mFitplane1

Usage

Overview

Uses least squares to fit a plane (excluding outlier pixels) to an image. It is used on the difference images generated using mDiff or mDiffExec.

Options

-b border

Number of border pixels to ignore at edges of image.

-d level

Turns on debugging to the specified level (1-3).

-l

Level only: don't fit a slope; just get a zero level.

-s statusfile

Output and errors are written to statusfile instead of stdout.

Arguments

in.fits

Input FITS file is a difference file between two other FITS files, as can be generated using mDiff.

Result

The plane fit to the image is of the form:

fit = A*x + B*y + C

where x is the "horizontal" pixel offset from CRPIX1 in the FITS header and y is the "vertical" offset from CRPIX2. Since all reprojected images use the same reference pixel, this is a uniform definition for x,y for the whole image set.

The fitting is a simple least squares, with an iterative loop to exclude points more than 2 sigma (sigma defined as the rms from the previous loop).

The rms output is the value computed above. The xmin, ... ymax output correspond to the range of x,y values found while fitting. The rms is for information only but the xmin, ... ymax are used in the background fitting (mBgModel). crpix1 and crpix2 are the reference pixels for each axis, as determined from the FITS header.

Messages

OK

[struct stat="OK", a=A, b=B, c=C, crpix1=crpix1, crpix2=crpix2, xmin=xmin, xmax=xmax, ymin=ymin, ymax=ymax, xcenter=xcenter, ycenter=ycenter, npixel=npixel, rms=rms, boxx=boxx, boxy=boxy, boxwidth=boxwidth, boxheight=boxheight, boxang=boxang]

ERROR

Argument to -b (string) cannot be interpreted as an integer

ERROR

Cannot open status file: statusfile

ERROR

Image file filename missing or invalid FITS

ERROR

FITS library error

ERROR

general error

WARNING

Too few pixels to fit

WARNING

Too few pixels for bounding box

WARNING

Singular Matrix-1

WARNING

Singular Matrix-2

WARNING

allocation failure in ivector()

Examples

$ mFitplane 2mass-atlas-990322n-j0640266.fits

[struct stat="OK", a=-8.9198e-11, b=-2.54173e-10, c=5.24277e-05, crpix1=808, crpix2=212.5, xmin=-808, xmax=167, ymin=-210.5, ymax=638.5, xcenter=-320.871, ycenter=213.014, npixel=314299, rms=0.393003, boxx=-320.92, boxy=212.424, boxwidth=835.421, boxheight=509.274, boxang=-29.5537]