Back to Programs

mosaic

mosaic creates a mosaic image from the CCD fits files of a given exposure. The output image is a square of size 8192/binning. If not all 8 fits files are present, or if the files are subrasters, mosaic places the available images at their correct position within the mosaic image.

Details:

The primary purpose of mosaic is to assemble the full IMACS camera image, for viewing and manipulation with IRAF routines. Note that the assembled image is not astrometrically accurate, the 8 chip images are placed immediately next to each other, with no attention to correct chip offsets and rotations. The coordinate system of the mosaiced image is, however, that used by the routines apertures, spectral-lines, spectral-map, and adjust-offsets.

The routine display8 also displays the images of all 8 chips in a IRAF image window, with the same orientation and coordinate system. Which routine should you use? If your only purpose is viewing the image, and if the image is a full 8-chip 1x1 binned image, use display8; mosaic takes additional time to run, and fills your disk with additional large files. However, if you wish to do anything else with the assembled image (further processing, or examining with IRAF routines such as imexam), or it you are working binned data or with subrasters, you must use mosaic, since display8 cannot handle these, and IRAF routines like imexam need a real file to work with.

Back to Programs