Swift/XRT detection of the nova candidate TCP J17562787-1714548

ATel #15910; Kirill Sokolovsky (UIUC), Kim Page (U. Leicester), Elias Aydi, Laura Chomiuk, Jay Strader (MSU), Jennifer Sokoloski (Columbia), Justin Linford (NRAO), Koji Mukai (NASA/GSFC)
on 21 Feb 2023; 01:02 UT
Credential Certification: Kirill Sokolovsky (kirx@scan.sai.msu.ru)

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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.

ZTF photometry of the possible progenitor

CBAT Transient Object Followup Reports page