The SWIFT BAT Software Guide Version 6.3 30 ... - HEASARC - Nasa

D.16. BATOCCULTGTI 171
D.16 BATOCCULTGTI
D.16.1 NAME
batoccultgti - compute BAT good time intervals due to occultation
D.16.2 USAGE
batoccultgti infile outfile ra dec
D.16.3 DESCRIPTION
batoccultgti computes the occultation good time intervals for a particular source during a BAT
observation. Occultation of the earth, moon and/or sun can be considered. The BAT field of view
is large enough that any of these bodies may occult cosmic sources. Note that this task is used
for a single source, usually for data selection. If operating on a sky image, the batoccultmap task
should be used.
Users can also check whether a source is within the X% partially coded field of view of the BAT
using the “FOV” constraint. Users need to simply specify a partial coding threshold. However,
users should be warned that the coordinate transformations and partial coding levels are not exact
(to within a few degrees).
In addition to the partial coding check, users can also constrain the target to be in a certain
position in the field of view, either in tangent plane coordinates (using the im{x,y}{min,max}
parameters), or in polar coordinates (theta,phi).
Normally, the user must supply the “SAO” file created by prefilter. This file contains the
positions of the earth, moon and sun as a function of time. The “sizes” of the earth, moon and
sun are configurable in this task. If the user is only performing a field of view check (i.e. not the
earth, moon or sun), then it is possible to use a Swift attitude file (“sw*sat*.fits”), along with the
att type=“ATT” parameter.
This task calls the FTOOLS ‘maketime’ and ‘ftcopy’, which must be present.
D.16.4 PARAMETERS
infile [filename ]
The name of the “SAO” file produced by prefilter. This file should contain the columns TIME,
RA, DEC, ROLL, SAT ALT, MOON RA, MOON DEC, SUN RA, SUN DEC, EARTH RA,
EARTH DEC. The file may also be a Swift attitude file if only field of view constraints are
being checked, and if att type=“ATT”.
outfile [filename ]
The name of the output good time interval file. This is a standard OGIP-compatible GTI
file.