Update to Guide 8.0

(2010 Jul 12) Fix to problem with getting comet/asteroid updates: The Minor Planet Center, the source for Guide's updates to comet and asteroid data, was hacked in February. Since then, the files used by Guide haven't been updated. (They are still present on the old MPC servers, so when you use Guide's update functions, you get a mid-February version of the update. So it seems as if you've been updated, but you really haven't.)

This is now fixed.

(2010 Jul 12) Some new satellites of outer planets: In the Go To... Planets list, you'll see several new satellites listed. Several existing ones have been updated (for example, Nix and Hydra were previously based on some pretty shaky ephemerides.) Far more objects really ought to appear, but supporting them would require pre-integrated ephemerides that are rather bulky. They'll appear in Guide 9. If you've a particular interest in being able to access these objects, please let me know, and I'll e-mail you the files.

(2010 Jul 12) Ability to limit number of asteroids shown: The Asteroid/Comet Options dialog now has a check-box to "show all asteroids". Un-check this, and an option to limit the number of asteroids shown becomes enabled. Thus, you can tell Guide to show (for example) only the first thousand, or 10000, or ten, numbered asteroids.

The reason for this is that the total number of asteroids in mpcorb has gotten to the point where, if Guide is attempting to draw them at all times, things can bog down. This is especially true if you change the date and time a lot. There is a lot of clever code in Guide dedicated to ensuring that a half million asteroids can be displayed briskly, but even with these tricks, you can find yourself waiting a few seconds for the screen to update. Limit Guide to showing, say, 30000 asteroids, and things become about ten times faster. And many users are not interested in full asteroid display anyway.

(2010 Jul 12) Ability to sync ASCOM scopes: If you've set up Guide to control your scope via ASCOM, you can now sync the scope to Guide. To do this, move around in Guide so that the center of its screen matches the center of the scope's field of view. (For example, if M57 was in the center of the scope's field, you would center M57 in Guide, too.) Then, click on the Add Alignment Star button in the Scope Pad.

(2010 Jul 12) SDSS-7 used in place of SDSS-6: If you go into the Settings... Toolbar dialog, you'll see that the last entry is "Download SDSS Release 7 data". The new release covers slightly more of the sky. (Ideally, Guide would have some way to show you the area that's covered -- it's quite irregular -- but I've not found any sort of coverage chart in a vector form suitable for the purpose. You basically have to use the download button and see if anything appears.)

(2010 Jul 12) UCAC-3 numbering modified: UCAC-3 has rapidly passed from its original designation scheme to an alternative, and a new, final scheme has been settled upon.

Originally, UCAC-3 stars all had numbers ranging from 1 to slightly over 100 million, giving each star a sequential number with no gaps. Then VizieR chose the MPOS number, which runs from 1 to slightly over 140 million, with many gaps. The final decision, made by USNO, was that a UCAC-3 identifier consists of '3UC' followed by a three-digit zone identifier running from 1 to 360, a dash, and six digits. Thus, '3UC314-159265' would be the 159265th star in zone 314.

Guide will now show the correct identifier for all UCAC-3 stars, both when shown from the original data files and from VizieR downloads.

Also, if you have the UCAC-3 data on your hard drive, you can use Go To... Object name and enter (for example) "3UC314-159265", and Guide will find the relevant star.

Also, the 'more info' section is more informative, with some UCAC-3 specific glossary definitions.

(2010 Jul 12) Ability to generate lists of on-screen asteroids: Alan Cahill made a request on the Guide user list for the ability to have the Tables... Current Asteroids list limited to the area currently on the screen. This struck me as an excellent idea. I don't have a really good solution for it, but for the nonce, one can do this: Use Tables... Current Asteroids, and enter the desired magnitude limit followed by an asterisk (*).

Hence, entering (say) "17" would get a list of all asteroids currently at mag 17 or brighter, around the entire sky. Entering "17*" would limit that list to those asteroids in the current field of view.

This also applies to comets.

(2010 Jul 12) Ability to download UCAC-3 data from VizieR: Guide already has the ability to download pieces of large datasets from VizieR. In August 2009, the UCAC-3 star catalog was released by USNO, and then appeared on Vizier. UCAC-3 is likely to become the star catalog of choice for stars too faint to be listed in Tycho-2; it's a major leap forward in star catalog technology, making UCAC-2 and all forms of GSC obsolete.

With this update to Guide, one can zoom in on a small area and download UCAC-3 data for just that region. To do so, use Extras... Get Star Catalog Data... Get UCAC-3 Data. After a pause to download the data, it will be superimposed on the Guide chart; you can then right-click on UCAC-3 stars and get "more info" about them.

Alternatively, one can go into Settings... Toolbar, scroll down about 3/4 of the way through the list of toolbar buttons, and turn on the "UCAC-3 data via Internet" toolbar button.

Thanks go to John Greaves for helping to get this feature to work.

(2010 Jul 12) Ability to display UCAC-3 data from DVD or hard drive: You can get the entire UCAC-3 from this Vizier site. The actual data is in the 360 .bz2 files. You'll have to download all of them, then decompress them with the archiving utility of your choice. In decompressed form, they consume a bit more than 8 GBytes, and the compressed form is not a lot smaller.

If the idea of downloading many gigabytes of data is daunting, you can request that the data be sent to you on a double-sided DVD. E-mail ücác3@usnô.nåvy.mìl (removing diacritical marks, of course!) to request a disk.

Once you have the data, you can have Guide show UCAC-3 data, either straight from the DVD or by copying the files to a folder on one's hard drive. (The latter should be faster, and will enable all the files to be available at once; when reading from the DVD, one can only "see" half the sky at any given time.)

With this update, you can put the UCAC-3 DVD in the DVD drive, start up Guide, and it will automatically display data from the DVD. If you copy the UCAC-3 files to a folder on your hard drive, you'll need to tell Guide what that folder is. To do so, run Guide, hit Alt-J, and enter a line such as


Guide will then look in that folder, instead of to the DVD.

(2010 Jul 12) Small improvement and a fix to distance/position angle display: When you drag a line with the mouse to measure the distance and position angle between two points on the screen, or right-click on two objects and hit Insert to get the same data, you previously got just the distance and PA, plus the differences in RA and dec in degrees, arcminutes, and/or arcseconds. Jeff Buell pointed out that it might also be helpful to get the difference in RA in units of time, and this is now shown.

This can be useful, in particular, to visual observers: if two objects are at similar declinations but separated by 67 seconds of RA, one can go to the first object, wait 67 seconds, and the second object will drift into view. (This assumes an undriven scope, of course.) Also, some people measure double star separations in a similar manner, timing how long it takes between star A and star B drifting past a reticule.

These points led me to realize a little bug in this procedure. The angular separation between two points is unaffected by your choice of coordinates: if two stars are 3.14159 degrees apart, they will be that far apart in J2000, B1950, apparent coordinates of date, etc. But the position angle and the separations in RA and dec do depend on the choice of epoch. No one would normally notice it (and, in fact, nobody has in the years this function has been available). But it does cause a small error, and this is now fixed: if you click on two objects, then Num-0, then change the epoch shown in the legend and hit Num-0 again, all the numbers (except the angular separation between the objects) will change slightly.

(2010 Jul 12) Printing from help/more info fixed: For an embarrassingly long time, this function was almost completely broken, working on only a few types of (mostly older) printers. You now will get the standard Windows printing dialog, and can select the printer and page(s) to be printed, and it all should Just Work.

(2010 Jul 12) Fix for an asteroid display problem: Andy Puckett pointed out that asteroids would sometimes disappear when using MPCORB. This happens when one displays asteroids for a given date, and changes that date by a few weeks. If you change it by more than about a month, there's no problem (in fact, if asteroids vanish, you can advance by a month, then go back a month, and asteroids will reappear.) This proved to be a bug in Guide's code to speed up asteroid display, and is fixed.

(2010 Jul 12) Fix for a daylight "saving" time problem: This year, DST began in the United States on 8 March. Except in Guide, where DST starts on 15 March. Apparently, the Microsoft C library used in Guide does not properly handle situations where the month in which DST changes starts on a Sunday. That hasn't happened since 1998, which is why this bug slid past me.

Oddly enough, this bug affects certain time functions, but not others. (Specifically, _ftime() is off by one hour, but time() is correct.) I was therefore able to work around this issue.

Alternatively, one can use the fix described here, setting TOFFSET=-1. Or one could wait until Sunday.

(2010 Jul 12) Extended command-line options: Certain command-line options didn't work correctly, as Peter Suma pointed out on the Guide user list. This has been fixed; the options listed here all ought to work correctly now.

(2010 Jul 12) Fix for crashes at startup time: Guide had a bug that could cause it to have a fatal crash when it started. I had no reports of it actually crashing; I never saw it until I started running Guide in Wine in Linux. (Click here for more on running Guide in Wine.) But if you see such crashes, this update should fix them.

(2010 Jul 12) Revised caption handling: The Legend dialog now contains a multi-line edit box wherein one may compose a caption. Previously, there was an "add caption line" button, which prompted you to add a new line of text; and a "clear caption" button which cleared all the text. This was limiting and counterintuitive. I'm embarrassed to admit this, but the only reason it worked that way was that in the original DOS version, I had no multi-line edit control. For some reason, it didn't occur to me that the Windows version need not be similarly limited.

(2010 Jul 12) Display of comments from Hipparcos update: Recently, the Hipparcos data was re-analyzed, resulting in more accurate information about the distances, parallaxes, and proper motions of bright stars. (The new figures have roughly half the error of the old, sometimes better than that.) To display these new data in Guide, you should download this file (about 8.7 MBytes compressed) to your Guide folder. It will probably be decompressed automatically by your browser; if not, decompress it.

When you click on a star with Hipparcos data (most stars brighter than about magnitude 8), "more info" will show the usual Hipparcos data. Just below this will be a section titled "Remarks from 'new' Hipparcos". Be warned that at present, there's not much data shown. A revised parallax is shown, for example, but that's not reflected in the distance and luminosity computed by Guide. For those figures, the. original Hipparcos data is still used. This will be fixed.

(2010 Jul 12) Ability to show "star trails": Scott Degenhardt requested the ability to click on a star, then add a "trail" showing what stars would be at that particular alt/az for a given time span. He has a very specific application for this: he sets up several telescopes in scattered places to observe occultations of stars by asteroids. Thus, he might visit a given place a few hours before the actual occultation, and want to point the telescope at a star field, with the scope's drive shut off. When the actual occultation occurs, the star and asteroid should be drifting through the scope's field of view.

So Scott basically needed a trail extending from the star to the west, showing what stars would be passing through that particular alt/az in the hours before the occultation. To do this, he would first set up Guide to show the star and target asteroid at the time of the occultation. (Perhaps the easiest way to do this would be to use the table of asteroid occultations for 2010: one would go to Tables... Miscellaneous Tables, select the 2010 occultations, perhaps type the name of the asteroid to find it in the list, and click on the highlighted text. Guide would reset to that date/time and center on the event.)

Next, right-click on the target star. Hit Alt-J; you'll be requested to "enter test flag". Enter 1.

You can now go into Animation... Add a Trail. Set a negative step size (remember, we're interested in the hours before the occultation), and generate the trail. It will point to the west of the star. If you find a particular field of interest ("gee, it would be nice to just point at this bright, easily-found star"), you can right-click on the trail at that point to get the time at which it will be passing through the correct alt/az.

This has turned out to be useful to several people observing asteroid occultations using video cameras.

(2010 Jul 12) Fix to CCD frame rotation bug: Kevin Cooper pointed out that if one sets a non-zero "rotation" angle in the Inversion dialog, then attempts to rotate the CCD frame with the mouse don't work correctly. This is fixed.

(2010 Jul 12) Leap second for end of 2008 added: Of interest only to precision nuts: it was recently announced that a leap second will be added at the end of 2008. . On 31 Dec 2008, 23:59:59 will be followed by 23:59:60, followed by 1 Jan 2008 0:00:00. This is the first leap second to be added in two years. Guide now includes this leap second in its calculations.