Pointing information in Gleam

Last Update: 06/01/2010 15:48 -0700

As of v3r3p3 + HEAD1.163 Gleam has the capability to save pointing information in the merit tuple. There are three elements:

1. A TDS class Exposure: this has a minimal subset of the D2 database. Contents are
   • mission elapsed time, in seconds
   • absolute position vector (direction to zenith)
   • Earth position (lat, lon)
   • Orientation (direction of z and  x axes)
2. The Algorithm ExposureAlg: uses GPS from flux to obtain pointing information for the current mission elapsed time, puts an Exposure object onto the TDS
3. The Algorithm meritAlg: Defines a root TTree for exposure only.

Notes:

• We need code (in the astro package) to compute the "missing" values for the FT1 and FT2 data bases.
• It is not tested yet. We need a test program that follows a single source through many orbits, and verifies that the orientation can be reconstructed.