SKYSAT v0.65 by Randy John

SKYSAT is a 16-bit graphical satellite prediction program that also indicates possible flares from IRIDIUM and other satellites. It runs on DOS, WIN3.1, WIN95, WIN98, WinNT, WinXP, OS/2 and SoftWindows (on Mac). A math coprocessor is NOT required. Please let me know if you find any bugs (let me know if it works too). The first thing to test is to see if it predicts anything correctly at all for your location.

This screenshot shows a very good 0.14 degree flare. The 'x' marks where the maximum flare occurs and Venus (blue) has just risen.

 

Mirror angle vs. magnitude.

See my plots of mirror angle vs. magnitude. This is the data collected by Ron Lee (and thanks to all those who contributed) with SKYSAT mirror angles added. Here is a plot. Here is a plot with mirror angles greater than 10 removed to get rid of the noise. Here is a 98k Excel spreadsheet. Here is the raw data (click here). There seems to be a flare which is not accounted for by the three MMA's. Bram Dorreman has seen quite a few of these. If you look at IRIDRPT.TXT you will see some blank mirror angles. I was not able to match up the observation with the elsets that I had on hand either because my elsets were too new to match the older reports or possibly because of a recording error. In any case, the satellite in question just didn't show up at the expected time, if it did, I recorded it.

 

SKYSAT revision history.

Version 0.65 o Extended the planet data to 2025.

Version 0.64 o Changed the web and email addresses.

Version 0.63 o Velocity was incorrectly calculated for hyperbolic orbits.

o Changed the web and email addresses.

o Y2K.

Version 0.62 o SKYSAT.MIR was case sensitive in some circumstances.

o Changed 'Minimum acceptable mirror angle' to 'Maximum…'.

Version 0.61 o Fixed 'date with no time' bug.
Version 0.6 o The orientation and number of mirrors can be customized on a per satellite basis.

o Detects flares from satellites other than Iridium.

o Hyperbolic orbits can be used via state vectors.

o SKYSAT now detects multiple flares per pass.

o Header and trailer information in the elset file is now ignored.

o Optional log file output for Find Flares command.

Version 0.5 o Added support for machines without math coprocessors.

o Added the much requested 'Find Iridium Flare' command.

o Fixed a date display problem.

Version 0.411 o Removed code that accessed COM1. This fixed the OS/2 problem (or anyone with a device (mouse) on COM1).

o Initialized an uninitialized variable.

Version 0.41 o Added error checking to AF.DAT.

o NT DOS window does not get messed up (as much).

o Switched the left/right arrow keys with the up/down arrow keys.

o Added the R command (redraw sky).

o F10 now works during the Order command.

Version 0.4 o Added moon and planets.

o F-keys always work.

o You can go forwards and backwards in time.

o Bigger display.

o More information is displayed.

o More controls added (arrow keys and page up/down).

o More and friendlier error checking.

o Better INT 10 handler (and a reduced need for it).

o Won't blow up if the elset file is too big.

Version 0.32 o There is a new format for LOCATION.DAT. It now includes the default elset file name and a delay period for fast computers.

o Several changes to the README file.

o F-keys work fine with ANSI.SYS (they always did).

o If no standard magnitude is in the elset file a value of 5.5 is used.

o F8 scans for the maximum flare (to the second).

o Much friendlier error messages if the input files are not as expected. This includes the 'error at line 1832781' problem.

Version 0.31 Added F8 (search for flare).
Version 0.3 Handles elset errors more gracefully (well, a first attempt at least).
Version 0.2 Added a symbol for the sun.
Version 0.1 First version.

 

Bugs.

o Error 207. See below.

o In a Win95 DOS window the cursor disappears on program exit.

o In a Win95 DOS window it fails if you run it twice.

o In a WinNT DOS window the screen gets messed up if an error occurs.

 

Downloads:

skysat.zip The package.

You will also need an elset file. See Other web sites below.

 

Auxiliary files:

readme.txt (included in ZIP) Required reading (changes made in 0.62).
algo.txt The IRIDIUM mirror algorithm.
test1.exe A Turbo Pascal program that does nothing.
test2.exe A Turbo Pascal program that prints 'Hello world'.

 

Error 207:

If SKYSAT fails with error 207, try disabling the math coprocessor. To do this, start a DOS window and type 'SET 87=N' then 'SKYSAT'. This only affects the current DOS window and only programs compiled with certain Borland compilers. If you get this error, please help by sending me information about your CPU manufacturer and type.

 

Reporting errors:

When reporting errors please include the version number. If you are using the most recent version it will be helpful for me to have the error address (xxxx:yyyy), I can usually get the line number from this. It may be necessary to collect the error message in a file. To do that, just run "SKYSAT > K.DAT" and the output will be redirected into the file called K.DAT which you can then mail to me.

 

Other web sites:

Visual Satellite Observers home page Lots of information on satellites, including pointers to elsets.
Iridium flare page at VSOHP Iridium information and Rob Matson's IRIDFLAR.
Heavens Above Web based Iridium flare predictions.

 

Send mail to skysat@comcast.net.

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