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Gaia17aiq - Possible Supernova between two Interacting Galaxies

ATel #10082; D. Denisenko (Sternberg Astronomical Institute, Lomonosov Moscow State University)
on 16 Feb 2017; 12:04 UT
Credential Certification: Denis Denisenko (d.v.denisenko@gmail.com)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 10091

New optical transient Gaia17aiq of magnitude 17.6 was observed by Gaia on 2017-02-06.43 and 06.50 UT. It was published on Feb. 14 (eight days after the detection) as hostless blue transient with Transient Name Server ID 2017ati. The object is actually located between two apparently interacting galaxies PGC 28268 and PGC 28299 = Zw VII 293. Gaia position of the object (rounded to 0.1") is 09 49 56.70 +67 10 59.6 (J2000.0). That places Gaia17aiq 37" East and 11" South of PGC 28268 position and 67" W and 38" N of the nucleus of PGC 28299 (PGC 28268 has a shape of cometary nebula without a distinct nucleus in IR or UV, while PGC 28299 does have a bright nucleus and a "tail" towards its neighbor).

A series of unfiltered 60-sec exposures was obtained remotely from Mayhill, NM, using iTelescope.Net T11 instrument (0.50-m f/6.8 reflector + FLI ProLine CCD + f/4.5 focal reducer) on 2017 Feb. 16 from 08:18 to 08:28 UT. The bright Moon (phase 0.81) was 80 deg away. The magnitude of Gaia17aiq (unfiltered with V zero point) was measured to be 16.50 using the nearby star SDSS J094942.68+671035.6 with Vmag=15.68 from APASS DR9 (A. Henden et al., 2016). Animation of 2017 Feb. 16 image with DSS red plate is shown at http://scan.sai.msu.ru/~denis/Gaia17aiq-DSS-T11-anim.gif and the color-combined DSS chart centered at Gaia17aiq position (sum of 3 infrared, 3 red and 3 blue POSS-II plates taken in 1988-2000) is uploaded to http://scan.sai.msu.ru/~denis/ZwVII293-dss5x5.jpg (5'x5' FOV).

At the redshift of VII Zw 293 (z=0.01305, E. Falco et al., 1999) distance modulus is m-M=33.8. Assuming that the transient is a Supernova in the pair of interacting galaxies, that corresponds to Gaia17aiq absolute magnitude of M=-17.3 on Feb. 16 (and M=-16.2 when first detected by Gaia on Feb. 06). Correcting for extinction (AV=0.323, according to E. Schlafly et al., 2011) we obtain M=-17.6 on Feb. 16, still too faint for type Ia Supernova. Spectroscopic identification and continued photometric follow up of Gaia17aiq = AT 2017ati are strongly encouraged.

Author thanks Education Support Foundation "Noosfera" for providing the access to iTelescope network.