What To Do When You Get an Exception Report for STIS
If something appears to have gone wrong with your STIS observations, you will get an email (usually within several days) containing an HST exception report. It asks you to download the affected data from MAST, determine whether its flux and S/N reached the expected levels, and determine from a quick-look inspection whether it appears anomalous in any other way. Here we provide a checklist with more specific steps for inspecting STIS data for potential problems. More detailed discussions of these steps may be found on the STIS web pages.
- Review the Target Acquisition files to determine whether the STIS acquisition (ACQ) was successful. A jupyter notebook is available to aid in assessing STIS ACQs.
- If the ACQ was fully or partially affected, check the flux levels and wavelength scales, since both can be affected by off-nominal slit centering.
- Inspect the recorded exposure times in the FITS headers as well as the count rates and S/N in the SCI extensions to determine if the data that were acquired are sufficient for the scientific goals of the program. The take data flag (TDF) log provides some information on missing exposure time and problems with the ACQ or guiding.
- If the observations were obtained in TIME-TAG mode, another jupyter notebook can be used to check that the count rate as a function of time during the exposure behaved as expected.
- For observations with the most precise position requirements (smallest STIS apertures, coronagraphic observations) consider downloading and inspecting the “jitter” files (JIT), which record the status of the observatory pointing and other statistics during the scientific exposures. A visual representation of the HST jitter during each exposure can be found on STIS’s jitter monitor.
If you wish to repeat the observations, please submit a Hubble Observation Problem Report (HOPR) within three months (90 days) of the date that the failed data were taken, following the instructions provided in the email. Be sure to clearly describe which observations you are seeking to repeat and provide justification for the request, particularly if it is for more orbits than the ones directly impacted by the problem. As always, please contact the Help Desk if you have any concerns.