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

# mBgExec(1)

Run mBackground on all the images in a metadata table

## NAME

mBgExec - Run mBackground on all the images in a metadata table

## SYNOPSIS

mBgExec \[-p *projdir*\] \[-s *statusfile*\] \[-d\] \[-n(o-areas)\] images.tbl corrections.tbl corrdir

## DESCRIPTION

Runs mBackground on all the images in a metadata table, using the corrections generated by mFitExec.

## OPTIONS

- \-p *projdir*

  Specifies the path to the directory containing the projected images.

- \-s *statusfile*

  Writes output message to *statusfile* instead of to stdout

- \-d

  Turns on debugging

- \-n

  Indicates that no area images are present (assumes equal weighting for each pixel)

## ARGUMENTS

- images.tbl

  Image metadata table generated by mImgtbl.

- corrections.tbl

  Table of corrections generated by mFitExec

- corrdir

  Directory where output images should be written

## RESULT

Output FITS images will be created in the directory specified by *corrdir*, with names that are the same as the uncorrected images.

## MESSAGES

- OK

  \[struct stat="OK", count=*num-images*, nocorrection=*num-skipped*, failed=*num-failed*\]

- ERROR

  MPI initialization failed

- ERROR

  Cannot open status file: *statusfile*

- ERROR

  Cannot access *corrdir*

- ERROR

  *corrdir* is not a directory

- ERROR

  Invalid image metadata file: *images.tbl*

- ERROR

  Need columns: cntr and fname in image list

- ERROR

  Too many entries in image list for compiled program

- ERROR

  *mBackground error*

## EXAMPLES

In this example, **images.tbl** describes the unprojected or projected images (filenames are the same if **mProjExec** was used), and **corrections.tbl** was generated using **mBgModel** after running **mDiffExec** and **mFitExec** on those images.

- $ mBgExec -p proj images.tbl corrections.tbl corr

  \[struct stat="OK", count=16, failed=0\]

corr now contains the images with background removal applied.

## 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.