---
name: "mExec"
section: "1"
platform: "linux"
package: "montage"
version: "6.1+dfsg-1+b1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/mExec"
---

# mExec(1)

Create a 2MASS, SDSS or DSS mosaic based on a size and location

## NAME

mExec - Create a 2MASS, SDSS or DSS mosaic based on a size and location

## SYNOPSIS

mExec \[-q\] \[-r *rawdir*\] \[-n *ntilex*\] \[-m *ntiley*\] \[-l\] \[-k\] \[-c\] \[-o *output.fits*\] \[-d *level*\] \[-f *region.hdr* \| -h *header*\] survey band \[*workspace-dir*\]

## DESCRIPTION

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.

## OPTIONS

- \-q

  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*.

- \-l

  "Level-only" flag (see **mBgModel**)

- \-k

  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).

- \-c

  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)

## ARGUMENTS

**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 \[u, g, r, i, z\] DSS \[DSS1, DSS1R, DSS1B, DSS2, DSS2B, DSS2R, DSS2IR\]

- workspace-dir

  Directory where intermediate files will be created.  If no workspace is given, a unique local subdirectory will be created (e.g.; ./MOSAIC\_AAAaa17v)

## RESULT

**\[struct stat="OK", workspace="***workspace-dir***"\]**

*The output mosaic(s), and any intermediate files (if the "-c" flag was not used) will be inside workspace-dir.*

## MESSAGES

- *OK*

  *\[struct stat="OK", workspace="workdir"\]*

- *ERROR*

  *Must have either header file (-f) or header text (-h)*

- *ERROR*

  *Can't open original header template file: \[region.hdr\]*

- *ERROR*

  *Can't open workspace header template file: \[region.hdr\]*

- *ERROR*

  *Can't create proper subdirectories in workspace (may already exist)*

- *ERROR*

  *Can't open header template file*

- *ERROR*

  *Can't open expanded header file: \[big\_region.hdr\]*

- *ERROR*

  *survey has no data covering expanded area*

- *ERROR*

  *survey has no data covering this area*

- *ERROR*

  *No data was available for the region specified at this time*

- *ERROR*

  *Bad WCS in input image*

- *ERROR*

  *Can't open mosaic file: \[mosaic.fits\]*

- *ERROR*

  *Can't open save file: \[image.fits\]*

- *ERROR*

  *Output wcsinit() failed*

- *ERROR*

  *Error from another Montage module*

## EXAMPLES

*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*

  *\[struct stat="OK", workspace="/path/to/workdir"\]*

## BUGS

*The drizzle algorithm has been implemented but has not been tested* *in this release.*

*If a header template contains carriage returns (i.e., created/modified* *on a Windows machine), the cfitsio library will be unable to read it* *properly, resulting in the error: \[struct stat="ERROR", status=207,* *msg="illegal character in keyword"\]*

*It is best for the background correction algorithms if the area* *described in the header template completely encloses all of the input* *images in their entirety. If parts of input images are "chopped off"* *by the header template, the background correction will be affected. We* *recommend you use an expanded header for the reprojection and* *background modeling steps, returning to the originally desired header* *size for the final coaddition. The default background matching assumes* *that there are no non-linear background variations in the individual* *images (and therefore in the overlap differences). If there is any* *uncertainty in this regard, it is safer to turn on the "level only"* *background matching (the "-l" flag in mBgModel.*

## COPYRIGHT

*2001-2015 California Institute of Technology, Pasadena, California*

*If your research uses Montage, please include the following* *acknowledgement: "This research made use of Montage. It is funded by* *the National Science Foundation under Grant Number ACI-1440620, and* *was previously funded by the National Aeronautics and Space* *Administration's Earth Science Technology Office, Computation* *Technologies Project, under Cooperative Agreement Number NCC5-626* *between NASA and the California Institute of Technology."*

*The Montage distribution includes an adaptation of the MOPEX algorithm* *developed at the Spitzer Science Center.*