(cba:news) (cba:chat) March stars
jp42 at columbia.edu
Fri Mar 16 18:22:22 EDT 2018
Yes, I strongly recommend intense coverage of AT Cnc, for as many hours
as you can get it. Best *morning* target for the next 1-2 weeks is AM
CVn - also intensive.
Duplicating coverage on AM CVn isn't bad - in fact, it's highly
desirable. AM CVn has three periodicities: at 525 s, 1051 s, and 1028
s. The first two are generally the strongest; but because they're
superhumps - not stable on long timescales - they have to be removed in
order to track the orbital 1028 s signal. Somewhat tricky, but can
always be done if the data are DENSELY distributed. That's the key -
dense coverage. This is true for most CBA programs, to some degree -
but never as much as AM CVn, because separating these closely spaced
frequencies is critical.
On 3/16/2018 5:03 PM, Shawn Dvorak wrote:
> As an extra incentive, AT Cnc is currently in a Z Cam standstill. The
> AAVSO data shows it "got stuck" around mag 13.6 near the end of
> January. Although the data is a bit sparse, it seems to be showing a
> 0.4 mag amplitude variation with a ~6.5 day period. Interesting, but
> possibly just a coincidence. It looks like I'll have mostly clear
> skies tonight so I'll get a longish run on it from 0:30 - 06:30 UT
> On 03/04/2018 07:34 PM, Joe Patterson wrote:
>> Dear CBAers,
>> Muchas gracias for all the great data you've been sending, especially
>> re the DQ Her stars which you've been covering so faithfully. It's
>> been a winter of ice and mishap and hard work - nothing really
>> serious but maybe I got kind of soft after a semester off from work.
>> The DQs are relatively sparse in the (northern) springtime sky, so
>> that program can rest - a little. Here are my recommendations for
>> northern observers:
>> 1. AT Cnc. Probably a very ancient nova, and our last campaign
>> showed a credible signal around 28 minutes. Very desirable to get
>> long runs now, the more the better.
>> 2. NY Ser. Reputed to be in a standstill state now around 15.5 - I
>> think the first such event observed in this star's sparse history.
>> Excellent morning target.
>> 3. AM CVn. Perhaps the least exciting star to observe (always within
>> 0.15 mag of 14.2), but very important since it is the prototype of
>> one of the most important classes - the mass-transferring double
>> white dwarfs. We have a TENTATIVE detection of period change through
>> 2016, but a good 2018 season should nail it down. This calls for
>> steady coverage through April (especially) and March.
>> 4. HT Cam. A DQ Her star for which we'd like to get a particularly
>> accurate estimate of period change.
>> 5. BK Lyn. What's it doing this year? Pretty steady, or cycling
>> like the ER UMa stars. Spot checks will be fine, not necessarily
>> time series.
>> And for southern observers:
>> 1. V598 Pup. Lots of activity in this fascinating recent nova.
>> Except for Berto, who always seems to spot the most interesting
>> jewels, we've never observed it before.
>> 2. IM Nor. Back in the sky now. At 18.5, maybe only Gordon can work
>> on it. But some eclipse timings in the new season - i.e. maybe 20-25
>> hours of coverage - would be great to add to our >95% completed paper
>> on this star.
>> 3. V959 Mon. Another recent nona for which we need the 2018 orbital
>> light curve. It's a long period, so your runs need to be at least 4
>> 4. WX Pyx. Keep going on this one, the Pdot is still kinda insecure.
>> (I think; Enrique would know for sure).
>> And both hemispheres: SW Sex. We've never done a good job on it, and
>> there's no excuse for it. ALL the SW Sexers have been good to us...
>> so let's give the prototype a chance!
>> Those are my recs. Enrique may send his, of course.
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