Note also the papers by Kruk et al. on final calibration of
HUT 1 and HUT-2 (ApJS, 122, 299) data.
Data Handling
5) How do I retrieve HUT data?
Data retrieval proceeds in much the same way as most other MAST-archived
datasets. Go to the
how to search HUT data
page for instructions and the
HUT search
page for downloading of data. Data will be returned very quickly in a tarred
file consisting of many zipped data files and an ASCII filetypes.txt file
explaining some of the contents. For further information go to the
HUT data products
page.
7) What are the instrumental error sources in HUT data?
Unwanted time-dependent signals (dead time, phosphor persistence).
Airglow in emission lines (geocoronal Lyman alpha can be the dominant
feature in the spectrum).
Extreme UV contamination (white dwarf only; corrected from model
atmospheres estimates).
Telluric absorption (yes, there is atmosphere above the Shuttle!).
Flux loss from field astigmatism (extended sources only).
pointing-jitter errors (jitter corrected every 2 secs).
The calibrated data consist of corrections for all these error sources.
See the
calibration chapter of the HUT
data handbook.
8) Did HUT lose sensitivity during its missions?
Yes, the losses were noticeable on an approximately 48 hour timescale,
particularly in the far-UV. This is modeled in Figure 5 of Kruk et al.
(ApJS, 122, 299, 1999). By the end of the mission the sensitivity of the
detector (CsI photocathode) had decreased by 26% at 912 Å
and 5% at 1840 Å.
9) What were the differences between HUT1 and HUT2?
The second mission:
lasted longer (16 days compared to 8 days; 205 hours of on-target time vs.
40 hours).
made more observations (385 of 265 targets, compared to 136 of 87 targets).
had greatly improved pointing stability.
had less sensitivity to extreme-UV contamination because of SiC coatings
on the optical elements.