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One bright CV and one pure PSN Ia detected by MASTER

ATel #4761; P. Balanutsa, S. Shurpakov, D. Denisenko, V. Lipunov, E. Gorbovskoy, 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), V. Shumkov, V. Yecheistov, P. Podvorotny (MASTER team members), H. Levato, C. Saffe (ICATE), C. Mallamaci, C. Lopez and F. Podest (Observatorio Astronomico Felix Aguilar; OAFA)
on 25 Jan 2013; 14:54 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

Subjects: Optical, Cataclysmic Variable, Supernovae, Transient

MASTER OT J183120.64+301935.5 - new bright CV

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 18h 31m 20.64s +30d 19m 35.5s on 2013-01-24.15161 UT. The OT unfiltered magnitude is 16.5m (limit 18.8m). There is no minor planet at this place. We have reference image without OT on 2013-01-24.15161 UT with unfiltered magnitude limit 17.0m.

The object was in outburst on 1990 July 22 POSS-II blue plate, but at quiescence (~21.5m) on other Palomar plates. Comparison of 1951 and 1990 blue Palomar plates is uploaded to http://master.sai.msu.ru/static/OT/J183120+301935-DSS-Blue.jpg (4'x4' FOV with 2x zoom). The object is present in GSC 2.3.2 with coordinates 18 31 20.697 +30 19 35.23 and jmag=16.81. It also has an ultraviolet counterpart GALEX J183120.7+301934 (FUV=17.44+/-0.06, NUV=17.14+/-0.03). Obviously it was in outburst during GALEX observations.

There is nothing at this position in USNO-B1.0, 2MASS, 1RXS catalogs, as well as in GCVS and AAVSO VSX. No previous outbursts were detected by Palomar/NEAT project with 6 images obtained on 3 different nights in 1997-1998 and by CRTS.

The object was also bright (unfiltered magnitude 16.3-16.4) on 8 MASTER-Tunka images on 2012 Sep. 09.550-09.633 UT. Based on the amplitude of variability (~5m) and detection of previous outbursts we conclude that MASTER OT J183120.64+301935.5 is a dwarf nova of UGSS or UGSU type. Follow up observations are required.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/183120.64301935.5.png

MASTER OT J171427.91+230333.8 - PSN Ia

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 17h 14m 27.91s +23d 03m 33.8s on 2013-01-25.11937 UT. The OT unfiltered magnitude is 17.2m (limit 18.6m). The OT is seen in 2 images. There is no minor planet at this place. We have reference image without OT on 2011-04-15.04177 UT with unfiltered magnitude limit 19.9m.

Nothing is present at this position on 9 DSS plates and their combination, as well as on the color-combined SDSS image to ~23.5m. No object was detected by Catalina Sky Survey. This area of sky was observed by Palomar/NEAT project on 13 different nights from 2000 June 05 to 2005 Aug. 12. A total of 33 images was obtained, no outbursts were detected.

There are several galaxies inside 25 arcsec circle. The most bright galaxy is PGC 59899. The OT offset from PGC 59899 is 96.1E and 43.8S. In any case the OT distance from the host galaxy is very large and thus we propose it to be SN Ia candidate.

This is possible so called "Pure" SN Ia (Pruzhinskaya, M. V. et al., Astronomy Letters, Volume 37, Issue 10, pp. 663-669, 2011).

Spectral observations are required.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/171427.91230333.8.png

List of optical transients discovered by MASTER

Global MASTER Robotic Net