[vsnet-alert 16837] NSV 2026 outburst cycle

[Denis Denisenko]

J. Caron and F. Kugel have reported outburst of NSV 2026 (dwarf nova
in Taurus) on 2014 Jan. 23 in [cvnet-outburst 5792]. They have also
commented: "apparently it has about one outburst per year". Actually
this star is a very active dwarf nova with a short outburst cycle
which is not determined yet, almost 80 years after the discovery.
Since the galactic latitude is only -8 deg, Catalina Sky Survey is
rarely visiting this area of Taurus, and the coverage is very sparce.
Yet it is 4.5 deg south of the ecliptic (currently being occulted by
the Moon every month, last time on 2014 Jan. 13) which takes away
another ~20% of observations during the lunar conjunctions.

I have checked MASTER data and found that the previous outburst
occured just a month ago, on 2013 Dec. 29! It was not reported to
vsnet-alert because of the flood of MASTER own discoveries in the end
of the year (32 OTs in two weeks). Additional outbursts had been
reported to various mailing lists before. I have collected them in the
table below.

NSV 2026
  20121224.056  15.15C  BRT (Eddy Muyllaert)
  20130102.051  14.94C  BRT (Eddy Muyllaert)
  20130107.029  17.44C  BRT (Eddy Muyllaert)
  20130206.999  14.13C  BRT (Eddy Muyllaert)
  20131205.062  >158CR  J.Caron and F.Kugel
  20131229.853  13.56C  MASTER-Kislovodsk
  20131229.883  13.59C  MASTER-Kislovodsk
  20140123.790   137CR  J.Caron and F.Kugel

Yet another outburst was reported by Seiichi Yoshida in [vsnet-alert
14295] two years ago together with two previous detections in February
and November 2011:

NSV 02026
  20110204.555   148C   MISAO project
  20111121.609   139C   MISAO project
  20120226.486   140C   MISAO project

February-March 2012 outburst was well covered by Ian Miller and Roger
Pickard (see AAVSO light curve generator). However, it seems to be
that the orbital period was not measured.

T. Kato et al., 2012 based on SDSS colors estimate P=0.080d with 87%
of NSV 2026 being of SU UMa type (9% are left for WZ Sge type, and
remaining 4% - for the long period SS Cyg type):

SDSS J052958.81+184809.8 (u=17.59 g=17.55 r=17.18 i=16.93 z=16.79)

The star is very active on Palomar plates, never being of the same
magnitude in the same band. (There are 3 blue, 3 red and 2 infrared
plates plus one Quick-V). USNO-B magnitudes are:

USNO-B1.0 1088-0074412 B1=18.15 R1=17.07 B2=17.82 R2=15.02 I=16.45
and GSC 2.3.2 Vmag is 17.28.

Finally, there is a faint ROSAT X-ray source 1RXS J052954.9+184817
formally 56" from NSV 2026, but within the error radius (62"). ROSAT
flux is 0.00140+/-0.0065 cnts/s and hardness ratios HR1=1.00+/-0.40,
HR2=1.00+/-0.64.

Nightly monitoring is needed to establish the outburst recurrence
cycle and the type of this cataclysmic variable.

Denis Denisenko