Functions related to WCS


Functions

cpl_error_code irplib_wcs_xytoradec (const cpl_wcs *wcs, double x, double y, double *ra, double *dec)
 Convert x, y coordinates (physical) to RA, DEC (World).
cpl_error_code irplib_wcs_radectoxy (const cpl_wcs *wcs, double ra, double dec, double *x, double *y)
 Convert RA, DEC (World) to x, y coordinates (physical).
double irplib_wcs_great_circle_dist (double ra1, double dec1, double ra2, double dec2)
 Compute the great-circle distance between two points on a sphere.

Function Documentation

cpl_error_code irplib_wcs_xytoradec ( const cpl_wcs *  wcs,
double  x,
double  y,
double *  ra,
double *  dec 
)

Convert x, y coordinates (physical) to RA, DEC (World).

Parameters:
wcs The World Coordinate System solution
x The X coordinate (Physical)
y The Y coordinate (Physical)
ra The RA coordinate (World) (returned)
dec The DEC coordinate (World)
This function is a convenient wrapper around cpl_wcs_convert.

Definition at line 63 of file irplib_wcs.c.

Referenced by irplib_cat_get_image_limits().

cpl_error_code irplib_wcs_radectoxy ( const cpl_wcs *  wcs,
double  ra,
double  dec,
double *  x,
double *  y 
)

Convert RA, DEC (World) to x, y coordinates (physical).

Parameters:
wcs The World Coordinate System solution
ra The RA coordinate (World) (returned)
dec The DEC coordinate (World)
x The X coordinate (Physical)
y The Y coordinate (Physical)
This function is a convenient wrapper around cpl_wcs_convert.

Definition at line 115 of file irplib_wcs.c.

double irplib_wcs_great_circle_dist ( double  ra1,
double  dec1,
double  ra2,
double  dec2 
)

Compute the great-circle distance between two points on a sphere.

Parameters:
ra1 Right ascension of first point [degrees]
dec1 Declination of first point [degrees]
ra2 Right ascension of second point [degrees]
dec2 Declination of second point [degrees]
Returns:
Non-negative distance [degrees].
See also:
http://en.wikipedia.org/wiki/Great-circle_distance (on 2005-10-23)

Definition at line 160 of file irplib_wcs.c.

Referenced by irplib_stdstar_find_closest(), and irplib_stdstar_select_stars_dist().


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