{
  "bibcode": "2017GCN.20410....1S",
  "body": "S. J. Smartt, (QUB), K. W. Smith (QUB), M. E. Huber (IfA),\nK. C. Chambers (IfA), D. R. Young, D. E. Wright (QUB), M. Coughlin\n(Harvard), L. Denneau, H. Flewelling, A. Heinze, E. A. Magnier (IfA),\nA. Rest (STScI), B. Stalder (IfA), A. S. B. Schultz, C. W. Stubbs\n(Harvard) J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland (IfA)\n\nFurther to Chambers et al. GCN 20383, we report that we covered 632\nsquare degrees on the first night (beginning 57758.3) . We estimate\nthis corresponds to a probability of containing the source of 33%.  We\nhave since reduced this area to the higher probability central region,\nrecovering 357 sq degrees and a containment probability of 26% (based\non the LALInference map, GCN 20385).\n\nImages were taken in the Pan-STARRS i-band in a series of overlapping\n45s exposures, with typically 4-8 images at each position.  These were\ncombined into stacks and subtracted from the Pan-STARRS1 3Pi reference\nimage (Chambers et al. arXiv:1612.05560, and available at\nhttp://panstarrs.stsci.edu).\n\nUsing techniques discussed in Smartt et al. (2016, MNRAS, 462, 4094),\nwe have located and vetted transients with quality filters and a\nmachine learning algorithm on the images. We recover 6 iPTF objects\nand 15 old transients known before the GW alert (given at the end for\ncompleteness). ATLAS17aeu was recovered as discussed in Chambers et\nal.  (GCN 20407)\n\nIn the following table, we give our 55 targets, sorted by magnitude.  The\nlightcurve trend is given (LC trend), indicating the change in\nmagnitude between earliest and latest MJD of detection. To select\nthese targets we required a minimum of 2 detections over 2 separate\nnights.\n\nOur area is completely within the SDSS DR12 footprint, and we give the\nredshifts (p for photometric and s for spectroscopic) of the host\ngalaxies.  Objects with no obvious host are labelled \"hostless\".  Some\ntargets are coincident with faint sources in SDSS for which\nstar/galaxy separation and photo-z estimates are not reliable and we\nnote these.  We have removed obvious AGN and candidate AGN (low level\nvariability associated with galaxy cores), as well as stellar\nvariables.\n\nIn the comments we note iPTF coincidences (Singer et al. GCN 20401;\nKasliwal et al. GCN 20364). A small number of candidates have a low\nreal-bogus (RB) machine learning factor and should be treated with\ncaution. All have been scanned by human reviewers. \n\nThe photometric redshifts from SDSS should not be used as a robust\nfiltering for distance (see discussion in Smartt et al. 2016), but we\nprovide them as a guide.\n\nWe are targeting the objects with changing lightcurves with\nGemini+GMOS.\n\nName \tRA\t                 DEC          LC trend\t  Earliest mjd\tmag\t         Latest mjd  z       Comment\nPS17df\t08:50:02.42\t+46:39:48.8  fading 00.09 57758.43699\t18.39\t57759.4911  0.038 s iPTF17bo\t\t\nPS17fg\t08:48:46.25\t+44:00:24.6  fading 00.15 57758.42737\t18.89\t57761.4882  0.060 s iPTF17bq\t\t\nPS17fr\t08:11:52.10\t+25:25:21.4  rising 00.57 57758.43263\t19.19\t57761.4619  0.199 p iPTF17cf\t\nPS17fe\t09:00:21.22\t+63:50:49.8  fading 00.09 57758.39189\t19.60\t57759.4726  0.245 p\t\nPS17du\t09:14:30.59\t+54:28:34.4  fading 00.04 57758.42705\t19.75\t57759.4660  0.045 s 0.6\" from core\t\t\nPS17dp\t09:00:51.09\t+45:26:44.3  rising 00.06 57758.39978\t19.97\t57759.5043  0.051 s \t\t\nPS17gl\t08:34:50.85\t+61:13:02.2  rising 00.07 57758.39093\t20.04\t57759.4635  0.038 s \t\nPS17ft\t08:16:52.72\t+26:27:25.3  fading 00.05 57758.44356\t20.05\t57761.4790  0.042 s \t\nPS17fs\t08:14:47.53\t+27:50:12.2  fading 00.11 57758.45845\t20.09\t57761.4891  0.118 p iPTF17ch\t\nPS17bz\t08:04:49.22\t+29:19:48.8  fading 00.08 57758.40250\t20.23\t57761.4809  0.047 s \t\nPS17fb\t08:49:18.13\t+44:38:31.1  rising 00.01 57758.41320\t20.30\t57759.4831  0.151 p\t\nPS17fh\t07:55:14.13\t+26:25:11.5  fading 00.14 57758.39608\t20.32\t57761.4492  0.119 p\t\nPS17fw\t08:19:05.64\t+23:20:42.8  fading 00.04 57758.40905\t20.35\t57761.4478  0.034 p\t\nPS17gb\t08:21:17.00\t+51:10:17.1  rising 00.13 57758.38839\t20.36\t57759.4635  0.197 p \t\nPS17fa\t08:47:22.51\t+51:08:17.4  fading 00.02 57758.44371\t20.41\t57759.4865  0.497 p \t\nPS17en\t08:40:22.10\t+38:43:25.0  fading 00.07 57758.44053\t20.41\t57761.4923  0.673 p iPTF17fa\nPS17dy\t08:13:00.78\t+41:18:26.9  rising 00.00 57758.42812\t20.43\t57761.4760  0.282 p iPTF17fb\t\nPS17er\t08:41:57.26\t+40:55:07.7  rising 00.36 57758.45114\t20.44\t57761.4854  0.296 p \t\nPS17fj\t07:59:30.67\t+28:27:03.8  fading 00.37 57758.41011\t20.46\t57761.4771  hostless \t\t\nPS17fl\t08:02:09.73\t+28:49:44.7  rising 00.32 57758.42406\t20.47\t57761.4876  0.080 p\t\nPS17dw\t07:49:25.36\t+20:28:00.6  fading 00.05 57758.38695\t20.48\t57759.4846  0.171 p\t\nPS17fv\t08:18:15.52\t+43:45:03.4  fading 00.06 57758.45210\t20.56\t57761.5017  0.188 s\nPS17gf\t08:24:43.98\t+35:29:45.8  rising 00.14 57758.46042\t20.62\t57761.4786  0.362 p \t\nPS17gr\t08:20:14.14\t+27:13:44.2  fading 00.20 57759.47191\t20.64\t57761.4792  hostless \t\nPS17gk\t08:33:00.93\t+38:51:04.7  fading 00.18 57758.43419\t20.68\t57761.4721  0.163 p\t\nPS17fy\t08:19:47.91\t+42:39:45.9  fading 00.09 57758.41450\t20.73\t57761.4678  0.166 p \t\nPS17gv\t08:54:41.22\t+57:10:45.9  rising 00.08 57758.46079\t20.82\t57759.5027  0.076 p\t\nPS17gm\t08:35:15.00\t+48:27:06.2  fading 00.04 57758.44909\t20.83\t57759.4940  0.159 p \t\nPS17fx\t08:19:36.86\t+48:06:38.9  fading 00.04 57758.42693\t20.84\t57759.4803  hostless\t\t\nPS17dk\t08:55:48.76\t+46:55:04.8  rising 00.10 57758.42465\t20.85\t57759.4746  0.567 p \t\nPS17fp\t08:06:52.00\t+34:18:04.4  fading 00.22 57758.43602\t20.85\t57761.4726  0.193 p \t\nPS17fm\t08:02:26.56\t+26:20:07.5  fading 00.05 57758.42467\t20.85\t57761.4661  hostless low RB factor\t\t\nPS17dj\t08:54:13.87\t+48:19:42.7  rising  00.05 57758.44299\t20.86\t57759.4844  0.382 p \t\t\nPS17ea\t08:30:11.01\t+32:57:35.8  rising  00.32 57758.43602\t20.88\t57761.5046  0.110 p \t\nPS17fn\t08:05:51.40\t+28:42:51.9  rising  00.59 57758.44882\t20.88\t57761.4973  0.072 p \t\nPS17ga\t08:20:47.13\t+30:24:47.9  fading 00.03 57758.45271\t20.90\t57761.4895  r=22.35, faint source\t\nPS17fo\t08:06:49.10\t+28:16:05.9  rising  00.27 57758.44882\t20.92\t57761.4804  0.179 p \t\nPS17gg\t08:30:06.42\t+48:28:34.4  fading 00.17 57758.43638\t20.93\t57759.4841  0.144 p  low RB factor\t\nPS17cj\t08:10:23.04\t+23:59:52.6  fading 00.10 57758.39319\t20.94\t57761.4614  r=22.9, faint source\t\t\nPS17dh\t08:50:43.44\t+56:42:44.0  rising  00.06 57758.43403\t20.95\t57759.4998  hostless  \t\t\nPS17fu\t08:17:35.59\t+47:05:06.3  rising  00.23 57758.41830\t20.95\t57761.4746  0.040 s\t\t\nPS17ei\t08:37:00.85\t+38:42:47.2  fading 00.01 57758.44228\t20.98\t57761.4775  hostless \t\t\nPS17fz\t08:19:57.24\t+45:12:59.8  fading 00.17 57758.44267\t21.14\t57761.4625  0.175 p \t\nPS17gj\t08:32:56.15\t+41:12:22.3  rising  00.08 57758.44494\t21.17\t57761.4882  0.276 p \t\t\nPS17ec\t08:35:47.59\t+46:25:09.4  rising  00.11 57758.46003\t21.24\t57759.4855  0.403 p \t\nPS17dx\t08:05:30.92\t+36:26:24.8  fading 00.08 57758.40284\t21.33\t57761.4500  hostless\t\t\nPS17dz\t08:24:48.80\t+30:53:37.3  fading 00.10 57759.48293\t21.35\t57761.4982  0.308 p \t\nPS17el\t08:39:41.07\t+39:24:30.2  fading 00.03 57758.45160\t21.37\t57761.4788  hostless\t\nPS17gt\t08:11:47.50\t+37:44:39.4  rising  00.12 57759.47465\t21.42\t57761.4739  0.348 s\t\t\nPS17cw\t08:38:37.02\t+42:57:05.4  fading 00.12 57758.44623\t21.46\t57761.4923  0.35  p\t\t\nPS17gw\t08:48:29.00\t+43:24:48.4  rising  00.05 57759.47696\t21.54\t57761.4915  hostless \nPS17gd\t08:23:08.94\t+43:55:57.1  rising  00.06 57758.44611\t21.56\t57761.4711  r=22.4, faint source\t\t\nPS17b\t08:23:44.47\t+36:53:39.2  rising  00.15 57759.49179\t21.62       57761.4837  0.224 p \nPS17gs\t08:11:41.68\t+38:28:22.4  fading 00.06 57759.47749\t21.63\t57761.4760  r=22.45, faint source \t\t\nPS17gu\t08:11:48.78\t+37:18:50.3  fading 00.19 57759.46588\t21.99\t57761.4715  r=22,faint source\t\t\n\n\nThis object was only detected on one night (we have no coverage of the\nspecific area afterwards), but has a high RB factor and is coincident\nwith a starforming galaxy. Hence it appears real, but we caution that\nwe do not have multiple night detections.\n\nPS17co\t08:13:46.29\t+18:59:02.4  rising 00.02 57758.40522\t18.30\t57758.4070  0.124 s \t\n\nThe following transients were all recovered in our imaging, but were\ndiscovered and reported well before G268556 was discovered.\n\nAT2017M      08:23:09.79\t+25:53:22.9 aka MLS150212-082310+255323\t\nAT2017N      08:25:42.74\t+39:19:00.6\t\t\nPS1-14amh    07:55:40.63\t+26:46:18.0\t\nSN2016hrv    08:33:21.92\t+52:31:50.4\t\nASASSN-16el  08:56:39.07\t+52:06:08.0\t\nAT2016iyx    08:43:24.73\t+37:32:45.8\nAT2016jax    08:32:53.76\t+42:08:01.6\nSN2016gil    08:10:13.72\t+33:57:25.6 \nSN2016ins    08:07:27.35\t+25:07:47.3\nAT2016jau    08:00:40.94\t+28:19:31.8\nSN2016hqh    07:57:05.78\t+23:08:55.2\nAT2016jci    07:56:05.83\t+28:22:35.3\t\nAT2016jay    09:21:43.35\t+61:31:59.6\t\nAT2016hys    08:14:42.11\t+38:24:08.5",
  "circularId": 20410,
  "createdOn": 1483995914000,
  "email": "s.smartt@qub.ac.uk",
  "subject": "LIGO/Virgo G268556:  Pan-STARRS1 observations and summary of transient sources",
  "submitter": "S. J. Smartt at Queens U Belfast  <s.smartt@qub.ac.uk>",
  "eventId": "LIGO/Virgo G268556"
}