NAME

evalvg - Calculate EST & SES angles from ephemeris data

USAGE

evalvg root_name otb_name

DESCRIPTION

EVALVG computes the earth_satellite_target angle (EST) and the sun_earth_satellite (SES) angle and produces an output table with the time history of these two angles.

Both the ephemeris table and the obi table are read to provide information about objects positions and Julian day during the observation. Only the file root is required as input. Both file names (_eph.tab,_obi.tab) are derived from the root by the code. The files must be in the same directory.

Currently this task runs on RDF data only. If REV0 data is input, an error message will be displayed on the screen and the task aborted.

The output table contains four columns: sc_time, est_angle, ses_angle, obi_num.

PARAMETERS

tab_root ="" prompt = Input table root name (_eph.tab,_obi.tab)

Required input file root name for the RDF ephemeris table (_eph.tab) and the obi table (obi.tab). Ephemeris table contains objects positions for all obi's and obi table has Julian day during mission for each obi.

otb_name ="" prompt = output table file name

Required Output filename. The file is written in table format. The name may be specified by supplying the rootname and "_ang.tab" extension will be appended. For example input "vgtest" becomes "vgtest_ang.tab". Each row in the table represents 1 bin of folded data. The column titles and definitions are as follows:

	sc_time   ----- start time of the bin in space craft time 
	est_angle ----- earth_satellite_target angle 
	ses_angle ----- satellite_earth_sun angle 
        obi_num   ----- obi number 

Table header is also created which is same as obi table.

(display = 1) [int]

The display level. A few of the parameters and computed time intervals are displayed to the user for those who like to see that things are happening. Input 0 for no output, 1 for output filename and 5 for the maximum level.

(clobber = no) [boolean]

Boolean flag specifying whether or not the output table can be overwritten if it already exists.

EXAMPLES

1. Read RDF tables and create a file "vgtest_ang.tab"

	xp> evalvg 
        Input table root name: rh110267n00 
        output orbit angles table name:  vgtest

	Creating output file: vgtest_ang.tab