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

# mBestImage(1)

Determine which image covers a location "best"

## NAME

mBestImage - Determine which image covers a location "best"

## SYNOPSIS

mBestImage \[-d *level*\] images.tbl ra dec

## DESCRIPTION

Given a list of images and a position on the sky, determine which image covers the location "best" (i.e., the one where the position is farthest from the nearest edge).

## OPTIONS

- \-d *debug*

  Turn on debugging to the specified level (1 or 2)

## ARGUMENTS

- images.tbl

  Input table of image metadata (as generated by **mImgtbl**).

- ra

  RA of location of interest (in degrees)

- dec

  Declination of location of interest (in degrees)

## RESULT

**\[struct stat="OK", file="***filename***", edgedist=***distance***\]**

*or*

**\[struct stat="OK", file="***filename***", url="***fileurl***", edgedist=***distance***\]**

**where** *filename* **is the name of the "best" image found in** *images.tbl* **and** *distance* **is measured from the point of interest to the nearest edge of the image.  If the input table included a URL column, the output message will also include the image's URL.**

## MESSAGES

- **OK**

  **\[struct stat="OK", file="***filename***", url="***fileurl***", edgedist=***distance***"\]**

- **OK**

  **\[struct stat="OK", file="***filename***", edgedist=***distance***"\]**

- **ERROR**

  **Invalid image metadata file:** *images.tbl*

- **ERROR**

  **Need columns: cntr and fname; ctype1 ctype2 nl ns crval1 crval2 crpix1 crpix2 cdelt1 cdelt2 and crota2 or cd matrix / ra dec ra1 ... dec4**

- **ERROR**

  **Bad WCS for image** *fitsfile*

- **ERROR**

  **No image covers this position.**

## EXAMPLES

**Given a table of image metadata describing images covering a 0.5 by 0.5 degree area around m31 (2mass\_m31\_j.tbl), narrow it down to the image which includes the best coverage of one particular location:**

- **mBestImage 2mass\_m31\_j.tbl 10.7 41.2**

  **\[struct stat="OK", file="2mass-atlas-971024n-j0080033.fits", edgedist=0.008436\]**

## 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.**