geoflashers : prograde or retrograde spinning ?

From: Kurt Jonckheere (
Date: Thu Dec 26 2002 - 07:46:03 EST

  • Next message: Kevin Fetter: "RE: New Russia Launches"

    hello all,
    thanks to the recent interesting discussions on geo-flashers and some
    analysis of flash periods of Gorizont I did for the BWGS meeting
    (I will report on this later), I'm trying to get out of lurking status again
    A while ago (in fact 10 May 1999), during some synodic effect discussions,
    Rob proposed to try to find out the direction (prograde/retrograde) of the
    spin axis of a geostationary flashing satellite by making timings from
    observation sites separated by at least 20 degrees longitude.
    Anyhow, as the Gorizont satellite body is cylindrical, I find it difficult
    to explain flashes assuming it rotating along the longest satellite body
    axis(spin).  So I assume it is rotating along the short satellite
    body axis("tumble"), which is also the long solar array axis
    (the paddlewheel like Rob calls it).
    If the rotation axis is more or less parallel to the earth axis then flashes
    over America will occur some X seconds later OR earlier than over Europe.
    If the rotation axis is more or less in the equatorial plane, then flashes
    will probably be seen at about the SAME time at both locations.
    (please correct me if I got messed up somewhere...:-)
    So doing this check will give some rough idea on how and around what
    axis these birds are rotating, notice that all of these are retired.
    Rob or Bjoern can do some nice things with these obs...
    Right now, Gorizont 14 (87- 40 A = 17969) and 23 (91- 46 A = 21533) are
    visible from Europe and are low in the East for the Americans.
    Also Gorizont 17 and Radua 27 are visible from Europe and will
    move to the West in the next week or so.
    Yesterday, I observed Gorizont 23 flashing at mag +8, with a period of
    about 55 seconds.  Unfortenately, wheather isn't good, so I don't know
    if the others are easily to see for the moment.
    This time of the year is also holiday season for quite a few I suppose,
    so the ideal moment, to organize some simultanous Europe - US
    geo observing session.
    People interested from one of both sides can contact me off-list
    to define a target observing window and some target satellites
    (currently Gorizont 14 and 23).
    Kurt (
    Unsubscribe from SeeSat-L by sending a message with 'unsubscribe'
    in the SUBJECT to

    This archive was generated by hypermail 2b29 : Thu Dec 26 2002 - 07:55:45 EST