sexphot computes calibrated photometric magnitudes from a list of FITS images and plots the resulting light curves. It uses the program sextractor to extract raw magnitudes. The raw magnitudes are converted to calibrated magnitudes using zero-point magnitudes read from the FITS headers (keywors ZMAG, ZMAGERR),  If these keywords are not found, the program uses a user-input global value (option -z) or, defaults to a pre-defined list of filter-specific ZP values. 

The program reads a (required) input conifguration file containing a list of FITS image names, a title, and a list of targets with names and coordinates. The configuration  file has five sections: 

  1. A list of FITS images (can be wild-carded, as shown below). Prefix each line with letter I
  2. Filter code, prfeix line with letter F
  3. A title string. Prefix with letter T
  4. Linear ephemeris: Barycentric JD, period (days). Prefix with letter E
  5. A list of star coords, with the reference star listed last. Prefix with letter S

Version: 2.0, 1 Dec 2018

Known bugs/issues: Does not use ZP mag in FITS header (uses default values or user-supplied 

Example input config file:

# Input FITS files (wildcard allowed)

I *.fts

# Filter code


# Title

T NSVS 14256825

# Linear ephemeris BJD0, period (days) Nasiroglu AJ 2017

E 2455793.84005 0.110374083

#Stars: list order: target, checkstar[s], reference star

S NSVS14256825  20:20:00.47 +04:37:56.9 

S Checkstar1  20:19:51.37 +04:35:50.9 

S Reference      20:20:06.73 +04:40:17.6

Usage: sexphot [options]

sexphot computes photometric magnitudes using sextractor, plots light curves


  --version     show program's version number and exit

  -h, --help    show this help message and exit

  -s sigma      Sextractor detection threshold [default 5]

  -c config     phot config file name [no default]

  -d outfile    Output csv file name

  -l            Plot median line

  -J jdrange    JD range (JDmin, JDmax)

  -t            Solve for time of minimum [default False]

  -v            Verbose output

  -w width      Minimum fit width, sample times [default 20]

  -y yrange     Differential plot yrange [default: autoscale]

  -z Zeropoint  Zero-point magnitude, defaults to FITS header value

Example: ./sexphot -c nsvs1425.sexphotin -t

Saved light curve of all stars as NSVS14256825_lc-all.png

Saved differential l.c. plot NSVS14256825_2018-11-29_lc.png


© Robert Mutel 2018