T_APER
Name
T_APER
Purpose
Driver procedure (for APER) to compute concentric aperture photometry.
Explanation
Data is read from and written to disk FITS ASCII tables.
Part of the IDL-DAOPHOT photometry sequence
Calling Sequence
T_APER, image, fitsfile, [ apr, skyrad, badpix, PRINT=, NEWTABLE=,
/EXACT, /SILENT, SETSKYVAL = ]
Inputs
IMAGE - input data array
FITSFILE - disk FITS ASCII table name (from T_FIND). Must contain
the keywords 'X' and 'Y' giving the centroid of the source
positions in FORTRAN (first pixel is 1) convention. An
extension of .fit is assumed if not supplied.
Optional Inputs
User will be prompted for the following parameters if not supplied.
APR - Vector of up to 12 REAL photometry aperture radii.
SKYRAD - Two element vector giving the inner and outer radii
to be used for the sky annulus
BADPIX - Two element vector giving the minimum and maximum
value of a good pixel (Default [-32765,32767])
Optional Keywords Inputs
/EXACT - If this keyword is set, then intersection of the circular
aperture is computed exactly (and slowly) rather than using
an approximation. See APER for more info.
/PRINT - if set and non-zero then NSTAR will also write its results to
a file aper.prt. One can specify a different output file
name by setting PRINT = 'filename'.
/SILENT - If this keyword is set and non-zero, then APER will not
display photometry results at the screen, and the results
will be automatically incorporated in the FITS table without
prompting the user
NEWTABLE - Name of output disk FITS ASCII table, scalar string.
If not supplied, then the input FITSFILE will be updated with
the aperture photometry results.
SETSKYVAL - Use this keyword to force the sky to a specified value
rather than have APER compute a sky value. SETSKYVAL
can either be a scalar specifying the sky value to use for
all sources, or a 3 element vector specifying the sky value,
the sigma of the sky value, and the number of elements used
to compute a sky value. The 3 element form of SETSKYVAL
is needed for accurate error budgeting.
Prompts
T_APER requires the number of photons per analog digital unit
(PHPADU), so that it can compute Poisson noise statistics to assign
photometry errors. It first tries to find the PHPADU keyword in the
original image header, and if not found will look for the GAIN,
CCDGAIN and finally ATODGAIN keywords. If still not found, T_APER
will prompt the user for this value.
Procedures
APER, FTADDCOL, FTGET(), FTINFO, FTPUT, READFITS(), SXADDPAR,
SXPAR(), WRITEFITS
Revison History
Written W. Landsman ST Systems Co. May 1988
Store results as flux or magnitude August 1988
Added SILENT keyword W. Landsman Sep. 1991
Changed ERR SKY to ERR_SKY W. Landsman March 1996
Replace TEXTOUT keyword with PRINT keyword W. Landsman May 1996
Check CCDGAIN or ATODGAIN keywords to find phpadu W. Landsman May 1997
Converted to IDL V5.0 W. Landsman September 1997
Updated for new FTINFO calling sequence W. Landsman May 2000
Added /EXACT keyword W. Landsman June 2000