Wednesday, April 7, 2021


Following the posting on the Central Bureau's Transient Object Confirmation Page about a possible Nova in Sgr (TOCP Designation: PNV J17581670-2914490) we performed some follow-up of this object through a TEL 0.6-m f/6.5 astrograph + CCD located in the El Sauce Observatory in Chile and operated by Telescope Live network (MPC Code X02).

This transient has been discovered by Andrew Pearce at 8.4 mag (unfiltered) on 2021-04-04.825 UT using a Canon 1100D DSLR camera with a 100mm f/2.8 lens.  Total exposure time was 20 seconds (2 x 10s images stacked). Rob McNaught reported non-detection on 2021-04-02.776 UT (unfiltered limiting mag 11.0).

On images taken on April 06.40, 2021 we can confirm the presence of an optical counterpart with B-filtered CCD magnitude +8.955 (R-filtered & V-filtered images were saturated in 5-second exposures) at coordinates:

R.A. = 17 58 16.08, Decl.= -29 14 56.4

(equinox 2000.0; Gaia DR2 catalogue reference stars for the astrometry).

Our confirmation image (click on it for a bigger version):

An animation showing a comparison between my image and the archive POSS1 plate (1996-09-12). Made with TYCHO software by D. Parrott. Click on it for a bigger version.

According to ATel #14513,  K. Taguchi et al. obtained a spectrum of this transient on 2021-04-05.828 UT using the fiber-fed integral field spectrograph mounted on the 3.8-m Seimei telescope at Okayama Observatory of Kyoto University. Their spectrum shows Balmer lines, Fe II lines, and the Na I D line. According to their spectrum and the brightness, they conclude that this object is a classical nova (with a spectrum similar to those of the slow nova V1280 Sco in the early stage).

Below is part of the discovery image by A. Pearce showing the nova. The bright stars to the top right are gamma 1 and 2 Sgr.  South is to the top and east to the right. (Click on it for a bigger version)

Credit: A. Pearce

This nova has been designated N Sgr 2021 No. 2 (with permanent GCVS designation V6595 Sgr).

by Ernesto Guido, Adriano Valvasori, Marco Rocchetto

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