(cba:news) July stars

Joe Patterson jop at astro.columbia.edu
Tue Jul 9 06:50:03 EDT 2013

Dear CBAers,

New stars for the new season.

It's time to end the HS1813+61 coverage.  The star has wandered between 
a high-ish and a low-ish luminosity state, and the periodic content has 
been complicated by that feature.  Definitely for analysis in the cold 
light of winter... and time to end 2013 coverage.

And time to replace this "Dra" star by a new kid in Draco: ASASSN-13ax, 
discovered in a supernova search (and therefore using the supernova 
lingo as an identifier).  In our familiar language, which Taichi Kato 
likes/promotes and which is well suited to our objects, it would be 
OTJ180005.78+525635.3.  Sitting up there in Draco, perfectly positioned 
for summer coverage.  Enrique has been observing it for a few days, and 
last night it grew the strong superhumps which are the 
always-good-for-admission ticket to our club.  In particular, it's very 
likely a WZ Sge star, erupting from mag 21 to 13.5, with some unknown 
but probably long recurrence period.  It's still at mag 14 and will 
probably flash great superhumps for a couple more weeks.  Probably. 
Anyway, it's a superb target for long runs.

We're getting ready to publish our decade-long (but somewhat sporadic) 
coverage of V1974 Cyg and V1432 Aql, and both stars need a final fix of 
2013 data.  These two require pretty long coverage, in order to parse 
among the (known or putative) signals closely spaced in frequency.  One 
month of dense data would bring these campaigns to an end.

And the big star in the June CBA world has been PNV1915+07, which has 
been getting great coverage by practically all of our usual suspects - 
especially Enrique, Jim Jones, and Greg Bolt.  This WZ Sge star, now 
faded to 16.3, continues to delight with its big periodic wave.  Since 
the 2013 outburst is the first-ever-recorded, and indeed the first time 
the star publicly announced its existence, we don't know what the future 
will bring.  Let's make sure our telescopes are there to find out!

The DQ Her stars (intermediate polars) can take a rest in mid-summer, 
i.e. now.  The two exceptions are V1223 Sgr and IGR1654-19 (Scaringi et 
al. 2011, A&A 530, A6); each needs a few nights to tie down the 
long-term cycle count.

Finally, don't forget NR TrA and V617 Sgr!  These stars have great light 
curves and need your help.  The first is the known remnant of Nova TrA 
2008, while the second is a suspected (OK, only by me... but still) 
remnant of a recent but unnoticed nova event.

We're very likely to have a AAVSO+CBA meeting in mid-June 2014, and I 
especially hope that some of our seldom-seen members can attend.  It'll 
be at Big Bear, or possibly some other southwestern USA location.  More 
info when the details harden up.


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