Detailed Description

Provides routines to compute time delay between two detectors.

Author: David Chin, Kipp Cannon

Synopsis

#include <lal/TimeDelay.h>

Description

The function XLALTimeDelayFromEarthCenter() Computes difference in arrival time of the same signal at detector and at center of Earth-fixed frame.

The function XLALLightTravelTime() computes the light travel time between two detectors and returns the answer in INT8 nanoseconds.

The function XLALPopulateAccuracyParams() creates an instance of InspiralAccuracyList populated with the light-travel times between the detectors, using just the previous function. The function XLALPopulateAccuracyParamsExt(), however, creates an instance of InspiralAccuracyList populated with the real travel time of a putative signal for the given time and the given sky location (in right ascension and declination, both given in degrees).

Algorithm

TBA. See Anderson, et al. [5] in the mean time.

Note that GPS time is passed with both the detectors. The GPS time of the second detector is ignored, and the GPS time for the first detector is taken to be the time when the signal arrives at the center of the Earth. In practice, this time will be the time of detection of a signal at the first detector, but, as in Anderson, et al., we make this approximation as it makes little difference. This time is used to compute a GMST which gives us the orientation of the Earth.

Prototypes
double	XLALArrivalTimeDiff (const double detector1_earthfixed_xyz_metres[3], const double detector2_earthfixed_xyz_metres[3], const double source_right_ascension_radians, const double source_declination_radians, const LIGOTimeGPS *gpstime)
	UNDOCUMENTED. More...

INT8	XLALLightTravelTime (const LALDetector aDet, const LALDetector bDet)
	Compute the light travel time between two detectors and returns the answer in `INT8` nanoseconds. More...

REAL8	XLALTimeDelayFromEarthCenter (const double detector_earthfixed_xyz_metres[3], double source_right_ascension_radians, double source_declination_radians, const LIGOTimeGPS *gpstime)
	Compute difference in arrival time of the same signal at detector and at center of Earth-fixed frame. More...

Files
file	DelayTest.c
	Tests `TimeDelay` code.

Function Documentation

◆ XLALArrivalTimeDiff()

double XLALArrivalTimeDiff	(	const double	detector1_earthfixed_xyz_metres[3],
		const double	detector2_earthfixed_xyz_metres[3],
		const double	source_right_ascension_radians,
		const double	source_declination_radians,
		const LIGOTimeGPS *	gpstime
	)

UNDOCUMENTED.

Definition at line 37 of file TimeDelay.c.

◆ XLALLightTravelTime()

INT8 XLALLightTravelTime	(	const LALDetector *	aDet,
		const LALDetector *	bDet
	)

Compute the light travel time between two detectors and returns the answer in INT8 nanoseconds.

Definition at line 105 of file TimeDelay.c.

◆ XLALTimeDelayFromEarthCenter()

REAL8 XLALTimeDelayFromEarthCenter	(	const double	detector_earthfixed_xyz_metres[3],
		double	source_right_ascension_radians,
		double	source_declination_radians,
		const LIGOTimeGPS *	gpstime
	)

Compute difference in arrival time of the same signal at detector and at center of Earth-fixed frame.

Definition at line 83 of file TimeDelay.c.