acatpars: Default astrometry file format parameter set

Package: astcat

Usage

acatpars

Parameters

ftype = "stext"

The astrometry file format. The current options are:

stext

Simple text. Records are newline delimited and fields are whitespace delimited.

btext

Blocked text. Records are newline delimited and fields are offset and size delimited.

ccsystem = "j2000"

The default celestial coordinate system. The coordinate systems of most interest to users are "icrs", "j2000", and "b1950". For more detailed information on all the celestial coordinate system options type "help ccsystems".

standard astrometry file fields

The following parameters define the standard astrometry file fields. The parameter names are the same as the standard field names. The parameter values are the standard field descriptions.
Every astrometry file returned by a catalog query or created by the user must contain the standard fields ra and dec. The remaining fields are optional and may or may not be present in either the original catalog or the astrometry file produced by a catalog query.
The format of the standard fields is "fieldno [units [format]]" for simple text files and "foffset fsize [units [format]]" for blocked text files where the quantities in "[]" are optional. Standard fields with "" valued field descriptions are assumed to be undefined.

id = ""

The standard id field. The data type is character. The default units and format values are "INDEF" and "%20s".

ra = "1 hours"

The standard right ascension / longitude field. The data type is double. The default units and format values are "hours"and "%11.2h".

dec = "2 degrees"

The standard declination / latitude field. The data type is double. The default units and format values are "degrees"and "%11.1h".

era = ""

The standard right ascension / longitude error field. The data type is double. The default units and format values are "asecs" and "%6.3f".

edec = ""

The standard declination / latitude error field. The data type is double. The default units and format values are "asecs" and "%6.3f".

pmra = ""

The standard right ascension / longitude proper motion field. The data type is double. The default units and format values are "masecs/yr" and "%7.3f".

pmdec = ""

The standard declination / latitude proper motion field. The data type is double. The default units and format values are "masecs/yr" and "%7.3f".

epmra = ""

The standard right ascension / longitude proper motion error field. The data type is double. The default units and format values are "masecs/yr" and "%7.3f".

epmdec = ""

The standard declination / latitude proper motion error field. The data type is double. The default units and format values are "masecs/yr" and "%7.3f".

catsystem = ""

The standard celestial coordinate system field. The data type is character. The default units and format field values are "INDEF" and "%15s". If defined the value of this field overrides the coordinate system defined by the csystem parameter. Supported values of catsystem are "icrs", "fk5", "fk4", "fk4-noe", "ecliptic", "galactic", and "supergalactic".

equinox = ""

The standard celestial coordinate system equinox field. The data type is character. The default units and format field values are "INDEF" and "%15s". Equinoxes are typical expressed as Julian epochs e.g. "J2000.0", Besselian epochs e.g. "B1950.0", or years "2000.0".

epoch = ""

The standard celestial coordinate system epoch field. The data type is character. The default units and format field values are "INDEF" and "%15s". Epochs are typical expressed as Julian epochs e.g. "J2000.0", Besselian epochs e.g. "B1950.0", years "2000.0", or Julian date if the epoch value > 3000.0.

px = ""

The standard parallax field. The data type is double. The default units and format values are "msecs" and "%6.3f".

rv = ""

The standard radial velocity field. The data type is double. The default units and format values are "km/sec" and "%6.3f".

epx = ""

The standard parallax error field. The data type is double. The default units and format values are "msecs" and "%6.3f".

erv = ""

The standard radial velocity error field. The data type is double. The default units and format values are "km/sec" and "%6.3f".

mag = ""

The standard magnitude field. The data type is real. The default units and format field values are "mags" and "%8.3f".

color = ""

The standard color field. The data type is real. The default units and format field values are "mags" and "%8.3f".

emag = ""

The standard magnitude error field. The data type is real. The default units and format field values are "mags" and "%8.3f".

ecolor = ""

The standard color error field. The data type is real. The default units and format field values are "mags" and "%8.3f".

xp = ""

The predicted x coordinate field. The data type is double. The default units and format field values are "pixels" and "%9.3f".

yp = ""

The predicted y coordinate field. The data type is double. The default units and format field values are "pixels" and "%9.3f".

xc = ""

The centered x coordinate field. The data type is double. The default units and format field values are "pixels" and "%9.3f".

yc = ""

The centered y coordinate field. The data type is double. The default units and format field values are "pixels" and "%9.3f".

exc = ""

The centered x coordinate error field. The data type is double. The default units and format field values are "pixels" and "%9.3f".

eyc = ""

The centered y coordinate error field. The data type is double. The default units and format field values are "pixels" and "%9.3f".

imag = ""

The standard instrumental magnitude field. The data type is real. The default units and format values are "mags" and "8.3f".

eimag = ""

The standard instrumental magnitude error field. The data type is real. The default units and format values are "mags" and "8.3f".

Description

The acatpars parameters define the default astrometry file format. These parameters are used if the input astrometry file does not contain a standard header describing the file format. By default standard headers are written by all astcat package tasks which create astrometry files. If the astrometry file does not have a header the acatpars parameters are used to define one.

By default acatpars assumes that the input astrometry file is a simple text file, ftype = "stext", with newline delimited records and whitespace delimited fields. In this case users can define the fields by setting the appropriate standard file parameters to a string with the following format, e.g.

parname = "fieldno [units [format]]"

     ra = "1 hours"
    dec = "2 degrees"

where fieldno is the field or column number in the record. The units and format strings are optional and reasonable defaults are supplied if they are missing. Currently the units information is only used for decoding coordinate fields. For other fields the units should be left at their default values. The format information is used when an application has to decode a field into a numeric value modify it in some way and rewrite it.

If ftype is set to "btext" for blocked text the input astrometry file is assumed to be a text file with newline delimited records and fixed size fields. This format can be used to describe astrometry files with fields containing embedded blanks such as id fields. In this case users define the fields by setting the appropriate standard file parameters to a string with the following format, e.g.

parname = "foffset fsize [units [format]]"
     ra = "1 15 hours"
    dec = "16 15 degrees"

where foffset and fsize are the field offset and size in characters. Formats and units are treated in the same way as they for simple text files.

The fundamental coordinate system of the astrometry file is set by the csystem parameter. This is a global parameter applying to the entire astrometry file . Its value is overwritten if the "catsystem" standard field is defined, in which case the astrometry file may contain entries in many different fundamental coordinate systems.

Examples

1. List the astrometry file format parameters.

cl> lpar acatpars

2. Edit the astrometry file format parameters.

cl> acatpars

3. Edit the astrometry file format parameters from the afiltcat task.

cl> epar afiltcat

4. Save the current acatpars parameter values in a text file called acat1.par. Use the saved parameter set in the next call to the afiltcat task.

cl> epar acatpars
cl> afiltcat ... acatpars=afilt1.par ...

Time requirements

Bugs

See also

afiltcat