NAME

grafpath -- Create a list of component table names for an observing mode.

USAGE

grafpath obsmode

DESCRIPTION

This task produces a list of component table names for the components which lie in the optical path of a specified observation mode. The other taks in the synphot package compute the combined throughput for an observation mode by multiplying the individual throughputs of the components in the optical path together. These component throughputs are stored in SDAS tables. This task shows you the component tables that synphot uses for a specified observation mode if you want to investigate why the other synphot tasks produce the results they do.

An observation mode is a list of keywords separated by blanks or commas which uniquely specifies an optical path through the telescope. The keywords which make up the observing mode specify the instrument, detector, aperture, filters, and/or gratings used. These keywords may occur in any order and in either lower or upper case. Defaults are available in many cases so that if some keywords are omitted, the defaults will be used.

This task and other tasks in the synphot package determine the components in the optical path for an observing mode from the graph table. The tasks then find the STSDAS tables containing the throughputs for these components in the component lookup table. The names of these two tables are read from the grtbl and cmptbl parameters in the refdata parameter set. The default values of these parameters are set to get the tables most recently installed in the CDBS database.

PARAMETERS

obsmode [string]

A string containing observation mode keywords. Keywords within the string are separated by whitespace or commas. Keywords are used to match optical components from the graph table. Matching is not case sensitive. A warning message is printed if the keyword is not found in the optical path. At the user's option, the observation mode string may be placed within the band() function.

(refdata = "") [pset name]

Parameter set for reference data used in calculations. This pset contains the following parameters:

area = 45238.93416:  HST telescope area in cm**2.

grtbl = "crcomp$hstgraph_*":  HST graph table.  By default, this
        uses the most recent version. 

cmptbl = "crcomp$hstcomp_*"  Instrument component table.  By 
        default, this uses the most recent version.

EXAMPLES

1. Write a list of component table names for the default observing mode of the WFPC:

  sy> grafpath wfpc

2. Create the list of component table names for the FOC f/96 observing mode:

  sy> grafpath foc,f/96

3. Enclose the obsmode expression in a band function:

  sy> grafpath "band(foc,f/96)"

REFERENCES

Written by B.Simon based on XCAL code written by Keith Horne

SEE ALSO

calcband