man mExamine (1): Information about the sky coverage of a FITS image

SYNOPSIS

mExamine [-d][-p ra dec radius] image.fits

DESCRIPTION

  mExamine returns information about the sky coverage of a FITS
  image (assuming WCS keywords in the header) and optionally
  pixel statistics for a region in the image.

OPTIONS

-p ra dec radius

  Return information about a region (central pixel value, min, max
  values and location, etc.)  Coordinates and radius are in
  degrees unless given a "p" suffix, in which case they are in pixels.

-d

Turn on debugging.

ARGUMENTS

image.fits

  FITS file to examine. If the file has multiple HDUs, you can add
  that to the file name, e.g., "m51.fits[2]".  If an HDU is
  a datacube, you can select a plane ("m51.fits[2][256]").  Even if
  there is a single HDU, you need to specify it if you want to
  specify a cube plane ("m51.fits[0][512]").  Note that this syntax
  may require quotes around the file name string to avoid confusing
  your shell.

RESULT

If successful, returns the following:

       proj     Image projection
       csys     Coordinate system
       equinox  Coordinate system equinox
       naxis    Number of axes in the file
       naxis1   Image width (in pixels)
       naxis2   Image height
       naxis3   Data cube depth (only if NAXIS > 2)
       naxis4   Data cube fourth dimension (only if NAXIS > 3)
       crval1   WCS reference coordinate for first axis
       crval2   WCS reference coordinate for second axis
       crpix1   Pixel value for reference coordinate
       crpix2
       cdelt1   Pixel scale (degrees)
       cdelt2
       crota2   Rotation of image (E of N)
       lonc     Sky coordinate of image center
       latc
       ximgsize Image size (degrees)
       yimgsize
       rotequ   Rotation of image in Equatorial (J2000)
       rac      Equatorial (J2000) coordinates of image center
       decc
       ra1      Equatorial coordinates of four image corners
       dec1
       ra2
       dec2
       ra3
       dec3
       ra4
       dec4

and optionally

       radius   Radius of pixel region (degrees)
       radpix   Radius in pixels
       npixel   Number of pixels in region
       nnull    Number of null pixels
       aveflux  Average flux for region
       rmsflux  RMS of region fluxes
       fluxref  Flux for reference location
       sigmaref RMS of fluxes
       xref     Pixel coordinates of reference location
       yref
       raref    Equatorial (J2000) coordinated of reference location
       decref
       fluxmin  Same for pixel with minimum flux
       sigmamin
       xmin
       ymin
       ramin
       decmin
       fluxmax  Same for pixel with maximum flux
       sigmamax
       xmax
       ymax
       ramax
       decmax

   If you specify region that is all blank, npixel will be zero, nnull will
   be the total number of pixel examined, and the flux related parameters will
   all be zero.

MESSAGES

ERROR: No ra, dec, radius location given or file name missing
ERROR: File name missing
ERROR: Cannot open FITS file test.fits
ERROR: Cannot find WCS keys in FITS file test.fits
ERROR: WCS initialization failed.
ERROR: Location off the image.
ERROR: Error reading FITS data.

EXAMPLES

mExamine -p 202.5 47.0 0.01 aJ_asky_980527n0240232.fits: [struct stat="OK", proj="SIN", csys="EQUJ", equinox=2000.0, naxis1=512, naxis2=1024, crval1=202.5213942, crval2=47.1131924, crpix1=256.5, crpix2=512.5, cdelt1=0.0002778, cdelt2=0.0002778, crota2=0.0034, lonc=202.5213942, latc=47.1134702, ximgsize=0.142222, yimgsize=0.142222, rotequ=0.0034, rac=202.5213942, decc=47.1131924, ra1=202.6260252, dec1=46.9706487, ra2=202.4171950, dec2=46.9706407, ra3=202.4166112, dec3=47.2553630, ra4=202.6265617, dec4=47.2553710, radius=0.0100000, radpix=36.00, npixel=5476, nnull=0, aveflux=136.807, rmsflux=0.853615, fluxref=137.3, sigmaref=0.578143, xref=309, yref=105, raref=202.5000208, decref=46.9999951, fluxmin=135.042, sigmamin=-2.06764, xmin=328, ymin=77, ramin=202.4922870, decmin=46.9922153, fluxmax=152.299, sigmamax=18.1493, xmax=307, ymax=117, ramax=202.5008338, decmax=47.0033286]

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.