Very Bright CV discovered by MASTER-ICATE (Argentina)

ATel #5144; C. Saffe, H. Levato, (ICATE), C. Mallamaci, C. Lopez and F. Podest (OAFA) V. Lipunov, D. Denisenko, E. Gorbovskoy, N. Tiurina, P. Balanutsa, V. Kornilov, A. Belinski, N. Shatskiy, V. Chazov, A. Kuznetsov, V. Yecheistov (Moscow State University, SAI), V. Yurkov, Y. Sergienko, D. Varda, E. Sinyakov, A. Gabovich (Blagoveshchensk Educational University), K. Ivanov, S. Yazev, N. Budnev, E. Konstantinov, O. Chuvalaev, V. Poleshchuk, O. Gress, A. Frolova (Irkutsk State University), V. Krushinsky, I. Zalozhnih, A. Popov, A. Bourdanov (Ural Federal University), A. Parkhomenko, A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk solar station of the Pulkovo observatory RAS), P. Podvorotny, V. Shumkov, S. Shurpakov (MASTER team members),
on 18 Jun 2013; 16:45 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

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MASTER OT J142023.5-485540 - very bright CV

MASTER-ICATE very wide-field camera (d=72mm f/1.2 lens + 11 Mpix CCD) located near San Juan, Argentina has discovered OT source at (RA, Dec) = 14h 20m 23.5s -48d 55m 40s on the combined image (exposure 275 sec) taken on 2013-06-08.048 UT. The OT unfiltered magnitude is 12.1m (limit 13.1m). There is no minor planet at this place. The OT is seen in more than 10 images starting from 2013-06-02.967 UT (275 sec exposure) when it was first detected at 12.4m. We have reference image without OT on 2013-06-02.057 UT (250 sec exposure) with unfiltered magnitude limit 12.6m.

Since the image scale of MASTER-WFC is 21" per pixel, we estimate the error in both coordinates to be about 15". The position of the OT is formally 17" from the faint ROSAT X-ray source 1RXS J142023.5-485554 (error circle 16", flux=0.0342+/-0.0120 cnts/sec, HR1=1.00+/-0.33 HR2=-0.18+/-0.34). The inspection of DSS plates shows the blue star in the error circle with the large variability between the red plates taken on 1990-06-15, 1993-06-20 and 1998-06-16. The star is listed in USNO-B1 catalogue as USNO-B1.0 0410-0368216 (14 20 23.472 -48 55 58.68 pmRA=0 pmDE=0 B1=N/A R1=13.35 B2=13.98 R2=14.15 I=13.31). Its position is 4" from the X-ray coordinates. Color-combined DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J142023-485554-BRIR.jpg (10'x10' FOV).

The star has an ultraviolet counterpart GALEX J142023.5-485557 (FUV=16.22+/-0.02 NUV=16.13+/-0.01). There is nothing at this position in GCVS and AAVSO VSX. This area of sky in Lupus is not covered by SDSS.

The archival observations by ASAS-3 project have a variable object near this position ASAS 142023-4856.0. It is showing large-amplitude variability with frequent outbursts to 13.3-13.5m and a few superoutbursts to 12.7m, sometimes fading below the limit of ASAS project (~15.5m).

Based on the multiple outbursts in the past and UV detection we conclude that MASTER OT J142023.5-485540 is a new cataclysmic variable. ASAS archival light curve suggests it is likely a dwarf nova of UGSU or ER UMa subtype.

Follow up observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/142023.5-485540.jpg

We are grateful to State contract No. 11.G34.31.0076 and State Contract No. 14.518.11.7064 with Russian Ministry of Science and Education