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.