J/A+A/545/A144 Astrometric observations of Deimos (Pasewaldt+, 2012)
New astrometric observations of Deimos with the SRC on Mars Express.
Pasewaldt A., Oberst J., Willner K., Waehlisch M., Hoffmann H., Matz K.-D.,
Roatsch T., Hussmann H., Lupovka V.
<Astron. Astrophys. 545, A144 (2012)>
=2012A&A...545A.144P 2012A&A...545A.144P
ADC_Keywords: Planets ; Positional data
Keywords: astrometry - ephemerides - planets and satellites: individual: Deimos
Abstract:
Between July 2005 and July 2011 Mars Express performed 50 Deimos
approaches. 156 SRC images were acquired and used for astrometric
(positional) measurements of the small Martian satellite. For this
study, we have developed a new technique, where the center-of-figure
of the odd-shaped Deimos was determined by fitting the predicted to
the observed satellite limb. The prediction of the limb was made based
on the moon's known shape model. The camera pointing was verified and
corrected by means of background star observations. We obtained a set
of spacecraft- centered Deimos coordinates with accuracies between 0.6
and 3.6km (1 sigma). Comparisons with current orbit models indicate
that Deimos is ahead or falling behind its predicted position along
its track by as much as +3.7km or -4.4km, respectively, depending on
the chosen model. Our data may be used to improve the orbit models of
the satellite.
Description:
Astrometric measurements were obtained from frame images of the SRC on
Mars Express. Camera pointing was controlled and corrected with
background star observations, made just before and after the Deimos
encounter.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 96 136 Astrometric observations of Deimos relative to
the Mars Express spacecraft position
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See also:
J/A+A/487/755 : CCD observations of Martian Satellites (Veiga+, 2008)
J/A+A/488/361 : Mars Express astrometric observations of Phobos (Willner+ 2008)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Image Image Name
13- 22 A10 "Y-M-D" Obs.date Image acquisition date (UTC)
23 A1 --- --- [T]
24- 35 A12 "h:m:s" Obs.time Image acquisition mid-time (UTC)
36 A1 --- --- [Z]
39- 46 F8.4 deg RAdeg Right ascension (J2000.0) wrt spacecraft
position
49- 56 F8.4 deg DEdeg Declination (J2000.0) wrt spacecraft
position
61- 66 F6.4 deg e_Pos One sigma error of Right ascension/Declination
68- 76 F9.2 km Xpos X coordinate of Mars Express spacecraft in
Mars-centered J2000.0 frame
78- 86 F9.2 km Ypos Y coordinate of Mars Express spacecraft in
Mars-centered J2000.0 frame
88- 96 F9.2 km Zpos Z coordinate of Mars Express spacecraft in
Mars-centered J2000.0 frame
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Acknowledgements:
Andreas Pasewaldt, andreas.pasewaldt(at)dlr.de
(End) Patricia Vannier [CDS] 27-Jun-2012