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(cba:news) Fwd: Fwd: BK Lyn (Joe Patterson) [2011-04-13T19:20:02Z]



-------- Original Message --------
Subject: 	Fwd: BK Lyn
Date: 	Wed, 13 Apr 2011 21:02:54 +0200
From: 	Enrique de Miguel <edmiguel63@xxxxxxxxx>
To: 	Joe Patterson <jop@xxxxxxxxxxxxxxxxxx>



Hi Joe,
I've sent this message to the cba-chat, but for some reason it
doesn't get through. Any problem if you forward it to the
distribution list? Two GSC designations in the table included
below were wrong in the original message and they have
been now corrected.

Note that there is non-cataloged variable in the field, which
I think is the comp you used in the 93 CBA paper with Skillman.

Thanks,
Enrique

Begin forwarded message:


*From: *Enrique de Miguel <edmiguel63@xxxxxxxxx
<mailto:edmiguel63@xxxxxxxxx>>
*Date: *13 April 2011 19:16:08 GMT+02:00
*To: *cba-chat@xxxxxxxxxxx <mailto:cba-chat@xxxxxxxxxxx>
*Subject: **BK Lyn*

As Joe pointed out, this star is persistently showing negative
superhumps. Currently peak-to-peak variations are ~0.20 mag,
but they used to be as large as ~0.6 mag 20-30 days ago.
Nice target ......

I've proceeded to calibrate a number of stars in the field of BK Lyn
in the B and V bands. For BK Lyn followers, appropriate values
and comments are given below, along with a DSS chart. Keep
in mind that I'm not a "calibrator" and these values should be
regarded as a guide. The bluest "bright" target in the field (apart
from BK Lyn) is #4 (GSC 2496-0893), with B-V=0.53. This is the one
I'm using as comp star for BK Lyn.

Note that star #9 (GSC 2496-0739) seems to be a (non-catalogued)
variable (details below). Incidentally, this seems to have been
used as comp star in Skillman and Patterson A&A 417, 298 (1993).

Enrique


Calibrating BK Lyn field

#label name V B-V erV erBV
2 GSC 2496-1004 14.950 0.714 0.004 0.005
3 GSC 2496-1453 14.890 0.925 0.004 0.004
4 GSC 2496-0893 13.897 0.533 0.003 0.004
5 GSC 2496-0769 13.991 0.610 0.003 0.004
6 GSC 2496-1173 14.010 0.783 0.001 0.004
7 GSC 2496-1374 14.286 0.672 0.007 0.003
8 GSC 2496-0907 13.529 0.839 0.002 0.006
9 GSC 2496-0739 13.262 0.941 0.006 0.012
10 GSC 2496-1579 14.260 0.773 0.005 0.003
11 GSC 2496-1060 14.852 0.620 0.009 0.008

Comments:
1. Values based on measurements carried out on 4 nights (8, 9, 10, 12
April 2011) under excellent conditions.
2. Errors indicate standard deviations about the mean value
calculated over the 4 nights and do not include errors
associated with the transformation. The latter are less
than 0.012 in B band and less than 0.010 in V band.
3. Star #12 is NSVS 7454553 (pulsating RRab Lyr).
4. The bright star in the SE is WASP-13 (star hosting an exoplanet).
5. Star #9 is a non-catalogued low-amplitude variable star, with peak-
to-peak variations of ~0.06-0.07. The periodicity is still uncertain,
but very likely P=0.741(9) d (if pulsating) or multiples of P if
eclipsing.
6. Nightly values of B-V for BK Lyn show slight variations. For
the 4 calibration nights these values are: 0.025, -0.048, 0.036,
and 0.059, values which are otherwise expected for a target of
this nature. These are instantaneous values and not nightly
averages.