[vsnet-alert 16079] Another 14m dwarf nova in Draco by MASTER

Denis Denisenko d.v.denisenko at gmail.com
Wed Jul 31 00:12:51 JST 2013

Following the discovery of "new old" CV in Andromeda by Anastasia
Lazareva (see [vsnet-alert 16054] for details), we have checked all
transients in MASTER-Tunka and MASTER-Kislovodsk databases which fall
inside the 30" circles around ROSAT sources. The result is a discovery
by Pavel Balanutsa of one more relatively bright dwarf nova MASTER OT
J161700.81+620024.9 in Draco with the past outbursts missed by MASTER
and Catalina Sky Survey. The new CV is located 14" from 1RXS
J161659.5+620014 (flux 0.0179+/-0.0043 cnts/s, hardness ratios
HR1=0.52+/-0.25, HR2=0.60+/-0.20). It varies from 17.8m at quiescence
to 14.3m in outbursts. Yes, both ROSAT flux and maximum brightness are
the same as for the CV in Andromeda!

The short discovery paper has appeared in arXiv last night:
New Cataclysmic Variable 1RXS J161659.5+620014 in Draco
P. Balanutsa, D. Denisenko, E. Gorbovskoy, V. Lipunov

Here are the outburst dates and magnitudes from MASTER database:

MASTER OT J161700.81+620024.9 = 1RXS J161659.5+620014
  20120911.536  14.39  MASTER-Tunka
  20120911.588  14.39  MASTER-Tunka
  20130121.987  14.31  MASTER-Kislovodsk
  20130122.017  14.43  MASTER-Kislovodsk
  20130127.707  15.05  MASTER-Amur
  20130127.739  14.78  MASTER-Amur

Two fainter outbursts were observed by Catalina Sky Survey on 2010
June 19 (15.2m) and on 2012 Apr. 27 (15.6m). They were probably just
below the transient detection threshold, and thus not discovered by

The new object at quiescence is identical to the ~17m star:
USNO-A2.0 1500-06057914  16 17 00.86 +62 00 24.9  R=16.6  B=16.2
USNO-B1.0 1520-0252429  16 17 00.917 +62 00 24.93 pmRA=14  pmDE=0
B1=16.25 R1=16.56 B2=17.73 R2=16.80 I=16.35
GALEX J161700.9+620024 FUV=17.82+/-0.06 NUV=17.76+/-0.04

What's most important, this new CV is present in SDSS photometric
catalogue with very blue colors:

SDSS J161700.91+620024.8 u=16.43 g=16.14 r=16.21 i=16.35 z=16.41

Negative color indices (g-r) = -0.07, (r-i) = -0.14 suggest a small
contribution from the secondary component and likely a short orbital
period. Usually such systems are SU UMa-type dwarf novae. MASTER OT
J161700.81+620024.9 is definitely a good target for monitioring from
the Northern hemisphere. Moreover, with ~17m at minimum one can
probably measure the orbital period at quiescence with the 30-40 cm
telescopes and unfiltered CCD. For observers with GoTo system, the new
object is located 4' North and 2' West of NGC 6123 galaxy (14m).

MASTER-Kislovodsk discovery and reference images:

The object is ranked 20th-22nd brightest among ~180 cataclysmic
variables discovered by MASTER, if you look at the list of MASTER OTs
sorted by magnitude: http://observ.pereplet.ru/MASTER-OT-mag.html

Denis Denisenko
Member of MASTER team at SAI MSU

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