[Aavso-photometry] Dr. Sarty's HMXB support - some information for CCD observers

[Richard Huziak]

Hi all!

We've followed these stars for 3 seasons now, and have analysed V831 Cas 
thoroughly, just to find more mysteries.  More data is required to 
support RV measurements during the period Gordon has indicated, and 
afterward, for whomever wants to do long time-series throughout the 
season.  Long nightly time-series is most valuable.  Single hit points 
don't help us much.


LPH029  = V831 Cas
When reducing, we usually do a 2-star ensemble using p & b which seem to 
be stable.  Trusting other stars in the field is a bit hit and miss.  
The V831 Cas field is a tricky one, since it is on the outskirts of NGC 
663, a cluster that has a great many dSct stars.  Note that Gord's chart 
labels most of them, but be aware also of the 5 new variables at the 
bottom of his list (m, V, W, X, T), four that are or are likely 
additonal dScts (0.01 or 0.02 amplitude) and one that is a new EA (0.27 
amplidute, per = 6.161d).    Even stars with 0.01 amplitudes do NOT make 
good ensemble stars in this case, since the amplitude of V831 is 0.03 
mag with at least 3 distinct periods, of which the shortest is approx 
0.1d.  The star has not varied more than 0.03V over the 3 seasons, but 
shows nice periodicy and an interesting light curve.  So drive up your 
exposures to improve your SNR - you will need nice, clean images with 
decent exposure lengths, and TS of 4 hours length or more so that we get 
complete cycles.  Those who like multiple variables to analyse will love 
this field.  With a decently wide CCD camera, you can solve for at least 
19 variables, and maybe discover more very low amplitude dScts.  The 
most interesting other vars are star n = BY Cas (Ceph), star T = VSX 
J014602.9+612631 (EA).  We can always use more data on m, V, W, X, T to 
help determine or refine their periods.


LPH115 = 1H 1936+541 = DM+53 2262 = VSX J193252.3+535245
We know less about this field.  We have 3 seasons on it, but we have not 
analysed all the data yet.  However, the variations are larger and 
longer than V831 Cas.  The amplitude is about ~0.12V and period is >0.2d 
(if it is periodic at all).  However, nightly curves seem to vary in 
form.  Much more data in the form of long nightly time-series is 
desired.  I can't give much advise on which stars should be used for 
reference, though c seems the best.  Note that star b *might* be 
slightly variable.  However, evidence of its variability is weak.  There 
are no known variables other than LPH115 in the field.

Thanks in advance to those who will provide data during and after the 
campaign.

BTW - Dr. Sarty is also an AAVSO visual guy - (SGE) and does occasional 
visual work from his backyard with an 18" dob when he's not using much 
bigger scopes :-)

rick (HUZ)


-- 
* * * * * * * * * * * * *
Richard Huziak
Manufacturing Engineering
SED Systems
Saskatoon, SK, Canada
tel. (306) 933-1676
<huziak at SEDSystems.ca>
* * * * * * * * * * * * *