The rtcorr guide




rtcorr is a program for doing extinction correction on Real Time photometry data. The program is completely non-interactive. One input file is given and a few options can be invoked. The output retains the format of the rtp output files, adding a few header lines with information on the processing steps applied. The rtcorr program requires two additional files with information to start the extinction correction; one file named TELESCOPE that gives information about the observatory and instrument used (and which will be the same for all targets of a given run), and one file named TARGET which gives specifics for the current TARGET. See below for details on how to create these files.

rtcorr execution


The TELESCOPE file

The TELESCOPE file should look something like this:
Observatory:"Nordic Optical Telescope"
Longitude:"-17d53m06.3s" # Negative for West / Positive for East
Latitude: "+28d45m26.2s"
Altitude: "2465.5m"
Instrument: "ALFOSC"
Filters: "XUBVRIWrX" # Filter in position 012345678
The longitude and latitude values are used for the extinction correction. The observatory and instrument names used only read by rtp to put in the data file headers, overriding the FITS keywords. The filters sequence is important. It tells rtcorr what filter correspond to which extinction coefficient in the TARGET file. rtpextracts the filter number from the FITS header and puts this in the output files. rtcorr then selects the filter letter based on the position of the letters in the Filters string. For standard filters the order is rarely changed.

The TARGET file

The TARGET file should look something like this:

# Target information:
TARGET: "PG 1336-013"
RA(B1950): "13h36m13.3s"
DEC(B1950): "-01d46m34s"
# Observationrun information:
DATE: "2001-05-04"
TIME(UT): "22:30:45"
# Extinctioncoefficients
K_U: "0.49"
K_B: "0.30"
K_V: "0.15"
K_R: "0.09"
K_I: "0.05"
K_W: "0.15"

The target name is only passed on to the output files for information purposes, together with the coordinates and date/time of start. The target coordinates and start time is of course used for calculating the airmass. The extinction coefficients given here are typical for La Palma, but may change significantly depending on the conditions.

Copy the TELESCOPE and TARGET files

The easiest way to get started with rtcorr is simply to copy the TELESCOPE and TARGET files from the ~fastphot directory.

Output files

rtcorr normally produces three output files.


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Last modified: Tuesday, 31-Apr-2001 12:08:31 ACT