Updated features in Guide 5.0, Part II
Improved GSC star lists
(Added 23 Jan 97) You can generate lists of all GSC stars on the screen by hitting F8. Some people have used this to generate lists for use in their own software (astrometry, charting, etc.) These lists have always been provided with resolution rounded off to about 1/20 arcsecond and to 1/10 magnitude. Since the errors in GSC data are several times these amounts, this has been mostly a matter of academic interest at best.
However, the matter has been raised from time to time, when people notice that positions given with "more info" (which match the original GSC exactly) can vary by as much as 1/20 arcsecond from the corresponding positions given by F8. This difference has been repaired. One side benefit of the repair is that you get a few extra data fields with the F8 list (such as the GSC plate identifier).
Support for RealSky CDs
(Added 23 Jan 97) Some basic support is now in place for display of RealSky data. This works with WGUIDE and with Windows Guide; getting it to work with GUIDE.EXE, the 16-bit DOS software, is unlikely (the memory constraints are too severe).
To display RealSky data, you will need both the Guide upgrade and a separate RealSky software upgrade (about 238 KBytes). UnZIP the RealSky upgrade in your Guide directory.
Start up either Windows Guide or WGUIDE, and find the part of the sky for which you are interested in seeing RealSky data. You can either hit Ctrl-F6, or (in "long menu" mode in Windows) select the "RealSky image" option in the Display menu. In either case, you'll be prompted to enter a size for the RealSky image, in arcminutes.
Start small (say, 15 arcminutes). One slight problem with the RealSky software is that large images often stress the available memory in the system; to cover a large area, one must make several small areas.
Once you've entered the desired field size and hit Enter, Guide will switch to the RealSky image decompression software (GETIMAGE). It will figure out which RealSky CD is needed, and prompt you to insert it. Do so, and hit Enter twice. (It may prompt you for a third Enter; CD-ROM caching can cause this to happen.) GETIMAGE will pause for anywhere from a few seconds (small image, fast machine) to a minute or two (large image, slower machine). It will close down and return to Guide, and the RealSky data will be shown. Take out the RealSky CD, and re-insert the Guide CD.
You can repeat this process to make several images for several parts of the sky. To get rid of all the RealSky images, hit Alt-F11. You'll be prompted to confirm that yes, you do indeed wish to get rid of all the images.
New hotkey to re-center the CCD frame
(Added 23 Jan 97) If you point the cursor at a particular spot in the sky and hit Ctrl-F8, the CCD frame will be recentered on that spot.
New hotkeys for selecting date/time
(Added 23 Jan 97) Some of the more "keyboard-oriented" users of Guide have asked for a way to change Guide's date and time that is not as heavily mouse-dependent as the Time Box. Hit Ctrl-F9, and Guide will prompt you to "Enter day:" Your reply can be in any of the following formats:
(DOS software only) When the Time box is on the screen, you can use 'C' to toggle Julian/Gregorian, 'J' to select Enter Julian day, F1 through F12 to select months January through December, 'Z' to select a new time zone, 'H' to enter a new hour, and 'M' to enter a new minute. These changes will eventually appear in Windows, too... but it appears that most keyboard-oriented people are also DOS users. So I did that system first.
(Added 24 Feb 97) My distributor in Germany pointed out that using slashes to separate day/month/year is very US-centric; much of Europe uses periods (month.day.year) instead. So I made suitable revisions in Guide, so one can enter
and so on.
Saturn's rings properly displayed
(Added 23 Jan 97) If you have bitmapped planets turned ON, Saturn's rings will now also be shown properly bitmapped. The calculations concerning which parts of the rings are in shadow are now exactly correct (some approximations were used before).
New radio, quasar, other datasets
(Added 23 Jan 97) The Guide 5.0 CD contains several datasets previously not used in the program. These include catalogs of quasars, several radio catalogs, BL Lac objects, active galactic nuclei, the Downes and Shaara catalog of cataclysmic variables, the Guide Star Photometric Catalog (GSPC), and the Catalog of Nearby Stars.
While these datasets may be of interest to some, they have been enabled mostly as a "teaser" for a feature to be released in Guide 6.0: namely, the ability to add any astronomical database to Guide (as long as that database is in text format). Specify the format of the data and its epoch, and you'll be able to display it in Guide, click on objects, and get "more info" about them. As a display of this capability, I've set it up to work with all of the above datasets. To see it in action, start up Guide and hit Alt-F9. This will bring up a list of datasets; you can then select them to toggle them on (by default, all of them are off).
Once you're done and hit "OK", Guide will display those datasets; you can click on them and get data about them, much as you would any other dataset in Guide. At present, no controls are provided over colors, magnitude limits, or labelling. These additions, and the ability to add your own datasets, will probably have to wait for Guide 6.
Improved handling of RealSky (rectangular areas, better memory usage)
(Added 4 Feb 97) Several people mentioned that it would be nice to be able to access non-square regions from RealSky. To do this, hit Alt-F6 (as before) and enter the size in the form "width x height". For example, entering 30x20 would result in an area 30 arcminutes wide and 20 arcminutes high.
Also, I found that the GETIMAGE program supplied by the Space Telescope Science Institute (used by Guide to actually decompress and extract the images from the RealSky CD) consumes four bytes for every pixel, instead of the two bytes/pixel actually needed. This had two results. First, GETIMAGE could fail to generate some larger images that, in reality, it should be able to do. Second, it probably results in slower speed in some systems where excessive use of virtual memory takes place.
Also, a less important enhancement: GETIMAGE now tells you how much progress it has been made, using a "percent completed" indicator. To get the memory improvement and the progress indicator, you'll have to download the latest RealSky files (about 238 KBytes).
Ticks, grids, labels in ecliptic, galactic, alt/az coordinate systems
(Added 4 Feb 97) Some controls have been added to the "Spacing" dialog box, used to control the appearance of grids, ticks, side labels, and hatches. In the past, these markings were shown in equatorial coordinates only. The only "adjustment" available was for the epoch.
Now, each marking can be shown in one of four coordinate systems: equatorial, ecliptic, galactic, or alt/az. The choice is made from a set of radio buttons at the bottom of the dialog box.
Hotkey to show line of variation
(Added 15 Feb 97) This is a very specialized capability, but if you are trying to recover or identify a long-lost asteroid (or one whose orbit is simply not well-determined), it can be useful.
Guide (both DOS and Windows) can now show the line of variation for comets and asteroids. Hit Ctrl-F11 (yes, Guide is running low on available hotkeys!) and you'll be prompted to enter the length of the line of variation, in days. (One day is usually a sufficient value for most purposes.) When you do this, all asteroids and comets will be shown with a line segment sticking through them, connecting the point where the object would be if it were a day "ahead" in its orbit with the point where it would be if it were a day "behind" in its orbit.
Entering zero will, logically enough, turn this feature off.
Ability to add new comets and asteroids directly from MPC data
(Added 15 Feb 97) Gareth Williams, at the Minor Planet Center, has very kindly provided orbital elements for comets and asteroids in the native format of Guide (and of some other popular astronomy software). At present, you can get data for currently visible comets, Critical List minor planets, and distant minor planets (for example, Kuiper belt and Chiron-type objects.)
You can download these files from http://cfa-www.harvard.edu/iau/Ephemerides/Soft02.html in either ASCII text or HTML format (Guide will be bright enough to ignore the additional tags that come with HTML).
Once you have downloaded the file(s) you want, run Guide and hit Ctrl-F12. (This will not stay a hotkey for long; I will add something to the "add a comet" utility to handle the task.) You'll be prompted to enter the filename. Do so, and Guide will process that file, updating its comets from the new MPC data, and making sure that duplicate comets are not created.
By the way, the "Critical List minor planets" are numbered objects that are in dire need of having their positions measured in order to improve knowledge of their orbits. Some may have been examined only briefly; others were examined for a long time, but haven't been measured recently. Either condition means that knowledge of their orbits slowly deteriorates. If you have a CCD camera and are looking for new challenges, I strongly encourage you to start imaging these objects, measure their positions using Charon, and report your data to the MPC.
One minor warning: the data for orbits from the above site have had all angles truncated to .001 degree (=3.6 arcsecond) precision. The only people who will notice, I suspect, will be those doing astrometry; you may see slightly increased residuals in Charon.
Use of "standard dialogs" in Windows Guide
(Added 21 Feb 97) In the past, when you created a PostScript file (using the Alt-P option) or updated comet information using the MPC files, you got a simple "Enter filename:" dialog box in both DOS and Windows. Of course, Windows users are more familiar with the standard box with a list of files, another list of available drives, and so forth. I was remiss in not using this style of dialog box earlier, but that oversight is now repaired; hit Alt-P or Ctrl-F12, and (in the Windows software) you'll get a "proper" dialog box requesting the file name.
Age of moon in "quick info"
(Added 24 Feb 97) To the data listed for the moon, both in "quick info" and when you click on the moon itself, I have added its age (days since last new moon).
Digital Sky Survey (DSS) in addition to RealSky
(Added 11 Mar 97) In response to a question from Greg Roberts, I revised GETIMAGE (the program provided to read RealSky data) to also read the Digital Sky Survey, the 100-CD catalog of which RealSky is a compressed version. This involved no changes to Guide itself; all you need do is download the latest RealSky files (about 238 Kbytes), and copy the file LO_COMP.LIS from the DSS CDs.
Definition of the line of variation
Generally speaking, if the orbit of an asteroid or comet is so poorly defined that it might be off its predicted position by (say) a degree, it will still be found very close to the line of variation. This means that the object will stay in roughly the same orbit (same major axis, eccentricity, inclination, ascending node, and argument of perihelion), but it will run "fast" or "slow". This is the reason why, when a periodic comet returns, it often happens that simply correcting the time of perihelion will get you a decent orbit. For example, when P/Swift-Tuttle passed us in 1992, it arrived about a decade later than expected, but otherwise in much the same orbit as in 1862.
The ability to show the line of variation can therefore be helpful to people trying to recover a comet or asteroid, or trying to find a "prediscovery" on an elderly plate. Instead of scanning all areas around a predicted position, one can focus solely on points on the line of variation.
Animation dialog box
(Added 25 Mar 97) The animation menu previously in Guide had some serious drawbacks. Most have now been remedied. In the Windows software, there is now one dialog box to handle starting, stopping, and changing the direction and speed of animation. It is accessed through the animation menu, and remains visible until closed (something that was a problem before). It has switched to a more intuitive "tape recorder" interface, with buttons to animate forward and backward, and to take single steps forward and backward.
In the DOS software, the "tape recorder" has become part of the menu itself. Apart from this, the changes are the same.
Satellites of Uranus and Mars
(Added 25 Mar 97) The five largest moons of Uranus, and the two moons of Mars, have been added. You can display them, click on them, and get "more info". At present, they don't show up in the "Go To Planet" and "Set Home Planet" boxes; this is mostly because I am rethinking the wisdom behind those boxes, and may replace them soon with something better.
Middle button to zoom out one level
(Added 25 Mar 97) Click on the chart with the "middle button" of a three-button mouse, and Guide will recenter the chart there and zoom out one level.
Three-button mice are scarcely universal and appear to be primarily a US fad. I'll have to come up with a way to make this feature readily available on two-button mice.
Ability to use GETIMAGE as a standalone program
(Added 25 Mar 97) I expected that most use of the GETIMAGE utility would be through Guide, for extracting and displaying RealSky images. This has indeed been mostly true, but there have been requests for a way to shut off the "Re-insert the Guide CD-ROM" message, from people who would just like to process a few dozen (or a few hundred) images.
To do this, download the latest RealSky/DSS software (about 130 KBytes) and edit ENVIRON.DAT with a text editor. Remove the last line (which begins with "GUIDE=").
(Added 21 May 97) Soon, Guide will support color printing. Figuring out what such printouts will look like becomes much easier if one hits the Ctrl-F3 hotkey. Guide then swaps from a black background to a white background. When the ability to print in color is completed, this will be the mode you'll use to plan the charts. (In Windows, this option is also available in long menus, under "Extras".)
"Direct to screen" mode
(Added 21 May 97) (Windows only) By default, Guide draws a chart by erasing the old one on the screen and then drawing lines, stars, and so forth onto the screen. Hit Alt-F12, and Guide will toggle from this behavior and will instead draw the chart in memory, and copy it onto the screen. There are two advantages to doing this. First, on some computers, it may be a lot faster; the "usual" way of drawing involves a lot of work for the video card, and with this new method, a lot of that work is avoided.
Second, it paves the way (in Guide 6) for much better animation. Currently, all animation fixes stars to the center of the screen; you can't, for example, keep Jupiter fixed to the center of the screen and watch the satellites orbit, or keep the horizon fixed and watch stars rise and set, or watch stars drift over millennia from the effects of proper motion. Guide 6 will let you do all this, and the ability to copy a chart "direct to screen" is important in making that possible. (This option is also available in long menus, under "Extras".)
Making a graphics file
(Added 21 May 97) (Windows only) A long-standing wish of Guide users has been the desire to create .PCX, .TIF, or Windows .BMP files from Guide. I hadn't found any way whatsoever to do this, until now; the ability to make .BMP images has been added to Guide.
Hit Alt-F10, and Guide will provide a dialog box offering a selection of three color levels: two-color (black and white), 16-color, and 256-color. Also, you can set the size of the image; by default, this is 800x600. Once you click "OK" here, Guide will prompt you for the name of the file to be created, and will then proceed to create that image file. (This option is also available in long menus, under "Extras".)
A word of warning: some fonts don't work properly with monochrome .BMP creation. This appears to be a driver problem. If the text on a .BMP is garbage, select a new font.
USNO A1.0 display
(Added 28 May 97) The USNO A1.0 catalog is the current recordholder for the World's Largest Star Catalog, with nearly 500 million stars. It covers the entire sky, and was created by scanning in Palomar and UK-SERC plates. Both red and blue plates were scanned, and objects appearing on only one plate were thrown out. This helps to evade the GSC problem of spurious objects, and also means that color data is available through comparing the red and blue magnitudes.
Also, the precision of the positions is already better than that in the GSC. The authors would like to recalibrate USNO using the Hipparcos data, resulting in still better precision. The catalog is distributed on a set of ten CD-ROMs, but is available only to researchers with a demonstrated need for the data. Unlike the GSC, it cannot be reproduced for profit; it's highly doubtful that this catalog will see use in commercial software.
Given that the USNO A1.0 CDs are not widely available, you can instead download small portions from Lowell Observatory, which has set up a means to request data for a given region in RA/dec. Save it in "binary" form as the file A10.DAT, in the Guide directory of your hard drive, and Guide will display it when you zoom in on that area. (You don't need to change any settings in Guide to do this.)
However, at least two Guide users are researchers using A1.0, and I have updated Guide to allow access to the CDs. If you wish to use A1.0 data in Guide, you need the A10.ZIP file (removed from this site to free up space, as Guide 5 drifted into obscurity; e-mail me if you need a copy.)
Once you have the needed files, the interface is similar to that for RealSky; you hit Shift-F11, and are prompted to enter a field size in arcminutes. You're then prompted to enter one or more A1.0 CD-ROMs for that area. Guide then uses that data for charts. You can repeatedly hit Shift-F11 and add coverage for new areas. (In Windows, there is a menu option for this in the "long menu" mode.)
"Normally", you will simply notice that the limiting magnitude in the covered area has gone from the mag 14 limit of the GSC to the (approximately) mag 20 limit of the A1.0. You can click on A1.0 stars to get their red and blue magnitudes. Click for "more info", and Guide will tell you the dates and times when the red and blue plates were taken for that object.
You can also turn "colored stars on" using the same switch normally used to render PPM stars in color. Guide will then use the color data in the A1.0. The result is not always helpful; right now, there are cases where the data indicates stars that are "redder than red" (the red magnitude is 8 brighter than the blue) and "bluer than blue" (opposite problem). There are entire areas where every star is deep red, or where they are all deep blue. Generally, the colors do provide a decent indicator. I base this statement on having checked a few Miras and other low-temperature variables, which were uniformly much redder than surrounding stars. The USNO folks hope to eventually improve the photometry, given the always-uncertain existence of adequate funding.
You can clear off the A1.0 data by entering a field size of zero.
Finally, you can generate lists of A1.0 stars in a given area, just as with GSC stars. Soon, I expect to have such lists used in the Charon astrometry software... which is one of the main reasons for my interest in USNO A1.0.
(Added 28 May 97) In the Windows software, the "long menu" mode offers a new "Tables" menu at the top level. This menu provides options to make tables of lunar data (rise/set and libration for each day), lunar phases, apogees/perigees, lunar eclipses, Jupiter's satellite events, and transits of Jupiter's Great Red Spot (GRS). The tables are shown on the screen, and can be saved to files or printed.
In the DOS software, this menu can be reached only through the Shift-F8 hotkey.
People interested in GRS transit times should read the next section.
Great Red Spot setting and display
(Added 28 May 97) (Windows only) By default, the Great Red Spot (GRS) is shown at System II longitude of 51 degrees. (System II is the longitude system used for objects in the "middle latitude" zones on Jupiter.) This longitude was derived from observations made just before Jupiter reached conjunction with the Sun. Like most terrestrial clouds, the GRS tends to move over time; by now, it has moved several degrees from that longitude. Therefore, I've added a menu option to long menus, underneath "Settings"; click on it, and you're prompted to enter a new System II longitude for the GRS. These values are often published in _Sky & Telescope_.
Getting up-to-date GRS longitudes has been a problem, but John D. Sabia has recently started listing this data on his Web site. Click here for current GRS longitude data.
On 28 Jun 97, this Web site gave a value of 62 degrees, 11 degrees from the default value in Guide.
The value you provide will be used in "quick info" to predict the next GRS transit; in the "tables" when you generate a table of GRS transits; and in displaying the bitmapped image of Jupiter when you zoom in on it.
By the way, the GRS previously "floated" because the image is of the clouds of Jupiter, and therefore never apt to be accurate. But it occurred to me that there was no good reason not to at least make the GRS accurate, even if no other feature would be.
Font size, style controls
(Windows only) (Added 11 Jun 97) In "long menu" mode, the Extras menu contains new options to reset the font used on screen charts and on printouts. The selected fonts will be used for everything (labelling objects, legend, RA/dec labels) on the chart.
A word of warning: some fonts don't work properly with monochrome .BMP creation. This appears to be a driver problem.
(Windows only) (Added 11 Jun 97) If you set alternate colors, and set up a color printer, then Guide will print in color.
Data Shown shortcut
(Added 11 Jun 97) Clicking on the data types shown in the legend will now bring up the Data Shown dialog.
Projections: stereographic, orthographic, gnomonic
(Added 11 Jun 97) The "Settings" menu now also provides a way to set the chart projection. The default is the stereographic projection; this preserves the shapes of objects, and is about the closest thing to an "ideal" chart projection.
On charts drawn with the gnomonic projection, great-circle lines appear as straight lines. The price for this convenience is bad distortion at larger fields of view. This capability was requested by meteor observers; on charts made with this projection, the meteor trails are straight lines emitting from the radiant.
The orthographic projection is really intended to show "earth-from-space" views. At present, it is not very useful. But if I add the ability to show maps of the earth with eclipse/occultation/transit/lunar graze trails, it will become interesting.
Clusters of galaxies shown as pentagons
(Added 11 Jun 97) The ads for the Millennium Sky Atlas, being produced by Sky & Telescope using Hipparcos data, show clusters of galaxies as pentagons, instead of as the "double circle" used in Guide. I liked this idea, and have appropriated it for use in Guide.
Updated German-language menus
(Added 11 Jun 97) My distributor in Germany has sent a new file for the German-language menus, dialogs, etc. This translates all of the more recent text added to Guide.
Improved bitmap planets
(Added 11 Jun 97) Previously, zooming in on bitmapped planets resulted in seeing "blocky" areas on the planets. This has been fixed by interpolating points in the image, making for a somewhat better appearance.
Europa, Io, and Pluto with bitmaps
(Added 20 Jun 97) I have found a very nice bitmap showing Io in color, and reasonable bitmaps for Europa and Pluto. Zoom in on these planets, and their features will be accurately displayed. Particularly interesting is to zoom in on Io when it is on the west side of Jupiter, and its trailing edge is facing us. The volcano Pele, originally found by the Voyager probes, is very obvious as a large red ring.
I am quite confident that the maps of these new objects are drawn correctly, except in the case of Europa. That map was unlabelled, and it is possible that the hemispheres are reversed.
The Io and Europa maps are from Galileo data, and the Pluto map is from Hubble observations. I have hopes that further Galileo observations will yield new maps for Ganymede and Callisto, and perhaps a better one for Europa.
Central meridians for all planets
(Added 20 Jun 97) I added central meridians for several objects several months ago. Thanks to data downloaded from the Bureau des Longitudes, this capability has been extended to all planets, and Jupiter's System III longitude, used by radio astronomers and probably reflecting Jupiter's actual rotation, has been added. The result is that you can now get physical ephemeris data for all planets, and you can see a bitmapped image on Pluto.
A minor addition for solar observers: the current Carrington solar rotation number is shown, as is the time on which it started.
Planets as names or symbols; switch for full planetary precision
(Added 20 Jun 97) The Data Shown dialog in Windows contains two new check boxes. One causes planets to be labelled by name instead of symbol. The other toggles between "low precision" planetary positions (accuracy about 1 arcsecond) and "full precision" (about .01 arcsecond). This second checkbox replaces the earlier toggle in the Test Menu. It performs the same action, but is more logically placed.
In the DOS software, the same options are provided inside the submenu for planets in the Data Shown menu.
Movable legend with more styles
(Added 20 Jun 97) The Legend menu now has options to put the legend at the top or bottom of the screen, either at left, center, or right, and in either a "vertical" or "horizontal" style.
SA 1.0 display
(Added 20 Jun 97) Guide can now display SA 1.0 data from the SA 1.0 CD-ROM, using almost exactly the same method used to display A1.0 data. The only difference is that, when prompted to enter a particular A1.0 CD-ROM for an area, you must insert the SA1.0 CD-ROM. Guide will automatically detect the difference, and grab the data.
As with A1.0 itself, to display such data in Guide, you must first download this file (about 140 KBytes) and unZIP it in your Guide directory.
SA1.0 is an excellent catalog for astrometry; in fact, that is really the sole purpose of the catalog. I intend to revise the Charon astrometry package to make use of it. It is not really intended for display purposes; many bright stars are omitted from it. Unlike A1.0, it is freely available.
The only problem Charon will have with SA1.0 is the absence of bright stars. Charon relies on the ability to match star patterns; eliminate most of the bright stars, and it has a very hard time properly matching stars from your CCD image to stars from the catalog. So this improvement may not happen right away.
Spanish-language user interface
A Guide user in Spain, Alberto Romero, has translated the files required for Guide to display menus and most text in Spanish. As a result, an "English/Spanish" option has been added to the "long menus" in the Windows software. In both DOS and Windows software, hitting the single quote (') key toggles between English and Spanish.
(Added 15 Jul 97) Due to a blunder on my part, the last update contained the correct software to read the Spanish-language menus and other text, but the .ZIP files didn't actually contain those menus and text! That error is now fixed. If you've already downloaded the update with the missing Spanish-language files, then just download this small file (11 KBytes) and unZIP it in your Guide directory.
Italian-language user interface
(Added 27 Aug 97) Giuliano Pinto, a Guide user in Italy, has just translated all files needed for Guide 5.0 (and, soon, 6.0) to display menus and text in Italian. You don't actually need to download the entire update to make use of this option; all you need do is to download this file (82 KBytes) and unZIP it in your Guide directory. The "long menus" in Windows Guide will then display an "English/Italian" option.
In both DOS and Windows, you can also use the double-quote key (") to toggle between English and Italian.