Thursday, October 31, 2019


Following the posting on the Central Bureau's Transient Object Confirmation Page about a possible Nova in Scutum (TOCP Designation: PNV J18395972-1025415) I 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.  

On images taken on October 31.01, 2019 I can confirm the presence of an optical counterpart with R-filtered CCD magnitude about +8.4 (saturated in a 10-second exposure) at coordinates:

R.A. = 18 39 59.71, Decl.= -10 25 41.9

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

This transient was discovered (discovered magnitude 11.5 g-Sloan Filter) by the All-Sky Automated Survey for Supernovae (ASAS-SN) on 2019 Oct. 29 at 01:12UT and reported to Transient Name Server (TNS) on Oct. 29 at 02:07:49 UTC as ASASSN-19aad = AT 2019tpb. According to CBET 4690, several independents discoveries have been reported to the Central Bureau of a nova in Scutum: Koichi Nishiyama (unfiltered magnitude 9.4 on Oct. 29.397), Hideo Nishimura (unfiltered magnitude 9.8 on Oct. 29.421), Shizuo Kaneko (unfiltered magnitude 9.8 on Oct. 29.462) (on AAVSO VSX is reported also Fujio Kabashima as independent discoverer). 

Spectroscopy by S. C. Williams et al. (see ATel #13241) & by  M. Pavana et al. (see ATel #13245) show that AT 2019tpb/ASASSN-19aad is a Galactic nova in the early stages of eruption.

N. Samus writes that the permanent GCVS designation V659 Sct has been assigned to this nova.

Below my confirmation image (sum of two unfiltered 30-sec exposure through a 0.6-m f/6.5 astrograph + CCD; El Sauce Observatory, Chile). Click on the image for a bigger version: 

An animation showing a comparison between my image and the archive POSS1 Blue plate (1951-07-30).

Below the same animation with a larger field of view. At the bottom left of V659 Sct you will notice a star occupying a different position in the new image with respect to the 1951 archive image. This star (Gaia designation DR2 4155146598548456064) is a high proper  motion star. Most stars are so distant that their apparent motion even over hundreds of years is all but negligible to naked eye observers. Some stars have very significant movements compared to the background stars (Click on it for a bigger version:

Below an image that is the difference between the new image and the archive image useful to highlight the "new" objects. There you can easily see the new galactic nova V659 Sct and the  high proper motion star.

by Ernesto Guido