(cba:news) V380 Oph
jop at astro.columbia.edu
Tue Aug 7 09:31:15 EDT 2012
We're hoping to get an HST observation of V380 Oph, which has entered a
low state, quite soon. To do that we have to monitor it visually with
sufficient depth to get an idea of how bright it is. The fainter, the
better... partly because it certifies that the white dwarf is dominating
the light (the aim of the observation), and partly because a BRIGHT V380
Oph will fry the detectors (and therefore be forbidden by NASA).
Snapshot magnitudes of V380 Oph are the main thing that's needed, rather
than time series, which of course are our usual specialty. And - again
unusual for us - "it's too faint for me" is not really an appropriate
reaction here. Add frames, lengthen exposures, do whatever you need to
measure the magnitude. It's likely to be around magnitude 18-19, maybe
The HST observation probably won't happen till mid-September, but to
proceed with the planning, we need some knowledge of its variability
pattern. Some of these deep-low-state stars have brief flares by a
couple of magnitudes, while others just sit there inert, faint, and
unvarying. Over the next few weeks, we need to learn more about V380
Oph in that regard!
We'll also be trying this with big scopes, where S/N isn't a problem...
but a few snapshots don't really answer the question. We need to know
the pattern of variability, and that's where CBAers can provide the answer.
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