[vsnet-alert 17076] MASTER OT J192809.82+551616.5 fading rapidly after outburst by ~7m

[Denis Denisenko]

MASTER robotic telescopes network has detected an interesting
large-amplitude optical transient in Cygnus which was published on
Mar. 21 in ATel #5994, http://www.astronomerstelegram.org/?read=5994
The object was observed several times over the last week by three
observatories constraining the outburst time to within one day from
March 16th:

MASTER OT J192809.82+551616.5
  20140315.686  <166C   MASTER-Kislovodsk
  20140316.778   159C   MASTER-Amur
  20140320.749   167C   MASTER-Amur
  20140322.743   174C   MASTER-Tunka

Object was first discovered by Pavel Balanutsa in Mar. 20 data, and
only after that we have found Mar. 16 detection (on the images with a
poor limiting magnitude). MASTER discovery and reference images:
http://master.sai.msu.ru/static/OT/192809.82551616.5.png

There is nothing at this position on the sum of digitized Palomar
plates (2xB, 2xR, 2xIR) to the limiting magnitude ~22.5.
Color-combined DSS finder chart:
http://master.sai.msu.ru/static/OT/J192809+551616-BRIR5x5.jpg (2x
zoom). This area of sky is outside of SDSS, NEAT and CRTS coverage.

Outburst amplitude is about 7m or more. The rapid fading is in
contradiction with the large amplitude which seems to be too much for
a normal outburst or UGSS type dwarf nova. Experts opinion is needed!
It could be a classical Nova with a maximum missed on Mar. 17-19. Or
it may be another AM CVn type dwarf nova. The object is probably too
faint now for the time series. Maybe somebody has observed the OT
after the publication in ATel two nights ago? In any case, BVRI
photometry can tell the truth about the object's color and distinguish
between the dwarf nova and classical Nova.

Also, checking the databases of ASAS-SN and MISAO project for Mar.
16-20 would help a lot.

Denis Denisenko
Member of MASTER team at SAI MSU