#!/usr/bin/perl # User front-end form input interface for HEXTErock WWW tool. This is a Perl # script, not a web page, since it must form today's date and a day-of-year # calendar to aid the user. use POSIX; $ENV{'PATH'} = ""; # more secure for CGI require("cgi-lib.pl") || die "Failed to find cgi-lib.pl in /your/script/directory.\n"; # Calculate the UT date for the form's default input ($sec, $min, $hour, $dd, $mm, $yy, $wday, $yday) = gmtime; $mm++; $yday++; # Deal with the 1900 / 2000 problem in the gmtime() function and form a string # containing the day's date: if ($yy > 95.0) { $yy +=1900;} else {$yy +=2000;} $todaydate = sprintf("%4.4d%2.2d%2.2d.75", $yy, $mm, $dd); # print the HTML header (using the subroutine in cgi-lib.pl) print &PrintHeader; # print the plain HTML part of the web page, including the HTML form print < HEXTErock - HEXTE cluster background positions on the sky Presenting...

HEXTErock - HEXTE cluster background positions on the sky

(with ASM catalog sources)

The HEXTE clusters A and B can beamswitch, or "rock", along the RXTE spacecraft's Z and Y axes to sample the background either side of the source, offset by either 1.5 or 3.0 degrees.

For a given observation with RXTE's science (x-axis) pointing at the source, the Y and Z rocking axes depend on the spacecraft's roll angle, which is defined and constrained relative to the Sun. The resulting HEXTE clusters' background positions on the sky therefore depend on the date of the observation.

HEXTErock is a software tool provided by the HEXTE instrument team which will calculate these positions for you. The most recent HEXTErock software (written in C) is available for download via anonymous ftp. HEXTErock can also be run by using the form below, which will produce a sky plot showing the HEXTE clusters' fields of view, together with x-ray sources from the RXTE All Sky Monitor catalog.

Note that RXTE cannot observe sources within 30 degrees of the Sun, so those planning RXTE observations should first use the HEASARC tool VIEWING to determine the permissible ranges of observing dates for their source.

To calculate the HEXTE cluster background positions for an RXTE observation, please complete the following:

  • UT date of observation (YYYYMMDD.dd): (this example is 18:00 UT today, $yy day $yday)
  • J2000.0 source Right Ascension (0.0 to 360.0): degrees

  • J2000.0 source Declination (-90.0 to +90.0): degrees

  • RXTE roll offset from sun (-90.0 to +90.0 degrees, or DEF for default):
    • EOD # Next set up the little day-of-year calendar for this web page @months = ("Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"); @daysinmonth = (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31); $daysinmonth[1] = 29 if &leapyear($yy); # Add up the days elapsed in the year for the start ('zeroth') ofeach month: $doybases[0] = 0; for ($j = 1; $j < 12; $j++) { $doybases[$j] = $doybases[$j-1] + $daysinmonth[$j-1]; } # Output the little day-of-year/date conversion calendar as a pull-down list print qq|\n"; # Print out the "footer" of the web page: print <

    Rossi X-ray Timing Explorer

    High Energy X-ray Timing Experiment (at UCSD)

    The HEXTErock software was written by Philip Blanco, a member of the HEXTE instrument team at the University of California, San Diego. EOT exit; # ------------------------------------------------------------------------ # subroutine to determine if a year is a leap year sub leapyear { local ($year) = @_; ((!($year % 4)) && (!(!(($year % 100) || (!($year % 400)))))); }