Ganymede Ganymede is the largest of the four large satellites of Jupiter found by Galileo. It has an extremely rugged surface, crossed by folded rills of uncertain origin. General Catalog of Variable Stars GCVS Most of the data on variable stars in Guide comes from the General Catalog of Variable Stars, or GCVS, a list of data for over 28,000 variables. Over 2,200 additional variables (those found after the GCVS's creation in 1982) were provided from an AAVSO list. geocentric Geocentric means "using the Earth as the center". Its most common use was in the theory that the Earth is the center of the universe, with the Sun and other objects revolving around it. In this program, the term has a more specific use. A particular datum is "geocentric" if it is measured from the center of the Earth. A topocentric datum is measured from the surface of the Earth, and a heliocentric one is measured from the center of the Sun. Get Ax.0 data Shift-F11 If you have the ten-CD set of USNO A1.0 disks, or the eleven-CD set of A2.0 disks, or the single-CD SA1.0 or SA2.0 disk, you can extract data from them and display it in Guide. The process is quite similar to the one used for RealSky images. To extract Ax.0 or SAx.0 data, center the chart on the object of interest, and click on the Get Ax.0 data in the Extras menu. Guide will ask for the size of the area to extract, in arcminutes; and will provide check-boxes to distinguish between A1.0/SA1.0 and A2.0/SA2.0. You'll also get a list of which CDs are needed. (Usually, only one will be needed. But the area you want may be on the border between two disks.) Swap in the disk Guide asked for (or the SAx.0 disk), and Guide will extract the data from it. In DOS, you can also access this option with the Shift-F11 hotkey. Getting a list of hotkeys You can get a list of all the hotkeys that Guide understands at any point in the program by hitting the '?' key. globular cluster Scattered around the rim of our own galaxy and around most others are globular clusters: round balls of thousands to millions of densely packed stars. A good example is M-13 (Messier 13) in the constellation Hercules; you can recenter on it using the Go to Messier option under the Go To menu. You'll have to zoom in pretty far before you see the individual stars in the cluster. To the unaided eye, M-13 is a faint, fuzzy patch, but it contains many thousands of stars. Most globulars have either a Messier or NGC number. You can find others, such as Omega Centauri, 47 Tucanae, and the Palomar and Terzan objects, in the Globular Cluster dialog under the Go To menu. Globular clusters are shown as a circle with a cross inside followed by a Messier, NGC or IC number. Globular clusters are very different from open clusters. They contain many more stars, are farther away (usually thousands of light-years away), and have some of the oldest stars in the galaxy in them. Glossary page 1 3K background a sin i A1.0 A2.0 AAVSO Abell aberration absolute magnitude accretion disk ACT catalog Add a Trail Add DSS image Add to Print Queue ADS AGK Albedo Algol-type Alpha CVn Alpha Cyg altitude AM Her Amor angstrom angular diameter Animation aperture circle aphelion apogee Apollo apparent magnitude AR Lac arcminute arcsecond argument of perihelion artifact Asteroid diameter asteroid astrometric binary astrometry Astronomical twilight astronomical unit Aten AU autumnal equinox azimuth B magnitude B-V B1950 Background Dialog Balmer Barnard Bayer BD Be star Besselian epoch Beta Cep Beta Lyrae binary BL Her BL Lac black hole blended object Bright Star Bright Star BT magnitude BY Draconis Callisto Caption on/off carbon star cataclysmic variable CCD frame CD celestial equator Centaur central meridian Cepheid variable CGCG chart area Chart mode Chinese calendar circumpolar Civil twilight cluster of galaxies cluster colongitude Colors Menu comet common proper motion constellation borders constellation labels constellation lines constellation contact binary COPERNICUS corrector CP CPD CPM dark nebula Data Shown declination degree Delete a Mark Delta Cep Delta Sct Delta-T diffuse nebula display menu DM Doppler effect double star DSS Durchmusterung Dynamic Parallax Dynamical Time Eccentricity eclipsing binary Ecliptic coordinates Ecliptic elliptical variable elongation emission line emission nebula emulsion Ephemeris Items Ephemeris Time ephemeris epoch of elements epoch Equation of time equatorial radius equidistant Escape velocity ESO/Uppsala ESO ET Europa Exposure start Extras menu "Fast" nova Field rotation rate File Menu Filter Find Conjunction First quarter FK Com FK5 Flamsteed flare Flattening Fluctuating X-ray Flush Print Queue FOKAT-S FU Orionis Full moon full screen Fundamental Katalog 5 galactic coordinate galactic standard of rest galaxy Gamma Cas gamma ray Ganymede GCVS General Catalog of Variable Stars geocentric globular cluster gnomonic Go to City Go to Country Go to Mark Go To menu Go to planet feature Great Red Spot Greek letter Greenwich Sidereal Time Gregorian grids Group Membership GRS GSC identifier GSC GSR GST Guide Star Catalog GUIDE H alpha H beta hatches HD Hebrew calendar heliocentric Henry Draper Hickson High-Precision Subset Hilda HIP Hipparcos home planet dialog HPS HR HR Hubble class IC inclination of orbit Index Catalog index marks infrared intercalary month interferometry Inversion dialog Io IRAS irregular variable Islamic calendar isophotes IUE J2000 Jalali (Persian) calendar jansky JD Jet Johnson Julian calendar Julian Day Julian epoch Jupiter Keyzer kilometer kiloparsec km Kuiper belt La Caille Language menu Last quarter latitude LBN LDN LEDA legend dialog Level Size Libration light curve light-year limb angle Line of variation Local Events only Local Group Local Sidereal Time Location dialog Long period variable long. ascending node longitude LPV LST luminosity class luminosity Luna lunisolar LX-200 Lyman Lynd's Bright Lynd's Dark m sin3i Magellanic Cloud magnetic variation magnitude Main Menu main sequence Make .BMP File Make Ephemeris Margins menu Markarian Mars MCG mean anomaly mean solar day measurements dialog Mercury Merged Catalog of Galaxies meridian Messier meteor shower meteor meter MHD microwave Minor Planet Center Minor Planet Circular Mira type MK Morphological Catalog of Galaxies MPC Mu Cep nadir nanometer Nautical twilight Nearby star Nebula Databank nebula Neptune neutral hydrogen neutron star New Catalog of Suspected Variables New moon NGC2000 NGC non-star nova NSV nutation Object Pick dialog obliquity to orbit occultation double open cluster opposition point orbital elements Orion type orthographic Overlay menu Overlay Pick dialog Palomar Observatory Sky Survey parallax parity parsec Partial Events penumbra Perek-Kohoutek periastron perigee perihelion PGC photographic magnitude PK planet planetary nebula plate Pluto polar radius Polarization Position angle POSS PPM precession Preliminary designation Principal Galaxy Catalog Printer setup prograde Project Pluto Projection menu prominence proper motion pulsar PV Tel Quasar Quick Info R CrB RA/dec format radial velocity radiant Rapid irregular RASNZ RC3 "Real slow" nova RealSky image redshift Reflecting binary reflection nebula refraction repeating nova Republican calendar retrograde right ascension rise/set times rotation period rotational velocity RR CrB RR Lyrae RS CVn RV Tauri S Dor SA1.0 SAC SAO Saturn Save a Mark Schmidt Scope Pad SD Select Printer selenographic Semimajor axis Semiregular long-period separation Set Location Settings menu Sharpless Show Eclipse side labels Sidereal Time sidereal Sky Commander slope parameter Slow irregular "Slow" nova solar constant Solar rotation number solstice speckle interferometry spectral type Spectroscopic Binaries spectrum SS Cyg stereographic SU UMa summer solstice Sun supernova supplemental plate SX Arietis SX Her SX Phe Synchronous rotation T Tauri Tables menu TD Telrad terminator Third Reference Catalog ticks tides time zone dialog Titan TLE Toolbar Dialog topocentric totality transit time transition variable trigonometric parallax Trojan Twilight Tycho Input Catalog Tycho Type I supernova Type II supernova U Gem UGC Ultraviolet FeII ultraviolet umbra Universal Time Uppsala General Catalog Uranus user added dataset user object dialog USNO UT UV Ceti UV v sin i V-I van den Bergh variable Venus vernal equinox Virgo infall visible light Visual magnitude limit visual magnitude VT magnitude W Vir Washington Double Star wavelength WDS white dwarf winter solstice Wolf-Rayet X-ray burster X-ray irregular X-ray jet variable X-ray novalike X-ray reflector X-ray variable X-ray Yale YY Ori Z Andromedae Z Aqr Z Cam zenith zodiac zoom level Zwicky ZZ Ceti GN Atlas of Galactic Nebulae The "Atlas of Galactic Nebulae" includes 1547 nebulae that appear on the POSS or the ESO/SRC Atlas. The "Atlas of Galactic Nebulae" shows positions, sizes, and images of all included nebulae. It was one of the most important sources for the Nebula Databank. Reference: Neckel, Th., Vehrenberg, H. 1985: Atlas Galaktischer Nebel Teil I to III. Go to .TDF object The Go to .TDF object option, inside the Go To menu, is used if you want to find an object in one of the user added datasets. When you click on this option, Guide will show all of the currently available user added datasets (as well as a few that are supplied with the program). Click on one, and enter an object identifier from that catalog, and Guide will recenter on that object. Go to Abell cluster This option is used when you want to recenter on a cluster of galaxies by typing in its Abell catalog number. When you select this option, you are asked for an Abell catalog number. If you enter one, you will recenter on that object. You can also hit escape at that point to cancel. Go to Abell planetary This option is used when you want to recenter on a planetary nebula by typing in its Abell catalog number. Abell planetaries are mostly dim, "challenge" objects. When you select this option, you are asked for an Abell catalog number (from 1 to 86). If you enter one, you will recenter on that object. You can also hit escape to cancel. This catalog shouldn't be confused with the Abell catalog of clusters of galaxies. Go to Arp This option is used when you want to recenter on a galaxy by typing in its Arp catalog number. When you select this option, you are asked for an Arp number. If you enter one, you will recenter on that object. You can also hit escape at that point to cancel. Go to Asteroid ; This option lets you type in the name or number of an asteroid that you wish to recenter on. You can enter the asteroid's number (for example, "1" for the asteroid Ceres), its name (such as Vesta, Juno, or Mr. Spock), or its preliminary designation (usually a year followed by one or two letters, given an asteroid until its orbit has been well-determined.) You can reach this option at any point in Guide by hitting the semicolon (;) hotkey. Go to Barnard This option is used when you want to recenter on a dark nebula by typing in its Barnard catalog number. When you select this option, you are asked for a Barnard catalog number. If you enter one, you will recenter on that object. You can also hit escape at that point to cancel. Go to Bayer/Flamsteed This option is used to find a star by its Bayer or Flamsteed designation, and recenter on it. When you select this option, you will first be shown a menu of the 88 constellation abbreviations. You pick a constellation, at which point you will be shown a list of all the Bayer and Flamsteed stars for that constellation. If you pick one of these, you will recenter on that object. You can hit escape at any point to cancel. You can also find a Bayer or Flamsteed star using the Ctrl-B option. This method does not rely on menus, and can be helpful to those who prefer not to use a mouse. Go to CGCG This option is used when you want to recenter on a galaxy by typing in its CGCG (Catalog of Galaxies and Clusters of Galaxies) number. When you select this option, you are asked for a CGCG catalog number. If you enter one, you will recenter on that object. You can also hit escape at that point to cancel. A CGCG designation consists of two numbers, separated by either a space or a minus (-) sign. Sometimes a letter is added. Go to Common Star Name When you select this option, you will see a list of about 200 common names for bright stars, such as Rigel, Deneb, and Betelgeuse. If you pick one of these names, you will recenter on that star. Go to Constellation > This option shows a menu of the 88 officially recognized constellations. Click on one, and you will be recentered on that constellation. You can also reach this menu with the > hotkey, or by clicking on the constellation shown in the menu. Go to coordinate coordinates menu Alt-[ The Go to coordinate submenu, inside the Go To menu, provides four different ways to find a point in the sky by entering coordinates: Enter RA/Dec Enter ecliptic coordinates Enter galactic coordinates Enter altitude/azimuth Find opposition point In DOS, you can reach this menu with the Alt-[ hotkey. Go to Country Go to City If you have used the show eclipse option to display an eclipse, transit, or occultation chart in Guide, the Go To menu will list the options Go to Country and Go to City. "Go to Country" will bring up a list of 173 nations. Click on one, and Guide will recenter the chart on that nation. A similar list of all cities would be huge, so Guide only will list those cities in the current chart area. If you wanted to find Sydney, for example, you would have to first zoom in on Australia, and only then use the "Go to City" option. Click on "Sydney", and Guide would recenter on that point. The world-wide chart shown by Guide is always centered on latitude 0, longitude 0, and these "Go To" options are grayed out when that chart is being displayed. Go to Double Star This option is used when you want to recenter on a star by typing in its double star designation. When you select this option, a menu appears of over 130 double star catalogs, such as the ADS (Aitken Double Star) and both Struve catalogs. Click on the desired catalog, and you will be asked to type in the number of the star you want. Guide will then recenter on that star. Go to Durchmusterung This option lets you find stars in the DM (Durchmusterung) catalog. You do have to specify which of the four sections of the DM you wish to use: the BD (Bonner Durchmusterung; covers stars from about -1 declination to +89); the SD (Sudentliche Durchmusterung; from -1 to -23); the CD (Cordoba Durchmusterung; from -22 to -89); or the CPD (Cape Photographic Durchmusterung; from -18 to -89).