Supernova SN 2021gmj in NGC 3310 galaxy: an image – 20 Mar. 2021
We observed the bright supernova SN 2021gmj (was AT 2021gmj supernova candidate) in the galaxy NGC 3310, as part of our supernova follow-up program: here it is our image.
NB: Spectroscopic analysis showed this transient to be a type II supernova!
The image above comes from the average of five, 180-seconds exposures, unfiltered, remotely taken with the “Elena” (PlaneWave 17″+Paramount ME+SBIG STL-6303E) robotic unit available as part of the Virtual Telescope Project. The supernova is indicated by an arrow in the upper left inset. The sky was bright (twilight + bright moon) and transparency was not at its best.
The apparent host is the remarkable spiral galaxy NGC 3310, in Ursa Major, placed at about 35 millions of light years. [Considering such a distance, if this is a type Ia supernova, it could potentially reach a magnitude of 11 this is now confirmed to be a type II supernova]. As for the transient, we estimated SN 2021gmj as bright as mag. 15.1 (unfiltered, R-mags for the reference stars from the Gaia DR2 star catalogue). This transient was discovered today, 20 Mar. 2021 by the DLT40 surveyand hopefully spectroscopy will be available soon.
Further observations will follow, weather permitting.
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I just went back and reexamined my image of 3310 taken 19 March at 0346 UT. No sign of the SN.
Thanks for letting us know, Patrick! Keep up your great work!