TCP J17562787-1714548 (ATEL 15910)

It is somewhat unusual for a nova to show shock-powered X-rays visible to Swift/XRT less than two days after eruption. This may suggest that the transient is a very fast nova and/or a nova embedded in the wind of an evolved donor star.

Possibly a nova that erupted in symbiotic environment.

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ATEL #15910 ATEL #15910

Title: Swift/XRT detection of the nova candidate TCP J17562787-1714548 Author: Kirill Sokolovsky (UIUC), Kim Page (U. Leicester), Elias Aydi, Laura Chomiuk, Jay Strader (MSU), Jennifer Sokoloski (Columbia), Justin Linford (NRAO), Koji Mukai (NASA/GSFC) Queries: kirx@kirx.net Posted: 21 Feb 2023; 01:02 UT Subjects:Ultra-Violet, X-ray, Nova, Transient

The candidate nova TCP J17562787-1714548 was discovered by Y. Sakurai, H. Nishimura, and A. Pearce using DSLR camera images with the first reported detection on 2022-02-18.834 UT at an unfiltered magnitude of 11. Follow-up astrometry by multiple observers reported via CBAT Transient Object Followup Reports page suggests Gaia DR3 4144602552564272000 (G=18.1, Plx=0.20+/-0.18 mas) as a possible progenitor that shows irregular variability in archival ZTF and ATLAS photometry (T. Kato, vsnet-alert 27432).

Swift observed TCP J17562787-1714548 for 1.9ks on 2023-02-20.58. Swift/XRT detected an X-ray source with a net count rate of 0.043 +/-0.006 cts/s at the position of the transient. Most of the counts are above 3 keV, consistent with heavily absorbed (n_H > 10^23 cm^-2) thermal emission with kT > 1 keV. The Galactic absorbing column density in the direction of the source is n_H = 3.86x10^21 cm^-2 (Kalberla et al. 2005 A&A, 440, 775), suggesting the presence of source-intrinsic absorption. The XRT detection cannot be attributed to optical loading that should manifest itself as spurious soft (rather than hard) emission. Swift/UVOT detected a UVW1= 12.35 +/-0.02 (Vega system) ultraviolet source at the position of the transient.

It is somewhat unusual for a nova to show shock-powered X-rays visible to Swift/XRT less than two days after eruption. This may suggest that the transient is a very fast nova and/or a nova embedded in the wind of an evolved donor star.

We thank the Neil Gehrels Swift Observatory team and PI, Brad Cenko, for rapid execution this ToO observation.

<a href="https://ztf.snad.space/dr13/view/332207100098232">ZTF photometry of the possible progenitor</a>

CBAT Transient Object Followup Reports page: http://www.cbat.eps.harvard.edu/unc onf/followups/J17562787-1714548.html