Mir Marathon - SIX visible passes in one night!

Dave Mullenix (djmullen@facstaff.wisc.edu)
Tue, 11 Jun 1996 05:45:58 -0500

Walter Nissen wrote:

>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. 

I would assume that that's once per year for the northern hemisphere
and again six months later for the southern?

>These seasons repeat at the solstice every year, but not always in the 
>same week.  Why not?

I think it depends on Mir's orbit - it has to be making visible passes
near the solstice.  For instance, if the @#$%* weather had co-operated,
I could have seen five passes on Saturday-Sunday, June 8-9, but I don't
_think_ I'll be able to do that later this month because not enough passes
will be during night hours.

>> 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 

>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,

Yep!  That's exactly when those times are for.  I really blew this because
I not only got the date wrong, I didn't give the pass times for the NEXT 
night, when I saw Mir SIX times!  I'd forgotten that myself until I re-read
my log.  (It's kept on computer and those 25 line screens can fool you.)

That was also the night with the very bright skies for the first and last
passes.  Because I no longer trust myself to abstract entries from my log,
here's a copy of the two night's entries.  A few notes: The lines starting
with "*Mir" are output lines from TrakSat's search function.  The asterisk
just means I saw the satellite.  I also have codes for couldn't find it,
clouded out, attacked by skunk, etc.  WPPG and WPBD are two observing sites,
one a block west and one a block north of my home.  Cherokee Marsh is a 
darker site about a mile away.  

The last two lines, which start with "*Sun" are from TrakSat's individual
satellite output.  Why I have two separate lines, with slightly different
times, I no longer remember.  I see that I mention "92.175 Keps" and
"92.178".  Since you said that was a reboost shortly before these
observations, I must have been
checking with the two latest sets of Keps.  "WX Chan" is the weather channel.  
TrakSat times are UT followed by CDT.  Any times in the comments are CDT and
from WWV.  The number after the direction of the pass (e.g. "S TO E 26") is
the maximum elevation of the pass.  I think the numbers after that are the
minimum range to the satellite and the maximum elevation for the pass.

      * Mir Marathon!  Five passes in one night!  Saw them all. *
*Mir          27Jun92 02:52:03 26Jun92 21:52:03  S  TO E   26    851 00:05:03 
    WPPG - bright naked eye, visible almost to E. horizon.  Very clear nite
*Mir          27Jun92 04:27:48 26Jun92 23:27:48  W  TO NE  45    575 00:06:48 
    WPPG - bright, peeking through hole in low clouds
*Mir          27Jun92 06:05:25 27Jun92 01:05:25  NW TO NE  19   1046 00:05:25 
    WPBD - dim, barely visible to naked eye.
*Mir          27Jun92 07:42:22 27Jun92 02:42:22  NW TO NE  22    945 00:05:22 
    WPBD - dim visible.  Sat is 2 minutes behind 92.175 Keps. 92.178 ok
*Mir          27Jun92 09:18:29 27Jun92 04:18:29  NW TO SE  77    416 00:06:29 
    WPBD - Glorious!  Hi, bright.  Found in binocs about 10 degrees high.
      *         Mir Marathon - SIX passes in one night!         *
*Mir Complex  28Jun92 02:01:11 27Jun92 21:01:11  S  TO E   14   1231 00:03:11 
    WPPG - sunset:20:42 Binocs only through thin clouds, not vis to eye,
    obvious in binocs when in field.  Very bright, full color vision, could
    easily read map in light from western sky.  No stars vis to nkd eye
*Mir Complex  28Jun92 03:35:45 27Jun92 22:35:45  SW TO NE  75    422 00:06:45 
    WPPG - High, bright naked eye.  KA9OBP's car broke down 2nite
*Mir Complex  28Jun92 05:13:11 28Jun92 00:13:11  NW TO NE  21    945 00:05:11 
    Cherokee Marsh - dim naked eye
*Mir Complex  28Jun92 06:50:36 28Jun92 01:50:36  NW TO NE  18   1032 00:04:36 
    WPBD - dim naked eye.  9 sec early passing Mirfak
*Mir Complex  28Jun92 08:26:50 28Jun92 03:26:50  NW TO E   45    545 00:06:50 
    WPBD - dim naked eye
*Sun 28Jun92 10:07:00.0   199.65  20.52    970.76  21:16:19 -23:51:09 401  Y
*Sun 28Jun92 10:08:00.0   179.47  14.47   1199.73  22:40:20 -32:24:43 400  Y
    WPBD - binocs in daylight.  Wx chan: Dawn @ 5:20  Very bright sky, no
    stars or planets visible to eye, only Saturn vis in binocs.  Could easily
    read a starmap, full color vision, sky to NE very bright.  Went out 40
    min early, summer triangle & Saturn naked eye.  Mir above horizon abt
    280 deg, peaks 23 deg el under Altair (225 deg), passes 7 d below
    Saturn.  Practiced sweeping up to Altair and Saturn from landmarks.
    5:06:40 AM - couldn't find it passing under Altair.  5:07 AM - found
    it easily just before passing under Saturn.  Followed until 
    5:08 AM, 180 az, 15 elev.  Swept up after taking eyes from binocs twice.

Anyway, this is a more accurate description of my Mir Marathon.  I think that
six visual sightings in one night may be the most possible.  I ran passes
for several different lattitudes a few months ago and the mid lattitudes
seem to be best for seeing Mir.  I sure don't think I'll ever squeeze a
seventh pass
in from here.  

However, I wonder if Mir can be seen in daylight with binoculars or a
telescope? Has anybody tried?  How about Saturn and Jupiter?  If they're
visible in daylight, I think that Mir would be too, given a decent phase
angle.  I'm
not sure if this would give more than six passes, though.  I'm at work and
don't have software to check.

Dave Mullenix, N9LTD