[vsnet-grb-info 22418] LIGO/Virgo S190510g: Pan-STARRS and ATLAS observations and candidates

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24517
SUBJECT: LIGO/Virgo S190510g: Pan-STARRS and ATLAS observations and candidates  
DATE:    19/05/13 11:31:11 GMT
FROM:    Stephen Smartt at Queen's U/Belfast  <s.smartt at qub.ac.uk>

S. Srivastav, K. W. Smith, S. J. Smartt (QUB), K. Chambers, M. Huber,
T. de Boer, J. Bulger, J. Fairlamb, C.-C. Lin, T. Lowe, E. Magnier
A. Schultz, R. J. Wainscoat, M. Willman (IfA, Univ. Hawaii),
D. R. Young, O. McBrien, J. Gillanders.  D. O'Neil, P. Clark, S. Sim
(QUB), L. Denneau, H. Flewelling, A. Heinze, J. Tonry, H. Weiland
(IfA, Univ. Hawaii), A. Rest (STScI), B. Stalder (LSST), C. Stubbs
(Harvard)

We report observations of the BAYESTAR skymap of the BNS event S190510g
(The LIGO Scientific Collaboration and the Virgo Collaboration, GCN
24442) with the Pan-STARRS1 telescope (Chambers et al. 2016,
arXiv:1612.05560C) and the ATLAS telescopes (Tonry et al. 2018, PASP
PASP, 13, 164505). 

We acknowledge that is now a marginal candidate (LSC & VC, GCN 24489)
and note that we completed our scanning of the BAYESTAR skymap, before
the LALInference map was available (resulting in a final 4%
probability coverage).

For Pan-STARRS1 : images were taken in the PS1 w and i-bands (Tonry
et al. 2012, ApJ 750, 99) in the standard NEO search sequence. At each
pointing position a sequence of quads (4 x 45 sec) was taken. This
observing sequence ensures exactly the same pointing position for each
of the quads.

The PS1 images were processed with the IPP (Magnier et al. 2016,
arXiv:1612.05240) and difference images were produced using the
Pan-STARRS1 Science Consortium 3Pi images as reference
frames. Transient candidates were run through our standard filtering
procedures, combined with a machine learning algorithm (Wright et
al. 2015, MNRAS, 449, 451) and all candidates were
spatially cross-matched with known minor planets, and major star,
galaxy, AGN and multi-wavelength catalogues (as described in Smartt et
al. 2016, MNRAS, 462 4094).

For ATLAS, we observed with sequences of 4 x 30s, typically reaching
o ~ 19.5 in each pointing (e.g. Weiland et al. GCN 24107).

We covered the small probability region of the LalInference map (total
summed probability of 4%) at 13-14hrs (the 6hr region was not visible
from Hawaii).  We began taking Pan-STARRS data at 2019-05-10 07:09
(UTC), ~4.2 hrs after the GW trigger. ATLAS started at a similar time.

No new extragalactic transient candidates were discovered with ATLAS
within the 90% contour (brighter than about o ~ 19.5) 

In the PS1 data, the following 23 transients were found lying within
the 90% contour of the LALInference map. We give them 3 ranks : 

Rank 1 candidates are plausibly within the distance range reported by
the LIGO-Virgo analysis (~130 Mpc < d < ~220 Mpc). This comes from
host galaxy association and their spectroscopic or photometric
redshifts. 

Rank 2 candidates are not obviously associated with a catalogued
host galaxy. 

Rank 3 candidates are probably associated with a galaxy outside the
distance range.

Name      | PS Name | RA (J2000)  | Dec (J2000) | Disc. MJD  | Disc Mag | Notes
-------------------------------------------------------------------------------
Rank 1 
AT2019ezb | PS19xv  | 13 43 59.78 | +01 50 32.7 |  58613.30  |  20.50 i |  (1)
AT2019far | PS19aaf | 14 17 22.53 | +05 01 08.7 |  58613.48  |  20.29 i |  (2)

Rank 2 
AT2019ezc | PS19yn  | 13 24 04.80 | -09 02 05.8 |  58613.34  |  20.16 i | 
AT2019eya | PS19yi  | 13 27 23.56 | -07 01 41.2 |  58613.39  |  20.78 i | 
AT2019fam | PS19yp  | 13 39 00.66 | -04 28 30.7 |  58613.39  |  20.25 i | 
AT2019eyg | PS19yz  | 13 42 05.60 | -09 43 24.7 |  58613.35  |  20.60 i |  
AT2019fal | PS19zf  | 13 46 08.91 | -03 22 40.1 |  58613.39  |  20.92 i |   
AT2019eyp | PS19zh  | 14 05 46.51 | +03 25 21.4 |  58613.50  |  21.36 w |
AT2019eyu | PS19aaj | 14 06 15.69 | +03 45 58.4 |  58613.48  |  20.57 i |  

Rank 3 
AT2019exz | PS19yh  | 13 17 59.93 | -04 36 33.5 |  58613.39  |  19.93 i |  (3)
AT2019faa | PS19xz  | 13 21 30.14 | +01 59 03.5 |  58613.30  |  21.02 i |  (4)
AT2019ezy | PS19xx  | 13 27 22.91 | +01 28 19.0 |  58613.30  |  20.11 i |  (5)
AT2019fan | PS19yo  | 13 28 01.32 | -03 47 08.3 |  58613.39  |  20.76 i |  (6)
AT2019eyi | PS19xs  | 13 31 45.46 | -00 04 26.5 |  58613.30  |  20.23 i |  (7)
AT2019eza | PS19xr  | 13 51 04.52 | +03 54 53.4 |  58613.30  |  20.42 i |  
AT2019fae | PS19yd  | 13 51 53.52 | +00 45 54.8 |  58613.30  |  20.68 i |  (8)
AT2019fac | PS19yb  | 13 53 05.69 | +08 16 45.3 |  58613.30  |  20.84 i |  (9)
AT2019eyf | PS19yg  | 13 58 13.27 | +05 13 28.2 |  58613.30  |  19.87 i |   
AT2019eyv | PS19aah | 14 03 35.78 | +08 11 25.3 |  58613.48  |  21.14 i |  
AT2019fbj | PS19abe | 14 05 22.17 | +06 35 48.7 |  58613.48  |  21.14 i |  
AT2019eyn | PS19zk  | 14 07 17.08 | +08 23 33.3 |  58613.48  |  20.49 i |  (10)
AT2019ezl | PS19zx  | 14 13 00.93 | +07 50 02.5 |  58613.48  |  20.09 i |   
AT2019ezv | PS19aau | 14 17 39.18 | +02 08 39.1 |  58613.50  |  19.80 w |  (11)


(1) Probable host is SDSS J134359.83+015034.4 at a spectroscopic z = 0.072 or D ~ 323 Mpc (NED), yielding an absolute i-band magnitude of ~-17.0 mag 
(2) Probable host is SDSS J141300.92+075002.6 at a spectroscopic z = 0.058 or D ~ 259 Mpc (NED), yielding an absolute i-band magnitude of ~ -16.8 
(3) Probable host is GALEXASC J131800.06-043633.9 at a spectroscopic z = 0.132 or D ~ 603 Mpc (NED) 
(4) Probable host is SDSS J132130.22+015903.0 at a photometric z = 0.291 +/- 0.141 or D ~ 1431 Mpc (SDSS) 
(5) Probable host is SDSS J132722.06+012818.6 at a photometric z = 0.068 +/- 0.012 or D ~ 308 Mpc (NED) 
(6) Probable host is LCRS B132526.4-033142 at a spectroscopic z = 0.087 or D ~ 388 Mpc (NED) 
(7) Probable host is SDSS J133145.14-000431.3 at a photometric z = 0.185 +/- 0.018 or D ~ 899 Mpc (SDSS) 
(8) Probable host is 2MASX J13515347+0045515 at a spectroscopic z = 0.088 or D ~ 389 Mpc (NED) 
(9) Probable host is SDSS J135153.50+004551.2 at a photometric z = 0.230 +/-0.151 or D ~ 1148 Mpc (SDSS) 
(10) Probable host is 2MASX J14071678+0823347 at a spectroscopic z = 0.115 or D ~ 532 Mpc (NED) 
(11) Probable host is SDSS J141738.94+020831.9 at a spectroscopic redshift of z = 0.129 or D ~ 584 Mpc (NED)