MDM Trouble Report for 2005 Apr 11

Telescope: 1.3m
Observer(s): Martin Bureau, Bettina Gerken (Oxford University)
Instrument: Direct Imaging, f/7.6, echelle

Problem(s) Encountered:
Twice during the night the bias level of the CCD went crazy, with huge
horizontal streaks with high counts. The first time it occured during
twilight after badly saturating the CCD, but the second time there was
no obvious reason. Both times, multiple  wipes ,  clear ,  df ,  sf ,
... and more images did not solve the problem. However, both times and
for an unknown reason, the problem was solved after taking many
biases. Both times, the first bias taken was again bad but the second
and following biases were ok.

The images concerned can be found in
/data/tambora/visitor/Direct/50411/050411_*

First time: 014-018 bad bias level, following 019-021  ok .
  2nd time: 053-058 bad bias level, following 059-061  ok .

*Note also that IRAF seems to have a new feature: it (and only it)
does not recognize and can not deal with leading 0's in directory
names. Any idea why?

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Submitted on 2005 Apr 12 [6:54:51]