The NDWGSGET task extracts FITS cutout images output from the NDWFS survey using region specifications supplied by the user.
A single cutout region can be specified by the ra, dec, rawidth, decwidth, fcsystem, and filters parameters. Multiple cutout regions may be specified in a regions file regions which as the following format.
ra1 dec1 ra/xwidth1 [dec/ywidth1 [fcsystem1 [filters1]]] ra2 dec2 ra.xwidth2 [dec/ywidth2 [fcsystem2 [filters2]]] raN decN ra/xwidthN [dec/ywidthN [fcsystemN [filtersN]]]
The right ascension and declination values define the center of the field and must be hours and degrees. The right ascension and declination widths must be in arcminutes. X and Y widths must be in pixels. X and Y pixel width values are distinguished from ra and dec width values by a trailing 'p' character. The decwidth / ywidth, coordinate system, and filter list values are optional and default to the value of rawidth, and the values of the fcsystem and filters parameters respectively.
The cutout images are written to output, one cutout image for each specified. If the extraction region overlaps more than one NDWFS survey image, then the cutout image is extracted from the NDWFS survey image which has the largest overlap with the extraction region. The survey images are assumed to have a common projection system, and the cutout image are aligned only to the nearest pixel. Undefined pixels in the cutout images are assigned the value blank.
By default the cutout image names have the form "imroot_coords_filter.fits" where imroot is "NDWFS", coords is an IAU-like coordinate designation, and filter is the filter id. Users may specify their own output image names in output. If there are more output images than output image names then default output image names are constructed for the "extra" cutout images.
1. Extract all the images in the NDWFS survey that overlap the region defined by ra = 14:28:07.0, dec = +34:55:00, rawidth = 2.0, decwidth = 2.0.
cl> ndwfsget "default" 14:28:07.0 +34:55:00 rawidth=2.0 decwidth=2.0 \
filters="Bw,R,I"
2. Repeat example 2 but specify a region that is 200 pixel in size.
cl> ndwfsget "default" 14:28:07.0 +34:55:00 rawidth=200p decwidth=200p \
filters="Bw,R,I"
3. Extract cutouts using a regions file. Note that dec/ywidth defaults to the value of ra/xwidth, the coordinate system defaults to the value of the fcsystem parameter, and the filter list default to the values of the filter parameter.
cl> type regfile 14:28:07.0 +34:55:00 1.0 14:28:07.0 +34:55:05 1.0 00:00:00.0 +00:00:00 1.0 14:28:07.0 +34:54:55 1.0cl> ndwfsget "default" filters="Bw,R,I" regions=regfile