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Table A.2.
World coordinate system keywords for solar imaging data used in SALSA. Generic keywords.
| World Coordinate System - Helioprojective keywords | ||
|---|---|---|
| Keyword | Default Value | Description |
| WCSNAMEA | ’Helioprojective-cartesian’ | Name of coordinate set. String. Set by T2006 and A611. |
| CTYPE1A | ’HPLN-TAN’ | Axis labels. Set by T2006 and A611. |
| CTYPE2A | ’HPLT-TAN’ | Axis labels. Set by T2006 and A611. |
| CRPIX1A | 180.5 | Reference pixel: center of image in pixels. Set by T2006 . |
| CRPIX2A | 180.5 | Reference pixel: center of image in pixels. Set by T2006. |
| CUNIT1A | ’arcsec’ | Angles in arcsec. Set by T2006 and A611. Arcsec is allowed by WCS. |
| CUNIT2A | ’arcsec’ | Angles in arcsec. Set by T2006 and A611. Arcsec is allowed by WCS. |
| CDELT1A | 0.55 | Plate scale (i.e. pixel size). Set by T2006. Here in arcsec as in A611. |
| CDELT2A | 0.55 | Plate scale (i.e. pizel size). Set by T2006. Here in arcsec as in A611. |
| CRVAL1A | 0.0 | Helioprojective x (solar x) coordinate of the reference pixel in arcsec. Set by T2006. Here in arcsec as in A611. |
| CRVAL2A | 0.0 | Helioprojective y (solar y) coordinate of the reference pixel in arcsec. Set by T2006. Here in arcsec as in A611. |
| CTYPE5 | ’TIME’ | This is in relation to REF_TIME, per frame. Time found in TIME_TAG under extension TIMEVAR. |
| CUNIT5 | ’s’ | Unit for fifth axis. Seconds in relation to REF_TIME, per frame. Time found in TIME_TAG under extension TIMEVAR. Normally preceding midnight. |
| DSUN_OBS | 147296035413.001 | Distance between observer and Sun in meters. Set by T2006 and A611 with A611 precision. |
| RSUN_REF | 696000000.0 | Radius of the Sun in meters. Set by T2006 and A611 with A611 precision. |
| RSUN_OBS | 6.96e8 | Observed radius of the Sun in arcsec. Set by T2006 and A611 with tabled A611 precision. |
| HGLN_OBS | 0 | Heliographic longitude of the observer, in degrees. Set by T2006 and A611. |
| HGLT_OBS | −0.47 | Stonyhurst heliographic latitude of the observer, in degrees (in this coordinate set identical to the classical “B0”). Set by T2006 and A611. |
| SOLAR_P | 11.6872 | Degrees. "rotate image by -solar P angle to get solar north up". Set by A611. |
| SOLAR_P0 | 11.6872 | Degrees. "rotate image by -solar P angle to get solar north up". Set by SNET. |
| REF_TIME | 2014-12-11T19:09:13 | Date and time. Time used for coordinate calculations. Set by A611. Note that, in the ASA scripts, this is typically “refTime”, without the underscore. |
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