ASAS-SN Discovery of A Likely, Heavily-Obscured Galactic Nova ASASSN-16ig

ATel #9343; K. Z. Stanek (Ohio State), S. Kiyota (Variable Star Observers League in Japan), C. S. Kochanek, J. S. Brown, T. W.-S. Holoien, J. Shields, G. Simonian (Ohio State) B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong, S. Bose, Ping Chen (KIAA-PKU), L. Chomiuk, J. Strader (MSU), J. Brimacombe (Coral Towers Observatory)
on 8 Aug 2016; 18:33 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)

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During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Cassius" telescope in CTIO, Chile, we detect a new transient source, most likely a classical nova, near the Galactic center:

 
Object       RA (J2000)    DEC (J2000)    Gal l (deg)   Gal b (deg)    Disc. UT Date   Disc. V mag  
ASASSN-16ig  18:01:07.735 -26:31:42.01     3.813           -1.741       2016-08-6.96     13.3 

ASASSN-16ig was discovered in images obtained on UT 2015-10-01.29 at V~13.3 mag, and it proceed to rise to V~12.9 on 2016-08-08.17. We do not detect (V>17.3) the object in images taken on UT 2016-08-05.96 and before. No previous outbursts are detected in the previous 39 epochs of ASAS-SN data at this location since ASAS-SN started observing the Galactic center in March 2016.

 
JD           Observation Date    V mag  V err  
2457605.48   2016-08-04.97       >17.74   
2457606.47   2016-08-05.97       >17.36   
2457607.46   2016-08-06.96        13.3  0.02 
2457608.68   2016-08-08.17        12.9  0.02 

Follow-up multi-band photometry obtained on UT 2016-08-08.125 by S. Kiyota using iTelescope 43-cm telescope in New Mexico yields the following magnitude measurements: B=14.8, V=12.9, R=11.7, I=10.5. Assuming an intrinsic color of (B-V)_0 ~ (V-I)_0 ~ 0.0 as a reasonable first guess for the intrinsic color of the nova candidate (e.g., van den Bergh, S.; Younger, P. F. 1987), and using multi-band photometry from S. Kiyota, we arrive at an approximate value of interstellar reddening of E(B-V)~1.9 and E(V-I)~2.4. That translates to A_V~6.0, using the ratio of A_V/E(V-I)=2.5 from Stanek (1996). This estimate is consistent with the ``upper limit'' given by the total line-of-sight V-band extinction (12.2 mag) found by using the NED Coordinate & Extinction Calculator and the Schlafly et al. 2011 extinction maps.

To get an approximate estimate for the absolute magnitude for ASASSN-16ig, we assume a distance to object is 2kpc-15kpc, a distance modulus of 11.5-15.7 mag, and our estimate for A_V. This yields an absolute V-band magnitude of V~-4.6 - -8.8 on 2016-08-08.17 on for ASASSN-16ig. While only approximate, this range is consistent with a Galactic, heavily-obscured nova.

We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported by NSF grant AST-1515927, the Mt. Cuba Astronomical Foundation, and the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU.