ImageSum

ImageSum - Summarize FITS files in a directory

Space Telescope Science Institute

Synopsis

Recursively search a directory for FITS files and produce a summary table with WCS-derived positions, image sizes, and header metadata. Useful for locating images that cover a given RA and Dec.

Command Line Usage

ImageSum.py [-h] [-out outname] dirname

Required Arguments:

dirname

Directory to search recursively for FITS files.

Optional Arguments:

-h

Print this documentation and exit.

-out outname

Set the output filename. Default: Image_Sum_{dirname}.txt

Description

Searches for all *.fits* files (including .fits.fz) in the specified directory and subdirectories. For each file, extracts metadata from headers and calculates image center and size from WCS information.

Handles multi-extension FITS (MEF) files by processing each image extension separately.

Output Columns

Source_name Object name from OBJECT header keyword Filter Filter name from FILTER header keyword Exptime Exposure time in seconds Image_type Derived from filename (e.g., “ha”, “sii”, “r”) RA Right ascension of image center (degrees) Dec Declination of image center (degrees) width Image width in degrees (corrected for cos(dec)) height Image height in degrees mag Photometric zeropoint (MAGZERO), or -999 if missing seeing Seeing FWHM (SEEING), or -999 if missing filename Full path to the FITS file ext Extension number within the file

Example

ImageSum.py DECam_SUB2
ImageSum.py -out all_tiles.txt DECam_SWARP

Primary Routines

table_create Main routine that builds the summary table list_image_extensions Identify image extensions in MEF files get_image_center_and_size_from_header Calculate WCS-derived image geometry

History

240813 ksl Coding begun

Functions

get_image_center_and_size_from_header(header)

Calculate the center coordinates (RA, Dec) and size in degrees

list_image_extensions(filename)

print_header_image_info(header[, description])

Convenience function to print image information from header in a readable format.

steer(argv)

table_create([xdir, outname])

Module Contents

ImageSum.get_image_center_and_size_from_header(header)

Calculate the center coordinates (RA, Dec) and size in degrees of a FITS image from its header containing WCS information.

Parameters:

headerastropy.io.fits.Header

FITS header containing WCS keywords and NAXIS information

Returns:

dictDictionary containing:

  • ‘center_ra’: RA of image center in degrees

  • ‘center_dec’: Dec of image center in degrees

  • ‘width_deg’: Width of image in degrees

  • ‘height_deg’: Height of image in degrees

  • ‘pixel_scale_ra_deg_per_pix’: Pixel scale in RA direction (deg/pixel)

  • ‘pixel_scale_dec_deg_per_pix’: Pixel scale in Dec direction (deg/pixel)

  • ‘image_shape’: Tuple of (ny, nx) image dimensions

  • ‘wcs’: WCS object for further coordinate transformations

ImageSum.list_image_extensions(filename)
ImageSum.print_header_image_info(header, description='FITS Header')

Convenience function to print image information from header in a readable format.

Parameters:

headerastropy.io.fits.Header

FITS header containing WCS and dimension information

descriptionstr

Optional description for the output

ImageSum.steer(argv)
ImageSum.table_create(xdir='DECam_SUB2', outname='')