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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, 2012 day 137)
  • 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
    HEXTE: High Energy X-ray Timing Experiment


    Send questions or comments to Philip Blanco
    pblanco@ucsd.edu