(cba:news) NSV1436, ER UMa, BK Lyn, DW UMa

Joe Patterson jop at astro.columbia.edu
Mon Apr 4 07:07:10 EDT 2011

Dear CBAers,

Some comments on other recent and present campaign stars.

I wanted to remind that ER UMa does continue to be a good target for 
coverage at/near quiescence (around 15.0-15.3).  We don't need the 
many-longitude-all-night light curves... but it will be very interesting 
to study the coherence of the powerful negative superhump over a long 
interval - and the 60-day baseline already is a great start.

The exact origin of negative superhumps is still mysterious, and where 
the amplitudes are large, that's where we're likely to learn the most. 
Some of the amplitudes are impressively - even disturbingly! - large. 
That's true of ER UMa, V503 Cyg, BK Lyn, and DW UMa.  And speaking of 
the latter two...

We have only sparse data on DW UMa this year, but it does appear that 
the negative superhump is having a bad year (not yet visible).  So let's 
drop that one.  BK Lyn, on the other hand, is sprouting large negative 
superhumps, as it did in our long 2000 campaign.  So that one is very 
definitely worth pursuing - and in fact, since it got significantly 
pushed aside by erupting dwarf novae and other seductions around 9 hr 
right ascension, increased for the next month or so.  Josch Hambsch has 
been observing it assiduously, but the other coverage has been sparse. 
Another month would be great!

I'm pessimistic about NSV 1436.  Perseus looks good to the naked eye 
during April evenings... but not so much for photometry.  We haven't got 
a definite result out of the light curves so far, and it gets worse each 
day.  I think we should suspend this one.


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