The file format used by GCX for star catalogs, recipies and observation reports consists of lists of token-value pairs. Each list is enclosed in brackets. The value part of each pair can be a number, a string (enclosed in double quotes) or another list. The order of the pairs within the list is not important.
A file can contain several top-level lists. Each such list is called a ``frame''. A typical recipy frame looks like:
( recipy ( object "aucyg" ra "20:18:32.76" dec "34:23:21.3" equinox 2000 comments "generated from tycho2" ) sequence "tycho2" stars ( (name "2680-1551" type std mag 7.48 ra "20:17:54.500" dec "34:05:25.22" perr 0.0071 comments "p=T " smags "v=7.344/0.020 b=8.654/0.020 vt=7.483/0.011 bt=9.024/0.017" flags ( astrom ) ) (name "2680-1588" type std mag 7.79 ra "20:16:56.755" dec "34:08:22.86" perr 0.0057 comments "p=T " smags "v=7.795/0.020 b=7.745/0.020 vt=7.790/0.011 bt=7.731/0.015" flags ( astrom ) ) (name "aucyg" type target mag 9.5 ra "20:18:32.76" dec "34:23:21.3" comments "p=V t=M s=M6e-M7e m(p)=9.50/15.30" flags ( var ) ) ) )An observation report frame can look like:
( observation ( filter "b" object "aucyg" ra "20:18:39.31" dec "34:23:05.6" equinox 2000 mjd 53236.9839856 telescope "SCT" aperture 30 exptime 20 sns_temp 238.3 latitude "44:25:50.0" longitude "-26:06:50.0" altitude 75 airmass 1.223 observer "R. Corlan" ) noise ( read 7 eladu 2 flat 0 ) ap_par ( r1 5 r2 9 r3 13 sky_method "synthetic_mode" ) (name "AU_CYG_39" type std mag 12.1 ra "20:17:47.15" dec "34:32:01.4" smags "v=12.062/-0.001 b-v=1.982/-0.002 b=14.044/0.002" imags "b=-7.256/0.167" residual -0.209 stderr 1.25 noise (photon 0.13 sky 0.074 read 0.075 scint 0.0021) flags ( astrom centered ) ) (name "AU_CYG_10" type std mag 13 ra "20:17:44.52" dec "34:21:00.0" smags "v=12.961/-0.001 b-v=0.765/-0.001 b=13.726/0.001" imags "b=-7.991/0.089" residual 0.208 stderr 2.33 noise (photon 0.066 sky 0.038 read 0.038 scint 0.0021) flags ( astrom centered ) ) (name "aucyg" type target mag 9.5 ra "20:18:32.76" dec "34:23:21.3" comments "p=V t=M s=M6e-M7e m(p)=9.50/15.30" smags "b=12.642/0.085" imags "b=-8.867/0.042" noise (photon 0.031 sky 0.017 read 0.017 scint 0.0021) flags ( var centered ) ) ) transform ( band "b" zp 21.509 zperr 0.074 zpme1 1.29 ) )A typical catalog frame would be:
( catalog (comments "Internal catalog output") stars ( ( name "piuma" type catalog ra "08:39:11.70" dec "65:01:15.0" flags ( var ) ) ( name "lpup" type catalog ra "07:13:31.90" dec "-44:38:39.0" flags ( var ) ) ( name "piori" type catalog ra "04:54:15.10" dec "02:26:26.4" flags ( var ) ) ) )
All three forms of the star file have in common the top-level token stars which is followed by the list of all stars within the frame. Each star is also represented by a list, having some of the following tokens:
name | string | The name of the star; |
type | symbol | The type of the star: std for standards, target for targets, catalog far catalog objects and field for field stars; |
ra | string | Right ascension in HMS format; |
dec | string | Declination in DMS format; |
perr | number | Position error in arc seconds; |
equinox | number | Equinox of coordinates; |
mag | number | Generic magnitude of the star, used for display purposes only; |
smags | string | A string describing the standard magnitudes of the star and their errors. See Section 7.7 for the format; |
imags | string | A string describing the instrumental magnitudes of the star and their errors; |
noise | list | A list of components of the star's instrumental noise model; |
residual | number | The residual of the star after the zeropoint fit; |
stderr | number | The standard error (scaled residual) of the star after the zeropoint fit; |
flags | list | A list of reduction flags. |
Some top-level tokens of the star files are:
stars | list | List of stars in the frame; |
recipy | list | A list of recipy parameters. Most important are the target object and field center coordinates; |
observation | list | Parameters of the ccd frame from which the data was obtained. See Section 7.5 for more details; |
catalog | list | Identifies the frame as a catalog frame. The most important token in this list is comments; |
sequence | string | The source of the standard magnitudes in the star list; |
noise | list | A list of parameters of the CCD noise model used to calculate instrumental errors; |
ap_par | list | Parameters used by the aperture photometry routine (aperture sizes and sky estimation method); |
transform | list | transformation coefficients, zeropoint and extinction coefficients used to calculate the standard magnitudes of target stars. |
The native star format can be converted to a tabular format using the report converter function as described in Appendix E.