(cba:news) Fwd: target stars for July-Aug

[Joe Patterson]

Great summary from Enrique.  A few other comments:

1. AM CVn.  A few CBAers, esp. David Cejudo, have been tracking this guy 
past its usual experiation date.  These have accomplished our goal - to 
explore the correation of the negative and positive superhumps signals. 
And to my surprise, shown that period changes in the two signals 
*correlate* - just the opposite from what we'd expect from basic physics 
(which essentially means that we have to explore some non-basic 
physics!)  So: campaign concluded.

2. V1674 Her.  Yes, a really great choice!  Good for a V fiter now, if 
you have a good one.  We still don;t know much about periods, but 
Hercules will be gracing our sky for a long time.  This one just has the 
whiff of a really great star.

3. V1974 Cyg.  With our (mostly new, inspired by T Pyx and IM Nor) 
interest in novae of short P_orb, this one takes on new interest.  Lots 
of not-quite-critical-mass data from past years, easy to redeem if we 
can get really solid coverage in summer-fall 2021.

4. DQ Her.  Only if you can resolve the 71 s pulse.  Long runs with 20 s 
time resolution will do it.  You don't have to resolve EVERY pulse - 
this thing is stable over weeks to months... and a 20 s integration (for 
example) is mathematically equivalent to an instantaneous measure at the 
mid-point of the integration.  Assuming your recorded times are in fact 
the mid-points of the integrations.  (But admittedly, it's an ambitious 
target for small copes.  Lew Cook does great with it - but I think he 
has a 26" scope.)

5. "Nova Sco 1437" and V4743 Sgr.  Both really good southern targets, 
amd likely IPs.

6. CI Aql.  Another winner, as Enrique says.  Long runs really 
desirable, since Porb is so long.

The year's teaching is finally over... and I'm out of zoom jail (I 
think).  That'll help me keep up with all the data.

joe

-------- Forwarded Message --------
Subject: 	(cba:chat) comments and summer CBA targets
Date: 	Sat, 3 Jul 2021 12:54:49 +0200
From: 	Enrique de Miguel <edmiguel63 at gmail.com>
Reply-To: 	cba-chat at cbastro.org
To: 	cba-chat at cbastro.org



Hi all,

   The term is (nearly over) and I expect to have more time over the 
summer to catch up with CBA data analysis. Here are some recommendations 
for the coming weeks/months.

Nova Her 2021 (V1674 Her). This nova is still too bright, which makes it 
difficult to detect tentative periodicities. The main signal considering 
the data from the last 7-8 days shows a tiny signal (full amplitude of 
~0.009 mag) at a frequency of 172.31 c/d (8.357 min) which is consistent 
with the period reported in ATEL #14740 (data from the Zwicky Transient 
Facility). This is most likely the spin period of the dwarf nova. It 
will probably become easier to detect the signal once the brightness 
decreases.There is a shorter period, but I wouldn't give too much credit 
at this stage. Let's see.


We are basically done with the following targets:

IGR J16547-1916 (nice job from Shawn and Sjoerd);
V1025 Cen (Berto!);
NR Tra (Gordon!);
EX Hya;
WX Cen (great coverage from Josch)
Swift J0939.7-3224 (Josch!)
WX Pyx
IM Nor (faint, but no problem for Gordon ...)
Nova Sco 1437 (great joint coverage from Gordon + Berto)


Some further data would be nice for the following targets:

CI Aql (recurrent eclipsing nova). Many of you guys are contributing to 
the coverage
of this star; some more data would be welcome.

V603 Aql; I haven't had time to analyze the 2021 data (Josch + Tonny), 
but I will sometime this weekend. In the mean probably, worth keeping 
this old nova in our list.

V2731 Oph; remember to consider exposures as short as possible (Psp = 
128 s).


_Summer targets to be included in the observing list for the next months:_


V617 Sgr; V Sge-type star (eclipsing, Porb = 4.97 h) with a rather long 
positive Pdot (increasing orbital period). Josch, quite appropriate for 
your observing scheme.

V1223 Sgr; steady coverage over the next months

V4743 Sgr; Nova 2003 + IP; a bit faint (m ~ 17.5), but don't miss this 
one. As far as I can tell, no spin signal has ever been reported for 
this nova, but our data shows a clear signal (most likely, spin of the 
dwarf nova) at 23.65 min. Probably, the IP with the largest negative 
Pdot we have from all the IPs we usually follow. Josch, you may want 
to give this target a try.

RX J2133.7+5107, FO Aqr, AO Psc, V2306 Cyg, V2069 Cyg, V1033 Cas, our 
usual summer targets. Steady coverage over the next months.


I still have to analyze data from V1974 Cyg from the past 2-3 seasons, 
but this is always a good target. This star (m ~ 17.1) requires long 
runs. And for the fearless, V1500 Cyg. This one is faint,  m~18.5, but 
we the modulation is of large amplitude (~1 mag full amplitude). Walt, 
you got beautiful light curves last season .... The period is long (~3.3 
h) so you can use long time exposures.

I haven't made any mention to typical targets, such as DQ Her or AM CVn. 
These are Joe's targets and it's up to him to decide.

I'll keep you posted with comments and suggestions.

   Enjoy !!!

   Best regards,

   Enrique



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