Astrometry procedures

All arguments for these procedures and functions can be arrays. All require existence of GeoParms variable. A default can be created by using get_geoparms

utc2ut1(utc$<$_real$>$)

Function. Returns UT1 in seconds, with UTC input in seconds.

ut12gst(utc$<$_real$>$[,ut1$<$_real$>$])

Function. Returns GST in hours, inputs are in seconds.

hourangle(gst$<$_real$>$,ra$<$_real$>$)

Function. Return hourangle in hours, with inputs also in hours.

zenithangle(ha$<$_real$>$,dec$<$_real$>$)

Function. Return zenithangle in degrees with inputs ha in hours and dec in degrees.

mirrorangle(ha$<$_real$>$,dec$<$_real$>$)

Function. Return mirrorangle in degrees with inputs ha in hours and dec in degrees.

horizon2equatorial(coord$<$_real$>$)

Function. Return equatorial coordinates for input horizontal coordinates X=east, Y=north, and Z=up.

equatorial2horizon(coord$<$_real$>$)

Function. Return horizon coordinates for input equatorial coordinates X=projection of local meridian on equator, Y=east, and Z=north.

angle2horizon(coord$<$_real$>$)

Function. Return horizon coordinates for input azimuth and elevation angle in degrees. No GeoParms required.

equatorial2angle(coord$<$_real$>$)

Function. Return hour angle in hours and declination in degrees for input equatorial coordinates. No GeoParms required.

topostar,times$<$_real$>$,stars$<$_char$>$,startable,ra,dec

Compute apparent declinations and right ascensions for a list of times (in seconds UTC) and corresponding stars. (The arrays time and stars have to have the same number of elements therefore.) The startable is a standard STARBASE startable. The geoparms structure has to be loaded.

calcastrom

Procedure. Compute astrometric variables in scans structure.

calcvis

Procedure. Compute estimated visibilities, i.e. normalized visibilities.

referencestation,station$<$_char$>$[,class$<$_char$>$]

Change reference station for data of specified class (default all classes) to station.

precess,theta,jy,ra,dec,direction

Precess J2000 position angles (theta) to current Julian Year epoch (jy) for direction=1, from current to J2000 for direction=-1. (see: Heintz, "Double stars", p. 33). Input theta is in radians, dec in degrees, ra in hours; output is in radians.