AstroNote 2022-50

We selected AT 2022bdw / ZTF22aaahtqz / PS22avi / ATLAS22dth for classification based on its photometric properties and location in its host galaxy by using the Lasair (Smith et al. 2019) 13TDE-candidatesv3.1 alert stream created by D. Young based on a filter by M. Nicholl.

We obtained a spectrum with the Floyds spectroraph mounted on the Las Cumbres 2-meter Faulkes Telescope North in Haleakala, Hawaii, on 2022-02-23 05:18 UT as part of the StarDestroyers program (PI: I. Arcavi). The spectrum, which we make publicly available on the TNS, displays a broad emission feature consistent with He II 4686A and broad Halpha emission on top of a blue continuum. As such it is possibly a new member of the "TDE H+He" class (van Velzen et al. 2020). Narrow H-alpha emission is likely associated with the host, as it is seen in an archival SDSS spectrum taken at that position.

We use S. Goldwasser's Python implementation of SuperFit (Howell et al. 2005) and find a good fit with the TDE AT 2018hyz but also with the Type II supernova SN 2012aw. Both spectral comparisons are uploaded to the TNS.

The ZTF public light curve, as retrieved from Alerce, shows the event is possibly peaking at a magnitude of ~17.5, corresponding to an absolute magnitude of ~-18.7. This is luminous for a Type II supernova, especially when so blue (which is typical of their early phases). On the other hand this is less luminous than typical TDEs which peak at ~-20 (though fainter TDEs have been observed).

Ground-based optical followup is planned using the Las Cumbres Observatory network.