(cba:news) just Maxi = ASASSN-18ey... OK, also V1974 Cyg

Joe Patterson jop at astro.columbia.edu
Wed Sep 4 10:22:23 EDT 2019

Hi CBAers,

We're nearing the end of the time-series campaign on this star.  We've 
learned a few things.
(1) No matter how short you take your integrations, you see violent 
variations.  Quite unlike CVs, but seen in some black-hole X-ray novae 
(where the variations extend down to milliseconds).  So for our 
purposes, there is no particular need or want for fast integrations 
(since that information is basically in the X-ray).

(2) The huge 17-hour signal of last year is gone.  There are some waves 
suggesting a timescale around 10-20 hours.  It's not yet clear if 
there's a stable period (or two???) in there.  And it may not ever be 
clear, since the Earth's travels shorten our window at 4 minutes/day. 
For these candidate timescales, changes in airmass are worrisome.  But 
it's likely our data are the world's best, so let's do our best and 
leave honorably.  Try to get these long time series for around another 
1.5 weeks.

(3) Tracking the decline from the August-September echo is a different 
story.  That's where "follow the star into a tree" is called for... but 
very short time series (10 minutes) are OK.  Ideally it should be V 
(because it's a standard magnitude), but "clear" is OK too, especially 
if you can estimate the difference.  Remember - AS ALWAYS - avoid RED 
comparison stars!  (And, to the extent possible, keep the same one.)

David Cejudo has been faithfully tracking V1974 Cyg, but without a lot 
of help.  Too much razzamatazz over Maxie.  That's "old" nova is 
definitely a good target for observation - as is, in the morning sky, 
the newly faded PX And.

joe p

p.s. the recurrent nova V3890 Sgr is also worth a peek.  If it starts to 
show fast variability, even more so.

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