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Alert Notice 709: Supernova in NGC 4457 - SN 2020nvb (= AT 2020nvb = ATLAS20rvf)

July 2, 2020

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- Time Sensitive Alerts:
- Cataclysmic Variables:

Observers are encouraged to participate in the AAVSO forums listed above for this event, and to visit the AAVSO CV Section webpage.

Event: Supernova in NGC 4457 (Vir) - SN 2020nvb (= AT 2020nvb = ATLAS20rvf)

Discovered by: Koichi Itagaki (Yamagata, Japan)

Discovery magnitude: unfiltered CCD magnitude 13 (using 0.5-m F/6.8 reflector+CCD (KAF-1001E))
Discovery date: 2020 July 1.5490 UT

Coordinates (2000.0): R.A. 12 28 58.79   Decl. +03 34 22.1  (from VSX)

Spectra: The following spectra indicating that SN 2020nvb is a Type Ia supernova have been reported:
   - P. Ochner et al. (ATel #13848, ATel #13849) on behalf of the Asiago Transient Classification Program, spectrum obtained on 2020 Jul. 1.55 UT using the Asiago 1.22-m Galileo Galilei Telescope equipped with the B&C spectrograph;
   - S. C. Williams et al. (TNS database), spectrum obtained 2020 Jul. 1.91 UT using the SPRAT instrument on the Liverpool Telescope.

Observing recommendations: Observations of all types (visual, CCD, DSLR, spectroscopy) and multiple bands as instrumentation permits are strongly encouraged as the supernova evolves.

Observations reported to the AAVSO:
2020 Jun. 30.2450 UT, 13.361 orange-ATLAS (J. Tonry et al., ATLAS team; via TNS database);
Jul. 01.260, 13.1 g (corrected) (ASAS-SN Sky Patrol, via P. Schmeer);
01.84912, 13.10 V (M. Morales Aimar, Spain);

Charts: Charts with comparison stars for SN 2020nvb may be created using the AAVSO Variable Star Plotter (VSP).

Submit optical observations: Please submit photometry and visual observations to the AAVSO International Database using the name SN 2020nvb.

Submit spectroscopic observations: Please submit spectroscopy reports to the AAVSO Spectroscopy Database (AVSpec).

a. P. Schmeer (Saarbruecken-Bischmisheim, Germany) reports SN 2020nvb is located 9" NNW of the center of NGC 4457.

Congratulations to Koichi Itagaki on his latest discovery!

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.

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