The mExec module is a mosaicking executive for 2MASS, SDSS, and DSS data. It includes remote data and metadata access. Alternatively, users can mosaic a set of data already on disk.
mExec [-q] [-r rawdir] [-n ntilex] [-m ntiley] [-l] [-k] [-c] [-o output.fits] [-d level] [-f region.hdr | -h header] survey band [workspace-dir]


Use mProjectQL for reprojections. Much faster but not quite flux-conserving.
-r rawdir
Provide path to directory containing original ("raw") data which will be reprojected and mosaicked. Not necessary if using mExec to retrieve remote data from the 2MASS, SDSS or DSS surveys.
-n ntilex
Number of output tiles to create along the X-axis - default is 1 for a single mosaicked image.
-m ntiley
Number of output tiles to create along the Y-axis - default is equal to ntilex.
"Level-only" flag (see mBgModel)
If retrieving data from a remote archive, the "keep" flag will leave the original data products on disk after generating a mosaic. Without this flag, raw data will be deleted (unless it was provided by the user with the "-r" flag).
Remove all temporary files and intermediate data products. Note: if not using the '-o' flag to specify an output file, this will also remove mosaic.fits.
-o output.fits
Provide your own filename for the output mosaic. Default filename is "mosaic.fits."
-d level
Print out additional debugging information (levels 1-4)


mExec must be provided with FITS header information. This can be in the form of a header template ("-f" flag), or the user can pass header text directly to the program ("-h" flag).

-f region.hdr
Path to header template used to create mosaic.
-h header
Provide header template as text input rather than point to a file; see sample shell script that makes use of this option.
survey band
If not mosaicking user-provided data ("-r" flag), must select one of the following combinations of survey and band:
  • 2MASS [j, h, k]
  • SDSS [u, g, r, i, z]
Directory where intermediate files will be created. If no workspace is given, a unique local subdirectory will be created (e.g.; ./MOSAIC_AAAaa17v)
[struct stat="OK", workspace="workspace-dir"]
The output mosaic(s), and any intermediate files (if the "-c" flag was not used) will be inside workspace-dir.


To create a small mosaic of the area around m31, located at coordinates "10.68469 41.26904":

$ mHdr m31 0.3 m31.hdr
[struct stat="OK", count="16"]
$ mExec -o m31.fits -f m31.hdr 2MASS J tempdir
[struct stat="OK", workspace="/path/to/tempdir"]

To mosaic your own collection of data, contained in the directory "raw":

$ mImgtbl raw raw.tbl
[struct stat="OK", count=16, badfits=0]
$ mMakeHdr raw.tbl raw.hdr
[struct stat="OK", count=16, clon=0.118289, clat=0.118288, lonsize=0.236660, latsize=0.236660, posang=359.999756, lon1=0.236618, lat1=-0.000042, lon2=359.999959, lat2=-0.000041, lon3=359.999959, lat3=0.236618, lon4=0.236620, lat4=0.236617]
$ mExec -o my_mosaic.fits raw.hdr workdir
[struct stat="OK", workspace="/path/to/workdir"]

Return Codes:

  • [struct stat="OK", workspace="workdir"]
  • [struct stat="ERROR", msg="Usage: mExec [-r rawdir] [-n ntilex] [-m ntiley] [-l(evel only)] [-k(eep all)] [-c(lean)] [-o output.fits] [-d(ebug) level] [-f region.hdr | -h header] survey band [workspace-dir]"]
  • [struct stat="ERROR", msg="Must have either header file (-f) or header text (-h)"]
  • [struct stat="ERROR", msg="Can't open original header template file: [region.hdr]"]
  • [struct stat="ERROR", msg="Can't open workspace header template file: [region.hdr]"]
  • [struct stat="ERROR", msg="Can't create proper subdirectories in workspace (may already exist)"]
  • [struct stat="ERROR", msg="Can't open header template file"]
  • [struct stat="ERROR", msg="Can't open expanded header file: [big_region.hdr]"]
  • [struct stat="ERROR", msg="survey has no data covering expanded area"]
  • [struct stat="ERROR", msg="survey has no data covering this area"]
  • [struct stat="ERROR", msg="No data was available for the region specified at this time"]
  • [struct stat="ERROR", msg="Bad WCS in input image"]
  • [struct stat="ERROR", msg="Can't open mosaic file: [mosaic.fits]"]
  • [struct stat="ERROR", msg="Can't open save file: [image.fits]"]
  • [struct stat="ERROR", msg="Output wcsinit() failed"]
  • [struct stat="ERROR", msg="Error from another Montage module"]