Spectroscopic confirmation of TCP J17282355-3113163 as a new Galactic nova in Scorpius
ATel #16184; Jay Strader (Michigan St), Kirill Sokolovsky (Illinois), Elias Aydi (Michigan St), Laura Chomiuk (Michigan St)
on 12 Aug 2023; 13:11 UT
Credential Certification: Jay Strader (strader@pa.msu.edu)
We report optical spectroscopy of TCP J17282355-3113163, which was first detected by BraTS on UT 2023-08-06.1. We recover significant detections via ATLAS forced photometry (https://fallingstar-data.com) in its orange filter starting on 2023-07-24.9 (two weeks before the BraTS discovery), at o ~ 17.3. We also find clear non-detections on 2023-07-23.1 (o > 18.8) and at earlier epochs.
On 2023-08-10.98 we obtained a low-resolution spectrum of this source using the Goodman spectrograph on the 4.1 m SOAR telescope, covering the wavelength range 4000-8000 A. The spectrum has a red continuum with strong broad emission lines that show complex structure. The strongest lines are H-alpha (FWHM about 920 km/s) and O I, followed by a large number of Fe II lines. This spectrum is consistent with a reddened classical nova. As the ATLAS light curve does not yet show a clear turnover, the nova could still be rising toward peak.
By astrometric calibration of the acquisition image using stars from Gaia DR3, we measure an ICRS position of 17:28:23.642, -31:13:17.65, with an approximate uncertainly of about 0.05" per coordinate. There is no pre-outburst counterpart at this location in any published optical or near-IR catalog nor in DECAPS2 r or z images, suggesting the pre-outburst source has r >~ 22.7.
We thank Sean Points and the rest of the SOAR staff for their help in executing these observations in a difficult situation. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministerio da Ciencia, Tecnologia e Inovacoes do Brasil (MCTI/LNA), the US National Science Foundation's NOIRLab, the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).
