AMSAT-NA Mir is Coming for Christmas!

Note: this was written in December 1994.

Just a heads up:

Mir begins a series of visible evening passes over North America this month. Most of us will have some excellent evening passes just before and after Christmas. Mir, the Space Shuttle and a couple of the "secret" recon satellites are the brightest objects in orbit. Mir looks like a very bright star moving across the sky. A typical pass is six to eight minutes long, from when you first see it until it disappears into the earth's shadow or fades out near the horizon.

I've found that people are very interested in knowing when and where to look to actually see Mir. I usually use tracking programs to look for good passes and plot them on star maps. Then I announce the times and where to look for the best passes on local 2-meter nets. We never fail to have several dozen people monitoring the repeater when pass time comes and everybody has a great time watching it. (And you can occasionally hear Mir on 145.55 while you watch it go over - an absolutely delightful experience!) You can hardly find a better way to introduce hams to hamsats.

If you'd like to try this, you'll need a tracking program that can calculate visible passes. To see a satellite, it not only has to be above your horizon, but the sun has to be down at your location while the satellite is still in sunlight above you. Most ham oriented tracking software only tells you when the satellite is above the horizon.

I normally use TRAKSAT 2.80 for most of my visual work. It shows orbits on a world map or on a star map. It can also output the data in text form (altitude, azimuth, range, etc) to a disk file. TrakSat 2.80 will work on XTs with Hercules monitors or better and if you have a slow computer you can let it chug away overnight, searching 30 days ahead and saving the results in a disk file you can read in the morning.

Once you've found a likely pass, it helps to plot Mir's path on a sky map. This lets you tell people things like, "Mir will pass through the bowl of the Big Dipper at 7:13 pm", which helps people find it.

If you decide to do this, I HIGHLY suggest you calculate and watch a few passes to get the hang of it before announcing it on the air. There are some pitfalls, such as a pass that looks great on paper, except that it's across the western sky and you're looking at the shadowed side of the space station, which makes it very dim and hard to see. Another problem is that Mir occasionally reboosts - fires its rockets to raise its orbit back up to where it should be. When it does this, of course, your predictions are toast.

Another program is even better for finding visual passes if you can figure out its arcane menu structure. This is SkyMap and it plots "near publication quality" star maps and then plots the satellite's path across them. Once you figure out how to tell it to do so, that is. SkyMap also has a great search routine that finds future visible passes very quickly - again, if you can figure out how to do it.

If anybody has any questions, I'd be happy to help. Email me at djmullen@facstaff.wisc.edu.

Thanks and Merry Xmas,

Dave, N9LTD


Feedback on this page to KB5MU. Thanks to Dave Mullenix, N9LTD, for permission to post his message here.

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