GCN Circular 20410
Subject
LIGO/Virgo G268556: Pan-STARRS1 observations and summary of transient sources
Date
2017-01-09T21:05:14Z (8 years ago)
From
S. J. Smartt at Queens U Belfast <s.smartt@qub.ac.uk>
S. J. Smartt, (QUB), K. W. Smith (QUB), M. E. Huber (IfA),
K. C. Chambers (IfA), D. R. Young, D. E. Wright (QUB), M. Coughlin
(Harvard), L. Denneau, H. Flewelling, A. Heinze, E. A. Magnier (IfA),
A. Rest (STScI), B. Stalder (IfA), A. S. B. Schultz, C. W. Stubbs
(Harvard) J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland (IfA)
Further to Chambers et al. GCN 20383, we report that we covered 632
square degrees on the first night (beginning 57758.3) . We estimate
this corresponds to a probability of containing the source of 33%. We
have since reduced this area to the higher probability central region,
recovering 357 sq degrees and a containment probability of 26% (based
on the LALInference map, GCN 20385).
Images were taken in the Pan-STARRS i-band in a series of overlapping
45s exposures, with typically 4-8 images at each position. These were
combined into stacks and subtracted from the Pan-STARRS1 3Pi reference
image (Chambers et al. arXiv:1612.05560, and available at
http://panstarrs.stsci.edu).
Using techniques discussed in Smartt et al. (2016, MNRAS, 462, 4094),
we have located and vetted transients with quality filters and a
machine learning algorithm on the images. We recover 6 iPTF objects
and 15 old transients known before the GW alert (given at the end for
completeness). ATLAS17aeu was recovered as discussed in Chambers et
al. (GCN 20407)
In the following table, we give our 55 targets, sorted by magnitude. The
lightcurve trend is given (LC trend), indicating the change in
magnitude between earliest and latest MJD of detection. To select
these targets we required a minimum of 2 detections over 2 separate
nights.
Our area is completely within the SDSS DR12 footprint, and we give the
redshifts (p for photometric and s for spectroscopic) of the host
galaxies. Objects with no obvious host are labelled "hostless". Some
targets are coincident with faint sources in SDSS for which
star/galaxy separation and photo-z estimates are not reliable and we
note these. We have removed obvious AGN and candidate AGN (low level
variability associated with galaxy cores), as well as stellar
variables.
In the comments we note iPTF coincidences (Singer et al. GCN 20401;
Kasliwal et al. GCN 20364). A small number of candidates have a low
real-bogus (RB) machine learning factor and should be treated with
caution. All have been scanned by human reviewers.
The photometric redshifts from SDSS should not be used as a robust
filtering for distance (see discussion in Smartt et al. 2016), but we
provide them as a guide.
We are targeting the objects with changing lightcurves with
Gemini+GMOS.
Name RA DEC LC trend Earliest mjd mag Latest mjd z Comment
PS17df 08:50:02.42 +46:39:48.8 fading 00.09 57758.43699 18.39 57759.4911 0.038 s iPTF17bo
PS17fg 08:48:46.25 +44:00:24.6 fading 00.15 57758.42737 18.89 57761.4882 0.060 s iPTF17bq
PS17fr 08:11:52.10 +25:25:21.4 rising 00.57 57758.43263 19.19 57761.4619 0.199 p iPTF17cf
PS17fe 09:00:21.22 +63:50:49.8 fading 00.09 57758.39189 19.60 57759.4726 0.245 p
PS17du 09:14:30.59 +54:28:34.4 fading 00.04 57758.42705 19.75 57759.4660 0.045 s 0.6" from core
PS17dp 09:00:51.09 +45:26:44.3 rising 00.06 57758.39978 19.97 57759.5043 0.051 s
PS17gl 08:34:50.85 +61:13:02.2 rising 00.07 57758.39093 20.04 57759.4635 0.038 s
PS17ft 08:16:52.72 +26:27:25.3 fading 00.05 57758.44356 20.05 57761.4790 0.042 s
PS17fs 08:14:47.53 +27:50:12.2 fading 00.11 57758.45845 20.09 57761.4891 0.118 p iPTF17ch
PS17bz 08:04:49.22 +29:19:48.8 fading 00.08 57758.40250 20.23 57761.4809 0.047 s
PS17fb 08:49:18.13 +44:38:31.1 rising 00.01 57758.41320 20.30 57759.4831 0.151 p
PS17fh 07:55:14.13 +26:25:11.5 fading 00.14 57758.39608 20.32 57761.4492 0.119 p
PS17fw 08:19:05.64 +23:20:42.8 fading 00.04 57758.40905 20.35 57761.4478 0.034 p
PS17gb 08:21:17.00 +51:10:17.1 rising 00.13 57758.38839 20.36 57759.4635 0.197 p
PS17fa 08:47:22.51 +51:08:17.4 fading 00.02 57758.44371 20.41 57759.4865 0.497 p
PS17en 08:40:22.10 +38:43:25.0 fading 00.07 57758.44053 20.41 57761.4923 0.673 p iPTF17fa
PS17dy 08:13:00.78 +41:18:26.9 rising 00.00 57758.42812 20.43 57761.4760 0.282 p iPTF17fb
PS17er 08:41:57.26 +40:55:07.7 rising 00.36 57758.45114 20.44 57761.4854 0.296 p
PS17fj 07:59:30.67 +28:27:03.8 fading 00.37 57758.41011 20.46 57761.4771 hostless
PS17fl 08:02:09.73 +28:49:44.7 rising 00.32 57758.42406 20.47 57761.4876 0.080 p
PS17dw 07:49:25.36 +20:28:00.6 fading 00.05 57758.38695 20.48 57759.4846 0.171 p
PS17fv 08:18:15.52 +43:45:03.4 fading 00.06 57758.45210 20.56 57761.5017 0.188 s
PS17gf 08:24:43.98 +35:29:45.8 rising 00.14 57758.46042 20.62 57761.4786 0.362 p
PS17gr 08:20:14.14 +27:13:44.2 fading 00.20 57759.47191 20.64 57761.4792 hostless
PS17gk 08:33:00.93 +38:51:04.7 fading 00.18 57758.43419 20.68 57761.4721 0.163 p
PS17fy 08:19:47.91 +42:39:45.9 fading 00.09 57758.41450 20.73 57761.4678 0.166 p
PS17gv 08:54:41.22 +57:10:45.9 rising 00.08 57758.46079 20.82 57759.5027 0.076 p
PS17gm 08:35:15.00 +48:27:06.2 fading 00.04 57758.44909 20.83 57759.4940 0.159 p
PS17fx 08:19:36.86 +48:06:38.9 fading 00.04 57758.42693 20.84 57759.4803 hostless
PS17dk 08:55:48.76 +46:55:04.8 rising 00.10 57758.42465 20.85 57759.4746 0.567 p
PS17fp 08:06:52.00 +34:18:04.4 fading 00.22 57758.43602 20.85 57761.4726 0.193 p
PS17fm 08:02:26.56 +26:20:07.5 fading 00.05 57758.42467 20.85 57761.4661 hostless low RB factor
PS17dj 08:54:13.87 +48:19:42.7 rising 00.05 57758.44299 20.86 57759.4844 0.382 p
PS17ea 08:30:11.01 +32:57:35.8 rising 00.32 57758.43602 20.88 57761.5046 0.110 p
PS17fn 08:05:51.40 +28:42:51.9 rising 00.59 57758.44882 20.88 57761.4973 0.072 p
PS17ga 08:20:47.13 +30:24:47.9 fading 00.03 57758.45271 20.90 57761.4895 r=22.35, faint source
PS17fo 08:06:49.10 +28:16:05.9 rising 00.27 57758.44882 20.92 57761.4804 0.179 p
PS17gg 08:30:06.42 +48:28:34.4 fading 00.17 57758.43638 20.93 57759.4841 0.144 p low RB factor
PS17cj 08:10:23.04 +23:59:52.6 fading 00.10 57758.39319 20.94 57761.4614 r=22.9, faint source
PS17dh 08:50:43.44 +56:42:44.0 rising 00.06 57758.43403 20.95 57759.4998 hostless
PS17fu 08:17:35.59 +47:05:06.3 rising 00.23 57758.41830 20.95 57761.4746 0.040 s
PS17ei 08:37:00.85 +38:42:47.2 fading 00.01 57758.44228 20.98 57761.4775 hostless
PS17fz 08:19:57.24 +45:12:59.8 fading 00.17 57758.44267 21.14 57761.4625 0.175 p
PS17gj 08:32:56.15 +41:12:22.3 rising 00.08 57758.44494 21.17 57761.4882 0.276 p
PS17ec 08:35:47.59 +46:25:09.4 rising 00.11 57758.46003 21.24 57759.4855 0.403 p
PS17dx 08:05:30.92 +36:26:24.8 fading 00.08 57758.40284 21.33 57761.4500 hostless
PS17dz 08:24:48.80 +30:53:37.3 fading 00.10 57759.48293 21.35 57761.4982 0.308 p
PS17el 08:39:41.07 +39:24:30.2 fading 00.03 57758.45160 21.37 57761.4788 hostless
PS17gt 08:11:47.50 +37:44:39.4 rising 00.12 57759.47465 21.42 57761.4739 0.348 s
PS17cw 08:38:37.02 +42:57:05.4 fading 00.12 57758.44623 21.46 57761.4923 0.35 p
PS17gw 08:48:29.00 +43:24:48.4 rising 00.05 57759.47696 21.54 57761.4915 hostless
PS17gd 08:23:08.94 +43:55:57.1 rising 00.06 57758.44611 21.56 57761.4711 r=22.4, faint source
PS17b 08:23:44.47 +36:53:39.2 rising 00.15 57759.49179 21.62 57761.4837 0.224 p
PS17gs 08:11:41.68 +38:28:22.4 fading 00.06 57759.47749 21.63 57761.4760 r=22.45, faint source
PS17gu 08:11:48.78 +37:18:50.3 fading 00.19 57759.46588 21.99 57761.4715 r=22,faint source
This object was only detected on one night (we have no coverage of the
specific area afterwards), but has a high RB factor and is coincident
with a starforming galaxy. Hence it appears real, but we caution that
we do not have multiple night detections.
PS17co 08:13:46.29 +18:59:02.4 rising 00.02 57758.40522 18.30 57758.4070 0.124 s
The following transients were all recovered in our imaging, but were
discovered and reported well before G268556 was discovered.
AT2017M 08:23:09.79 +25:53:22.9 aka MLS150212-082310+255323
AT2017N 08:25:42.74 +39:19:00.6
PS1-14amh 07:55:40.63 +26:46:18.0
SN2016hrv 08:33:21.92 +52:31:50.4
ASASSN-16el 08:56:39.07 +52:06:08.0
AT2016iyx 08:43:24.73 +37:32:45.8
AT2016jax 08:32:53.76 +42:08:01.6
SN2016gil 08:10:13.72 +33:57:25.6
SN2016ins 08:07:27.35 +25:07:47.3
AT2016jau 08:00:40.94 +28:19:31.8
SN2016hqh 07:57:05.78 +23:08:55.2
AT2016jci 07:56:05.83 +28:22:35.3
AT2016jay 09:21:43.35 +61:31:59.6
AT2016hys 08:14:42.11 +38:24:08.5