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Coordinate entries

The format for a coordinate line is

<ID> <RA> <Dec> Wt SL Offset X Y

The fields are:

<ID> Identification number of object.

<RA> Right Ascension of object. RA is in hours of time, and should be a sexagesimal string, that is standard hours minutes seconds (HH MM SS.SSS) format, although formats such as HH MM.MMMMM, or even HH.HHHH are also accepted.

<Dec> Declination of object. This is in degrees and should also be in sexagesimal format ( DD MM SS.SS), although formats such as DD MM.MMMMM, or DD.DDDDDD are also acceptable. The sign of the declination () is optional for northern objects but mandatory for southern objects.

[Wt] Weight for growing slits. Larger weights mean slits grow faster. Wt = 0.0 is reserved for fiducial stars used for aligning the mask. A centred hole is placed at the mask position of such objects, while slits are used for other (WT > 0) objects. Negative weights should not be used, except for WT = MISVAL = -32767, which marks a ``deleted" object.

[Sl] The slit length (or fiducial hole diameter). The default units are arcsecs, although this can be changed with the MMUNit keyword.

[Offset] The coordinate difference between the slit centre and object position: . The slits are drawn parallel to the axis, and therefore they have the same coordinate as the object. The default units are arcseconds, although this can be changed with the MMUNit keyword.

[X] The coordinate of the object on the mask in mm.

[Y] The coordinate of the object on the mask in mm.

The fields in angle brackets (<>) are required, while those in square brackets ([ ]) are optional. Fields are delimited by one or more spaces. Defaults are assumed for blank fields, and were denoted by a word starting with *. X and Y are written with a WRITE/CAT but are ignored by READ/CAT which recalculates them from the positions and field centre parameters.