carta
mBestImage(1)

mBestImage1

Determine which image covers a location "best"

Usage

mBestImage [-d level] images.tbl ra dec

Overview

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]

History

  • Debian 13 (Trixie) to Debian 10 (Buster): the text shown here
  • Debian 9 (Stretch)

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.

From montage 6.1+dfsg-1+b1 in Debian 13 (Trixie). Parsed by carta from the page's man source.