(cba:news) IGR J1955+00 and V1101 Aql

Joe Patterson jop at astro.columbia.edu
Wed Jul 22 17:24:43 EDT 2015

Hi CBAers,

The data you've submitted on J1955 *does* show that the 81 minute 
periodic humps have very red colors, as we speculated/expected on the 
hypothesis that it's a magnetic CV (AM Her star).  Experiment done.

We don't need any more filtered data on it - you can go back to 
white-light observing and improve the time resolution.  Most of all, we 
need to splice the various time series, to establish a common 
instrumental scale.  For stars near the equator, oceans create a 
problem.  In particular, our Spanish observers should take the star 
pretty far into the west, and eastern USA observers (Shawn?) should pick 
it up as soon as possible in the east.  Now's the time, since it 
transits near local midnight.

There may be a signal vaguely near 0.7-1.1 c/d (in addition to the huge 
81 minute signal), and we'll really need a range of longitudes to nail 
this down.  Very good star for AU-NZ observers too, for the same reason.

Joe Ulowetz's coverage of V1101 Aql shows that the big ~4 hr superhump 
signal is back.  We'd like to cover at least over one dwarf-nova cycle 
(~16 d), to see if it's roughly the same thing we studied in 2013-4.

LS IV-08 is a nice bright UX UMa star, and some day may reward us.  But 
I think not this year.  Berto and Rolf Carstens have been observing it - 
not much variability, and no hint of periods.  Let's drop the star and 
move on.

joe p
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