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file 1995-1999_S1-14_veiga.data.txt
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Contents:

Astrometric positions of the first eight largest satellites and the
Lagrangian satellites Helene, Telesto and Calypso, are given from
493 CCD frames taken at the oppositions in 1995 through 1999. The images
were obtained over 27 nights. The RMS is about 0."12 for the large
satellite (computed with TASS1.7) but 0."20 for Iapetus and 0."28
for Hyperion. For the Lagrangian satellites (computed from JPL positions)
it is about 0."21 for Helene, 2."02 for Telesto and 0."60 for Calypso.

The format and the conventions of the present catalog are the same
presented in (Vienne Thuillot Veiga et al 2001) and quite similar to the 
one of (Strugnell & Taylor 1990). The coordinates are given apart from 
a scale factor and from a rotation, but all astrometric corrections
are done. 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.

At the end of the catalog, there is  some lines which indicate how the 
reduction have been done and which corrections have been applied to get
 the coordinates. Specially, a column "catalog" indicates the source of 
the theoretical positions used to reduce the plates. 
Two other columns give the scale and the orientation of the frame. 
Note that the orientation refers to the true equator of the date. But 
it is possible to  touch up these parameters directly by comparing the 
"observed map" and the "computed map" (then given in the J2000 system, see 
Vienne, Thuillot & Arlot 2001).

Reference of the catalog:

Veiga C.H., R. Vieira Martins, Vienne A. et al 2003, CCD astrometric
observations of Saturnian satellites, A&A  400, 1095


Other references:

Strugnell, P.R., Taylor, D.B. 1990, A&AS 83, 289

Vienne A., Thuillot W., Arlot J.E. 2001, Astrometric reduction of CCD
observations of planetary satellites without reference star, in Note
Sci. et Tech. de l'I.M.C.C.E., S077

Vienne A., Thuillot W, Veiga C.H. et al 2001, Saturnian satellite
observations made in Brazil during the 1995 opposition with an astrometric
analysis, A&A  380, 727

Format:

In a FORTRAN code, lines are read with the format:
(i3,i5,i3,f11.7,f7.3,2i4,i2,1x,a2,a1,i2,i1,
2(1x,f13.7),2i2,2(1x,f7.3),3i3,2f10.3)
The meanings of each parameter can be found in (Strugnell & Taylor
1990), but we recall them below:
* opp: opposition number, 1=1874 to 122=1999. 
* year,m,utc: year, month and utc date of the observation
* tt-utc: TT-UTC in seconds
* obs: UAI observatory code from the Minor Planet Center, 
* ref: reference code of the catalog (we have chosen 303 for the present
  observations) 
* t.: observation type. 0=\alpha ,\delta  , 1=\Delta \alpha \cos \delta ,\Delta \delta  ,
  2=\Delta \alpha ,\Delta \delta  , 3=position angle, separation 
* obj.: subject satellite, reference satellite. 0 for Saturn, 1 to
  8 for S1 to S8, 12 for Helene, 13 for Telesto and 14 for Calypso
  (* 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) 
* fl.: flags of presence of the first and second coordinates 
* obs1, obs2 : first and second coordinates, it is 0 when the coordinate 
  is not present, see fl. 
* s: reference system. 0=mean equator and equinox B1950, 1=true equator
  and equinox of date of observation, 2=mean equator and equinox of
  J2000 
* f: reference frame. 0=topocentric, 1=geocentric, 2=heliocentric 
* o-c1, o-c2: residuals of observations in arc-seconds computed with
  TASS1.7, it is 999.999 when the residuals are not computed and it 
  is 888.888 when the residuals are greater than 100. in absolute value. 
* r: the number of the satellite used as reference in the computation
  of o-c
* -: 0 for no meaning and 1 when the frame was not used in the computation
  of the scale and the direction of the series (see se column) 
* se: the number of the series, the scale and orientation are the same
  for all the observations of one series). 
* xpix,ypix: original coordinates in pixels.

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