[vsnet-alert 16766] New faint active polar MASTER OT J025737.69+333750.7

[Denis Denisenko]

Vladimir Vladimirov has found the final optical transient from
December 2013 data concluding the recent New Year's eve flood of
discoveries by MASTER-Kislovodsk. The object has been published in
ATel #5726 together with two more new CVs already from 2014:
http://www.astronomerstelegram.org/?read=5726

MASTER OT J025737.69+333750.7 - new CV (18.3-21.3)

IDs from catalogs:
USNO-B1.0 1236-0048795 (02 57 37.729 +33 37 50.69 pmRA=0 pmDE=-16
B1=20.75 R1=N/A B2=20.08 R2=N/A I=18.66)
SDSS J025737.74+333750.5 (u=21.40 g=21.23 r=21.29 i=21.29 z=21.26)
GALEX J025737.7+333750 (NUV=21.45+/-0.26)

The star is faint even at maximum, but remarkable in many aspects.
First of all, it is beautifully located near the galaxy PGC 2036085
(offset 13"W 18"S). Strange that nobody has reported it as a SN
candidate before! Then, SDSS colors are very blue pointing at low-mass
secondary and short orbital period. Finally, there is an evident
variability in Palomar/NEAT archive which is a real treasure for data
mining.

I have downloaded 36 NEAT images of this field and measured the light
curve from 29 images on 9 nights in Oct. 2002 - Feb. 2003 when the
star was in a high state. Using period search software WinEffect by
Vitaly Goranskij, I have obtained the preliminary value of orbital
period P=0.062508d (90.01 minutes) which is very close to 16 cycles
per day. However, the period seems to be real, since the amplitude of
orbital variability is large (about 0.8m). Here is the phased light
curve (in relative magnitudes):
http://master.sai.msu.ru/static/OT/J025737+333750-LC_NEAT.gif

Though the object is faint, the large amplitude makes it a good target
for the photometry with the 40- and even 30-cm telescopes. It would be
great if somebody can obtain the light curve to see if the period
estimate from the NEAT data is correct or not.

MASTER discovery and reference images:
http://master.sai.msu.ru/static/OT/025737.69333750.7.png

Denis Denisenko
Member of MASTER team at SAI MSU