Simple Image Access Protocol
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