Time | Item | Who | Notes |
---|
5min | TSO Timing Precision | Kevin | - ISIM clock is not precise enough for TSO
- Use FPE clock for relative time and S/C clock for reference point
- Frequency of FPE clock has a slight temperature dependence (10 ppm variation in flux over 25 K variation in temperature)
- John Stansberry has had success getting CV3 data to check temperature stability of FPE
- Will discuss results next month
- Duration of "second" isn't always constant during an observation
- Offset may be applied during contact to correct drift in s/c clock
- Use engineering telemetry data to determine timing offset correction
- Current plan is to flag exposures in which an offset occurs
- Users will need to access engineering data to determine which integrations were affected
- Will need to write technical memo (TM) describing spacecraft clock correction, engineering mnemonic SCTA_OFFSET, and how to access engineering data to see where within the exposure the correction was applied
|
| MIRI | | - Working on generating simulated data for TSO MIRI Direct imaging Full Array mode, not high priority
- Still reviewing results of passing simulated data through pipeline
|
| Target fluence recommendations |
| - NIRCAM:
- NIRISS:
- Mean bias = 11.6k ADU
- Mean soft saturation = 50.5 ADU above bias (range is 43k-59k)
- Recommend ~35k ADU??? (~75% of saturation)
|
| Data Segmentation |
| - Files need to be segmented into chunks if they are too large
- Baseline version of segmentation code works, but doesn't optimize for different values of NGROUPS
- In some cases, the choice of 2GB per segment results in large level-2a products (e.g. 6 GB in size). The 2GB segment size is fine for a single level-1b FITS file. In the case that NGROUPS=3 though, there's very little "compression" due to ramp fitting in the level-2a products, and because the level-2a products inflate the original raw data from int16 to float32, as well as add several more float32 data arrays of the same size (ERR, DQ, ...), resulting in the level-2a products that were ~6 GB in size.
- Decision: Use size_level1b = size_level2a * ngroups / 10. Pick what the size_level2a we want, and then L1b and segment size will follow from there via the equation
- Work hasn't started on new version
- Will need to briefly discuss file segments in JDox TSO strategy pages and link to more detailed discussion
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