SIA ivo://ivoa.net/std/SIA International Virtual Observatory Alliance Doug Tody Ray Plante 2004-05-24 Data Access Layer Working Group dal@ivoa.net software standard virtual observatory The Simple Image Access Protocol is a protocol for retrieving image data from a variety of astronomical image repositories through a uniform interface. The interface is meant to be reasonably simple to implement by service providers. A query defining a rectangular region on the sky is used to query for candidate images. The service returns a list of candidate images formatted as a VOTable. For each candidate image an access reference URL may be used to retrieve the image. Images may be returned in a variety of formats including FITS and various graphics formats. Referenced images are often computed on the fly, e.g., as cutouts from larger images. http://www.ivoa.net/Documents/latest/SIA.html Other Research 1.0 http://sample.org/cgi-bin/sia GET text/xml+votable POS Search Position in the form "ra,dec" where ra and dec are given in decimal degrees in the ICRS coordinate system. degrees real SIZE Size of search region in the RA and Dec. directions in decimal degrees. degrees real FORMAT Requested format of images. string INTERSECT Choice of intersection of matched images with the region of interest. string NAXIS The number of pixels desired along each axis integer CFRAME the coordinate frame to impose on the image. string EQUINOX the epoch of the mean equator and equinox for the specified coordinate system reference frame (CFRAME). coordinate frame to impose on the image. string CRPIX the pixel position to locate the reference position in the output image. real CRVAL the world coordinates of the reference position in the output image in decimal degrees real CDELT the scale of the output image in decimal degrees per pixel real ROTANG the rotation angle to put into the output image's coordinate system real PROJ the projection to impose in the construction of the output image string VERB the level of verbosity in the output. string