LIGO/Virgo/KAGRA S230521k
GCN Circular 33848
Subject
LIGO/Virgo/KAGRA S230521k: Zwicky Transient Facility observations
Date
2023-05-22T04:35:25Z (2 years ago)
Edited On
2024-07-31T15:07:49Z (a year ago)
From
Tomas Ahumada at U. of Maryland <tahumada@astro.umd.edu>
Edited By
Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>
Tomas Ahumada (CIT), Viraj Karambelkar (CIT), Robert Stein (CIT), Gaurav
Waratkar (IITB), Anirudh Salgundi (IITB), Theophile du Laz (CIT), Igor
Andreoni (UMD), Michael Coughlin (UMN), Mansi Kasliwal (CIT), Varun
Bhalerao (IITB), Simeon Reusch (DESY), Jannis Necker (DESY), Shreya Anand
(CIT), report on behalf of the ZTF and GROWTH collaborations:
We serendipitously observed the localization region of LVC trigger S230521k
as part of routine Zwicky Transient Facility (ZTF; Graham et al., 2019;
Bellm et al., 2019) survey operations. We obtained a total of 100 images
covering g, r, and i bands for a total of 3810 seconds. These serendipitous
observations covered 1238.8 square degrees beginning at 2023-05-21T05:32:51
(2 minutes after the burst trigger time) corresponding to ~9% of the
probability enclosed in the localization region.
We queried the ZTF alert stream using Kowalski (Duev et al. 2019) through
Fritz (Coughlin et al. 2023) and emgwcave (Karambelkar et al. in prep), and
AMPEL (Nordin et al. 2019). We required at least 2 detections separated by
at least 15 minutes to select against moving objects. Furthermore, we
cross-match our candidates with the Minor Planet Center to flag known
asteroids, reject stellar sources (Tachibana and Miller 2018), and apply
machine learning algorithms (Mahabal et al. 2019). We require that no
spatially coincident ZTF alerts were issued before the detection time of
the LVC trigger.
Two sources passed our criteria and were inside the 95% error region:
|-----------------------------------------------------------------------------------------------------
| id | alias | ra | dec | mjd |
mag±err (ab) | filter |
|-----------------------------------------------------------------------------------------------------
| ZTF23aaladzz | AT2023jcp | 275.9841 | 24.9580 | 60085.36780 |
20.18±0.17 | r |
| ZTF23aaladoy | AT2016bqh/AT 2023jbu | 280.1828 | 27.0236 | 60085.36780 |
15.56±0.03 | g |
|-----------------------------------------------------------------------------------------------------
Forced photometry at the location of AT2023jcp detections 4 days prior to
the GW event merger time. Thus, we rule out this source as a candidate
counterpart. A source 0.1 arcsec from ZTF23aaladoy was previously reported
to TNS in 2016, thus we rule it out as a viable candidate.
Further follow-up of this localization region will continue as part of
regular survey operations.
ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC,
USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY,
Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan;
IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No
1440341. GROWTH acknowledges generous support of the NSF under PIRE Grant
No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et
al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019)
and Kowalski (Duev et al. 2019). GROWTH India telescope is located at the
Indian Astronomical Observatory (Hanle), operated by the Indian Institute
of Astrophysics (IIA). GROWTH-India project is supported by SERB and
administered by IUSSTF, under grant number IUSSTF/PIRE
Program/GROWTH/2015-16 and IUCAA.
GCN Circular 33858
Subject
LIGO/Virgo/KAGRA S230521k: Additional candidates from Zwicky Transient Facility
Date
2023-05-23T20:38:13Z (2 years ago)
From
Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>
Vishwajeet Swain (IITB), Harsh Kumar (IITB), Viraj Karambelkar (CIT), Anirudh Salgundi (IITB), Akash Anumarlapudi (UWM), Robert Stein (CIT), Tomas Ahumada (CIT), Michael Coughlin (UMN), Mansi Kasliwal (CIT), Theophile du Laz (CIT), Eric Bellm (UW), Igor Andreoni (UMD) report on behalf of the ZTF collaboration:
Zwicky Transient Facility (ZTF; Graham et al., 2019; Bellm et al., 2019) continued to serendipitously cover the localization region of LVC trigger S230521k. In our previous GCN #33848 (T. Ahumada et al), we announced two candidates from observations on the first night. Continued observations cover 20.5% of the probability of the localization region at least twice.
We queried the ZTF alert stream using Kowalski (Duev et al. 2019) through Fritz (Coughlin et al. 2023) and emgwcave (Karambelkar et al. in prep), AMPEL (Nordin et al. 2019), and ZTFReST (Andreoni & Coughlin et al., 2021). We required at least 2 detections separated by at least 15 minutes to select against moving objects. Furthermore, we cross-match our candidates with the Minor Planet Center to flag known asteroids, reject stellar sources (Tachibana and Miller 2018), and apply machine learning algorithms (Mahabal et al. 2019). We require that no spatially coincident ZTF alerts were issued before the detection time of the LVC trigger.
The following sources passed our criteria and were inside the 95% error region:
|-----------------------------------------------------------------------------------------------------
| ZTF id | TNS name | ra | dec | mjd | mag±err (ab) | filter |
|-----------------------------------------------------------------------------------------------------
ZTF23aalczjh | AT2023jfn | 202.39335 | 70.869591 | 60086.23392 | 20.25 ± 0.16 | g |
ZTF23aalczjc | --------- | 187.26158 | 70.850479 | 60086.19871 | 20.18 ± 0.23 | r |
ZTF23aakyfsk | AT2023jft | 180.89014 | 61.38805 | 60086.22718 | 20.40 ± 0.19 | g |
ZTF23aalcvpw | AT2023jfp | 173.47154 | 29.19382 | 60086.19722 | 20.36 ± 0.26 | r |
|-----------------------------------------------------------------------------------------------------
We followed up ZTF23aalczjh, ZTF23aalczjc and ZTF23aakyfsk with 0.7m GROWTH-India Telescope and found that:
ZTF23aalczjh and ZTF23aakyfsk are not showing any significant evolution.
ZTF23aalczjc is blue (g-r = -0.22 ± 0.1 mag) and shows weak evidence of fading in r band (0.68 ± 0.55 mag/day), but g-band is consistent with no evolution.
ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY, Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski (Duev et al. 2019). The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports operations of the telescope. Telescope technical details are available a https://sites.google.com/view/growthindia/.
GCN Circular 33861
Subject
LIGO/Virgo/KAGRA S230521k: MASTER new OT discovery
Date
2023-05-24T00:18:42Z (2 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V.Lipunov, Ya.Kechin (Lomonosov MSU), D.Buckley (SAAO),
K.Zhirkov, A.Kuznetsov, P.Balanutsa, A.Chasovnikov, O.Gress, N.Tiurina,E.Gorbovskoy, G.Antipov, D.Vlasenko, V.Senik,
V.Topolev, Yu.Tselik, Siyu Wu, V.Vladimirov, D.Cheryasov, D.Zimnukhov, T.Pogrosheva, V.Shumkov, K.Vetrov (Lomonosov Moscow State University, SAI,Physics Department),
C.Francile, F. Podesta, C.Lopez, R. Podesta (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,A.Corella,L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
N.M.Budnev, O.Ershova (ISU,API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational State University),
M.Gulyaev, E.Minkina (Lomonosov MSU)
MASTER OT J071612.28-415537.5 discovery
During LVC S230521k https://gcn.gsfc.nasa.gov/notices_l/S230521k.lvc
inspection survey (Lipunov et al. GCN 33849)
MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L )
discovered OT source at (R.A.,Dec.2000) = 07h 16m 12.28s -41d 55m 37.5s on 2023-05-23.71558 UT.
The OT unfiltered magnitude is 18.2m (mlim=19.0).
The OT is seen in 4 images. There is no minor planet at this place.
We have reference images on 2021-02-16 02:18:16UT with mlim=19.5,
on 2014-12-24.97843 UT with unfiltered mlim=19.7m and other, there is no outbursts at automatic light curve, but analysis of archive images will be continued.
Spectral observations and deep photometry are required.
Observations and analysis will be continued.