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Spectroscopic Classification of AT2019udc with the Lick Shane telescope

ATel #13263; M. R. Siebert, G. Dimitriadis, C. D. Kilpatrick, R. J. Foley, R. Nunez, K. McKinnon and P. Guhathakurta (UCSC)
on 5 Nov 2019; 07:13 UT
Credential Certification: Georgios Dimitriadis (gdimitri@ucsc.edu)

Subjects: Optical, Transient

We report the following classification of AT2019udc from spectroscopic observations with the Kast spectrograph on the Shane telescope on 2019 November 4 UT. The target was supplied by DLT40.

 
Name         | IAU Name  | RA (J2000)  | Dec (J2000)  |   z   | Type  | Phase  | Notes
DLT19o | AT2019udc | 01:53:11.21 | +04:11:47.00 | 0.006 | LBV | - | (1)

Notes: When the redshift is given to 2 decimal places, it is derived from the transient spectrum. Otherwise, the redshift is determined from the host galaxy. (1) Red spectrum (black body temperature ~ 4,500 K, assuming no host extinction) with a distinctive narrow H-alpha emission feature (FWHM ~ 1300 km/s), red-shifted at 260 km/s relative to the host (NGC 718, with spectroscopic redshift z = 0.005781). The (observed) absolute magnitude of the transient is M_r = -13.3, and dereddening by an appropriate amount to match the Na D absorption strength (EW ~ 6 Angstroms), we estimate a temperature of 15,700 K and an absolute magnitude of ~ -16. We consider these properties most similar to a reddened LBV outburst, however it is also consistent with a luminous red nova. We thank the Lick Observatory staff for helping with these target-of-opportunity observations.