Ska Engineering Telemetry Archive¶
Overview¶
The Ska engineering telemetry archive is a suite of tools and data products that make available the majority of all Chandra engineering telemetry since the start of the mission (1999:204). This includes about 6300 MSIDs. The telemetry are stored in a way that allows for very fast and efficient retrieval into memory. Typical retrieve rates are around 10^7 samples/sec. For an MSID sampled once per second this translates to about 3 sec per year of data.
The engineering telemetry archive consists of:
- Tools to ingest and compress telemetry from the CXC Chandra archive products.
- Compressed telemetry files in HDF5 format. Each MSID has three associated products:
- 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.
- A python module to retrieve telemetry values.
Pseudo-MSIDs¶
A small selection of pseudo-MSIDs that do not come in the engineering telemetry stream are also available in the archive. These are:
- SIM telemetry: SIM position and moving status (deprecated)
- EPHIN telemetry: level-0 science telemetry from EPHIN
- ACIS DEA housekeeping: status from the DEA (including detector focal plane temperature)
- Ephemeris: predictive and definitive orbital (Chandra), solar, and lunar ephemeris values
- Derived parameters: values computed from other MSIDs in the archive (ACIS power, orbital elements, PCAD, thermal)
For details see the documentation on Pseudo-MSIDs in the engineering archive.
