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#### 6.1.4 `addskycoords`

Usage:

       addskycoords [-epoch <expr>] [-inunit deg|rad|sex] [-outunit deg|rad|sex]
                    <insys> <outsys> <col-id1> <col-id2> <col-name1> <col-name2>

Add new columns to the table representing position on the sky. The values are determined by converting a sky position whose coordinates are contained in existing columns. The `<col-id>` arguments give identifiers for the two input coordinate columns in the coordinate system named by `<insys>`, and the `<col-name>` arguments name the two new columns, which will be in the coordinate system named by `<outsys>`. The `<insys>` and `<outsys>` coordinate system specifiers are one of

- `icrs`: ICRS (Right Ascension, Declination)
- `fk5`: FK5 J2000.0 (Right Ascension, Declination)
- `fk4`: FK4 B1950.0 (Right Ascension, Declination)
- `galactic`: IAU 1958 Galactic (Longitude, Latitude)
- `supergalactic`: de Vaucouleurs Supergalactic (Longitude, Latitude)
- `ecliptic`: Ecliptic (Longitude, Latitude)

The `-inunit` and `-outunit` flags may be used to indicate the units of the existing coordinates and the units for the new coordinates respectively; use one of `degrees`, `radians` or `sexagesimal` (may be abbreviated), otherwise degrees will be assumed. For sexagesimal, the two corresponding columns must be string-valued in forms like hh:mm:ss.s and dd:mm:ss.s respectively.

For certain conversions, the value specified by the `-epoch` flag is of significance. Where significant its value defaults to 2000.0.

Syntax for the `<expr>` , `<col-id1>` and `<col-id2>` arguments is described in the manual.

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STILTS - Starlink Tables Infrastructure Library Tool Set
Starlink User Note256
STILTS web page: http://www.starlink.ac.uk/stilts/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@jiscmail.ac.uk