msctvmarkto overlay coordinates from a catalog with known astrometry on your mosaic image. First, retrieve such a catalog from USNO:
cl> epar mscgetcat PACKAGE = mscred TASK = mscgetcatalog input = lfc267s List of Mosaic files output = testusno.cat Output file of sources (magmin = 14.) Minimum magnitude (magmax = 20.) Maximum magnitude (catalog= NOAO:USNO-A2) Catalog (rmin = 22.) Minimum radius (arcmin) (mode = ql)Exit with :go to execute.
Overlay the catalog on an image:
cl> mscdispl lfc267s fr=1 cl> epar msctvmark PACKAGE = mscred TASK = msctvmark coords = testusno.cat List of coordinates frame = 1 Display frame (output = ) Output file of pixel coordinates and labels (fields = 1,2,3) Fields for RA, DEC, and ID (wcs = world) Coordinate type (logical|physical|world) (mark = circle) Mark type (radii = 10) Radii of concentric circles (lengths= 0) Lengths and width of concentric rectangles (font = raster) Default font (color = 204) Gray level of marks to be drawn (label = no) Label the marked coordinates (nxoffse= 0) X offset in display pixels of number (nyoffse= 0) Y offset in display pixels of number (pointsi= 3) Size of mark type point in display pixels (txsize = 1) Size of text and numbers in font units (mode = ql)Exit with :go to execute. Circles will be drawn at the locations where the USNO objects should be. You should be able to recognize the patterns; I have found them offset by as much as 4 arcminutes. If it appears that the pointing is off, you can find the approximate offset using msczero. However, msczero requires a DATASEC header keyword that is not in the images. We make a little script to do this:
% foreach i (`cat nums.list`) % foreach j (1 2 3 4 5 6) % echo hedit lfc$i\s.fits\[$j\] DATASEC \[1:2048,1:4096\] add+ >> datasec.cl % end % endNow we run this script in IRAF, prep for msczero, and run it:
cl> cl < datasec.cl cl> set disable_wcs_maps="" cl> flpr cl> epar msczero PACKAGE = mscred TASK = msczero input = lfc167s List of mosaic exposures (extname= ) Extension name pattern (nframes= 2) Number of frames to use (cbox = 11) Centering box size (see imcntr) (mark = yes) Mark display? (logfile= default) Log file for measurements # MSCTVMARK Parameters coords = testusno.cat List of coordinates (fields = 1,2,3) Fields for RA, DEC, and ID (wcs = world) Coordinate type (logical|physical|world) (mtype = circle) Mark type radii = 20 Radii of concentric circles color = 204 Gray level of marks to be drawn label = no Label the marked coordinates (nxoffse= 20) X offset in display pixels of number (nyoffse= 0) Y offset in display pixels of number (pointsi= 3) Size of mark type point in display pixels (txsize = 2) Size of text and numbers in font units # Task query and internal parameters ra = 14:29:00.514 RA (hours) dec = 42:45:35.50 DEC (degrees) id = Identification mag = Magnitude limit update = no Update WCS zero point? updcoord= yes Update coordinate file? (fd1 = ) (fd2 = ) (mode = ql):go to execute as usual. Hit "m". The locations of USNO stars will be marked with circles; they will be offset if the pointing is wrong. Place your cursor on a circle and hit "s". Then place the cursor on the location of the star that the circle corresponds to and hit "z". Hit "m" to mark again - now the circles should match the star locations much better. If it looks ok, hit "q" to quit. Note the ra, dec offsets written to the screen.
cl> epar mscsetwcs PACKAGE = mscred TASK = mscsetwcs images = lfc*s Mosaic images database= mscdb$palomar/lfc/lfc-I.db WCS database (ra = ra) Right ascension keyword (hours) (dec = dec) Declination keyword (degrees) (equinox= equinox) Epoch keyword (years) (ra_offs= 96.) RA offset (arcsec) (dec_off= 115.) Dec offset (arcsec) (extlist= ) (mode = ql):go to execute. Note the ra_off and dec_off are set based on the results of msczero. At this point, you can continue with msccmatch and it should work (though 2 passes may still be needed).