Mir Marathon seasons, pretty ancient history
Walter Nissen (dk058@cleveland.Freenet.Edu)
Sun, 9 Jun 1996 18:24:09 -0400
> From: djmullen@facstaff.wisc.edu (Dave Mullenix)
> Subject: Mir Marathon
> To: amsat-bb@amsat.org, seesat-l@iris01.plasma.mpe-garching.mpg.de,
> colston@viagrafix.com (Lloyd Colston) relayed a message written
> by Dale Ireland to the amsat-bb mailing list:
> > Subject: WATCH MIR ALL NIGHT
> > Date: Wed, 05 Jun 1996 07:47:39 -0700
> >Newsgroups: sci.astro
> > From: Dale Ireland <direland@olympic.net>
> >Once a year the orbit of the space station MIR and the Earth's
> >inclination combine to produce a situation such that MIR nearly
> >follows the day-night terminator throughout it's orbit and so
> >is visible all night on every pass.
Thanks for mentioning this on SeeSat-L in a timely fashion.
The season for this phenomenon occurs only once a year for any specific
place, but, being related to the summer solstice, if you measure by the
calendar, these seasons come twice a year, near the summer solstices in
both Northern and Southern hemispheres.
QuickSat tells me with great precision what I can see from any particular
place during any particular slice of time, but the subject of general
visibility (is that a recognized term? I mean the questions of seasons of
visibility at various latitudes) has always been a bit mysterious to me.
I think I understand about these Mir Marathon seasons, but there may be
others who can correct or amplify.
These seasons repeat at the solstice every year, but not always in the
same week. Why not? There are numerous favorable nights in each season
near the ideal latitude. What is that latitude? Does that latitude vary
from year to year? Is there a "night" when Ron Dantowitz can pick it up 6
times in his rig, or even 7? Probably, but maybe Boston is too far North?
But even from an ideal latitude, it might not be possible every year, due
to weather.
> It may be possible to see
> >as many as 4 consecutive passes theoretically 5.
> Not just theoretically, it has been done. I saw Mir on five
> consecutive passes on the night of June 27-28, 1992. The passes
> were at 21:52, 23:27, 01:05, 02:42 and 0418 CDT (UT -5 hours)
> from Madison, Wisconsin, (-89.3819,43.0730).
2 52
4 27
6 5
7 42
9 18
> The first and last passes were in very bright twilight and
> required 7x50 binoculars to see Mir against the blue sky. The
> sun was barely below the horizon and there was enough light to
> easily read a newspaper and for full color vision. Mir was
> completely invisible to the naked eye on both the first and last
> pass.
I'm having a hard time reconciling all these details. Is it possible you
have done this more than once? The times you give are more consistent
with the previous night, which was only a day or 2 after a reboost, so
SPACECOM MM and drag factors were unstable, and hence unreliable. I
cobbled together this elset, which should be accurate to within a few
seconds in time:
Mir
1 16609U 86 17 A 92179.81981424 .00014453 00000-0 19928-3 0 387x
2 16609 51.5984 193.5233 0016999 217.5562 142.4233 15.55988427363931
I didn't waste any time computing the seriously, and increasingly,
obsolescent check digit.
QuickSat gives:
43.073 89.382 1000. Madison <----------- 1950 9.5 4 F F F F F
*** 1992 June 27 *** Times are UT *** 244 914
H M S TIM AL AZI C U MAG REVS HGT SHD RNG EW PHS R A DEC
16609 Mir Complex .1
2 56 33 .0 27 139 C 51 .1 -10.5 420 102 826 1.4 15 1745 -10.1
4 32 54 .0 44 335 C 66 .2 -9.4 418 118 587 2.0 115 1139 72.0
6 9 50 .0 19 353 C 84 2.6 -8.4 416 178 1051 1.2 136 735 65.6
7 47 3 .0 23 14 C 102 2.2 -7.3 413 266 929 1.3 136 548 66.7
9 23 48 .0 84 33 C 119 -1.1 -6.3 410 339 412 3.0 87 22 7 47.7
The first pass would hardly have been affected much by twilight. For
someone who earlier tracked it 19 over 353, the last pass should have been
pretty easy naked-eye, unless it was hazy.
Here are the next two nights, but I don't know if they fit any better.
*** 1992 June 28 *** Times are UT *** 244 915
H M S TIM AL AZI C U MAG REVS HGT SHD RNG EW PHS R A DEC
16609 Mir Complex .1
2 2 45 .0 15 134 C 47 1.4 4.5 420 216 1230 .9 12 1737 -18.6
3 38 52 .0 75 330 C 61 -1.0 5.6 419 184 434 2.8 89 1512 55.6
5 15 39 .0 22 347 C 78 2.3 6.6 417 176 957 1.3 134 746 66.7
6 52 52 .0 19 8 C 96 2.6 7.7 415 206 1036 1.2 137 6 1 65.5
8 29 47 .0 48 26 C 114 .1 8.7 412 261 543 2.1 116 121 70.7
*** 1992 June 29 *** Times are UT *** 244 915
H M S TIM AL AZI C U MAG REVS HGT SHD RNG EW PHS R A DEC
16609 Mir Complex .1
2 44 52 .0 59 144 C 57 -1.1 20.5 420 273 484 2.5 49 1628 16.2
4 21 28 .0 28 341 C 73 1.6 21.6 418 221 808 1.5 131 817 69.1
5 58 38 .0 18 2 C 91 2.8 22.6 416 186 1081 1.2 137 6 6 65.3
7 35 40 .0 31 21 C 108 1.2 23.7 413 189 737 1.6 128 356 69.7
9 12 10 .0 45 217 C 124 -.9 24.7 410 220 563 2.1 35 20 2 3.9
Cheers.
Walter Nissen dk058@cleveland.freenet.edu
---
Never throw away an elset.