Photometry of RSO#

Prepare FITS files#

Your RSO photometry FITS files should be in some directory. They should be named in order of creation, otherwise the script will lose the target In this case use fits_sort option in config_sat.ini file to sort the FITS files, see Prepare sat_config file.

Avoid names like file_1.fits, file_10.fits, etc. Preferred name patters is {date_folder}/{norad_folder}/{norad}_{HHMMSS of start}_{count}.fits

Or simply use: file_00001.fits, file_00002.fits and so on.

FITS files do not need to contain WCS solution, sat_phot.py script do not use it at all.

Starting from ver 1.0.1 sat_phot.py script can try to find object automatically on the first FITS file. If automatic script fails than it look for add additional keywords in the first FITS file header OBJX: <float> & OBJY: <float> or for config file (in section [OBJ_POS]) to tell the script where the target initially is situated on the frame.

Prepare sat_config file#

Example of sat_config.ini file can be found in project root directory. Photometry script will try to find config_sat.ini in working DIR or some other INI file that will be read as config file. Config file has few sections (see below).

Most important section is STD section. Here you should set the system zero-point & coefficient of extinction. Can be obtained in the process of system calibration (see Photometry system calibration). Filter (band) and all other parameters are optional.

You can sort your FITS files according to some KEY from FITS headers, if there is some filename issues.

[NAME]
NORAD = 43657
COSPAR = 18082A
NAME = COSMOS-2528

[orbit]
format = TLE            # TLE or OMM(JSON). Can read multiple data from one file
file = D:\Share\TPL-programs\WEB2\TLE\tle_2022_03_05.txt

[STD]
A = 14.5                # System zero-point
k = 0.1                 # coefficient of extinction in selected filter
gate = 10               # Window to search the object (in pixels)
Filter = R              # Filter name
Time_format = UT        # UT/JD optional parameter, default value = UT
min_real_mag = 15       # Min mag that can be obtained on photometry system
max_center_err = 2.0    # Maximum allowed error in center definition
fits_sort = DATE-OBS    # Header field to sort files by (without quotes). Default sorted by FITS name, without this option at all or set None.
header_time = DATE-OBS  # Keyword to obtain time from FITS header
time_moment = start     # 'start' 'end' or 'middle' of exposure

[OBJ_POS]
obj_x = 360       # object X position on first frame according to SAOImage ds9 software
obj_y = 312       # object Y position on first frame according to SAOImage ds9 software

[APERTURE]
ap = 8
an_in = 12
an_out = 16
saturated = False       # reject saturated data ? Default is False

[PLOT]
plot_errors = False     # Plot errors with ccd_plot.py script
auto_plot = True        # Plot graphs when result is ready
python = python3        # python3, python38, or something else
plot_command = /path_to_file/ccd_plot.py # abspath to ccd_plot.py

[DEBUG]
save_png = False     # save png of detected object. Default is False for faster processing
save_corr = False    # save mag corrections and other values in tmp_mag.txt

[SITE]
Name = Derenivka
lat = 48.5635505
lon = 22.453751
h = 231.1325

In general sat_phot.py has few options:

  • [path] Path to FITS files [REQUIRED]

  • [-c or - - config ] Specify config file [Optional]

  • [-s or - - start_file] Specify the name of the FITS file to start from [Optional]. Could be useful if photometry script fails in the middle of the file list. This can happen if the object is too faint. In such case you can use this option to start from required FITS. But first rename result file or it will be overwritten.

Warning For Windows users:

Try to avoid folder and file names with spaces. It can be interpreted as two or more parameters which leeds to incorrect work of the scripts