[vsnet-newvar 3807] Two MASTER OTs

[Taichi Kato]

   I agree that MASTER OT J141143.46+262051.5 is likely
an SU UMa-type dwarf nova.

===

ATEL #4814							     ATEL #4814

Title:	Two bright OTs detected by MASTER
Author:	V. Shumkov, V. Yecheistov, D. Denisenko, V. Lipunov, E. Gorbovskoy,
		P. Balanutsa, N. Tiurina, V. Kornilov, A. Belinski, N. Shatskiy, V.
		Chazov, A. Kuznetsov, D. Zimnukhov (Moscow State University, SAI),
		V. Krushinsky, I. Zalozhnih, A. Popov, A. Bourdanov, A. Punanova (Ural
		Federal University), K. Ivanov, S. Yazev, N. Budnev, E. Konstantinov,
		O. Chuvalaev, V. Poleshchuk, O. Gress, A. Frolova, (Irkutsk State
		University), A. Parkhomenko, A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk
		solar station of the Pulkovo observatory RAS), V. Yurkov, Y. Sergienko,
		D. Varda, E. Sinyakov (Blagoveshchensk Educational University), P.
		Podvorotny, S. Shurpakov (MASTER team members), H. Levato, C. Saffe
		(ICATE), C. Mallamaci, C. Lopez and F. Podest (OAFA)
Queries:	lipunov2007 at gmail.com
Posted:	15 Feb 2013; 01:58 UT
Subjects:Optical, Cataclysmic Variable, Transient

MASTER OT J082047.74+680423.3 - new CV

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 08h
20m 47.74s +68d 04m 23.3s on 2013-02-11.58751 UT. 
The OT unfiltered magnitude is 16.1m (limit 18.7m). 
The OT is seen in 2 images. There is no minor planet at this place. 
We have reference image without OT on 2012-10-20.79398 UT with unfiltered
magnitude limit 18.9m. 

The OT is identical to the star USNO-B1.0 1580-0143983 (08 20 47.641 +68
04 24.43 pmRA=-22 pmDE=4 
B1=20.16 R1=20.00 B2=20.02 R2=19.77 I=17.85). It was 1.5m brighter on 1999
Nov. 15 infrared plate than on 
1996 Dec. 19 plate. It has an UV counterpart with two entries in <a href="http://galex.stsci.edu/GR6/?page=mastform">GALEX
GR6</a>: 
GALEX J082047.6+680424 (FUV=20.72+/-0.29, NUV=20.18+/-0.13) and  
GALEX J082047.5+680424 (FUV=20.69+/-0.15, NUV=20.05+/-0.10). 

This area of sky is not covered by SDSS and Palomar/NEAT. There are no
previous detections in CRTS Data Release 2. 
Nothing is present at this position in 2MASS, 1RXS, GCVS and AAVSO VSX.

Based on the amplitude of variability we suggest that MASTER OT J082047.74+680423.3
is a new cataclysmic variable 
either of AM Her (polar) or SS Cyg (UGSS) subtype. 

Follow up observations are required. 
The discovery and reference images are available at: 
http://master.sai.msu.ru/static/OT/082047.74680423.3.png 

MASTER OT J141143.46+262051.5 - new bright CV

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 14h
11m 43.46s +26d 20m 51.5s on 2013-02-13.76514 UT. 
The OT unfiltered magnitude is 15.4m (limit 16.9m). 
The OT is seen in 2 images. There is no minor planet at this place. 
We have MASTER-Kislovodsk reference image without OT on 2012-12-27.138
UT with unfiltered magnitude limit 19.0m. 

The object was confirmed on three unfiltered MASTER-Kislovodsk images obtained
on 2013 Feb. 14.937-14.939 UT. 
The OT unfiltered magnitude on Feb. 14 images is 15.5m (limit 19.2m). 

The OT is identical to the star 
<a href="http://skyserver.sdss3.org/dr8/en/tools/explore/obj.asp?id=1237665440986038497">SDSS
J141143.46+262051.3</a> 
with the following magnitudes: u=21.68(17), g=21.66(6), r=21.67(9), i=21.95(17),
z=21.52(42). 
This faint blue star is also visible on Palomar plates with a small proper
motion between 1st and 2nd POSS epochs 
(1950 and 1994). It is present in catalogs as USNO-B1.0 1163-0236133 (14
11 43.460 +26 20 51.41 B1=20.54 B2=20.84) 
and in GSC 2.3.2 (14 11 43.453 +26 20 51.61 jmag=21.37). 

The star has also an UV counterpart GALEX J141143.4+262052 (FUV=20.90+/-0.40,
NUV=21.47+/-0.31). 
Nothing is present at this position in 2MASS, 1RXS, GCVS catalogs and in
AAVSO VSX. 
No previous outbursts were detected on 18 DSS plates taken in 1950-1997
and on 8 Palomar/NEAT images obtained 
on 3 different nights in 1998 and 2003. However, the star was detected
in outbursts by 
<a href="http://nesssi.cacr.caltech.edu/DataRelease/">Catalina Sky Survey</a>
on 2005 Apr. 09 (17.3m), 2009 July 4 
(16.7m) and 2012 May 22 (17.3m). 

Based on amplitude of variability (about 6m), blue color at quiescence
and presence of previous outbursts 
we conclude that MASTER OT J141143.46+262051.5 is a new cataclysmic variable,
most likely that of SU UMa (UGSU) 
subtype. 

Follow up observations are encouraged. 
The confirmation and reference image are posted at: 
http://master.sai.msu.ru/static/OT/J141143.46+262051.5.jpg 

<center><a href="http://observ.pereplet.ru/MASTER_OT.html">List of optical
transients discovered by MASTER</a></center>