RXTE in Flight

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 on 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 download. 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 Viewing Tool 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, 2009 day 131)
  • 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):

  • Rossi X-ray Timing Explorer

    High Energy X-ray Timing Experiment (at UCSD)


    The HEXTErock software was developed by Philip Blanco, a member of the HEXTE instrument team at the University of California, San Diego. This page is currently maintained by Edward J. Sabol (HEASARC) under the direction of the RXTE GOF.


    If you have a question about RXTE, please send email to one of our help desks.


    HEASARC | RXTE Home | Archive | Data Analysis | Proposals & Tools | Education & Outreach
    Help desk | Search || General Audiences: RXTE at a Glance | Multimedia | Snazzy Science || Sci/Tech Audiences: About RXTE | RXTE Results | GOF Services | Time lines & Status | SOF | Related Sites