Cheta Telemetry Archive#

The cheta telemetry archive is a suite of tools and data products that provide the majority of all Chandra engineering telemetry since the start of the mission (1999:204). This includes about 6300 MSIDs which are taken directly from CXC Level-0 (L0) telemetry decom, plus numerous pseudo-MSIDs that are derived from the primary engineering telemetry.

The telemetry are stored in a way that allows for very fast retrieval into memory. Typical retrieval rates are around 10^7 samples/sec, so for an MSID sampled once per second this translates to about 3 sec per year of data.

The data archive includes:

  • Full time-resolution data: time, value, quality.

  • 5-minute statistics: min, max, mean, sampled value, number of samples.

  • Daily statistics: min, max, mean, sampled value, standard deviation, percentiles (1, 5, 16, 50, 84, 95, 99), number of samples.

The cheta package includes:

  • A powerful MSID class to fetch, manipulate, and plot telemetry data.

  • Interface to the MAUDE telemetry server which uses the MSID interface.

  • User-definable classes to compute pseudo-MSIDs from archive MSIDs.

  • Tools to synchronize a local archive of telemetry data from the primary archive.