Supernovae SN 2021cah in UGC 2270 and SN 2021dpu in UGC 2261 galaxies: an image – 15 Mar. 2021
Spotting a supernova in a very distant galaxy is always cool, but what if you see two in two different galaxies, but on the same telescopic image, at the same time? This is the case for SN 2021cah and SN 2021dpu: enjoy this rare view.
The image above comes from the average of ten, 300-second 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 supernovae are indicated by an arrow in the upper left inset.
Viewing two supernovae at a glance, in the same, narrow field of view of the telescope and at the same time, is rare: we do not know of any previous case (Emmanuel Conseil kindly mentioned SN 2016iae and 2016ija in the same galaxy, NGCX 1532, not visible from Italy), so we’ve thought this opportunity was something we could not miss. And the host galaxies (the spiral UGC 2270 and elliptic UGC 2261 galaxies, possibly a pair placed at about 300 millions of light years) are nice, too.
We estimated SN 2021cah and SN 2021 dpu as bright as mag. 17.4 and 15.5, respectively (unfiltered, R-mags for the reference stars from the Gaia DR2 star catalogue). SN 2021cah was discovered on 7 Feb. 2021, while SN 2021dpu on 22 Feb. 2021, both by the Zwicky Transient Facility (ZTF) survey: they resulted to be type II and Ia supernovae, respectively.
Further observations will follow, weather permitting.
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