We are carrying out the "Pan-STARRS Search for Kilonovae" which is a focused search for intrinsically faint transients, or rapidly evolving transients in galaxies which are closer than 200 Mpc in the ongoing Pan-STARRS Near Earth Object surveys (see Smartt et al. AstroNote 2019-48 for details).
In normal survey mode, Pan-STARRS takes 4 x 45s exposures in w, i or z each night reaching 5 sigma magnitudes of w<22, i<21 and z<20.5 in each frame (see Chambers et al. 2016, 1612.05560).
We report the discovery of an intrinsically faint transient PS19gkq (AT2019ukm) in the host galaxy NGC 2770 , at a redshift of z = 0.007, or d = 30.1 Mpc (from NED). The transient was discovered at MJD 58794.60 (2019-11-07.60) at mag w = 21.0 +/- 0.2.It is offset from the this possible nearby host (NGC2770) by 120.50" S, 82.30" W (a projected 20 kpc radius from the galaxy centre). At this distance the absolute magnitude is M_w = -11.3 (assuming m-M = 32.3 and foreground exinction of A_r = 0.062). This is outside the optical disk of NGC2770 and such a faint absolute magnitude is unusual. It is possible this is a background supernova, and there is a g = 20.1, galaxy SDSS J090940.27+330641.3 at a distance 3.4 arcsec away (photz = 0.24). Follow up observation taken on mjd 58796.62 showed it had a a mag w=21.0 +/-0.1. Hence the lightcurve appears flat, and a background SN is plausible, but a spectroscopic observation is required.
Information on all objects discovered by the "Pan-STARRS search for kilonovae" will be made available at http://star.pst.qub.ac.uk/ps1threepi/. We will release AstroNotes for all these candidates and encourage spectroscopic classification or photometric follow-up. A finder is attached.
These discoveries are a byproduct of the Pan-STARRS NEO survey observations supported by the NASA Grants, including No. NNX14AM74G issued through the SSO Near Earth Object Observations Program.
Catalog | Name | Reported RA | Reported DEC | Reported Obj-Type | Reported Redshift | Host Name | Host Redshift | Remarks | TNS RA | TNS DEC | TNS Obj-Type | TNS Redshift |
---|---|---|---|---|---|---|---|---|---|---|---|---|
TNS | 2019ukm | 09:09:40.241 | +33:06:37.91 | 0.007 | 09:09:40.241 | +33:06:37.90 |
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