Computes the strain on a detector given a gravitational waveform.

Synopsis

lalsim-detector-strain [options] [file]

Description

The lalsim-detector-strain utility converts a gravitational waveform in file or standard input if file is absent into an induced detector strain on a specified detector. The input data should be in a three-column ascii format with the first column being the time of each sample, the second column being the plus-polarization of the gravitational waveform, and the third column being the cross-polarization of the gravitational waveform. The timestamps on the input file should be centered time 0 (conventions vary: some waveforms will end near time 0; others will be centered on time 0). The output is written to standard output in two column ascii format where the first column is the GPS timestamp of each sample and the second column is the strain induced on the detector.

Options

-h, --help: print a help message and exit
-v, --verbose: verbose output
-r, --radians: use radians rather than decimal degrees
-O, --overhead: signal from directly overhead
-D PREFIX, --detector-prefix=PREFIX: (required unless overhead) detector prefix (e.g., 'H1', 'L1', 'V1')
-t EPOCH, --gps-time=EPOCH: (required) time of arrival at earth geocenter (or at detector if overhead): this is added to the timestamp of the input data, which should be an waveform about time = 0
-a RA, --right-ascension=RA: (required unless overhead) right ascension in H:M:S format or decimal degrees
-d DEC, --declination=DEC: (required unless overhead) declination in D:M:S format or decimal degrees
-p PSI,--polarization-angle=PSI: (required) polarization angle in degrees

Environment

The LAL_DEBUG_LEVEL can used to control the error and warning reporting of lalsim-detector-strain. Common values are: LAL_DEBUG_LEVEL=0 which suppresses error messages, LAL_DEBUG_LEVEL=1 which prints error messages alone, LAL_DEBUG_LEVEL=3 which prints both error messages and warning messages, and LAL_DEBUG_LEVEL=7 which additionally prints informational messages.

Exit Status

The lalsim-detector-strain utility exits 0 on success, and >0 if an error occurs.

Example

The command:

lalsim-inspiral | lalsim-detector-strain -D H1 -a 1:23:45 -d 45.0 -p 30.0 -t 1000000000

outputs to standard output in two-column ascii format the strain induced on the LHO observatory detector from a 1.4 solar mass + 1.4 solar mass binary inspiral at 1 Mpc distance originating from source at right-ascension 1h 23m 45s, declination 45 degrees, and polarization angle 30 degrees that arrives at the geocenter at GPS time 1000000000. The first column contains the GPS time of each sample and the second column contains the induced detector strain at that time.

The command:

lalsim-inspiral | lalsim-detector-strain -O -p 0.0 -t 1000000000

produces a similar output, but now for a signal coming from directly overhead of a arbitrary detector with polarization angle 0 (optimally oriented); the GPS arrival time is now at the detector location.