I am pleased to be able to pass along these interesting details kindly
provided by the observer.
Cheers.
Walter Nissen
-81.8637, 41.3735, 256 m elevation
---
TELESCOPIC OBSERVATION OF ISS TRANSIT OF MOON
Geoff Chester predicted that ISS would transit the 73 deg altitude
Moon as seen from my south Arlington, VA neighborhood. Since a telescope
can easily be set on the Moon before the event, I used this opportunity
to try the Nissen challenge of using a telescope to observe the visual
angular extent of ISS (International Space Station).
I used a 15 cm richest-field f/5 Newtonian reflector at 24x which
gave a 3 deg field of view and observed from my patio at
282.9111 deg E long
38.8324 deg N lat 1927 North American datum
59 m above mean sea level.
I set the telescope so the Moon was at the edge of the field. The sunlit
ISS would move through the center of the field against dark sky before
transiting over the dark (but visible) portion of the disk and then onto
the sunlit portion of the gibbous Moon.
ISS passed through the field at the predicted time 2001 Nov 7 10:26 UT
(Wednesday morning local time). It showed a white, irregular shape of
definite size with no particular elongation. I was startled by its sudden
appearance and rapid motion (3 s to cross the field), so I did not
carefully observe the shape, but I did note a "notch" in the image. ISS
was definitely observed against the Moon's dark disk, which proves that
the Moon is at a higher elevation than the International Space Station!
My crude estimates of the ISS image "diameter" are:
1/6 of long diameter of the dark lunar crater Grimaldi (86 arc-sec from
scaling lunar chart), so ISS image diameter = 1/6 x 86 = 14.3 arc-sec
1/3 diameter of Jupiter (42.9 arc-sec D)
so ISS image diameter = 1/3 x 42.9 = 14.3 arc-sec
2/3 diameter of Saturn (20.3 arc-sec D)
so ISS image diameter = 2/3 x 20.3 = 13.5 arc-sec
Average of crude estimates = 14 arc-sec ISS image "diameter"
Just past culmination, my naked eye estimate is that ISS brightness
is 1/4 magnitude fainter than Sirius (V mag = -1.46),
so ISS V mag = -1.46 + .25 = -1.2 .
*********************************************************************
Using Walter's predictions,
I also observed ISS on 2001 Oct 25 22:48 UT (Saturday evening local time)
from the U.S. Naval Observatory in Washington, DC. Few objects were
visible in the twilight. At culmination ISS was as bright as Vega and
had the same white color, so ISS V mag = 0.03 .
ISS then appeared to pass very near to Mars (RA 20h 05m 41s,
dec -22d 36.3m) passing less than 0.1 deg above the planet. ISS appeared
to be 1/4 mag fainter than Mars (V mag = 0.0),
so ISS V mag = 0.0 + .25 = 0.2 .
Astrodynamically yours,
Victor J. Slabinski
-----------------------------------------------------------------
Unsubscribe from SeeSat-L by sending a message with 'unsubscribe'
in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org
http://www.satellite.eu.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Mon Nov 12 2001 - 13:55:24 EST