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2004/02/16 (121) Hermione event :
a bi-lobated asteroid and its satellite
occult TYC 1905-00864-1


Eric Frappa (updated : 2004 feb. 15)

On 2004 february 16/17 night, (121) Hermione occults a 9.2 magnitude Tycho star, high in a moonless sky, between epsilon and theta Gemini.


This stellar occultation is one of the most interesting event of these last years : (121) Hermione is a binary asteroid (Merline et al, IAUC 7980) and the main body has a bi-lobated shape (Marchis et al, 2003).


More, it's the first time that a prediction is attempted for an occultation by the satellite of an asteroid (Lecacheux, IAUC 8285).


Montage from Marchis et
al Keck-10m AO images


Predictions for occultation by
(121) Hermione

[ Initial prediction by Edwin Goffin ]
Updated prediction by Jan Manek
Updated prediction by Steve Preston

Detailed geographical maps for this event are in this directory.

Note 1 : these maps are made from Manek 2 and Preston 2 updates (feb. 8).
Central line of Preston 4 is
~20km more south than Preston 2, ~4km more south than Manek 2.

Note 2 : considering the configuration study of Hermione at occultation time (see below), the ground path width could be smaller than the one used in Jan Manek update.



Raoul Behrend (Geneve observatory) and AUDE group observers have determined that the occultation will occur during a minimum of the Hermione light curve.

Using a "snowman" model, Jerome Berthier (IMCCE) shows that the bi-lobated shape of Hermione will not be visible during feb. 16 occultation (animated gif - 173 Ko) :

Cyprus - 22h25 UTItaly - 22h29 UTFrance - 22h33 UT

Prediction for occultation by Hermione satellite (S/2002 (121) 1)

Jean Lecacheux calculations - Read the full story of this first attempt.

Detailed geographical maps for this event are in this directory.

Ground path width : ~18km.
Max duration : ~3s.


UPDATE (feb. 14, 21h17 UT) : J. Lecacheux obtains a 6 km small north shift of the satellite ground track, using improved coordinates for the pole of orbital precession, as determined by Pascal Descamps (IMCCE).

Geographical coordinates list : updated.
Detailed geographical maps : not updated (apply a 1/3 path width shift to the north).

Geographical coordinates for central line of the occultation by Hermione satellite - [text version]

(updated feb. 14)
  UTC        long.     lat.   |    UTC        long.     lat. 
                              |                              
22:26:00    34.920    36.054  |  22:30:36    14.441    42.047
22:26:06    34.454    36.221  |  22:30:42    14.007    42.145
22:26:12    33.990    36.386  |  22:30:48    13.573    42.242
22:26:18    33.527    36.549  |  22:30:54    13.139    42.337
22:26:24    33.065    36.710  |  22:31:00    12.706    42.431
22:26:30    32.605    36.869  |  22:31:06    12.272    42.524
22:26:36    32.147    37.027  |  22:31:12    11.839    42.616
22:26:42    31.689    37.182  |  22:31:18    11.405    42.707
22:26:48    31.233    37.336  |  22:31:24    10.972    42.796
22:26:54    30.778    37.488  |  22:31:30    10.539    42.885
22:27:00    30.324    37.638  |  22:31:36    10.106    42.972
22:27:06    29.871    37.787  |  22:31:42     9.673    43.058
22:27:12    29.419    37.934  |  22:31:48     9.240    43.143
22:27:18    28.968    38.079  |  22:31:54     8.807    43.226
22:27:24    28.518    38.222  |  22:32:00     8.374    43.309
22:27:30    28.069    38.364  |  22:32:06     7.941    43.390
22:27:36    27.621    38.505  |  22:32:12     7.508    43.471
22:27:42    27.173    38.643  |  22:32:18     7.075    43.550
22:27:48    26.727    38.780  |  22:32:24     6.642    43.628
22:27:54    26.281    38.916  |  22:32:30     6.210    43.705
22:28:00    25.836    39.050  |  22:32:36     5.777    43.780
22:28:06    25.392    39.183  |  22:32:42     5.344    43.855
22:28:12    24.948    39.314  |  22:32:48     4.911    43.929
22:28:18    24.505    39.443  |  22:32:54     4.478    44.001
22:28:24    24.063    39.572  |  22:33:00     4.045    44.072
22:28:30    23.621    39.698  |  22:33:06     3.612    44.142
22:28:36    23.180    39.824  |  22:33:12     3.179    44.212
22:28:42    22.739    39.947  |  22:33:18     2.746    44.280
22:28:48    22.299    40.070  |  22:33:24     2.313    44.346
22:28:54    21.860    40.191  |  22:33:30     1.880    44.412
22:29:00    21.420    40.311  |  22:33:36     1.447    44.477
22:29:06    20.982    40.429  |  22:33:42     1.013    44.541
22:29:12    20.543    40.546  |  22:33:48     0.580    44.603
22:29:18    20.105    40.662  |  22:33:54     0.146    44.665
22:29:24    19.668    40.776  |  22:34:00    -0.287    44.725
22:29:30    19.231    40.889  |  22:34:06    -0.721    44.784
22:29:36    18.794    41.001  |  22:34:12    -1.154    44.843
22:29:42    18.357    41.111  |  22:34:18    -1.588    44.900
22:29:48    17.921    41.220  |  22:34:24    -2.022    44.956
22:29:54    17.485    41.328  |  22:34:30    -2.456    45.011
22:30:00    17.050    41.434  |  22:34:36    -2.890    45.065
22:30:06    16.614    41.540  |  22:34:42    -3.324    45.118
22:30:12    16.179    41.644  |  22:34:48    -3.758    45.170
22:30:18    15.744    41.746  |  22:34:54    -4.193    45.220
22:30:24    15.310    41.848  |  22:35:00    -4.627    45.270
22:30:30    14.875    41.948  |                              

Observers

Maps of declared observers location for this event have been drawn by Oliver Kloes, for Spain/France and Italy.

Other links

EAON Hermione occultation page (english)
Jerome Berthier (IMCCE) Hermione page (french)
Massimo Corbisiero Hermione occultation page (italian)
Alfons Gabel Hermione occultation page (german)




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