Re: Followup: GRO Question

From: Bjoern Gimle (b_gimle@algonet.se)
Date: Tue May 30 2000 - 03:09:49 PDT

  • Next message: Bjoern Gimle: "Serious mistake Re: GRO Question"

    There are some inconsistencies between
    > http://pao.gsfc.nasa.gov/gsfc/gnews/052600/052600.htm#cgro
    and
    > http://spaceflightnow.com/cgrodeorbit/index.html
    and current elset at Alan Pickup's site:
    GRO              7.7  5.0  4.6  4.3 d   55       487 x 481 km
    1 21225U 91027B   00149.54294176  .00007277  00000-0  25715-3 0  8202
    2 21225  28.4609 114.0473 0004497 174.8580 185.2013 15.27184231390411
    
    The web sources give apogee as 508,510,511,512 km, elset and Orbitel gives
    487 km.
    SpaceflightNow gives the first burn time as 02:54 UTC (EDT+5h), but
    remaining times as EDT+4h
    According to the elset above, apogee is passed 01:52.
    OTOH, there is no need to fire at apogee for a near-circular orbit.
    The first burn is probably to place the perigee (or the final 80 km height)
    at the right latitude for June 4.
    Perigees are given as 508,349,249,150 km (computed) 510,350,250,150 km vs.
    356,253,150 km.
    There was also to be an engineering test burn on May 28. The elset above,
    epoch Apr 28 at 13 h UTC, is also the last available at OIG, and there is no
    indication of a change from the previous elsets, except natural decay.
    
    If the current apogee is accepted, the test burn neglectable, the 30 minute
    burns distributed as 9,7,7,7 minutes, and 349 km accepted as the new perigee
    height, Vec2TLE gives me:
    
    GRO  -36.9                                       487 x 349
    1 21225U 91027B   00153.07916667  .00018222  00000-0  25715-3 0  8214
    2 21225  28.4609  90.0130 0101388 220.8940 180.3101 15.49471557390961
    
    after the first burn,
    
    GRO  -28.8                                       487 x 249
    1 21225U 91027B   00154.11180556  .00070148  00000-0  25715-3 0  8226
    2 21225  28.4610  82.7512 0176640 232.9526 180.3094 15.66861298391126
    
    after the second.
    
    -- bjorn.gimle@tietotech.se (office)                         --
    -- b_gimle@algonet.se (home)  http://www.algonet.se/~b_gimle --
    -- COSPAR 5919, MALMA,    59.2576 N, 18.6172 E, 23 m         --
    -- COSPAR 5918, HAMMARBY, 59.2985 N, 18.1045 E, 44 m         --
    -- SeeSat-L / Visual Satellite Observer Home Page found at   --
    -- http://www2.satellite.eu.org/satintro.html      --
    
    
    
    
    
    -----------------------------------------------------------------
    Unsubscribe from SeeSat-L by sending a message with 'unsubscribe'
    in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org
    http://www2.satellite.eu.org/seesat/seesatindex.html
    



    This archive was generated by hypermail 2b29 : Tue May 30 2000 - 03:11:44 PDT