Updated software for Guide 7.0

This page will only help if you have a Guide 7.0 CD; click here for updates to Guide 6 or here for updates to Guide 5, or here for information about ordering Guide 7.

Italian users can get information about the 23 June 1999 changes here.

Japanese version here

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.

How to use the update files: To get the update and the features listed below, download one of the following three files and unZIP it in your Guide directory. Important: if you run Guide in a language other than English, you'll also need to download and unZIP one or more of the "language" files offered below. Also, it's a good idea to read through the list of new features (following the download section) to see what you're getting.

Improvements so far, in reverse chronological order:

(14 Nov 2001) Download and display of USNO A2.0 data: This is very similar to the function to download and display GSC-2.2 data. As with that function, there is now a toolbar button which, when clicked, goes out to a Web server (supplied by the European Southern Observatory, or ESO), and downloads A2.0 data for that chunk of the sky. When this is accomplished, the screen is refreshed and A2.0 data will appear on-screen.

Display of this data (limiting magnitude, fields of view shown at, etc.) can be controlled by going into "Extras... User-Added Datasets", and looking for "USNO A2.0 data (downloaded from ESO)".

Also as with GSC-2.2, some people may find that the toolbar button isn't appearing. If that happens to you, click here.

(4 Nov 2001) Single-click downloading of DSS images: For some time, it's been possible to download DSS images through Guide, to be shown in chart backgrounds. However, I developed a truly klutzy way of doing it (asking for a RealSky, not DSS, image, then setting the drive letter to 1:... not something that occurs to most users intuitively.)

You can now go into "Extras... DSS/RealSky images", and click on "DSS from Internet". Guide will then grab an image from the STScI server, covering the area currently shown on the screen. (This is done in the background, so you can do other things while waiting for the image to be downloaded.) It's essentially analogous to the function described below.

The images can be cleared by clicking on "Extras... DSS/RealSky images", then on "Clear RealSky images". This dialog also contains the controls to determine at what fields of view the images are shown, and to switch from positive (white stars on black background) to negative (black stars on white background).

By default, the image can be no larger than 15 arcminutes in a given dimension. If your field of view is greater than this, Guide clips the image down to that size. An image of that size can be downloaded in a minute or two over a 56K modem. If you wanted to change that size to, say, 7 arcminutes, you would edit the file GUIDE.DAT and add the following line:

MAX_DSS_DOWNLOAD=10

Also, there's a toolbar button for this function. If you find that Guide doesn't list the function under "Settings... Toolbar", click here.

(4 Nov 2001) Download and display of GSC 2.2 data: I actually added this feature a while back. I discussed it quite a bit on the Guide user mailing list, but just now realized that it never got mentioned on this page.

GSC-2.2 is essentially the successor to GSC-1.0, GSC-1.1 (the version most widely used, including in Guides 1.0 to 7.0), GSC-1.2 (a version created at STScI, but never distributed on CD-ROM and hence not in very widespread use), and GSC-ACT (a recalibration of GSC-1.1, to be used in Guide 8.0.) GSC-2.2 is based on more modern plates, provides additional photometry and a much deeper limiting magnitude, and should soon be revised to include proper motions. The Space Telescope Science Institute (STScI), the organization behind all versions of GSC, has set up a way to query GSC-2.2 via Internet; Guide now has a function that will download GSC-2.2 data to cover the current field of view, and to show it in two different ways. Click here for details on GSC-2.2 and how to use it in Guide.

(4 Nov 2001) Way to change DSO symbols: Previously, Guide's symbols for DSOs have been hardwired. There have been occasional inquiries as to how to change them to something different. Oddly enough, it's been possible to do this for "user-added datasets", but not for the built-in ones.

This has now been changed. Guide still defaults to showing the symbols as it always did; but you can add lines such as the following to GUIDE.DAT.

OPEN_CLUS_SYM=s2;e0,0,32;
PLANET_NEB_SYM=e0,0,32;m32,0;l48,0;m0,32;l0,48;m0,-32;l0,-48;m-32,0;l-48,0;
GLOB_CLUS_SYM=e0,0,32;m32,0;l-32,0;m0,32;l0,-32;
GALAXY_CLUS_SYM=m0,-32;l30,-10;l19,26;l-19,26;l-30,-10;l0,-32;
DARK_NEB_SYM=s2;b32;
DIFF_NEB_SYM=b32;
GALAXY_SYM=e0,0,10;m-32,0;l-20,-12;l20,12;l32,0;
ASTEROID_SYM=m-32,-32;l32,32;m-32,32;l32,-32;
PLANET_SYM=m-16,0;l16,0;m0,-16;l0,16;

These actually happen to match the existing symbols (except for the 'galaxy' symbol... this is normally shown as an ellipse with the right size/orientation for that galaxy.) They are defined using the system used for defining "custom" symbols for user-added datasets, except that no color should be provided; that's supplied elsewhere.

Certain other symbols used in Guide are also resettable:

CITY_SYM=c5;E0,0,10;
CAPITAL_SYM=c5;f5;0,-30;-12,20;22,-8;-22,-8;12,20;e0,0,20;
PICK_SYMBOL=e0,0,20;
XHAIR_SYMBOL=m-60,0;l60,0;m0,-60;l0,60;m-40,-10;l-40,10;m40,10;l40,-10;m10,40;l-10,40;m10,-40;l-10,-40;
SATELLITE_SYM=m-45,-15;l-15,-45;l15,45;l45,15;l-45,-15;e0,0,20;

The first two lines indicate that, in 'geo' mode (for eclipses, occultations, etc.), national capitals should be shown as stars inside circles, with other cities simply as filled dots. The third line indicates that, when you right-click on an object, it should be marked with a small circle. The 'XHAIR_SYMBOL' indicates how the central cross-hair (toggled within the 'Display... Ticks, Grids, Etc.' dialog) should be shown. By default, satellites are shown as triangles; the final line above resets them to be a circle with antennae on each side.

(10 August 2001) Control to show reversed (negative-mode) images: The "Extras... RealSky/DSS Images" dialog box now has a check-box for this option. Enable it, and images are shown as black stars on a white background, like a photographic negative.

(10 August 2001) Sharp-edged terminators on airless objects: Guide has previously shown a fuzzy terminator on all objects. It now does so only for planets except Mercury and Pluto, and for Titan (that is, all solar system objects with dense atmospheres). Everything else has a sharp-edged terminator. I'd gotten a few comments about this over the years, and decided it was time to Do It The Right Way.

(Well, not really. The Right Way would be to have elevation data so I could show realistic shadow effects. This would be remarkably easy to do, if only a suitably dense elevation data grid were available. Unfortunately, it's not.)

(10 August 2001) Bitmaps for Mercury: Previously, Mercury was shown only as a yellow shaded sphere. We now have two bitmaps for it, from very different sources. One bitmap comes from the Mariner 10 data, gathered back in the early 1970s; this only covers about half the planet, though the resolution in that half is very good.

The other bitmap covers the entire planet, albeit at far lower resolution, and was supplied by Johan Warell, of the Uppsala Astronomical Observatory. It's based on image data he obtained at the Swedish Vacuum Solar Telescope. The project is described in detail here. At present, this is the best data (as far as I know, the only data) for the hemisphere that Mariner 10 didn't see.

To get both bitmaps, download this file and unZIP it in your Guide directory (about 490 KBytes.) Start up Guide, right-click on Mercury, select "Display... Options", and select "Bitmap #1" or "Bitmap #2" to get the two maps.

(10 August 2001) Fix for three Galilean moons: It had been suggested to me by Don Bruns that it seemed likely that the bitmaps for Europa, Callisto, and Ganymede were off. I considered this quite possible, since I'd had no way to verify them; and planetary maps are not too standard in terms of whether they show longitudes 0 to 360 (common option) or -180 to +180 (less common option). But I had no way (so I thought) to check the matter.

It turns out that if you check the labelled features for these three moons, they don't match the image very well. Rotating 180 degrees helped quite a bit. The current version of Guide does this internally; you need not get fresh maps.

(5 June 2001) Bug fixes for hard drive installation: The recent addition of a better hard drive installation method involved enormous changes to Guide, and I expected that a slew of small bugs might erupt from this as people tried different configurations. That was indeed the case. Mostly, these involved "breaks" in asteroid and comet display, where objects failed to appear or had erroneous name or magnitude data. Also, Tycho-2 data could fail to appear or be shown in bizarre ways. In any case, the bugs reported to date are fixed in the new version.

(5 June 2001) Display of Steve Coe's NGC/IC observation notes: Steve Coe has posted notes from his observing sessions on the Saguaro Astronomy Club site, at

http://www.saguaroastro.org/archive/obsnotes.htm 

You can visit that site and download notes for a given constellation or constellations into the Guide directory; when you click for "more info" on an NGC or IC object, Guide will then display notes from those files. (Steve has given me permission to use this data on the Guide 8 CDs, but in the meantime, you'll have to download the data.)

I am quite enthusiastic about this new feature, since Steve's notes give you a much better idea as to what you can expect to see with an amateur scope than anything else in Guide. Data from the assorted catalogs is often not really intended to give you "small scope visual observing" information, and the view as seen on a DSS or RealSky image is quite frequently not what a visual observer is going to see. I hope to supplement this with data from other observers, to give information such as "Joe saw this much detail with a 6-inch reflector... Jane saw this much detail with a 90-mm refractor... Ed saw this with a 20-inch reflector." However, I've got to find a few such datasets and get permission to use them first.

(20 May 2001) Display of time/date labels on planet trails: In the past, you've been able to right-click on a moving object (asteroid, comet, natural/artificial satellite, planet), click "OK", then create a trail for it using the "Animation... Add a Trail" dialog. You will now see that this dialog contains additional controls, to toggle "Time labels on" (or off) and to set the "Time label freq".

This works in much the manner as the 'index marks' (controlled via the same dialog). Suppose you set a trail spacing of five minute, with the index mark frequency set to 3 and the time label frequency set to 12. In this case, the trail would be drawn with index marks at 15-minute intervals, with each hour labelled with the corresponding time.

Guide is reasonably intelligent here about suppressing unwanted information. In the above case, the hours alone would be shown (no date, no minutes/seconds). Were the labels shown at a two-day interval, only the day of the month would be shown (except for the first label of each month). And so on... its choices are usually logical.

(20 May 2001) Much better installation to the hard drive: I've provided a way to install Guide to the hard drive for about two years now, but it's been user-abusive and not particularly flexible. Two things have made it especially important to remedy this: most people have large enough hard drives to make such installs easy, and Guide 8 is going to be on two CDs.

At the end of the "Extras" menu, there is a new "Install to hard drive" menu option. Select this, and Guide brings up a list of items that can be installed.

If you intend to run Guide from the hard drive at all, you must select the "Minimum hard drive install" option. After that, you can mix-and-match at will. Select the items you want, then click "OK". Guide will copy them over to the hard drive. As long as you've got the "minimum hard drive install" checked, you'll be able to run Guide without needing the CD-ROM. (Guide will handle this intelligently; it looks for the CD-ROM when it starts up, and if it finds it, it will use data from it to cover anything not already on the hard drive. If it doesn't find the CD-ROM, it'll get by on whatever happens to be installed.)

Should you wish to revise your choices at a later date, you can return to this option, uncheck some items, and click "OK" again. Guide will remove any and all items cleanly.

NOTE TO THOSE USING THE ORIGINAL HARD-DRIVE-IZATION METHOD: Before using this new function, you must return to running from the CD. That is, restore STARTUP.MAR so that the cd drive line points to the "real" CD, and delete the files you copied from the CD to the hard drive.

(20 May 2001) Toolbar tips (sort of): Move the cursor over a toolbar icon, and you get a brief description of its purpose. "(sort of)" refers to the fact that the text appears in the title bar, rather than as a separate small window. Also, this function appears only in the 32-bit Windows software (it uses a function not supported in 16-bit Windows, and I don't see a way of doing it, ever, in that version.)

As you may already know, you can click on assorted items in the legend for some functions (e.g., click on the constellation shown and the "Go to Constellation" dialog appears; click on the RA/dec shown in the legend and the "Enter an RA/dec" dialog appears). Similar tips are shown for these.

Windows purists will probably react with horror, laughter, rage, incredulity, or curling into the fetal position at this utter departure from the "standards" of a Windows app. If I can figure out a suitable way to do it, I will redirect the text to the usual small window with a yellow background next to the cursor, just as everyone else does it. (Though I'll keep the title-bar display as an option for those who want it. Personally, I think it's an excellent use of normally wasted screen real estate, and I'm looking for other uses for that area.)

(20 May 2001) Display of Millennium Star Atlas page numbers in the legend: In the past, the Legend dialog had check-boxes enabling display of the page number of the Uranometria and/or Sky Atlas 2000 page currently under the cursor. The Millennium Star Atlas has been added to that list. (Click here for the C/C++ source code behind this function.)

(20 May 2001) LX-200 focus controls: If you go to "Settings... Toolbar" and look near the bottom of the list, you'll see that there are seven new toolbar buttons. Two allow you to "spin [the chart] left" and "spin right" by small increments. The others control LX-200 focussers: "Focus in", "Stop focus", "Focus Out", "Focus fast", and "Focus slow".

(30 Nov 2000) 'Generic object' finding: Under the 'Go To' menu, a new menu item has been inserted at the top of the menu: 'Object name'. When you select this, you're asked to enter the name of the object on which you want to recenter, and this can be almost any object in Guide's databases. For example:

m 57              (Messier object)
NGC 253           (NGC object)
sao 123456        (SAO-numbered star)
ugc 1234          (Uppsala catalog of galaxies)
Capella           (Common-name star)
alp UMi           (Greek-letter star)
ZZ Cet            (Variable star)
GSC 1234 567      (Hubble Guide Star Catalog star)
40 Eri            (Flamsteed-numbered star)
Vesta             (asteroid name)
Ganymede          (natural satellite name)
Neptune
1997 XF11         (asteroid provisional designation)
Mir Complex       (if you've got current satellite elements)
3C273             (quasar)

Most of the other star, galaxy, and other catalogs are also available in a "normal" manner. So most of the time, you can enter an object name in this function and expect Guide to find it.

There will be some ambiguous cases that will confuse Guide. For example: enter "io", and Guide won't know if you mean Io (the innermost Galilean satellite), or Io (the asteroid with that name). Similarly, Guide can't tell if 'mu cep' refers to m Cephei, the Greek-lettered star, or to MU Cephei, an object with a variable-star designation. In such cases, you may do well to use the 'Go To' menu structure to ensure that Guide knows you really are using a specific sort of designation.

This can also be accessed with the Ctrl-B hotkey. If, like me, you dislike use of the mouse, it can be convenient to hit Ctrl-B and type (for example) "zz cet<enter>", all without touching a mouse.

(30 Nov 2000) Function to simplify movie-making: The "Settings... Toolbar" dialog now offers, near the end of the list of available buttons, a new function: "Add a Movie Frame .BMP". Some graphics packages allow you to convert a series of images such as, say, FRAME001.BMP, FRAME002.BMP, FRAME003.BMP... into a movie. This function helps in making such a sequence.

Of course, your first step will be to toggle this button on. Do so, and you'll see a new toolbar button that looks as if you've got a few frames of film going by.

Making a movie then involves the following steps. You set up your first frame to whatever date/time/field of view/etc. you want, and use the "make a .BMP" function. You save the file with a number in it, say, MOVIE011.BMP.

You now adjust Guide to show your second frame (perhaps just by clicking the 'animation step forward' button), and click on the new toolbar button. Do this, and Guide makes a new .BMP file with the number in the file name incremented (in this case, to MOVIE012.BMP.) You then repeat as needed: each click of the toolbar button causes a new frame, with an incremented frame count, to be produced.

Admittedly, there is a remaining function that would be extremely helpful: one in which, after setting up MOVIE011.BMP, you could just tell Guide to create (say) 328 frames with the current animation parameters (that is, at whatever time step you chose, staying locked onto an object if you chose that, or locked onto a given alt/az if you chose that, and so on.) That would make movie creation almost trivial.

(30 Nov 2000) Display of six new Saturnian satellites: Over the last few months, the discoveries of six new satellites of Saturn have been announced: S/2000 S 1, S/2000 S 2, ... S/2000 S 6. All six are "irregular" satellites. There is a short page here describing these objects. The discoveries were announced on IAUC 7512 (discovery of satellites 1 & 2); IAUC 7513 (discovery of satellites 3 & 4); and on IAUC 7521 (discovery of satellites 5 & 6). Guide will now display these objects for dates from May 2000 to August 2001. (There are not enough observations yet to compute accurate dates past that point. In fact, computing predictions for satellites 3 and 4 over so large a span is probably a bad idea; only a short arc is available for each.)

The brightest of these objects reaches magnitude 20. None is a likely target for any but the largest of scopes.

(I would also have added the newly-discovered satellite of Jupiter, S/2000 J 1 = S/1975 J 1, except that I don't have much astrometry for it yet.)

(8 Aug 2000) Ability to switch the display of times to the GST, LST, TD, and LMT scales: If you look in the "Time Zone" selection list (accessible from the Time dialog; hit Alt-T, or click on the time shown in the legend, or use Settings... Time), you'll see four new entries near the bottom of the list:

Greenwich Sidereal Time (GST)
Local Sidereal Time (LST)
Dynamical Time (TD)
Local Mean Time (LMT)

Local Sidereal Time is probably of the greatest interest. LST reflects the RA currently at the meridian. If your LST is, say, 12:34:56, it means that the point at the zenith has RA=12h34m56s (and its declination is equal to your latitude... but then again, the declination of the point overhead is always equal to your latitude, all the time.)

LST is sufficiently useful that some people like the idea of having an "LST clock" running on their PC all the time. You can click here for a small sidereal clock program available on this site. It displays LST, GST, or GMT.

Greenwich Sidereal Time, as the name suggests, is the sidereal time at the Greenwich meridian. It will differ from LST by a constant, that "constant" being proportional to your longitude.

Be aware that there is no real "system" for Sidereal Time "dates". My advice would be to ignore the "date" shown when using GST or LST; only the hour-minute-second portion is really significant. Click here for the reason why this is so.

You can also have Guide display times in Dynamical Time. At present, this is within about 70 seconds of Universal Time; the difference reaches several hours as you go millennia into the past. People doing historical work may have some interest in this option. It's of virtually no observational help at all.

"Local Mean Time" is time adjusted for your exact longitude, as opposed to being in a "standard" time zone. For example: Project Pluto headquarters are at longitude -69.9 degrees, but this is in time zone -5 hours from Greenwich. Time zone -5 would be exactly accurate only for those at longitude -75 degrees.

Back in the 1800s, local time would be in use, so clocks here would lag Greenwich by 69.9/15 = 4.66 hours = 4 hours 36.6 minutes. I'm not sure, but I believe the adoption of standardized time zones was driven in part by railroad companies. Having a few whole-hour changes made for easier scheduling than having thousands of towns each with their own time scale.

IMPORTANT SAFETY NOTE: Sidereal Times are usually given as simply hours, minutes, and seconds, with no year, month, or day. The reason is that a "calendar" for Sidereal Time is not really defined. In the sidereal time scale, a year is about 366.25 days long (exactly one day longer than on "standard" time scales), corresponding to the fact that, in one year, the earth rotates about 366.25 times relative to the stars (even though it rotates only 365.25 times relative to the sun).

This caused something of a headache when I decided to treat "sidereal time" as being "just another time zone" in Guide. I adopted a scheme in which GST and UT coincide exactly at the fall equinox of 1999. As you move away from that date, they diverge by 3 minutes 56 seconds a day, or one day a year. Go back to 1900 (or ahead to 2100), and the two systems are out of whack by over three months.

Side note: I briefly considered evading this problem by causing Sidereal Time "dates" to be reckoned using a modified calendar in which April would have 31 days, thereby giving it exactly the added one day a year we need. By doing this, the "Sidereal Time date" would vary from the "UT date" by, at most, about 12 hours. (I picked April because it's close to the spring equinox. Insert the extra day at the spring equinox, and the error would go from +12 to -12 hours. I didn't put the extra day in March because I didn't want a 32-day month.) This would have resulted in a "Gregorian sidereal calendar", with perhaps a "Julian sidereal calendar" for dates before 1583. I then decided I'd made things confusing enough already!

(8 Aug 2000) Ability to re-define Delta-T: Some people doing work on historical eclipses and occultations have asked for a way to change the way Guide handles Delta-T, the difference between the Dynamical Time and Universal Time scales. Delta-T is quite well-defined for the modern era (about 1620 through 2002), but outside that range, there have been several formulae given to approximate it. By default, Guide uses the following, all taken from Meeus' Astronomical Algorithms. (I adjusted the constant term in the first formula to evade a big jump between its results and those of the currently-measured Delta-T.)

After the year 2002:

TD - UT = 64.5 + 123.5 * t + 32.5 * t2

Before the year 948:

TD - UT = 2715.6 + 573.36 * t + 46.5 * t2

Between 948 and 1620:

TD - UT = 50.6 + 67.5 * t + 22.5 * t2

where t = (year - 2000) / 100 = (JD - 2451545.) / 365.25 = Julian centuries from the year 2000, and TD-UT = Delta_T in seconds.

Suppose you wanted to maintain this behavior, except that between the years 1990 to 2010, you wanted TD - UT = 65 + 120 * t. (This is a passable linear approximation to the actual behavior of Delta-T over the last few years.) You would edit the file GUIDE.DAT and add this line:

DELTA_T=1990,2010:65,120,0

Guide would continue using its "normal" formulae outside that range, but between 1990 and 2010, it would use your formula.

You can also specify a particular, fixed Delta-T by setting the linear and quadratic coefficients to zero. For example, if you wanted to set Delta-T=87.3 seconds for all times, you'd use

DELTA_T=-100000,100000:87.3,0,0

You can add extra ranges, separated by ';'. If you so wished, you could duplicate the default behavior of Guide's Delta-T with the following:

DELTA_T=2002,100000:64.5,123.5,32.5;-100000,948:2715.6,573.36,46.5;948,1620:50.6,67.5,22.5

WARNING: I think it's safe to play around with other Delta-T formulae. It's certainly safe to do so in the sense that, if worst comes to worst, you can delete the DELTA_T line in GUIDE.DAT and recover the original, default behavior. One area that concerns me, though, is that lunar/planetary theories based on one version of Delta-T may not work very well when you attempt to "drop in" a totally different Delta-T formula. That has a lot of possible effects, and I've not begun to figure them all out yet.

(8 Aug 2000) Very minor changes to outer satellites: A newly-discovered outer satellite of Jupiter, S/1999 J 1, has been added to Guide. All of the outer satellites of Uranus found last year have been recovered now, resulting in large changes in their orbits (the original orbits were based on a short period of observation last summer and fall... the orbit I had for S/1999 U 2, in particular, turned out to be almost completely wrong.) The formula for the magnitude of Saturn's moon Japetus was revised to include a term from the Explanatory Supplement to the Astronomical Almanac that accounts for the extreme magnitude swings as it circles Saturn. (Japetus is nearly coal-black on one side, but fairly bright on the other side. Guide now takes this into account when computing Japetus' magnitude. Incidentally, if you zoom in on Japetus far enough to see its disk, you can see the "black side" and "bright side" in Guide.)

(15 May 2000) Use of NGC-IC Project data: The people at the NGC-IC Project have gone to considerable effort to clean up the errors in existing electronic versions of these catalogs. This involves observational work (that is, looking at the objects and verifying that the data on them is correct) and literature work (puzzling out which NGC designation was intended to correspond to which object(s).) The result is a tremendous improvement in accuracy over older catalogues such as the NGC2000 and RNGC.

Wolfgang Steinicke has kindly given permission for use of his version of the catalog. In Guide 8, it is expected that this data will form the basis for display of NGC and IC objects at all fields of view. In the present version, though, it is used only for zoom levels 1 through 5. (At levels 6 and up, Guide uses a much larger file, one that I'd rather not post on this site!)

However, if you download this file to your Guide directory (about 163 KBytes), NGC and IC objects will be drawn using NGC-IC Project data at levels 1-5. Aside from the error correction involved, this has some other benefits:

(15 May 2000) Display of some very minor natural satellites: If you zoom in on Jupiter, Saturn, Uranus, or Neptune, with display of planets set to On (or to a very faint limit!), you will see that each planet has some new inner moons. Of these, Amalthea (also known as J5, or Barnard's moon) is the only one of much observational interest. E. E. Barnard discovered it visually, with the 36-inch (91-cm) Lick refractor; it's usually mentioned as the last great visual discovery. I understand that some people have since observed it with much smaller instruments, all the way down to 12-inch (30-cm) reflectors. An occulting bar would obviously help.

Also added are three more moons of Jupiter, four of Saturn, eleven of Uranus, and six of Neptune. The common thread linking these objects is that each is a very small satellite close to the primary, and treated by JPL as moving in a "precessing ellipse", with the longitude of ascending node and of perihelion changing linearly with time. This meant that after adding Amalthea (the only one in which I really had much interest), the others came almost "for free" (same software, different numbers). The 25 new satellites, including their three-digit JPL IDs, are:

Jupiter:          Uranus:                Neptune:
505: Amalthea     706: Cordelia          808: Proteus
514: Thebe        707: Ophelia           807: Larissa
515: Adrastea     708: Bianca            805: Despina
516: Metis        709: Cressida          806: Galatea
                  710: Desdemona         804: Thalassa
Saturn:           711: Juliet            803: Naiad
615: Atlas        712: Portia
616: Prometheus   713: Rosalind
617: Pandora      714: Belinda
618: Pan          715: Puck
                  718: 1986U10 (no name yet)

Except for Amalthea, these are basically targets for Hubble or the Voyager probes (and now, the Galileo and Cassini probes).

My thanks go to Mark Showalter, who provided the orbital data I needed to do this. Incidentally, as is described here, you can download the C source code used for computing positions of these objects, as part of the basic astronomical functions library..

This gives Guide an almost-complete handling of natural satellites. Omitted are five faint Saturnians (Janus, Epimetheus, Helene, Telesto, Calypso). These are now discussed as a possible future improvement in Guide.

(15 May 2000) Faster MPCORB asteroid display: It's been possible to show asteroids from the MPCORB database in Guide for about a year now, but you've always had to pay a horrible performance penalty for this. On my 200 MHz Pentium, Guide could show asteroids from its "built in" data almost instantly; turn "Use MPCORB" on, and it slowed by about six seconds a redraw.

With the current version, display of asteroids from MPCORB is usually nearly instantaneous. You'll still see a slowdown the first time asteroids are drawn from a new MPCORB, and a slowdown each time the date changes to a new (UT) date. But 99% of the time, there will be no performance penalty associated with MPCORB.

(A much more minor improvement: you can now toggle between MPCORB and built-in data by hitting the Delete key.)

You do not really need to know anything about how this was accomplished, but should you be curious, read on:

The speed improvement occurs because Guide now "pre-generates" some data telling it where each asteroid will appear, and what magnitude it will reach, over a given day. Once that data is generated, Guide can use it to immediately disregard most of the asteroids as being too faint, or too far from the current RA/dec, to possibly appear on the chart. (Change MPCORB, or the current day, and Guide has to regenerate that data. That's why you still get slowdowns from time to time.) Previously, Guide had to do all the math for every asteroid in MPCORB, a computationally intensive task.

This is very similar to the "limit files" used for the built-in asteroids. People interested in the details of .LIM files should read the file \COMPRESS\ASTEROID.DOC on the Guide 7.0 CD. Guide builds a nearly identical file for MPCORB, except that instead of covering 50-day intervals, one-day intervals are used.

Similar trickery may allow Guide to display asteroids briskly from other planets (another situation where the built-in data becomes useless). But that will definitely have to wait until Guide 8 is shipped.

(15 May 2000) MPCORB gives last date of observation: Gareth Williams, of the Minor Planet Center, has kindly modified MPCORB a little so that you can get the last date on which an asteroid was observed. That date is now shown in "more info"; combine it with the observed arc of the object, and you can get a fair idea as to how necessary it is to get fresh observations on it.

(15 May 2000) Fix to picking of objects for eclipses/occultations: To see an eclipse or occultation of, say, SAO 123456 by Mars, it is necessary to right-click on (or "go to") that star, then right-click on (or "go to") Mars. Then you can click on "Extras... Show Eclipse", and see the path.

Unfortunately, things were rarely so simple. If you did a "go to" to Mars, then right-clicked on it, Guide would track both events and conclude that Mars cannot occult itself. So the "Show Eclipse" option would remain grayed out. Guide is now bright enough to ignore such duplicate events (clicking on or 'going to' the same object), and once in geographic mode, it does a better job of remembering which objects are involved in the event. This fixes the problems with "Next" and "Previous" mysteriously turning gray when you right-click on the geographic chart.

(15 May 2000) NexStar support: You should be able to go into the Scope Control dialog, and select "NexStar" and the serial port to which such a scope is connected. You should then be able to fire up the Scope Pad, and use the "Slew Scope" and "Slew Guide" options. (The others are not supported on the NexStar; if the documentation from NexStar is complete, then it indicates a very limited command set.)

So far, this has been tested by one person, James Ellis. After a bit of fiddling with the cable, he got the Guide-NexStar connection to work. (James also pointed out a Web site with good information on PC/NexStar communications: how to test them, and how to set up the cable.)

(15 May 2000) User-specified guider chips: (Note that much of this has changed in the Guide 8.0 update. The GUIDER_CHIP data is set within the ccds.nam file. Look at the end of that file for details.) For about a year, it's been possible to show the guider chip for an ST7 or ST8 in Guide. More recently, the ST9e guider chip was added. In reply to a recent request from Bernd Brinkmann, I added the ability to add a "custom" guider chip.

For the STx chips, Guide has "hardwired" data on chip placement and size. For a custom chip, you select the "main" chip just as you do now, in the CCD Frame dialog. Guide can get the size of your "custom" guider chip, and its position/offset relative to the main chip, from a line in GUIDE.DAT containing six (sometimes four) numbers. Here's an example:

GUIDER_CHIP=-.5, .6, .25, .19, 192, 165

(-.5,.6) = offset between the centers of the guider and main chip, with the size units being the width and height of the main chip. Thus, if the first two numbers had been (.5,.5), we'd be telling Guide that the center of the guider chip is exactly on the upper right corner of the main chip. (0,-.7) would mean the guider chip was a little below the center bottom of the main chip. And so on... as it is, the (-.5,.6) means that the chip is just a little above the upper left corner of the main chip.

(.25,.19) means the guider chip has 25% of the width, and 19% of the height, of the main chip. This places the lower right of the guider chip almost, but not quite, on top of the upper left of the main chip:

,-----,
|     | <- Guider chip
|_____|
   ,-----------------,
   |                 |
   |                 |
   |  Main chip      |
   |                 |
   |                 |
   '-----------------'

The units may seem a little odd. But an offset in RA/dec can't work very well if the scope rotates at all, and changes with focal length.

(192,165) means that the guider chip is 192 by 165 pixels (which, in fact, is the size for an ST4.) You can omit this if you wish; the only place it is used is when you zoom in very far on the guider chip, to allow Guide to show you the grid of pixels. Omit these numbers, and the only consequence is that Guide can't show you the pixel grid on the guider chip.

(30 Jan 2000) Eclipse mode time interval marks: Previously, when you displayed an asteroid occultation in Guide, the path was a plain gray strip indicating the area where the occultation was expected to occur. I noticed that the OCCULT program by David Herald, widely used for producing asteroid occultation charts, puts an ellipse at (say) five-minute intervals, indicating the occulted area at those instants.

I rather liked this idea, and have borrowed it for use in Guide. Set up an asteroid occultation (or a total or annular solar eclipse) as you normally would. The world map will appear in the usual manner. Under "Settings", you will see a new "Mark Interval" option. Click on this, and Guide will ask you for the spacing at which time interval marks should be shown.

For solar eclipses, I find that entering 15 (minutes) works nicely. For asteroid occultations, the path is narrower and usually moves more briskly, and an interval of one minute is sometimes just fine. Your aesthetic judgment may vary.

The option is almost useless for partial eclipses and lunar occultations. I'll have to figure out another display method for these.

Click here to see an example chart (about 41 KBytes). This shows the 11 August 1999 total eclipse, with circles at five-minute intervals on the path.

On certain charts, it can be nice to have some sort of 'index' mark. For example, on the above chart, every sixth circle is shaded differently, to indicate half-hours. To do that, just select the "Mark Interval" option again and enter 'i6'.

(30 Jan 2000) Filtering of asteroids: Previously, Guide allowed you to filter asteroids solely on the basis of magnitude. You could tell it to drop asteroids fainter than, say, magnitude 15.4, but that was the limit of your ability to select which ones appeared.

For most people, this limitation is not particularly troublesome. But it can be pleasant at times to filter asteroids on the basis of orbital parameters, and this is now possible. For example: suppose you wanted Guide to display only Jupiter Trojan asteroids. These are distinguished by having a semimajor axis (a) that is between 5.05 and 5.4 AU. To tell Guide to display only these asteroids, you would edit GUIDE.DAT and add this line:

ASTFILTER=5.05 < a & a<5.4

(This is worth giving a try, by the way... do it and turn asteroids 'On', and you can see two distinct clouds of Trojan-belt asteroids, 60 degrees ahead of and behind of Jupiter.)

Alternatively, if you dislike text editors, you can hit Alt-J and get a little dialog box asking you to "Enter a test flag:" You can then enter the text ASTFILTER=5.05 < a & a<5.4, and click OK.

You can also filter on the basis of limits in q (perihelion distance), Q (aphelion distance), e (eccentricity), i (inclination), P (orbital period), and d (distance from the earth). By combining these, you can define most of the major asteroid groups and families. For example, to define the Nysas, you would use:

ASTFILTER=2.41<a & (a < 2.5) & (e > .12 & e < .21) & (1.5 < i & i < 4.3)

(As the above indicates, you can use parentheses and spaces as you wish.) You can also filter on the basis of x (right ascension, in degrees) and y (declination, again in degrees.) The only real situation I can think of where you would want to do this is as follows. Let's say that you can't really image any asteroids below dec -20 (too close to your southern horizon). Let's say that the opposition point is currently at about RA=1h (15 degrees), and you want to know which asteroids are within 25 degrees of opposition. You could set up the following:

ASTFILTER=(y>-20) & (x>350 | x<40)

(The '|' means 'or'. I realize it's not as obvious as the '&' meaning 'and'; only C programmers will find it a familiar usage.) Do this, fire up Guide, and you can go into 'Tables... List Asteroids', and get a list of asteroids in that area down to your desired limiting magnitude.

Also, if you want to filter out Guide's built-in asteroids, using only those added with the 'Edit Comet/Asteroid Data' and 'Add MPC Comets/Asteroids', you would use this:

ASTFILTER=b

I don't actually envision many people making use of these filters, but they can be educational and (in rare cases) actually useful.

(30 Jan 2000) New Uranian satellites: In Summer 1999, the discovery and follow-up observations of three new irregular satellites of Uranus was announced in IAU Circulars. Guide now displays all three when you zoom in on Uranus. (Keep in mind that all three orbit at great distances from Uranus; zoom in very far, and they won't be in your field of view.)

The orbits are based on short arcs, so Guide won't show you their positions before early 1999 or after mid-2000.

For more information about these objects, and how their orbits were computed using Find_Orb, you should click here.

(30 Jan 2000) A few new 'miscellaneous tables': Stephen Kerr pointed me toward a list of worldwide asteroid occultations for 2000 (as opposed to the regional lists provided in the last update). Also, I generated lists of transits of Mercury and Venus. All three new tables now appear under 'Tables... Miscellaneous tables'.

(30 Jan 2000) Filtering cities by level of importance: I must admit that this has been present for a while; I simply forgot to mention it. When in eclipse mode, Guide will normally show immense numbers of cities at any field of view below 20 degrees. You can now hit '-' to omit the least important of these cities; keep doing it, and more cities will be dropped. Hitting '+' reverses this action.

This is somewhat analogous to the way '-' drops out the faintest stars in "normal", star charting mode, with '+' reversing that action. If you find that this doesn't work, you probably you need to get the revised geographic name dataset (about 55 KBytes).

(29 December 1999) New 'Miscellaneous' entry in Tables menu: Click on the new 'Tables'... 'Miscellaneous' menu item, and Guide will produce a list of assorted tables. Right now, this list includes tables of asteroid occultations visible from Europe, Japan, and North America in 2000; mutual planetary occultations; and mutual satellite events for Jupiter and Saturn.

If you click on (for example) one of the asteroid occultation table entries, Guide will set its date and time to that of the occultation, and will center on the asteroid.

Each list is stored in a file with extension .ETB (either "Event TaBle" or "English-language TaBle"). People interested in adding further tables, or in translations of tables, should click here.

(29 December 1999) Fix for Y2K bug in loading MPC orbital elements: My thanks go to Jim Roe for pointing this bug out, possibly before anyone else got caught by it. There was a Y2K bug involving the "Extras... Add MPC comets/asteroids" function, causing it to interpret some 2000 dates as 1900. This is the second Y2K bug found in Guide (the first, a bug in reading elements for artificial satellites, was fixed long ago). Few were probably affected by the current bug.

The "Add MPC comets/asteroids" function can extract elements in three different formats. The first (and originally only) format accepted is that of elements of comets and asteroids provided by the Minor Planet Center (MPC) for use in Guide. These files are not affected by the bug.

The second format is a 'multi-line' one, also originated by MPC and commonly found in Minor Planet Electronic Circulars, and also used by Find_Orb when you click on its "Save Elements" button. That format looks like this:

1996XX1
   Perihelion 1998 Mar 6.613520 TT
Epoch 1997 Oct 12.8 TT = JDT 2450734.3
M 322.61471              (2000.0)            P               Q
n   0.25814459     Peri.   70.72323     -0.48525244     -0.87437222
a   2.4428344      Node    48.30591      0.80130822     -0.44553172
e   0.5691006      Incl.    0.13910      0.34990742     -0.19228807
P   3.82           H   15.6      q 1.0526159
From 13 observations 1997 Oct. 12-22;   RMS error 0.618 arcseconds

The bug didn't affect Guide's handling of this format, either.

The third format, however, is that used in the MPC's "Daily Orbit Update" (DOU) files. As the name suggests, these are files produced daily giving 'fresh' orbital elements for asteroids, usually because new observations have become available for them. Each object has its orbital elements given on a single 80-character line, such as

J88R01V 13.9  0.15 J998A 284.006  91.007  11.221   4.556 0.08061   2.32754   6 W

The epoch is given as 'J998A', in the MPC's compressed format for epoch dates. Guide failed to recognize that 'Kxx..' epochs refer to the year 20xx.

(29 December 1999) Change in time zone handling: It used to be that, when you clicked on "Time Menu", then on "Time Zone", Guide gave you a small dialog box where you could select from about eight possible time zones. This included Universal time, plus a selection of zones for the Americas. For any other zone, you had to enter a difference in hours from Universal Time.

Now, you instead get a list box of time zones. Certain non-US zones are included, and more can be added.

Note to translators: the time zone data used to appear in STRINGS.* files. It's now in TIMEZONE.NAM, and can be translated in the same manner as other .NAM files.

(21 December 1999) Fix for problems in importing DSS images via Internet: Shortly after the new ability to import DSS images was posted, I got some reports of problems where images were not decompressed, or didn't download at all. Several of these appeared on the new Guide users mailing list, and these allowed me to diagnose the trouble and fix it. Also, the new version gives you a "progress report" concerning the amount of data downloaded.

To get the new fix, you'll have to download this REALSKY.ZIP file (about 65 KBytes) and unZIP it in your Guide directory.

The only downside to all this is that you must establish an Internet connection before you attempt to download an image. (Previously, Guide would start up a connection if one didn't already exist.)

(21 December 1999) Ability to click on events in 'help' to display them: Masaki Kouda suggested that, when a list of satellite passes is made, you ought to be able to click on a given event time and have Guide show you that event. For example, if the list shows that the Lacrosse 3 satellite goes into the Earth's shadow at such-and-such a time, you ought to be able to click on that time; Guide would then reset itself to that time and show you the Lacrosse 3 satellite entering shadow.

This idea has been implemented, and extends to almost every list of events shown in Guide. List lunar eclipses, for example, and click on the time shown for "totality begins", and Guide shows you the moon at the beginning of totality. Click on the time shown for "Io shadow begins", and Guide shows Io at that instant, with its shadow just touching Jupiter. And so on, for twilight times, lunar phase, apogee, and perigee dates, and equinox/solstice dates.

Help-text links to other parts of the help text are still shown in dark blue; the new 'links to set a time and find an object' are in purple.

This feature has been extended in another direction, on a test basis. I recently got a list of favorable asteroid occultations for North America for 2000, posted by David Dunham of IOTA on the Minor Planet Mailing List. Click on "About Guide", and on the "list of favorable asteroid occultations for 2000". You can then click on a given event, and Guide will show the asteroid and star at the time of the event. (Dunham indicated that lists for other parts of the world are in preparation.)

(21 December 1999) Better geographical names on Earth charts: You can click here to download an improved list of city names (about 55 KBytes). It's an "improvement" in several ways. Some level of importance (LOI) data has been added, so that large cities are rarely omitted in favor of small cities. The original dataset came from the Bureau des Longitudes in Paris, and about half of the dataset consisted of small towns in France. These have been eliminated, and the charts look much more reasonable in France now. Also, a few corrections have been made.

(21 December 1999) Czech-language support: Jan Manek has sent in the file to allow Guide to display most menus, dialog boxes, and information in Czech. To do this, you'll need to access the current Guide software and download this CZECH_G7.ZIP file (about 21 KBytes) to your Guide directory, and unZIP it. (There is also a link to this file in the grid of languages near the top of the page.)

Once you have done this, you can go into "Settings... Languages", and see that "Czech" has been added to the supported list. Also, you can turn on a "Czech" toolbar button in the Toolbar dialog, and you can toggle to Czech by hitting Alt-/.

(21 December 1999) New hotkey option for non-English versions: Jan Manek pointed out on the Guide users mailing list that, in creating the Czech version of Guide, he could either (1) leave the menu hotkeys as they are in the English version, or (2) select new menu hotkeys that make sense in Czech. (Of course, the same thing applies to all languages.)

In the first case, the 'File', 'Go To', 'Print', and 'Exit' options would look like this in the Czech version of Guide:

Soubir   F
Jdi na... g
Tisk    p
Konec   x

For the second case, they would appear as follows:

Soubir
Jdi na...
Tisk
Konec

Jan pointed out that people accustomed to the English version and its hotkeys would prefer option (1), even though it leads to odd keys off to the side of the menus. New users, though, would probably prefer option (2).

It is now possible for users to switch between the two options by hitting Shift-F3. (The few remaining users of DOS Guide should use Ctrl-6 instead.)

Note, though, that "alternative menu hotkeys" have not been defined in all languages yet, nor do they cover all menu hotkeys yet. Translators will want to read this text about how 'optional' hotkeys are defined.

(21 December 1999) Lists of satellite passes, rise/set times: When you right-click on an artificial satellite in Guide, you'll get its rise and set time. If it's above the horizon, this will be for the current pass; otherwise, the data will be for the next pass. You will also get the information that the satellite is either in sunlight during the entire pass, or in shadow during the entire pass, or enters or exits the earth's shadow during the pass.

Click for 'more info', and Guide will list (in addition to other data) the passes that satellite will make over your site for the next five days. Some basic data will be given for each pass, such as rise/set times, time of entering/exiting shadow, maximum altitude and magnitude reached, and the azimuths at which the satellite rises and sets.

Also, there is a new "List Satellite Passes" option in the Tables menu. When selected, it brings up a dialog such as this:

,--List satellite passes -----,
|                             |
|     _Mir Complex______      |
|                             |
|  Number of days: _____5__   |
|                             |
|  Show only if...            |
|     [X] Sunlit              |
|     Alt limit:      ___10_  |
|     Sun below alt:  ___-6_  |
|     Mag limit:      ____6_  |
|                             |
|   [ OK ]   [ Cancel ]       |
'-----------------------------'

In the above case, Guide would generate a list of passes of the Mir Complex over the next five days where Mir got at least ten degrees above the horizon. (Such a limit is extremely helpful. Set the "alt limit" to be zero degrees, for example, and you will find many passes where the satellite just barely appears over the horizon. This is especially true for lower-orbiting satellites.)

Because the 'Sunlit' box is checked, Guide will only list passes where Mir reaches the specified limiting magnitude (6) and where the sun is below the specified altitude (-6 degrees). Otherwise, you can get long lists of passes that occur in daytime, or at least in bright twilight; and also passes where the satellite is too dim for practical visual observation.

Of course, not all observation is visually based. Uncheck the 'Sunlit' box, and the magnitude limits and 'sun below alt' limit will be ignored. This is mostly useful if you're interested in radio communication with a satellite.

If you bring up the "List Satellite Passes" dialog after having clicked on a satellite, the name of that satellite will be entered by default in the dialog. Otherwise, the name will be set to '*', a 'wildcard' indicating that you want to see the passes of every satellite in the current .TLE file. The 'wildcard' feature can be quite useful; you can, for example, set it to 'GPS*' to have Guide display passes only for the GPS (Global Positioning System) satellites in a .TLE file, or to 'NOSS*' to get passes for the Naval Ocean Surveillance Satellites, and so forth.

(21 December 1999) Ability to use all of the A1.0 or A2.0 data on the hard drive: Guide and Charon have long supported use of the A1.0 and A2.0 datasets, by letting you either extract a part of the data from the ten or eleven-CD-ROM sets or by storing a downloaded portion on your hard drive.

Recent increases in hard drive capacity have caused some people to copy some or all of the entire A1.0 or A2.0 over to hard drive, consuming up to about 6 GBytes. If you do this, you can now tell Guide to display such data by adding a line such as the following to GUIDE.DAT:

A2_PATH=14.3;f:\a20;g:\;h:

In the above example, Guide will display of A2.0 data if the limiting star magnitude is past 14.3. At that point, it will check the directory F:\A20 for A2.0 files; if it can't find them there, it will check the root directories of G: and H:.

Please note that the above will cause Guide to display A2.0 directly; that is, it will automatically appear when the limiting star magnitude is (in the above case) 14.3 or fainter. You don't need to use the "Extras... Get Ax.0 Data" menu option.

A1.0 users, logically enough, would use the above, with 'A1_PATH' in place of 'A2_PATH'. SA1.0 or SA2.0 users would use 'SA1_PATH' or 'SA2_PATH', respectively.

Both A1.0 and A2.0 are provided in 24 files, each covering a 7.5 degree band in declination. If Guide cannot find some of these files, it accepts that fact and simply shows no Ax.0 data. This can permit a person such as myself, at latitude +45, to omit the six zones covering declinations -45 to -90, areas forever hidden from here. A warning, though: as the A2.0 disk organization and A1.0 disk organization pages make clear, leaving those six zones out only saves about 500 MBytes.

Charon will look at the same line in GUIDE.DAT. You just have to go into Charon's setting menu and select either "Match to A1.0" or "Match to A2.0".

List of improvements continues here