Zoom in on the Moon until it appears a hundred pixels across or so. Set ecliptic north to be at the top of the chart. Right-click on the moon, and click "OK" in the resulting dialog box.

    Now turn on the Animation dialog. Set it for one-day steps and click on the "locked on object" radio button. Now start animating. The interesting thing about this is that you can see three processes taking place at once: the moon's phase changing (rapidly), a slight swelling and shrinking as the moon goes from apogee to perigee, and a slight rocking back and forth due to libration. It's a good way to introduce someone to lunar motions. (The 'ecliptic north' feature helps to keep the moon from appearing to spin bizarrely. Celestial north and lunar north are not at all close to one another!)

    Depending on your machine, you may find you have to zoom out to get any real speed. Also, you'll probably find that turning off asteroids and comets brings the speed up a bit.

    By the way, it's also interesting to try the same process with Mars and Venus (zoomed in much farther, of course). With Mars, I set a step size of 5.13 days; this is quite close to 5 Martian "days", so with this setting, Mars appears to rotate slowly; but you quickly get a feel as to why some oppositions are so much better than others (and why few people bother to observe Mars, except when it's near to opposition.) With Venus, you have a good way to demonstrate the link between the apparent size of the planet and its phases.

    Considerably improved eclipse handling: (22 Jan 98) (Windows only) Previously, the "Show Eclipse" function would not actually search for an eclipse. It will now do so, if one object is the moon or if one object is the Sun and another is Mercury or Venus.

    For example, if you click on the Moon, and then click on the Sun, and then click on "Show Eclipse", Guide will search for the next eclipse. (Previously, if there was no eclipse that month, you got a "No eclipse found!" message.) Similarly, if you click on the Moon and a bright star, or the Moon and a planet, Guide will search for the next occultation of that object.

    Once the event is found and displayed in the "earth map mode", you will see two new top-level menu options: "Next" and "Prev". Clicking on these will cause Guide to search for the next or previous occultation or eclipse. In this manner, you can simply "flip through" events over time.

    Also, the portions of an event occurring in daylight are tinted cyan. If the event occurs in twilight, the track will be only slightly tinted; an event occurring in full darkness is indicated with a gray track. (One odd side effect of all this is that annular events are now shown in green, instead of red.)

    Updated Spanish text: I have just received a revised STRINGS.ESP file from Alberto Romero, bringing the Spanish-language text for almost all Guide's menus and text up to date.

    Missing file for eclipses put into place: (14 Jan 98) (Windows only) When you display eclipses, occultations, and transits in Guide, all menu items that are star-map-specific are supposed to vanish. But instead, people found that almost all menus disappeared in this mode!

    The error happened because a small text file, WIN_MENG.DAT, was missing. The version now on the site fixes this oversight. Unfortunately, there was a delay in posting this; like much of Maine and Quebec, we are having electrical outages, and one hit shortly after the 13 Jan 98 files were uploaded.

    Paths of eclipses, occultations, and transits: (13 Jan 98) (Windows only) You will notice that the Extras menu contains two new items: "Find Conjunction" and "Show Eclipse". You'll also notice that both items are grayed out.

    "Eclipse" is used as a general term for one object blocking out part or all of another object; in reality, this can be used to show eclipses, transits, occultations of stars by the moon, planets, and asteroids, or of planets and asteroids by the moon and each other. For brevity, this long list of possibilities will be lumped together in the word "eclipse".

    To see how this feature works, start up Guide and right-click on the moon. Then click on "OK", and go to the Sun and right-click on it; and again, click "OK". By right-clicking on those two objects, you have told Guide that you are interested in cases where the moon eclipses the sun.

    You'll see that the "Find Conjunction" and "Show Eclipse" options are no longer grayed out. (If you had right-clicked on, for example, two stars, or a star and an overlay object, these options would still be grayed out... neither object moves, so there is no conjunction!)

    When you click on "Find Conjunction", Guide will immediately locate the one that occurs closest to your current time. (Another word for this sort of event, of course, is a "new moon".) If you click on "Find Conjunction" again, Guide will advance by about a month to the next conjunction; in this manner, you can advance from one conjunction to the next. (Right now, this part about advancing to the next conjunction only works when one object is the moon!)

    Eventually, you will reach the new moon on 26 Feb 1998. This time, click on "Show Eclipse" instead. Guide will switch to a chart showing a map of the earth at Level 1, with the path of the eclipse shown. The menus will change to contain only those items that are still valid for maps of the earth (features such as "Go to Constellation" are not very useful with such maps, for example.)

    You can then zoom in on the map and change levels, much as you do with maps of stars in Guide. When you have had enough of this, you can click on the "Show Eclipse" option and revert to the usual display in Guide.

    A few notes about how this feature draws paths: In the case of a solar eclipse, there will be a central path that is red (for an annular eclipse, or any case where one object passes in front of another without covering it... transits of Mercury and Venus, for example) or light gray (for a total eclipse, or any case where the more distant object is completely blocked by the closer object... stars occulted by asteroids, planets, or satellites, for example.) If both objects have visible disks, then there will be areas next to the central path where the eclipse is partial; these will show up in shades of gray.

    Impressive as this feature is, there are a few improvements that will be made to it. Click here for a list of planned improvements to eclipse/occultation/transit drawing.

    Examples of eclipse/occultation/ transit path display: This feature can show the path on the Earth of any event where one body passes in front of another. It has been used to show paths of many solar eclipses, occultations of stars by planets and asteroids, and of stars, planets, and asteroids by the moon. Here are some screen shots, and the events they display:

  • The upcoming 26 Feb 98 total eclipse is shown, with a chart for the entire earth. A closeup view showing the eclipse path over Central America is also available.
  • The path of the recent occultation of SAO 56001 by asteroid 89 Julia, on 6 Jan 1998, is shown here. This event was used because David Dunham of IOTA (International Occultation Timing Association) posted some data about it to the sci.astro.amateur newsgroup. The path ran over the Northeastern part of the US.
  • The path of the 15 Nov 1999 transit of Mercury across the Sun is shown here. This event is unusual in that, in some parts of Australia and most of Antarctica, the event is not total; Mercury just skims the top of the Sun. The event is visible over most of one hemisphere; in the parts filled with red, the event is total, and Mercury will completely enter the solar disk. In the gray-shaded regions, Mercury will touch the solar disk, skim along without ever entirely entering the disk, and exit. Presumably, people located at the border between red and gray will see a greatly extended "black drop" effect, much as people on the edge of a total solar eclipse see shadow bands for a long time.
  • The path of the occultation of Ganymede by Venus on 22 Nov 2065 is shown here. Mutual planetary occultations tend to be extraordinarily rare events; click here for details on some interesting ones. The next such event involves Jupiter and Venus, in 2065. But "in passing", so to speak, Venus will also occult Ganymede. As the chart shows, the occultation will be total in South America and the southern part of Africa. From the east coast of the US and central Africa, the event will be a partial one.
  • Ultima 2000 control: (13 Jan 98) (Windows only) You may have noticed that, for some time, the Scope Control dialog has been expanded to "support" several new systems, such as the Ultima 2000, Dob Driver, CompuStar, and JMI/MicroGuider/Lumicon/Ouranos encoders. In truth, while radio buttons were added for these systems and code written to support some of them, none had been completely tried out and approved by beta testers yet... which is why this page has been silent about this "new feature".

    However, control for the Ultima 2000 has now been completely tested by Thierry Barrault, and it works. You must enter the Scope Control dialog, and select "Ultima 2000" and the correct COM (serial) port. When you click "OK", a new "Scope Pad" menu option will appear. This menu option toggles display of a small keypad, modelled after the LX-200 control. The Ultima 2000 has a rather limited command set, so the only buttons in the Scope Pad that work with the Ultima 2000 are the "Slew Scope" and "Slew Guide" functions. These work in the exact same manner as with the LX-200: "Slew Guide" causes Guide to read the telescope position and draw a chart of that part of the sky, and "Slew Scope" causes Guide to tell the telescope to move to whatever part of the sky you have displayed in Guide.

    By the way, some progress is being made on the other systems. The JMI/MicroGuider/Lumicon/Ouranos control, in particular, is quite advanced; it is hoped that success will be announced on this page soon.

    "Recent Changes" option in Help menu: (22 Dec 97) The Help menu now has a "Recent Changes" option that lists items recently changed in the software... essentially, the text on this page. It's true that one can get all the data on the changes directly from the Web page, but many people simply grab the updates without reading the Web page, and then wonder what has been changed.

    Background menu: (20 Dec 97) If you look in the Display Menu, you'll see that the toggles for Chart Mode and for the "red vs. normal colors" modes are missing. Instead, there is a new menu item, leading to the Backgrounds dialog box. This dialog has five radio buttons and two checkboxes. The radio buttons control how the background is drawn.

    "Normal colors", "chart mode", and "red mode" mean exactly what they always have meant. The "flashlight mode" is an inverted version of red mode, with a red background and black text; it's useful for providing some illumination for dropped eyepieces and such. "Realistic" mode draws a bright blue sky if the sun is above the horizon, and a black background if it is after astronomical twilight (with the sun more than 18 degrees below the horizon). In between, the background slowly changes from sky color to deeper shades of blue.

    The "realistic" mode may appear to be a gimmick, and I originally thought of it as such. But then I realized how much time can be wasted answering the question, "Will I really be able to see this event, or is it happening in the daytime?" Shading the background gives an immediate visual clue. The changing of sky brightness during twilight is not perfect, by the way. I expect to do some pretty careful study of the brightness vs. solar altitude function. But even with this, different monitor brightness levels will make realism hard to achieve.

    Further small point: You will notice that, in Red Mode and Flashlight, the menus, captions, desktop, and so on are changed to red and shades of red.

    The functions of the two checkboxes in the Background dialog are described in the following section.

    Objects on the horizon: (20 Dec 97) The Backgrounds dialog contains two checkboxes for "Show Ground" and "Horizon Objects". The former checkbox causes the entire half of the sky below your feet to have a red background. (Objects below the horizon do still show up through the background, though... an opaque ground would be more trouble than help!)

    The "Horizon Objects" checkbox toggles the display of a set of objects on the horizon. By default, this display includes a wide range of objects, including a boat, a mountain, several types of trees, a streetlight (an object all too many of us have on our horizons), a house, a barn, and a distant city.

    However, the real power of this feature is apparent when examining and modifying the file HORIZON.DAT in a text editor. You can easily move objects around the horizon, add new ones or remove old ones, and change their scale. Without much trouble, one can configure a horizon that matches your actual observing site. For my own copy, I have put a plane over the airport that is ten kilometers south of me, and a boat marking a pond visible from my site.

    Fields of view smaller than one arcsecond: (20 Dec 97) A few people have noticed that it's hard to zoom in far enough to see surface details on Pluto. All level sizes must be multiples of one arcsecond, the smallest possible field of view. Pluto has an apparent diameter of about .1 arcsecond, and some moons of outer planets are smaller still.

    This limitation has been removed, and field sizes now can be as small as .001 arcsecond. To make use of this, though, one generally has to go to level 20, and (through the Settings menu) change the level size from 1 arcsecond to something smaller. This is not really very useful, of course, and the value of the .001 arcsecond field is completely negligible at this point.

    Version number (date) in 'About Guide': (25 Nov 97) If you click on 'About Guide', the date of your current software is listed at the bottom. What with there being a few updates a month, it seemed logical to start keeping track in this manner.

    Hotkey for a 'full sky' view: (25 Nov 97) This was added, in part, for my own use in satellite observing: it is very common in this activity to ask Guide to go to a full-hemisphere view (Level 1) centered on the zenith. This took several keystrokes and mouse-clicks. So a new Alt-N hotkey was added, which instantly takes you to a zenith-centered full-sky view.

    Hour Angle in the Legend: (25 Nov 97) The Legend dialog now contains yet another check-box; this one controls display of the current hour angle for the center of the chart, as seen from your position.

    The main reason for this addition is that there are a lot of Guide users in Germany. The use of setting circles appears to be something of a lost art in much of the world, but a few people in Germany have mentioned that they do indeed use them, often, and would find it easier to do if Guide offered this option.

    New French and German interfaces: (25 Nov 97) Jean-Noël Moreau has sent a new STRINGS.FRA, and Eric-Sven Vesting has sent a new DEUTSCH.DAT, so the user interface in these two languages is now missing the assorted English text they had gained over the past month or two.

    Ephemeris options: (25 Nov 97) If you look in the Animation menu, you'll see a new option labelled "Ephemeris Items". This option brings up a dialog box filled with check-boxes to determine what items are to be listed when you use the "Make an Ephemeris" option. The result is an easy way to include or eliminate items from ephemerides.

    There are a few options in this dialog that could use some explanation. The "elongation" refers to elongation from the Sun, of course. The "phase angle" is often given in MPC ephemerides; it refers to the angle Sun-target-Earth (target at the vertex). When this is near zero, the object is near to opposition; a phase angle of 180 degrees, on the other hand, suggests that the object is transiting the Sun.

    The "In Shadow" field only works for artificial satellites; it gives an "I" if the satellite is Illuminated, or an "S" if it is in Shadow. (At some point, it may give a "P" if the satellite is Partially in shadow.)

    The "Lat/Lon" option also only works for satellites, and gives the point on the earth over which the satellite is currently situated.

    The final three options provide ways to filter out unwanted observations (and exist, for now, only in the Windows software). Click on the "Sunlit (satellites)" option, and data will only be listed for a satellite if it is actually sunlit. Click on the "Above Horizon" option, and data for any object will only be listed if it is above your horizon. Click on the "Sun below altitude" box, and you can ensure that only nighttime data is given; an edit box allows you to tell Guide how far below the horizon the sun must be. The default is six degrees, corresponding to nautical twilight.

    The default is for all three of these options to be OFF, so you see every line in the ephemeris, even if the satellite isn't at all visible. Click on all three, and data for a satellite will only be shown if all three of the key criteria are satisfied: the satellite must be sunlit, it must be above the horizon, and it has to be dark outside.

    Toggle for central cross-hair: (25 Nov 97) (Windows only) The Measurement Markings dialog contains a check-box now to toggle use of the central cross-hair. As before, you can hit 5 on the numeric keypad (in Windows) or Ctrl-numeric 5 (in DOS) to toggle the cross-hair... but a lot of people didn't read about that, and were frustrated by the inability to get rid of the thing.

    Use of RealSky South: (12 Nov 97) Guide can now use image data from the RealSky South CD-ROMs. To use it, you'll have to download the latest version of Guide from the top of this page; you'll also have to download and unZIP this file to get such essentials as header data, plate constants, and a revised GETIMAGE that can figure out which RealSky South CD is needed.

    Once you download and unZIP all this, you'll be able to go to a point below -14 declination (roughly; the limit varies a little with RA), and click on the "RealSky Image" option in the Extras menu. The only difference you'll see will be that, instead of getting the "RealSky data is not available this far south!" message, Guide will ask for a RS South CD-ROM, with a number from 9 to 18.

    By the way, if you have not received your RealSky South set yet, you can probably expect to see it quite soon.

    Generating trails and ephemerides for artificial satellites: (1 Nov 97) With the recent artificial satellite abilities, one can animate satellites in Guide, click on them, find them through the "go to" menu, and adjust their display in "data shown". It is natural to assume that one can generate trails for them and create ephemerides for them, just as you can with any other moving object such as a planet, comet, or asteroid.

    Until now, this was not actually so. But I have finally added these two capabilities. The only real difference (at present) is that, instead of showing the object-observer and object-sun distances in AU, one gets the object-observer and object altitude (height above the ellipsoidal earth) in kilometers.

    Obviously, one might want some data in a satellite ephemeris that does not appear in ephemerides for other objects. This is handled pretty well in the Ephemeris Items dialog box.

    Better prompting for RealSky/A1.0 CDs: (1 Nov 97) When you click on the options to extract RealSky or A1.0 data, Guide will now immediately provide a dialog box asking to insert the necessary CD, giving the CD number. This is slightly superior, in my opinion, to the previous system in which Guide went to a DOS program, which then determined what CD was needed.

    'OK' and 'Cancel' buttons labelled in other languages: (1 Nov 97) With a few exceptions, "OK" and "Cancel" buttons are now labelled correctly in languages other than English, in the Windows software. Previously, they remained labelled as "OK" and "Cancel", resulting in a mixed English/other language appearance that some people found jarring.

    At present, the only practical effect of this is to change "Cancel"; the European languages Guide shows right now use "OK". But Guide will eventually be showing Japanese and/or Chinese text, I hope; if this happens, people will really want a complete translation.

    Importing DSS images from Web sites: (20 Oct 97) Currently, there are at least six Web servers providing DSS (Digital Sky Survey) images. These are scanned versions of the Palomar Sky Survey, compressed to fit onto 100 CDs and covering the entire sky. (The RealSky CDs are a more highly-compressed version of the DSS.)

    You can get DSS images from the following servers.

    Space Telescope Science Institute
    European Southern Observatory
    DSS server (National Astronomical Observatory of Japan)
    Instituto di Radioastronomia, Bologna, Italy
    Leicester Database and Archive Service, University of Leicester, UK
    Canadian Astronomy Data Centre

    If you download or save the images as FITS files, then you can display them in Guide, superimposed on the charts. To do this, click on the "Import DSS Image" option in the Extras menu, and select a file (in DOS, you'll have to enter the file name). Guide will use the FITS header data to compute coordinates of pixels in that image and will display it on the screen.

    You can use the "Images" option in the Extras menu to temporarily shut off the display of all DSS and/or RealSky images.

    "Go to Satellite" option: (20 Oct 97) The Go To menu now has a new option to locate satellites. Click on this option and enter a satellite name, and Guide will search your current .TLE file for that satellite and will center on it. You need not enter the entire name; "mir c" will be enough to find "Mir Complex", for example. ("Mir" alone might find "Mir Debris SA" instead.)

    Easier translations: (14 Oct 97) Over the past few weeks, there have been inquiries about Dutch, Portuguese, Japanese, Chinese, and Arabic versions of Guide. It was clear that these would require some additional support in the Guide software, and Guide has been revised to simplify adding and testing new languages. Click here for details as to how additional languages can be easily added.

    (13 Oct 97) Non-bitmapped planets: One of the major new features of Guide 6 is the ability to show planets with bitmapped markings, so you can see where the Great Red Spot is on Jupiter, or plan observations of features on Mars, or see the shadows cast by Jupiter's moons on each other and on Jupiter, and so on. However, three people so far have come up with situations where they would like to optionally switch back to the "old-style" planets (drawn as outlined disks). This option is much uglier, but also much faster. If, as one person was doing, you are zooming in on the lunar limb to get an exact time for an occultation of Saturn, the extra time consumed with drawing the lunar bitmap is annoying.

    Therefore, there is now a check-box for bitmapped planets in the Data Shown menu.

    Artificial satellite display: (12 Oct 97) Guide 6 can now display artificial Earth satellites; you can animate them and click on them and get "more info". There are some subtleties to keep in mind, though.

    The main control for the display of artificial satellites is in the Data Shown menu. You'll notice that, to the existing 14 types of "data" shown, there is a 15th. Like the other types, you can control the color used in drawing satellites, their limiting magnitude, and you can turn them "on", "off", or "auto".

    You may find that, when you first download this update, that satellites are turned off. If so, turn them "on" or "auto". You may have to look around a little before finding a satellite; it's best to turn them "on", then use Go To... Horizon... Zenith, then go to zoom level 1. This gives you an "all sky" view.

    Once you have satellites on the screen, you can click on them and get "more info". Both provide very little data right now, but it's something that can be built on. You can also go into Animation and watch them move across the sky. (Be careful to start out with small animation steps. Artificial satellites zip along much more rapidly than the "usual" celestial objects in Guide!) You can even click on a satellite, then click on the "Moving" radio button in the Animation dialog (click here for more info on this option) , to keep the satellite centered while stars scroll past.

    There are three serious problems that must be addressed to get accurate satellite positions. First, you need to have your latitude/longitude fairly exact. For a low-earth satellite passing overhead, a 10-km error translates into "shifting" the satellite by over a degree. Second, your PC's clock should be as accurate as possible. Consider how much these satellites move in even, say, ten seconds, and you will see why this is so important.

    Third, you need to have up-to-date orbital elements. These come in fairly well-standardized text files called "Two-Line Elements" or "TLEs". The update files provide a simple set called BRIGHT.TLE to get you started. Depending on the satellite, these elements become outdated after a few days to a few weeks. At that point, you will have to download a new set of TLEs. (You'll also have to do this to get satellites not in BRIGHT.TLE.)

    Many TLE files give no magnitude information. Guide will handle such files, but it has to show all satellites in the file; the "auto" setting for satellites in the Data Shown menu is ignored. Click here for a site containing up-to-date TLE files with magnitude data. The site also contains files for such classes as "low-earth orbiters", "geosynchronous", "Molniyas", and so forth.

    Once you've downloaded these files, click on "Settings". Note the new option labelled "TLE=bright.tle". Click on it, and select your new file.

    When you click on a satellite and ask for "more info", Guide will give its epoch. This gives you some clue as to how recent (and, therefore, how good) the orbital elements are.

    Because of the newness of this option, much work remains to be done on improving it. Click here for a list of upcoming artificial satellite features.

    New animation options: (9 Oct 97) (Windows only) When you turn on the Animation Dialog, you'll see four new radio buttons at the bottom of the box. These provide three new ways to run animations. The top option, "RA/dec", is the "usual" sort of animation, with the center of the chart fixed in RA/dec while the animation runs. The other three are best described with examples. Each is a little tricky to understand, but they are well worth the effort.

    Turn on the Animation Dialog and zoom in on Jupiter at about level 12. Set the animation rate to about 15 minutes. Click on Jupiter, and click "OK" in the resulting dialog box, much as you normally might.

    Now click on the "Moving" (Target) option in the Animation Dialog and start animating. The effect of this option will be immediately obvious: while animating, the moving target you selected (Jupiter) stays at the center of the screen. In the past, watching Jupiter's moons in animation was annoying, because the planet kept wandering off the screen; but this new option forces a "moving target", such as a planet, asteroid, comet, or satellite, to stay at the center of the chart.

    One drawback will be immediately apparent: if Jupiter is to stand still, stars have to move. That takes some CPU power, and the results can be somewhat jerky. (This is also true of the remaining two options.) It is barely acceptable on my 100MHz '486.

    VERY IMPORTANT SAFETY TIP: You will probably want to go into the Display menu and turn "Direct to Screen" Off. Try it with "Direct to Screen" left On, and you'll see why this is urged: the screen flickers on each redraw.

    To see how the next option works, go to a Level 4 (20-degree) field of view. Click on "Go To... Horizon" and select "NE" (move to Northeast horizon). Go to the Inversion Dialog and select Zenith Up.

    You now have the horizon as a dark blue line near the bottom of the chart. Go back to the Animation Dialog, set a 5-minute stepsize, click on the "Horizon" radio button, and start animating.

    As the name suggests, the horizon will now stay fixed while everything else moves (stars rise above the northeast horizon). In general, the idea is that if you go to a particular altitude and azimuth (in this case, about 8 degrees above the horizon and at azimuth=45 degrees), that point stays fixed while stars, planets, and so forth rotate by.

    To demonstrate the final option, click "Go To... Nearby Star", and select Barnard's Star. Zoom down to Level 6 (five-degree field of view). Increase the animation step size to about 8 years/step. Click on the "proper motion" radio button, and start animating.

    In this particular field, Barnard's Star is the only one with really large proper motion. You'll see it slowly drift to the north, at about 10 arcseconds/year.

    Using this option for wider fields usually requires a much larger step size to get much in the way of visible motion. This is just another way of saying that most stars are quite close to being "fixed".

    (5 Oct 97) Until today, the software on the CD was free of known bugs. But one has just been found by Dan Altenloh; he wasn't able to get the RealSky/A1.0 system to work, because Guide insisted that these CDs be fed into drive F:. He doesn't have a drive F:.

    A little work on the software turned up the culprit, and it's fixed now.

    (4 Oct 97) So far, Guide as provided on the CD appears to be bug-free. However, the Windows software uploaded on 30 Sep had two small bugs, both now fixed. Bob Leitner pointed out that resetting colors could crash the program, and Rich Persico pointed out that the LX-200 connection crashed quite consistently.

    Contrast and "more info" for RealSky: When you click on a RealSky image, its current contrast setting is shown. (This is just a lead-in for actual contrast adjustment.) You can also click for "more info" to get the data from the header for FITS and SBIG images.

    Scrolled Help: "More info" and the glossary and hotkey list are no longer broken up into pages. Instead, they are shown as one long document with a scroll bar on the right-hand edge (a much more "Windows-like" behavior). In Windows, the help box is resizable. In DOS, it's not resizable, but it does consume the whole screen, instead of always being limited to the upper left (in high-res modes).

    A small point of interest to the (perhaps a dozen) EGA users: this also means that you can now get "more info" and other Help data on your EGA display. (EGA is indeed mostly obsolete, but some people have put their obsolete computers out in their observatories. It's one main reason that a 16-bit DOS version of Guide still exists.)

    Central cross-hair: Hitting '5' on the numeric keypad in Windows Guide (or Ctrl-numeric 5 in DOS Guide) toggles display of a cross-hair at the center of the screen. It can also be toggled (in Windows Guide) with a check-box in the Measurement Marking dialog, in the Display menu.

    Stars labelled by more catalog numbers and common names: The Star Display dialog already provided controls over the display of Bayer letters and Flamsteed, PPM, SAO, and GSC numbers. It now also provides control over display of common star names ("Sirius", "Hamal") and Hipparcos, HD, and Yale Bright Star (HR) numbers.

    New RA/dec format dialog box: The Settings menu contains a new "RA/Dec Format" setting. This dialog box lets you specify units for RA and dec, and toggle the use of leading zeroes and of "N/S" vs. "+/-". You can also set the epoch here, including with a brand-new option of using the epoch of date. It is a true marvel of user interface programming, in my humble (though biased) opinion.

    Exact distance between two objects: Click on one object and select "OK" (or "more info"), and repeat this for a second object, and hit Insert; and Guide will show the exact angular separation between the two objects. Added at the request of Paul Boltwood, who needed an _exact_ distance (as opposed to the rough one gathered by clicking with the mouse and dragging a line) in order to determine the image scale of his scope/CCD setup.

    (Slight correction to the above... In DOS, the hotkey is Ctrl-Insert. 'Insert' was already taken. And yes, Guide should be cleaned up to minimize the differences in hotkeys between DOS and Windows.)

    Transparent text:(Windows only) When Guide puts down a piece of text, it blacks out the background. Eric-Sven Vesting suggested that this was a really bad idea, and that Guide ought to just draw the text without destroying the background.

    As a partial test of how this would look, you can now hit Alt-J ("select test flag") and enter a 't'. Guide will then toggle to transparent text. (Right now, Bayer superscript numbers and some other odd cases don't get handled correctly; and the legend looks quite odd.)

    The biggest problem with transparent text, though, is that overlapping text looks especially bad. One solution to this (already described on the list of ideas for the future) would be to move text around so as to avoid collisions... once that's been done, transparent text might make a good default choice.

    Better auto spacing for measurement markings: Paul Boltwood suggested that the existing system for setting the spacing on grids, ticks, and so forth was flawed. If you select an "automatic spacing" for these markings, Guide looks for a spacing that puts two or three grids/ticks/whatever on each axis. This is a "one-density-fits-all" approach.

    Paul pointed out that it would be far more reasonable for "automatic" to mean "maintain the sort of spacing I have right now". If you had one side label every 50 pixels, Guide should interpret a click on "auto" to mean "always use the spacing that comes closest on one label every 50 pixels". I liked this idea very much, and implemented it shortly after the CDs went out into the world.