J/A+A/383/296 Saturnian Satellites positions (1996-2000) (Peng+, 2002)
Positional measuring procedure and CCD observations for Saturnian satellites.
Peng Q., Vienne A., Shen K.X.
<Astron. Astrophys. 383, 296 (2002)>
=2002A&A...383..296P 2002A&A...383..296P
ADC_Keywords: Solar system ; Planets ; Positional data
Keywords: planets and satellites: individual: Saturn -
techniques: image processing - astrometry
Description:
199 frames of CCD images of the major satellites of Saturn (Mimas,
Enceladus, Tethys, Dione, Rhea, Titan, Hyperion and Iapetus), obtained
on 1-meter telescope at the Yunnan Observatory during the years of
1996-2000, are measured. These positions are compared to the ones
computed with the Vienne & Duriez ephemerides (TASS1.7). The
calibrated parameters of the CCD scale and orientation are determined
by the comparison of their measurement coordinates with computed
positions of four bright satellites of Tethy, Dione, Rhea and Titan.
A catalog of 913 differential positions has been obtained. Analysis of
the data as inter-satellite positions shows that these observations of
the above mentioned four satellites have root-mean-square residuals of
0.04 arcsec in the sense of (O-C) (Observed minus Computed). The
positional measuring procedure is proved to be good enough to obtain a
small dispersion in the observations for the major Saturn satellites.
The format of the present catalog are very near to the one of
(Strugnell & Taylor, 1990A&AS...83..289S 1990A&AS...83..289S). The coordinates are
corrected by all astrometric effects. So, these positions are really
astrometric ones in that meaning that, no astrometric consideration is
necessary to use them, even if one wants to touch up the calibration.
Nevertheless, the raw pixels are also given in order to allow anyone
to reduce again the frames.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table7.dat 123 1311 The catalog
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See also:
J/A+AS/121/65 : 1990-1994 Saturn's satellites astrometry (Harper+ 1997)
J/A+AS/136/257 : Saturn's satellites in 1995/97 (Harper+ 1999)
J/A+AS/139/305 : Position of Saturn's satellites (1982-1988) (Veiga+, 1999)
Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Opp *Opposition number
5- 22 A18 "Y-M-D" Obs.Y *observations date
24- 29 F6.3 s TT-UTC TT-UTC difference
31- 33 A3 --- Obs [286] Observatory code from Minor Planet Center
35- 37 A3 --- Ref [302] Reference code of the catalog (here 302)
39 I1 --- ObsType *[0/1] Observation type
42- 43 A2 --- Obj *Subject satellite, reference satellite
45- 46 A2 --- Note *[0/1] The flag of presence of both coordinates
49- 60 F12.7 arcsec ObsRA The observed coordinates in Right Ascension
63- 74 F12.7 arcsec ObsDE The observed coordinates in Declination
76 I1 --- RefSys *[0/2] The reference system
78 I1 --- Frame [1] The reference frame. Here, 1=geocentric
80- 86 F7.3 arcsec O-CRA ?=999.999 Residuals of observations in
Right Asension
88- 94 F7.3 arcsec O-CDE ?=999.999 Residuals of observations in
Declination
97 I1 --- Rsat Reference satellite when o-c is computed
100 I1 --- --- [0] Index reserved
103 I1 --- NSer *The number of the series
105-113 F9.3 pix Xpos *?=99999.999 Original coordinate in X direction
115-123 F9.3 pix Ypos *?=99999.999 Original coordinate in Y direction
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Note on Opp:
Oppsition number. 119 for 1996 to 123 for 2000
Note on Obs.Y, Obs.M, Obs.D:
The date is not light time corrected for the UTC
Note on ObsType:
0 = alpha, delta
1 = Delta(alpha)cos(delta), Delta(delta)
Note on Obj:
0 for Saturn, 1 to 8 for S1 to S8
* when there is no reference satellite that is for observation
type 0, C for the center of the plate which is not a physical object
Note on Note:
0 = observation absent
1 = observation present
Note on RefSys:
0 = mean equator and equinox B1950
1 = true equator and equinox of date of observation
2 = mean equator and equinox J2000
Note on NSer:
1,2,3 and 4 is for 1996, 1997, 1999 and 2000 series respectively. The scale
and orientation are the same for all the observations of one series
Note on Xpos, Ypos:
Difference in raw pixel coordinate between subject satellite and reference
satellite in X- anf Y-direction
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Acknowledgements: Peng Qingyu
(End) Peng Qingyu [Univ. Jinan], Patricia Bauer [CDS] 27-Sep-2001