RE: Rosetta Obs

From: Ted Molczan (molczan@rogers.com)
Date: Thu Mar 03 2005 - 09:39:29 EST

  • Next message: Bill Dillon: "Re: Rosetta Obs"

    Joseph A. Dellinger posted obs by Bill Dillon at the George Observatory near
    Houston, Texas:
    
    Rosetta       C2005 03 01.18294 11 06 40.09 +02 24 00.0          17.0 R      735
    Rosetta       C2005 03 01.19055 11 06 37.60 +02 24 03.7          17.0 R      735
    Rosetta       C2005 03 01.19689 11 06 35.47 +02 24 06.6          17.0 R      735
    
    > the mags are really "unfiltered", but "R" is a good approximation.
    
    Mag 17 is very bright for the range, about 0.0089 A.U. (1.33 million km). See
    appended ephemeris. My formula predicts mag 21. Had the object been only 1000 km
    away, it would have been mag 1.4, unlikely for Rosetta's non-specular, 2.8 x 2.1
    x 2.0 m box-like body.
    
    Rosetta's low phase angle, 6.8 deg (see S-T-O column in ephemeris), meant that
    the observer was almost directly between it and the Sun. Since its large solar
    array (32 m span) is aimed at the Sun, it seems likely to have been flaring,
    i.e. sending a bright specular reflection toward the observer. Imagine an
    observer on Earth between the Sun and Rosetta in this artist's conception:
    
    http://satobs.org/seesat_ref/Rosetta/Rosetta.jpg
    
    The unusually bright obs at Czechia, some 22 h later, was made under similar
    conditions, with phase angle near 5.8 deg:
    
    http://satobs.org/seesat/Mar-2005/0022.html
    
    Ted Molczan
    
    
          Target Body: Rosetta (Spacecraft)
    Observer Location: Houston, TX
          Coordinates: 9521'37.1''W, 2945'25.9''N
    
      From: A.D. 2005-03-01 04:23 UT
        To: A.D. 2005-03-01 04:44   
                            
    *******************************************************************************
     Date__(UT)__HR:MN     R.A._(ICRF/J2000.0)_DEC         delta    deldot    S-T-O
    *******************************************************************************
     2005-Mar-01 04:23     11 06 39.86 +02 23 54.2  0.0089222014  -4.19264   6.8419
     2005-Mar-01 04:24     11 06 39.64 +02 23 54.6  0.0089205194  -4.19124   6.8406
     2005-Mar-01 04:25     11 06 39.42 +02 23 54.9  0.0089188379  -4.18984   6.8393
     2005-Mar-01 04:26     11 06 39.19 +02 23 55.2  0.0089171571  -4.18843   6.8380
     2005-Mar-01 04:27     11 06 38.97 +02 23 55.5  0.0089154768  -4.18702   6.8367
     2005-Mar-01 04:28     11 06 38.74 +02 23 55.9  0.0089137970  -4.18560   6.8354
     2005-Mar-01 04:29     11 06 38.51 +02 23 56.2  0.0089121179  -4.18418   6.8341
     2005-Mar-01 04:30     11 06 38.29 +02 23 56.5  0.0089104393  -4.18275   6.8328
     2005-Mar-01 04:31     11 06 38.06 +02 23 56.9  0.0089087613  -4.18132   6.8315
     2005-Mar-01 04:32     11 06 37.83 +02 23 57.2  0.0089070838  -4.17988   6.8302
     2005-Mar-01 04:33     11 06 37.60 +02 23 57.5  0.0089054070  -4.17844   6.8289
     2005-Mar-01 04:34     11 06 37.37 +02 23 57.8  0.0089037307  -4.17700   6.8276
     2005-Mar-01 04:35     11 06 37.14 +02 23 58.2  0.0089020550  -4.17555   6.8263
     2005-Mar-01 04:36     11 06 36.90 +02 23 58.5  0.0089003799  -4.17410   6.8250
     2005-Mar-01 04:37     11 06 36.67 +02 23 58.8  0.0088987054  -4.17264   6.8237
     2005-Mar-01 04:38     11 06 36.44 +02 23 59.1  0.0088970314  -4.17118   6.8224
     2005-Mar-01 04:39     11 06 36.20 +02 23 59.5  0.0088953581  -4.16971   6.8211
     2005-Mar-01 04:40     11 06 35.97 +02 23 59.8  0.0088936853  -4.16824   6.8198
     2005-Mar-01 04:41     11 06 35.73 +02 24 00.1  0.0088920132  -4.16676   6.8184
     2005-Mar-01 04:42     11 06 35.50 +02 24 00.4  0.0088903416  -4.16529   6.8171
     2005-Mar-01 04:43     11 06 35.26 +02 24 00.7  0.0088886707  -4.16380   6.8158
     2005-Mar-01 04:44     11 06 35.02 +02 24 01.1  0.0088870003  -4.16232   6.8145
    
    
    
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