More text about the updated software for Guide 7.0

(23 Jun 1999) Planet grids, display options: Assorted features allowing you to display labelled lunar craters, a more detailed lunar map, and so forth have been added over the last month or so, but they've been rather painful to access. This problem has been addressed, and some new capabilities added.

When you right-click on a planet now, you will see (in addition to the usual "OK", "More Info", and "Next" buttons) a "Display" button. Clicking on it will bring up a dialogue box that looks much like this.

,--- Planets ----------------[X],
|  [ ] Full precision           |
|  [ ] Label by name            |
|                               |
| -- Mars -------------------   |
|                               |
|  [X] Show features            |
|  Feature density:   ___100_   |
|  [ ] Label features           |
|  [ ] Grid                     |
|     _30_ x _30_ degrees       |
|  ( ) Shaded                   |
|  ( ) Line figure              |
|  ( ) Bitmap #1                |
|  (*) Bitmap #2                |
|  ( ) Bitmap #3                |
|  Contrast:   [       *    ]   |
|  Brightness: [  *         ]   |
|                               |
|     [ OK ]   [ Cancel ]       |
`-------------------------------'

The 'full precision' and 'label by name' check-boxes apply to all planets, and have the same meanings as the similar boxes in 'Data Shown'. The remaining functions are all specific to a given planet.

For each planet, you can tell Guide to show features on that planet (craters on the moon, assorted types of features on Mars, Venus, and many other planets and satellites). You can cause these features to be labelled by name, and select colors for the features and labels. Also, you can set a "feature density". If you want Guide to show more planet features, raise this number; to eliminate some of the more minor features, decrease it.

Also, you can check a box to have a lat/lon grid laid over the planet, and you can specify the grid spacing and its color.

For most objects, only one bitmap will be available, and the other two "bitmap" radio buttons will be grayed out. On others, two or perhaps all three buttons will be available. For all objects, it's possible to have the display be a simple shaded sphere, or a very basic, bare-bones "line art" display (in which the illuminated area is simply outlined, and the dark limb is shown with a fainter line.)

The slider controls apply to bitmapped planets. They allow you to adjust the contrast and brightness freely... which is especially helpful with the Clementine lunar map. That map shows some tremendous variations in contrast, from dark maria to bright highlands; you'll find that you're forever fiddling with contrast to get a particular part of the Moon to look good. Be aware that there are also hotkeys for contrast and brightness adjustment, plus some toolbar buttons for the same tasks.

(23 Jun 1999) Display of proper motion vectors: The Millennium Star Atlas has an interesting feature for star display: a line points out from each star on the chart, indicating the direction and amount of proper motion over a 1000-year period. In Guide, the "Star Display" dialogue box now has a control near the bottom for this:

PM vector (years):  ____0_

The default value (as shown above) is zero, indicating no vector at all. Setting that value to 1000 will give you a Millennium- like chart.

Admittedly, this is a useless feature. But it is interesting to play around with it and look at a few charts with it. It also helps a little in educational settings; you can use it to show the common proper motion of stars in the Pleaides, Hyades, and some similar clusters. It can help in seeing if double stars are "real", physical pairs, or if they are just two stars that lie in the same direction as seen from Earth.

(16 Jun 1999) 'Fixed magnitude limits' option: Ever since Guide 1.0 was released, there have been three options for the display of objects such as asteroids, galaxies, comets, and so forth: "off" (show no objects of this class), "on" (show all of them), and "auto" (show all objects down to a particular limiting magnitude, with that magnitude varying as you zoom in or out.)

There is now a fourth option for each class of data, "fixed". With this option, objects are shown to a limiting magnitude that does not vary as you zoom in or out. You'll see this when you enter the Data Shown dialog; there will be four columns of radio buttons, instead of three. And if you select the "fixed" button for, say, asteroids, and a magnitude limit of 13.4, then asteroids will always be shown to that limit, no matter what field of view is shown.

One correction must be made to the above statement. Certain classes of data are always shut off above a given level; for example, variable stars are not shown above level 6. To correct this, I will be adding a "field of view limit", so you can specify that (for example) variable stars are to be shown only if the field of view is less than 20 degrees wide.

In the Windows software, the only visible change in the user interface is the fourth row of radio buttons. In the DOS software, the workings of "Data Shown" have been revised, as follows. Clicking on a line in that menu will now always cause a sub-menu to appear, containing four radio buttons for that class of object, a limiting magnitude, a color, and perhaps a few options specific to that class of object. (The overall operation of this part of the DOS software actually makes logical sense now, a claim I could not previously make. It's rather a pity that it has been perfected just as interest in DOS is declining rapidly. But this is a common story in engineering: by the time you get it to work, it's obsolete.)

(16 Jun 1999) RA/dec "side labels" outside the chart: Most printed star atlases, such as Uranometria, Sky Atlas 2000, and Millennium, put the labels for RA/dec grids just outside the border of the chart. And almost all star charting software puts the labels just inside the border of the chart. Almost the only exception of which I am aware is MegaStar.

Putting side labels inside the chart area is still a good idea on-screen, where screen area is limited and a wide border just for labels would be wasteful. But on printouts, the labels are now placed outside the border. (If you disapprove of this behavior, and would prefer to put the labels back inside the border on printouts, edit the file 'guide.dat' in the Guide folder, and add the line

SIDE_LABELS=n

Furthermore: theoretically, labels could be placed on any of the four sides of the chart. Millennium puts labels on the top, bottom, and one side edge (either right or left, but never both) of a chart. Sky Atlas 2000 labels all four edges. It seems to me that labelling more than two edges is a waste of paper. Therefore, the "Margins" dialog (under "Settings") now has four check-boxes, so you can select which sides are labelled on printouts. The current default is to label all four.

Important note: If you currently have the margins set to be very small, the side labels may run off the paper. So you may find that, with this new feature, you will want to increase the margins on any side where side labels are used.

Soon, I expect to expand this "drawing outside the chart box" to allow for a legend in that area. Using a small text file, one will be able to set up where given legend items will go; I'll then provide a few such files so people can produce "Millennium-style charts", "Sky Atlas 2000 style charts", and so on (modified to account for the fact that Guide charts contain objects and features not found in printed atlases... for example, printed atlases obviously don't show moving objects such as asteroids, planets, and artificial satellites.)

(16 Jun 1999) Miscellaneous small changes:

(20 May 1999) High-resolution lunar images: Guide normally shows features on the moon to a resolution of about 7 km. You can now improve this about tenfold, to a resolution of about .7 km. Doing this will cost you 86 MBytes of hard drive space (to store the image) and $10 (for a CD-ROM of data from the Clementine probe). Click here for details and some screen shots showing the improvements.

(20 May 1999) New functions for planetary observers: Normally, as you move the cursor around the chart, Guide continuously updates the RA/dec in the legend. But now, if the cursor passes over the disk of a planet, the RA/dec will be replaced by the latitude/longitude of that point on the planet. For the moon, a chart number from Antonín Rükl's Atlas of the Moon will be given. (You can get this book through Kalmbach Publishing; click here for details.)

Also: normally, if you drag a line between two points on the chart, Guide shows their angular separation and position angle. But now, if both points happen to fall on the disk of a planet, Guide shows the distance between them in kilometers. This can be helpful in measuring features.

(20 May 1999, updated 20 March 2000) More accurate comet tail lengths and coma sizes: Previously, Guide has shown all comets as having a .1 AU tail, and with a head of diameter 5 arcminutes divided by the distance to the comet in AU. (In essence, this meant that the head was assumed to be about 425000 km across, no matter which comet was involved.) These guesses coincided with reality only by accident. But Andreas Kammerer, a Guide user in Germany, has done some extensive study of how comet tail lengths and coma sizes vary. Starting on 20 May 1999, comet tail lengths in Guide were computed using his formula to compute a more accurate tail length value. Later, on 20 March 2000, his formula to compute a more accurate coma size was also added to the program. Andreas Kammerer notes:

   "Of course such a simple formula [for the tail length] has some
shortcomings, for example:

- it does not distinguish between ion and dust tails
- it does not take into account the continuing heating for some
  time after perihelion, which results in a longer tail after
  perihelion than before for a given solar distance on average.
  Such an improvement, however, is on my project list...
  This shortcoming, however, can be partially compensated by using
  two different sets of brightness parameters, which many comets
  with q < 1 AU actually show (pre- and postperihelion).
- not a consequence of the formula but equally important:
  the assumption of a tail directed exactly in the anti-solar
  direction can affect the apparent tail length in a recognizable
  way in the case of deviating or bended (dust) tails.

Despite these shortcomings my formula is an improvement in
approximating the apparent visual tail length of a comet much
better than by using a constant value. Further, I would claim
that it give good results within a factor of 30% in about 80%
cases. By mentioning the short-comings in this glossary,
everybody should be able to rate the value of the results."

In early March 2000, Andreas sent me his formula for the coma diameter, with the following comments:

Of course, this formula too is only a rough guide for the
expected coma diameter. However, I tried it on a greater number
of comets visible during the last five years and can say, that
it calculates a visual coma diameter which on average
represents the actual coma diameter to within about 30%.
However, there are exceptions. For example the formula
underestimates the diameter of comet Hale-Bopp, but this was an
extraordinary comet by its own. Contrary, comet Hyakutake
actually showed a smaller diameter than the formula derives.
Also, for the rather strange comets C/1998 K5 (LINEAR) and
C/1999 S3 (LINEAR), both displaying a miniscule coma, the
formula does not work.

Summary: the formula gives only a rough guide for the diameter
of a comet, but by analysing a greater number of comets I think
it works as well as the tail length formula. Therefore I think
it should be worth to integrate it in GUIDE.

The formula gives the tail length L, in millions of kilometers, as follows:

mhelio = H + K * log10(r)
log10(Lo) = -0.0075*mhelio2 - 0.19*mhelio + 2.10
L = Lo * (1 - 10-4r) * (1 - 10-2r)

where H and K are the usual magnitude parameters, and r is the comets' distance from the Sun in AU. The diameter of the coma is computed using the following, somewhat similar formula:

log10(Do) = -.0033 * mhelio2 - .07 * m_helio + 3.25
D = Do * (1 - 10-2r) * (1 - 10-r)

where D is the coma diameter in thousands of kilometers.

(8 Apr 1999) New planet bitmaps for Mars, Venus, and Earth, and labelled craters/features on Mars and the Moon: Previously, Guide showed Mars using an ALPO map based on the 1995 opposition of Mars, and Venus and the Earth using bitmaps that basically reflect what a visual observer would see, except that the image of Earth was a "cloud-free" one.

With the new version, you can switch from these maps to ones that show Mars with a 1997 ALPO map; Venus as seen by the Magellan radar-mapping probe; and two new maps of the Earth (one based on topography, the other a "visual" map that includes clouds.) You can select which map is used for which object.

To do all this, you'll need to also download the "Planet Extras" file (about 580 KBytes) and unZIP it in your Guide directory. This file contains the extra images required to get the alternative planet bitmaps, and the files needed to show labelled objects on Mars and the Moon.

Click here for information on how to select a bitmap and labelling of features for each planet.

If you set your "home planet" to someplace other than Earth and look back at the Earth, and use this new feature, Guide will first switch to a view based on topography, then to a "realistic" view with clouds, then back to the initial view.

As it happens, you can also toggle to "alternative" bitmaps for the Moon and Pluto. None of them, however, are particularly helpful.

Features can be added freely to any planet, and to almost all natural satellites. If you want to revise the data for Mars or the Moon, or add features to other planets, click here.

You can right-click on these labelled features, and get "more info" for them. Be aware that both the right-click data and the "more info" are somewhat terse; Guide generally knows the feature name, lat/lon, and (for craters) diameter, and not much else. However, when you ask for "more info", you'll usually get some data on the namesake of a crater. More useful data ("what's the altitude of the sun as seen from this crater? When will the sun rise and set as seen from this crater?") will have to wait for another version.

(8 Apr 1999) Finding and listing planetary features: If you've used the planetary feature display option listed above to show craters and maria on the moon and a few similar features on Mars, you'll naturally start thinking that it would be nice to get a list of these objects, click on one, and have Guide center on it.

To do this, zoom in on the planet in question, and click on "Go To... Planet Feature". Guide will list the currently visible planetary features. (It won't list any feature that would be off-screen or that would be on the far side of the object.) Click on one, and Guide will recenter on that object.

For example, suppose you wanted to find the crater Copernicus. Center on the moon, zoomed out far enough so you can see the whole disk. "Go To... Planet Feature" will list about 750 objects. Select Copernicus, and wait for the redraw. Zoom in to about a ten-arcminute field of view, and you'll get a better view of this prominent crater.

Similarly, if you want a list of all objects in the current field of view, click on "Tables... List Planet Features". The resulting table (as with all Guide tables) can be viewed, printed and/or saved to a file.

(8 Apr 1999) New "slide show" feature: Frank Leiter suggested that it would help, in certain demonstrations he and members of his astronomy club do, if Guide could run through a series of pre-stored views. To accomplish this, a new "slide show" feature has been added.

It works as follows. Imagine that you have stored a set of mark files; one might show Saturn in crescent phase as seen from its satellite Japetus, the next a particular solar eclipse map, the next a view of a RealSky image, and so on. Imagine, too, that you have stored these with names such as "Slide 1 (Saturn/Japetus)", "Slide 2 (Aug 1999 eclipse)", and "Slide 3 (RealSky)".

For your demonstration, you would run Guide and click on "File... Go to Mark", and load the Saturn from Japetus mark. You would presumably discuss the resulting view with the audience, and then hit F7. This new hotkey will cause Guide to immediately load the next mark file, which will be the "Slide 2 (Aug 1999 eclipse)". Repeated presses of F7 will run through your entire slide show.

The slides will be shown in alphabetical order. If you want to jump to slide #7, then you can click on "Go To.. Mark" and load that mark file; hitting F7 will then resume with whichever mark file follows slide #7.

(8 Apr 1999) New LX-200 features: In the Windows software, the handling of LX-200 control has been revised considerably. Previously, you got "Slew Scope" and "Slew Guide" menu options when the LX-200 was enabled; now, a single "Scope Pad" option appears. (This was always the case with encoder-based systems and the Ultima 2000.)

Clicking on "Scope Pad" brings up a small dialog with the "Slew Guide" and "Slew Scope" options. Also, you have four slew speeds ("Slew", "Find", "Center" and "Guide") and four compass-direction buttons, just as with the LX-200 keypad. Choose the "Find" radio button and click on "W", and the telescope will move west at the 'finding' rate.

Clicking on the button in the center of the four compass-direction buttons will stop the slew. (It will also stop slews to objects.)

The "Add Alignment" star doesn't work yet (but should soon; and I expect it to allow Guide to greatly improve the LX-200 alignment. For the first step, Guide will use it to adjust LX-200 pointing in a simple but fairly effective manner; later, the full power of the mechanical error correction system already used for encoder-based systems will be added.)

Also: I know some people would like to make use of the focus and reticule brightness controls on the LX-200. This should be forthcoming. Also, some of the code to let you tell Guide that the LX200 should not be moved in certain places (where there are obstacles it can collide with, or where there are trees blocking the view) is written and should be added to Guide soon.

(8 Apr 1999) Fix to a Y2K bug involving artificial satellites: I had thought that Guide was Y2K-bug free. (Indeed, Guide 7 has been used to investigate phenomena after the year 10000 and before -10000, making it Y10K compliant; and handles numbered asteroids past #10000, making it A10K compliant.) But Igor Rozivika pointed out that artificial satellites were simply not displayed after 12:00 UT, 1 January 2000. This has been fixed.

(8 Apr 1999) Better Russian city data for eclipse mode: Igor Rozivika also supplied a new list of cities in Russian, for use in labelling cities in eclipse mode; and Guide's use of this data has been improved. Click here for details.

(8 Apr 1999) Magellan I control (probably): Frank Honer has kindly mailed a copy of the control codes for the Meade Magellan I encoder system (I'd had no luck trying to get this data from Meade). It appears that the protocol is essentially identical with that for the Meade LX-200, with two crucial differences: (1) only the "read scope position" commands work (since the Magellan I has no motors, the "move scope to this position" commands can't accomplish anything); and (2) the communication is done at 1200 baud (the LX-200 runs at 9600 baud).

If you run Guide and click on "Settings... Scope Control", you'll see a "Magellan I" radio button. Select this, and select the COM port used for your Magellan, and click OK.

A "scope pad" option will be added to the menu bar. Select it, and a small dialog will appear. Whenever you click its "Slew Guide" button, Guide will get the current scope location from the Magellan and re-center Guide's chart on that location. (None of the other buttons in the scope pad do anything yet, as far as the Magellan I is concerned.)

This might work with the Magellan II, also. I think they use the same command set, but I'm not sure of this.

(8 Apr 1999) Improvement for "real time" animation: Running Guide with "real-time" animation can be a bit of a pain. An animation step is taken about twice a second. This is not a bad idea when you're following low-orbiting artificial satellites. But if you are instead following planets or asteroids, or simply want to make sure the position of the horizon is updated from time to time, it is overkill; and such frequent steps consume a lot of the computer processing power.

Therefore, when you enter real-time animation mode now (by clicking "real time" in the Animation menu), Guide will ask you for the frequency of updates, in seconds. If you specify, for example, "60", then once a minute, Guide will update the display to reflect the current time. Since the horizon moves only a quarter of a degree in that time, such an update frequency should be ample. (Though again, for tracking satellites, the default frequency of .5 seconds becomes more reasonable.)

(8 Apr 1999) Still more hotkeys: You can now toggle to Russian by hitting Ctrl-R, or to Japanese by hitting Alt-, (Alt-comma). (These were the only languages without hotkeys.) Alt-[ will bring up the "make list of planet features" option. Alt-] will bring up the "go to a planet feature" option.

Note that these are all available through the menus as well, and that's probably how most people will use them. Only a few specific people (Russian and Japanese-speaking users, and some lunar observers) are apt to make use of these obscure hotkeys.

I'm also aware that the list of hotkeys has grown considerably. Windows Guide has 148 hotkeys; DOS, 168. (Certain combinations can be detected in DOS that Windows ignores.) A full list will be posted. (Possibly, a new feature allowing user configuration of hotkeys will be posted, too.)

(24 Mar 1999) Improvements for hotkeys: In the Windows software, you can now hit Ctrl-0 to center on the Sun, Ctrl-1 on Mercury, and so on, up to Ctrl-9 for Pluto. Ctrl-Minus centers on the Moon.

In DOS, these keys aren't recognized; instead, hitting '=' brings up the Go To Planet dialog, and then simply hitting '0' centers on the Sun, '1' on Mercury, and so forth.

Also, Bruce Andrews pointed out that in some menus, keys were used twice. This has been fixed.

(24 Mar 1999) New options for navigating in the geographic (eclipse) mode: When Guide shows charts of the earth, you'll see a new "Go To" menu and two new options in the Settings menu. The "Go To" menu has a "Go to Country" and "Go to City" option.

"Go to Country" brings up a list of 173 countries. Click on one, and Guide will recenter on it. "Go to City" is similar, but has to handle the fact that there are a lot of cities in the world. To keep the list reasonably short, only those cities that fall in the part of the world currently shown on-screen are listed. For example, to find Adelaide, Australia, you would first zoom in on Australia. "Go to City" would then list only cities in that region, and finding Adelaide in the list would be easy.

The Extras menu now has a "Make List of Cities" option. It works much as the "Go to City" option does, but instead creates a list of cities and their latitude/longitude data, which can be saved or printed.

The Extras menu also now has a "Set Lat/Lon from chart" option. You can zoom in on a given point in the world and click on this new option; when you switch out of eclipse mode, Guide will then use that point as your "viewpoint".

(17 Mar 1999) Use of Guide with the new MPCORB database: Discussion of this feature has moved here.

(17 Mar 1999) Improvements for scope control with encoders: With this version, the order in which certain steps are taken is considerably more logical. To hook Guide up to encoders, you first go into "Settings... Scope Control", select the COM port, resolution, and "JMI/MGIII" radio button, as before. When you then click OK, Guide will try to set the resolution of the encoders, and either report success or give an error condition. All this is as it always was.

Guide will then ask you to choose one of four types of mount: alt/az, alt/az on a platform, RA/dec ("normal" equatorial), or hour angle/dec. This step used to be delayed until the first alignment star was added, which was a little bizarre. The current method should make things a little more intuitive.

(17 Mar 1999) Still more assorted improvements for Russian and Italian users: Several of the translations/extensions of Guide into other languages are more complete now. Igor Rozivika and Alexander Anikeev sent in a file to allow Russian cities to appear in Russian, when in eclipse mode. Andrea Pelloni had already created a similar list for Italian; Giuliano Pinto has now extended it. Also, there are some more corrections provided for the English-language version of the city names.

Alexander Anikeev also translated the calendar data into Russian, so the extra calendar data in "Quick Info" will appear correctly in that language. Giuliano Pinto had already translated that file into Italian, but has fixed a few mistakes I added when I processed that file.

(17 Feb 1999) Workaround for "Make a .BMP" failures: A few people have mentioned having problems with the "Make a .BMP file" option in Guide's 'Extras' menu. When they attempt to make a .BMP file, they get a truncated or corrupted file. This happens in both the 16-bit and 32-bit Windows software.

The cause of this bug remains an almost total mystery, still under investigation. But there are two ways to "work around" the problem. The first makes use of the 'Print Screen' key; click here for details. The other method, regrettably, it only works in the 16-bit (Windows 3.1) software.

To do it, download the Windows 3.1 software at the top of this page and unZIP it in your Guide directory. This software supports both the "usual" way of making a .BMP file, and an "older" method that Microsoft used to support, but dropped in their 32-bit code.

The "older" method will be familiar to Guide 6.0 users. Guide 6.0 ran in 16-bit Windows, so the lack of 32-bit support wasn't a problem. To access it, run the 16-bit Windows Guide software and hit Alt-J. You'll be prompted to enter a test flag number. Type 3 and click OK.

From then on, the 16-bit Windows Guide software will create .BMP files in the "older" method. This means that, when you make a .BMP file, you'll be asked if you want a mono, 16 color, or 256-color image. You'll also be asked for the image size. Aside from this, the process is unchanged.

(17 Feb 1999) Method to make changes to the geographic names on eclipse charts: When you zoom in on charts of eclipses and occultations in Guide (charts of the Earth), Guide will label about 8000 major cities. The list it uses is a modified version of one found at the Bureau des Longitudes in France. The data is stored in the file \GEO\GEONAMES.DAT on the Guide CD.

Andrea Pelloni, a Guide user in Italy, wanted to change a few of names, remove a few, and add a few... in particular, certain city names in Italy that were given French spellings. You will see that the current Guide update .ZIP files contain one file, IGEO_ERR.DAT, that has only the changes (new cities, changed names, etc.) that were made by Andrea Pelloni. When you run Guide in Italian, therefore, you'll see cities in Italy with Italian names (as well as some outside Italy.)

Similarly, there is an English-language EGEO_ERR.DAT file, containing two cities not found in the original name data (Portland, Maine and Bowdoinham, Maine), and the English versions of four cities in Germany. A French-language user could easily make an FGEO_ERR.DAT, and so on. (So far, only the Italian IGEO_ERR.DAT and EGEO_ERR.DAT files exists.)

Editing IGEO_ERR.DAT should make the process used fairly apparent. Here are four example lines:

+37*21' -121*38' 803 Mont Hamilton
+34*13' -118*04' 803 Mont Wilson
+33*21' -116*52' 803 Mont Palomar
+40*01' +009*12' 608 # Limbe

The first three are changed names ("Mount" to "Mont"). The last is a deletion. In each case, the lat/lon is identical to the existing object, followed by the changed name. (In the case of Limbe, the '#' character indicates the city is removed. The 'Limbe' following it is a comment for merely human users, letting you know just what city has been removed.)

(17 Feb 1999, updated 10 July 1999) Ability to switch to larger toolbar buttons: Larger versions of many of the buttons on the toolbar are now available. You can get them by downloading this file into your Guide directory (about 28 KBytes) and unZIPing it. You can then run Guide and toggle between the "usual" toolbar and this new "big" toolbar by hitting Ctrl-U.

These new buttons were created by Andrea Pelloni and Steve O'Leary. If you wish, you can replace toolbar bitmaps (for either the "usual" or "big" toolbar). For example, suppose you wanted to modify the bitmap used for the "Go to Messier" function. Your first step is to edit the file TOOLBAR.DAT; this will tell you that the bitmap used for this function is called GO_MESS.BMP.

If a bitmap with this name is in your Guide directory, Guide will use this for the "usual" toolbar, instead of using the bitmap on the CD-ROM. (This is the reason your Guide directory now contains a file called SET_07.BMP , the toolbar button for "Go to Level 7". Some users found that the level 7 toolbar button didn't appear. Providing the 'new' button fixed this.)

If you create a subdirectory called TOOLBAR2, directly under your Guide directory, and put your new .BMP files in this subdirectory, then Guide will use them for the "big" toolbar. This also allows you to add "big" buttons for functions that currently lack them. (If you create such buttons, please e-mail them to me!)

By the way, in the (many) cases where there is no "big" button, Guide just uses the "usual" bitmaps instead.

(17 Feb 1999) Assorted improvements for languages: The "Toolbar" dialog, where you select which buttons appear on the toolbar, will now display in Russian, Italian, or German when you select one of those languages (otherwise, it stays in English.) Most of the languages supported by Guide are now "up to date" (all menus can appear correctly in that language, with no text left in English). The "Add a Comet" dialog box now shows up correctly in Russian. (Many thanks to the translators for this new data!)

(17 Feb 1999) Fix to an Ultima 2000 bug: Gary Derman e-mailed me a while ago to mention a problem with control of a Celestron Ultima 2000 through Guide. This one puzzled me for a long time, but I've finally worked out the bug (I'm just surprised no one else mentioned it... then again, U2000 users don't seem to be very common.) In any case, the current version of Guide will support the U2000 correctly.

(5 Jan 1999) USNO SA2.0 support: The USNO SA2.0 CD-ROM is a single-CD subset of the eleven-CD USNO A2.0 dataset. A2.0 is difficult to get, since not many copies were made; SA2.0, on the other hand, is widely available.

To use this, you'll need to not only grab the software update above; you'll also have to download this file (about 12 KBytes) into your Guide directory and unZIP it. You'll see that, when you ask for A1.0 data, there will be a radio button to choose A2.0 instead. In this case, "A1.0" and "A2.0" are generic terms for "A1.0 or SA1.0" and "A2.0 or SA2.0". Select the A2.0 button, insert your SA2.0 disk, and Guide will extract data and display it.

Important safety tip: Be aware that SA2.0, as was SA1.0, is of almost zero utility for drawing star charts. It was made by starting with A2.0 and eliminating 90% of the stars, selecting 10% that are of good quality for astrometry, and which are pretty uniformly distributed across the sky. (The idea is to make sure that, no matter where you are in the sky, there will be an adequate number of stars to let you do astrometry.) But the result does not resemble visible star patterns at all well!

It is possible, though somewhat frustrating, to use SA1.0 or SA2.0 with the Charon astrometry software. You can click here for information about doing this.

(5 Jan 1999) "Quick Info" gives date in several calendrical systems: At the bottom of Quick Info, the currently set date is shown as expressed in the Julian, Gregorian, Hebrew, Islamic, and French Republican calendars.

(16 Dec 1998) Level 7 toolbar button fixed: A lot of people have had problems getting the "Go to Level 7" toolbar button to appear. (It is supposed to appear by default, between buttons to go to levels 1, 4, and 10.) The bitmap supplied for that button is to blame; the error is now corrected. (This bug may not show up on your computer to begin with.)

As a minor side benefit: if you don't like a particular toolbar bitmap in Guide, you can replace it with your own bitmap. To see how, edit the file TOOLBAR.DAT; the name of each toolbar bitmap is given. If you create a bitmap with that name, placed in the Guide directory, Guide will use it in place of the "built-in" one. You can also rearrange the order of the toolbar buttons by re-ordering lines in TOOLBAR.DAT. A really small improvement, but I'm sure someone will want to do it...

(16 Dec 1998) Mars features fixed: Two people noticed a rather drastic problem with the features drawn on Mars: the wrong side was shown! For example, if Guide reported (correctly) that the current central meridian on Mars was 43 degrees, the actual features drawn on the chart corresponded to longitude 43+180=223 degrees. This has been fixed. (Other planets weren't affected. The cause was my putting the wrong bitmap for Mars onto the CD.)

(16 Dec 1998) System I and II central meridian data for Saturn: Previously, Guide showed only the System III central meridian for Saturn. This system corresponds to the motion of Saturn's interior, based on radio observations. System III data is also given for Jupiter, Uranus, and Neptune. For Jupiter, System I and II longitudes are given; System I matches the rotation rate near the equator, and System II is used at middle latitudes. (The Great Red Spot longitude is in System II, for example.)

It would seem that System I and II data could be useful for visual observation of features on Saturn, too, but getting the necessary formulae was a daunting task. The Explanatory Supplement to the Astronomical Almanac says (on page 404) that:

"For Saturn only System III [observed rotation of radio emissions; Desch and Kaiser (1981)] rotations are defined... The previously defined System I rotation system has been found to be of little use since the Voyager encounters with Saturn, and is no longer supported by the IAU."

This is reflected in the rotation rates given for Systems I and II on Saturn and Jupiter. The rates for Jupiter are given as 877.900 and 870.270 degrees/day, i.e., a precision of a thousandth of a degree per day. The rates for Saturn are given as 844.3 and 812.0 degrees/day, i.e., a precision of a mere tenth of a degree a day. The implication is that the rotation rates are so poorly known that System I and II longitudes for Satun aren't "stable" over long periods. (But they ought to be perfectly useful for short-term tracking of features on Saturn.)

Jeff Beish kindly provided the formulae needed to do the job, and I added them to Guide. When you click for "More Info" for Saturn, you'll get System I and II central meridians, just as with Jupiter.

(16 Dec 1998) Cities indicated with a red dot in Eclipse mode: Several people have mentioned that, in eclipse mode, it can be nearly impossible to tell where the actual city is. The label can be moved a bit to evade collisions, making things still harder.

So each labelled city is now shown with a small dot. (Should you prefer a different symbol, by the way, edit the file GUIDE.DAT with a text editor. The symbol is defined with the CITY_SYM= line; the format used is the same as that for symbols in user-added datasets, and is described here and in chapter 20a of the users manual.)

(16 Dec 1998) USNO A2.0 support: The USNO A2.0 CD-ROMs came out shortly after the Guide 7.0 CDs were made. Guide has been updated to reflect the changes made in A2.0 (the format was the same, but indices had to be rebuilt and there is an extra CD to contend with.)

To use this, you'll need to not only grab the software update above; you'll also have to download this file (about 120 KBytes) into your Guide directory and unZIP it. You'll see that, when you ask for A1.0 data, there will be a radio button to choose A2.0 instead.

Also, support for the A2.0 in Charon has been added.

(5 Jan 1999) A problem with Guide and the AMD K6, and a fix: Three Guide users have reported getting very strange asteroid and comet positions when running Guide 7.0 (32-bit version) on computers using the AMD K6 chip, instead of the more common Intel chips. The reason for this trouble is not entirely clear; in theory, math run on the two systems should yield identical results. But this is quite definitely not happening.

The solution to this problem is to download and unZIP this file (about 95 KBytes) to your Guide directory. The effect is to replace one of Guide's DLLs, the one that includes most of the math for asteroid/comet computations, with an "unoptimized" version. If you have run into this problem, and simply want to eliminate it, you need read no farther.

Both the above version of the LUNAR.DLL and the "usual" LUNAR.DLL were compiled under Microsoft Visual C/C++. Exactly why one works and the other fails is not known. In general, I have not seen Visual C/C++ produce buggy code (aside from those created by the programmer, of course!) I am by no means an advocate for Microsoft, but their tools generally work.

Visual C/C++, like most compilers, has various options to produce "optimized" code. When these are used, the compiler might look at an expression such as x = a*b+a*c, and recognize that rearranging it to read x = a*(b+c) would require one less multiplication instruction, resulting in smaller, faster code. (Admittedly, these terms "smaller" and "faster" are rarely linked in practice to Microsoft code... perhaps Microsoft does not use their own optimization switches.)

In rare instances, I've seen earlier Microsoft compilers produce bugs when attempting to optimize the code. (In some cases, it turned out that the bug was in my code; optimization just made a "benign" bug into a "malignant" bug.) In such instances, if I found no flaw in my code, I would recompile without optimizations, and all would be well again. That is essentially what has happened here.

I would suspect that the AMD K6 does not handle floating point math in a manner that is entirely compatible with Intel chips, but know little about the details of microprocessors. If anyone has information about this, please e-mail me.