| A photometry package |
Back to Stefan's Astronomical C-program packages page
By Stefan Spännare, November 2006, updated July 2007
Note, the package and the documentation can be downloaded below.
Perhaps this project is obsolete. It was many years ago since the author was
a graduate student at Lund Observatory and he has not been well updated what
has happened in the photometry research area the last years. Nevertheless
this photometry package is based on some ideas not seen in other photometry
packages (at that time). But the computer programs included here are not
necessarily better than others. If you don't find the photometry programs
themselves useful the package also includes many image processing and
auxiliary programs that can be worth looking at. You are very welcome to
download the package and the manual to see if you find it useful.
This is a user manual for some photometry and image processing computer
programs that the author made as a graduate student at Lund Observatory during
the years 1992-1997. The package contains about 100 separate C-programs in
total. Some of them are larger and more complicated, but most of them are
quite small. Some additions and changes have been made since then. The main
part of this document was written already summer 1998 but it has been much
updated since then.
The main purpose of this manual is to describe the star finding and photometry
program FINDSTARS with the help program FSORT (section 3) and the
program POLYFIT for photometry of well sampled stars on uneven backgrounds
(section 4). Detailed descriptions are given for these programs. But many
other useful routines are also described in this manual. For example the
program aperf for simple aperture photometry (section 9.5) and
several programs and tools to make simulated stellar field images (section 5,
6, 7, and 9). Section 8 is dealing with astronomical image formats and image
conversion programs. It is recommended to read this section before using the
programs. Some auxiliary programs are described in section 10. The programs
sscomp and sscomp3 are used to compare measured photometry
data with original data for simulated stellar fields (section 10.1.1). A short
theory section describing analytical PSFs and stellar errors caused by noise
are included in section 2. A program magnoise to calculate theoretical
such errors is described in section 10.1.10. The program eq2hor is
used make accurate conversion between equatorial and horizontal coordinates
for astronomical objects (section 10.3.1). Some programs that use FFT
are described in section 11. Some useful examples how to use the programs
(i.e. to make simulated stellar images and then measure the intensities of
the stars) are found in section 12. Finally how to compile the C-programs
is described in section 13.
For more information on the program POLYFIT see the first article
found here.
Some photometry measurement results and a comparison with DAOPHOT.
1. Crowded field measurements on simulated stellar fields with flat backgrounds.
2. Crowded field measurements on simulated stellar fields with uneven backgrounds.