Re: OCS lunar transit

From: Arnold Barmettler (
Date: Mon Apr 10 2000 - 01:34:29 PDT

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    Tristan Cools wrote:
    > The Optical Calibration Sphere(2000-04B) was predicted with Satspy to have
    > a very close pass to the Moon.  In fact when I continued to follow it, the
    > satellite did have a lunar transit !
    > I could not see it at the illuminated side of the Moon but became visible
    > when it was above the unlit side of the Moon.  It went out of transit at
    > 21h14m53s UTC(April 9).  A very short but intense experience !
    > I also have the impression that the OCS sphere isn't very steady.  Some
    > variations are visible on this satellite.  Maybe there is still something
    > attached to it.
    It's good to have another transit observation in the database! Some
    weeks ago I adapted my software to calculate transits with sun and moon,
    and lunar Iridium flares. I saw 2 transits, but did not succeed to see
    lunar flares, mainly due to bad weather (I hope so, at least...).
    For the current elsets (DOY 97) and your position Ryckevelde CalSKY
    +21h15m02.3s OCS             26062U 00004B
                                  Crosses the disk of Moon. Separation:0.05d
                                  Angular diameter: 0.5"  spherical,
    diameter: 3.6m
                                  Center line: 2.59km, az:101.8d ESE
                                  az: 270.1d W  h:  26.2d    dist: 1498.8km
    The sphere was pretty far away and the angular diameter was at its
    resolution limits for earthborn observation, hence I'm curious if there
    exists (unclassified) CCD-images of such small objects projected against
    the sun or the moon.
    What puzzles me is the difference in time of about 10 seconds for your
    observation: what error interval do you expect for the seconds given?
    This night there are 3 other lunar crossings for this site.
    Other recent observation reports of transits are welcome!
    Arnold Barmettler  (including online calculations of lunar flares,
    solar/lunar crossings of Mir, ISS, STS)
    --------------------------------------   .   -------------------------
    Arnold Barmettler, Dipl. Ing. ETH     +    +  Remote Sensing Labs  RSL
    Tel +41 1 635 6525           +       .            University of Zurich
    Fax +41 1 635 6842       *   .                 Winterthurerstrasse 190            *  CH-8057 Zurich (Switzerland)
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