[vsnet-grb-info 24464] LIGO/Virgo S191216ap: No significant candidates found in Pan-STARRS observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26563
SUBJECT: LIGO/Virgo S191216ap: No significant candidates found in Pan-STARRS observations
DATE:    19/12/22 21:46:21 GMT
FROM:    O. McBrien at QUB  <omcbrien02 at qub.ac.uk>

O. McBrien, S. J. Smartt, K. W. Smith, D. R. Young, J. Gillanders. S. Srivastav, P. Clark, D. O'Neill, M. Fulton (QUB), K.C. Chambers , M. E. Huber, A.S.B. Schultz, T. de Boer, J. Bulger, J. Fairlamb, C.C. Lin, T. Lowe, E. Magnier , R. J. Wainscoat, M. Willman (IfA, Univ. Hawaii), A. Rest (STScI), C. Stubbs (Harvard), T.-W. Chen (Stockholm) on behalf of the Pan-STARRS collaboration report:

We have surveyed the sky localisation region of the gravitational wave event S191216ap (The LIGO Scientific Collaboration and the Virgo Collaboration, GCN 26454) with Pan-STARRS1 (Chambers et al. 2016, arXiv:1612.05560), according to the most recently available skymap (LALInference.fits.gz, GCN 26505), and find 15 transient objects within the 90% probability contour. Our survey covers 58.8% of this contour’s area.

Our coverage began on MJD 58834.210 (UTC 2019-12-17 05:01:45), though poor weather limited observing time severely on this night. Observations continued over the following 3 subsequent nights, all comprised of 45 second tiling exposures in the PS1-r band.

Of the 15 objects found, 8 are known objects already registered on the Transient Name Server. For the remaining 7 objects, 6 appear to be supernova-like events, with relatively flat lightcurves and a host visible in the exposures, while 1 is an M-dwarf flare. We discuss these 7 new objects below:

PS19him (AT2019xfh) was discovered at coordinates RA=21:22:43.25, Dec=+08:47:04.9 and magnitude 19.10 +/- 0.09 on MJD 58836.233 in the PS1-r band. PS19him is associated with the galaxy SDSS J212243.21+084705.7 at a photometric redshift of 0.117 +/- 0.034. The object was detected on the subsequent night at a similar magnitude. The flatness of the lightcurve suggests this is a supernova.

PS19hir (AT2019xfj) was discovered at coordinates RA=21:24:08.71, Dec=+13:46:38.8 and magnitude 19.80 +/- 0.15 on MJD 58836.235 in the PS1-r band. PS19hir is associated with the galaxy 2MASS J21240870+1346392 with a photometric redshift of 0.170 ± 0.0245. The object was detected on the subsequent night at a similar magnitude. The flatness of the lightcurve suggests this is a supernova.

PS19hik (AT2019xej) was discovered at coordinates RA=21:28:18.25, Dec=+03:48:56.8
and magnitude 19.12 +/- 0.11 on MJD 58836.232 in the PS1-r band. PS19hik is associated with the galaxy 2MASS J21281825+0348568 at a photometric redshift of 0.2260 ± 0.0627. The object was detected on the subsequent night at a similar magnitude. The flatness of the lightcurve suggests this is a supernova.

PS19hix (AT2019xfr) was discovered at coordinates RA=21:14:34.24, Dec=+29:03:22.0 and magnitude 20.54 +/- 0.27 on MJD 58836.229 in the PS1-r band. PS19hix does not appear to be associated with any catalogued galaxy, but lies near a faint, extended source in the PS1 exposure which is likely a galaxy. Additionally, the object was detected on the subsequent night at a similar magnitude, leading us to believe this is a supernova.

PS19his (AT2019xfk) was discovered at coordinates RA=21:17:50.87, Dec=+29:32:55.1 and magnitude 20.78 +/- 0.29 on MJD 58836.229 in the PS1-r band. PS19his does not appear to be associated with any catalogued galaxy, but lies near a faint, extended source in the PS1 exposure which is likely a galaxy. Additionally, the object was detected on the subsequent night at a similar magnitude, leading us to believe this is a supernova.

PS19hiy (AT2019xgz) was discovered at coordinates RA=21:18:49.41, Dec=+12:38:49.5 and magnitude 20.15 +/- 0.25 on MJD 58836.260 in the PS1-r band. PS19hiy is associated with the galaxy SDSS J211849.20+123849.5 at a photometric redshift of 0.284 ± 0.106. The object was detected on the subsequent night at a similar magnitude. The flatness of the lightcurve suggests this is a supernova.
PS19hiv (AT2019xfn) was discovered at coordinates RA=21:14:01.57, Dec=+22:36:54.9 and magnitude 18.41 +/- 0.05 on MJD 58837.270 in the PS1-r band. PS19hiv is a fast fading, faint, red source. As such, we believe this to be an M-dwarf flare.