AstroNote 2019-128

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DRAFT
2019-11-11 10:25:42
Type: Object/s-Discovery/Classification
Pan-STARRS Search for Kilonovae: discovery of an intrinsically faint transient in NGC 2770 (30.1Mpc)
Authors: S. McLaughlin, S. J. Smartt, K. W. Smith (QUB), K. C. Chambers, M. Huber (IfA, Hawaii), S. Srivastav, O. McBrien, D. R. Young, J. Gillanders, D. O'Neill, P. Clark, S. Sim (QUB), T. de Boer, J. Bulger, J. Fairlamb, C.-C. Lin, T. Lowe, E. Magnier, A. Schultz, R. J. Wainscoat, M. Willman (IfA), T.-W. Chen (MPE), D. E. Wright (University of Minnesota), C. Stubbs (Harvard), A. Rest (STScI)
Source Group: Pan-STARRS1
Abstract:
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).  Here 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). 

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.

 

Show current TNS values
CatalogNameReported RAReported DECReported Obj-TypeReported RedshiftHost NameHost RedshiftRemarksTNS RATNS DECTNS Obj-TypeTNS Redshift
TNS2019ukm09:09:40.241+33:06:37.910.00709:09:40.241+33:06:37.90