ZTF20acozryr
GCN Circular 28841
Subject
ZTF20acozryr/AT2020yxz: Zwicky Transient Facility discovery of a fast optical transient with no associated GRB
Date
2020-11-05T21:01:37Z (5 years ago)
From
Michael Coughlin at U of Minnesota <cough052@umn.edu>
Michael Coughlin (UMN), Igor Andreoni (Caltech), Shreya Anand (Caltech),
Erik Kool (OKC), Ana Sagues Carracedo (OKC), Anna Ho (UCB), Mansi Kasliwal
(Caltech), Daniel Perley (LJMU) on behalf of the Zwicky Transient Facility
(ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH)
collaborations
We report the discovery of the fast optical transient ZTF20acozryr/AT2020yxz
with the Zwicky Transient Facility (ZTF, Bellm et al. 2019, Graham et al.
2019) at coordinates (J2000, <0.5���):
RA = 02:48:44.31 (42.1846d)
Dec = +12:08:14.08 (+12.1372d)
ZTF20acozryr was found by the new ���ZTF Realtime Search and Triggering���
(ZTF-ReST) project, which aims at near real-time identification of
compelling kilonova candidates in ZTF data using the methods described in
Andreoni et al. (2020d), independently of gravitational-wave or gamma-ray
triggers.
ZTF20acozryr was first detected on 2020-11-03 09:44 UT, hereafter labelled
T_det. It faded by ~0.7 mag in g-band in the first 0.9 days since T_det.
The transient was last detected on 2020-11-05 08:13:20 UT at r = 19.9 �� 0.2
mag. Stringent upper limits constrain the transient onset time to be within
~1 day from T_det. The color of the transient appears to be red, with
g-r~0.3 at T_det. The Galactic extinction on the line of sight is low, with
E(B-V)=0.10 mag (Planck Collaboration et al., 2015).
In the table below, we report photometry obtained on images processed in
real-time through the ZTF reduction and image subtraction pipelines at IPAC
(Masci et al. 2019).
-----------------��-------��-----��-----
Date (UT) | mag | emag | band
-----------------��-------��-----��-----
2020-11-03 09:44 | > 19.4 | - | g
2020-11-04 08:47 | 19.5 | 0.2 | g
2020-11-04 10:28 | 19.2 | 0.1 | r
2020-11-05 06:43 | 20.2 | 0.3 | g
2020-11-05 08:13 | 19.9 | 0.2 | r
-----------------��-------��-----��-----
ZTF20acozryr is located off the Galactic plane, with Galactic latitude
b_Gal = -41.5 deg. Deep Legacy Survey and Pan-STARRS1 images of the field
do not reveal any permanent source at the transient location. There are two
nearby sources reported in the Legacy Survey DR8 catalog. The first source
(RA, Dec = 42.1845d, 12.1358d) has a separation of 5.24 arcsec (with a
galaxy classification from DR8) from ZTF20acozryr and has reported
magnitudes of g=24.38 mag, r=23.45 mag, and z=23.04 mag. The second source
(RA, Dec = 42.1861d, 12.1395d) has a separation of 9.60 arcsec from
ZTF20acozryr (with a point source classification from DR8) and has reported
magnitudes of g=24.84 mag, r=24.07 mag, and z=23.49 mag.
There do not appear to be any publicly reported GRBs consistent with the
sky location between the last non-detection and the first detection.
We encourage spectroscopic classification and multi-wavelength follow-up to
discern the nature of ZTF20acozryr, a potential orphan afterglow candidate.
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 with Kowalski (Duev et al.
2019).
[GCN OPS NOTE(05nove2020): Per author's request, in the 2nd paragraph
the sentence "ZTF20acozryr was first detected on 2020-11-03 09:44 UT,..."
was changed to "ZTF20acozryr was first detected on 2020-11-04 08:47 UT,...".]
GCN Circular 28849
Subject
Correcton to GCN 28848: Swift observes ZTF20acozryr
Date
2020-11-06T07:58:44Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans reports on behalf of the Swift-XRT team:
GCN CIrcular 28848 incorrectly referred to GRB 201104C. This was due to a software error, not recognising 'ZTF20acozryr��� as a GRB name.
Swift is actually carrying out observations of the source ZTF20acozryr (Coughlin et al., GCN Circ. 28841) which has been possibly associated with GRB 201103B (Svinkin et al., GCN Circl. 28844), and has a redshift of 1.105 (Xu et al., GCN Circl. 28847).
The results of the automated search for an X-ray counterpart consistent with the ZTF position, and analysis of any source(s) found, will appear at the URL previous circulated, i.e.
https://www.swift.ac.uk/ToO_GRBs/00021039
Although the nature of this object has not been confirmed, the zeropoint for any source light curves will be set to the IPN trigger time, in the first instance.
We apologise for the confusion.
GCN Circular 28862
Subject
ZTF20acozryr/AT2020yxz (GRB 201103B): Assy optical observations
Date
2020-11-07T13:47:08Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), M. Krugov (FAI), V. Kim (FAI, Pulkovo Observatory), A.
Pozanenko (IKI), N. Pankov (HSE) report on behalf of GRB-IKI-FuN:
We observed the ZTF20acozryr/AT2020yxz (Coughlin et al., GCN 28841)
with AZT-20 telescope of Assy-Turgen observatory starting on Nov. 06
(UT) 19:10:28 in r'-filter. We detect the optical transient (Coughlin
et al., GCN 28841; Coughlin et al., GCN 28841; Xu et al., GCN 28846;
Xu et al., GCN 28854; Mao et al., GCN 28861; ) which can be afterglow
of GRB 201103B (Svinkin et al., GCN 28844; Evans et al., GCN 28858).
Preliminary photometry of the afterglow is following
Date UT start t-T0 Filter Exp. OT Err. UL (3sigma)
(mid, days) (s)
2020-11-06 19:10:28 3.06508 r'(AB) 60*60 20.84 0.06 23.1
The photometry is based on the nearby stars of PanSTARRS-PS1.
RA DEC r
02:48:57.72094 +12:12:04.2202 16.6938
02:48:41.68064 +12:09:59.6523 17.0772
GCN Circular 28875
Subject
ZTF20acozryr/AT2020yxz (GRB 201103B): Mondy, Kitab, TSHAO optical observations
Date
2020-11-09T23:22:50Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), E. Klunko (ISTP), A. Zhornichenko (KIAM), A. Kusakin
(FAI), I. Reva(FAI), A. Pozanenko (IKI), N. Pankov (HSE) report on
behalf of GRB IKI FuN:
We observed the ZTF20acozryr/AT2020yxz (Coughlin et al., GCN 28841)
with AZT-33IK telescope of Mondy observatory, RC-36 telescope of Kitab
observatory, and Zeiss-1000 of Tian Shan observatory. We detect the
optical transient (Coughlin et al., GCN 28841; Xu et al., GCN 28846;
Zhu et al., GCN 28854; Mao et al., GCN 28861; Belkin et al., GCN 28862;
Mao et al., GCN 28863) associated with afterglow of GRB 201103B (Ursi
et al., GCN 28831; Svinkin et al., GCN 28844; Evans et al., GCN 28858).
Preliminary photometry of the afterglow is following
Date UT start t-T0 Filter Exp. OT Err. UL. Telescope
(mid, days) (s)
2020-11-05 21:57:40 2.16938 CR 26*60 n/d n/d 19.0 RC-36
2020-11-06 15:42:41 2.92217 R 32*120 20.23 0.26 20.5 AZT-33IK
2020-11-06 16:56:13 2.97237 R 32*120 20.49 0.12 21.7 Z-1000
2020-11-08 14:13:52 4.85911 R 32*120 21.50 0.10 23.0 AZT-33IK
The photometry is based on the nearby stars of PanSTARRS-PS1
RA DEC r
02:48:57.72094 +12:12:04.2202 16.6938
02:48:41.68064 +12:09:59.6523 17.0772
GCN Circular 28876
Subject
ZTF20acozryr (GRB 201103B): GROWTH-India Telescope optical observations
Date
2020-11-10T15:25:55Z (5 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
K. Sharma (IITB), H. Kumar (IITB), P. Dorjay (IAO), J. Stanzin (IAO), U.
Stanzin (IAO), V. Bhalerao (IITB), G. C. Anupama (IIA), S. Barway (IIA),
report on behalf of the GROWTH-India collaboration:
We followed-up the optical afterglow ZTF20acozryr (Michael Coughlin et.
al., GCN #28841) of GRB 201103B, detected by the AGILE (GCN #28831) and IPN
(D. Svinkin et. al. GCN #28844), with 0.7 m GROWTH-India telescope. We
obtained 300-sec exposures in the SDSS r' filter over multiple nights.
Here are the photometric results from GIT observations:-
--------------------------------------------------
JD (mid) | Filter | Exposure | mag | e_mag |
--------------------------------------------------
2459160.322200 | r' | 300 x 20 | 21.08 | 0.08 |
2459163.145455 | r' | 300 x 30 | 21.91 | 0.06 |
--------------------------------------------------
Combining our photometric results with r/r' band measurements of Michael
Coughlin et. al., GCN #28841; D. Xu et. al., GCN #28846; D. Xu et. al., GCN
#28847; S. Belkin et. al., GCN #28862; we conclude that the source is
fading with a power-law index of 1.16 +/- 0.07. The magnitudes are
calibrated against PanSTARRs PS1 data release, (Flewelling et al., 2018)
and are not corrected for galactic extinction.
The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7 degree
field of view, set up by the Indian Institute of Astrophysics and the
Indian Institute of Technology Bombay with support from the Indo-US Science
and Technology Forum (IUSSTF) and the Science and Engineering Research
Board (SERB) of the Department of Science and Technology (DST), Government
of India (https://sites.google.com/view/growthindia/). It is located at the
Indian Astronomical Observatory (Hanle), operated by the Indian Institute
of Astrophysics (IIA).
GCN Circular 28880
Subject
ZTF20acozryr/AT2020yxz (GRB 201103B): Flattening of the optical light curve
Date
2020-11-11T11:54:49Z (5 years ago)
From
Gregory SungHak Paek at SNU <shpaek@astro.snu.ac.kr>
Gregory S.H. Paek (SNU), Myungshin Im (SNU), Joonho Kim (SNU), Gu Lim
(SNU), Mankeun Jeong (SNU), Chung-Uk Lee (KASI), Seung-Lee Kim (KASI),
Hyun-Il Sung (KASI), Taewoo Kim (DOAO), and Wonseok Kang (DOAO) and GECKO
team
We observed the ZTF20acozryr/AT2020yxz (Coughlin et al., GCN 28841) in
BVRI with various optical telescopes of the GW EM-Counterpart Korean
Observatory (GECKO). The facilities used for the observations are the 1.6-m
class telescopes of Korea Microlensing Telescope Network (KMTNet) located
in Siding Spring Observatory (SSO) and South African Astronomical
Observatory (SAAO), the 1-m telescope in Deokheung Optical Astronomy
Observatory (DOAO), the 1-m telescope the Mt. Lemmon Optical Astronomy
Observatory (LOAO), and the 0.36-m KIAS Chamnun Telescope (KCT) and RASA36
telescope in Chile. We calibrated flux with PS1 and APASS catalog, and the
magnitudes are in AB system. The magnitudes are not corrected for galactic
extinction. Preliminary R-band magnitudes are given for the most recent a
few epoch observations.
Obs.&Tel. DATE-OBS(UT) Filter Mag Error t-t0(days since
burst)
----------- ----------------------- ------ ------- -------
----------------------
DOAO 2020-11-08T19:51:31 R 21.6 0.1 5.07
KCT 2020-11-10T04:27:38 R 21.8 0.3 6.43
KMTNet-SAAO 2020-11-10T21:37:55 R 21.8 0.1 7.1
t0 = 2020-11-03T18:06:45.36 (Ursi et al., GCN 28831)
About a week after GRB occurs, the brightness seems to remain nearly
constant, suggesting a possible onset of a supernova component accompanied
with GRB.
We thank all the operators at GECKO facilities for performing the
observation.
Gravitational-wave EM Counterpart Korean Observatory (GECKO) is a network
of 10+ 0.5m to 1m class telescopes over the world.
GCN Circular 28883
Subject
ZTF20acozryr/AT2020yxz (GRB 201103B): Mondy continued optical observations
Date
2020-11-12T11:36:35Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), N. Pankov (HSE), A. Pozanenko (IKI), E. Klunko (ISTP),
report on behalf of GRB IKI FuN:
We continued observations of the ZTF20acozryr/AT2020yxz (Coughlin et
al., GCN 28841) with AZT-33IK telescope of Mondy observatory. We
detect the optical transient (Coughlin et al., GCN 28841; Xu et al.,
GCN 28846; Zhu et al., GCN 28854; Mao et al., GCN 28861; Belkin et al.,
GCNs 28862, 28875; Mao et al., GCN 28863; Kumar et al., GCN 28876;
SungHak et al., GCN 28880) at redshift z = 1.105 (Xu et al., GCN
28847) associated with afterglow of GRB 201103B (Ursi et al., GCN 28831;
Svinkin et al., GCN 28844; Evans et al., GCN 28858).
Preliminary photometry of the afterglow is following
Date UT start t-T0 Filter Exp. OT Err. UL. Telescope
(mid, days) (s)
2020-11-09 14:53:25 5.88657 R 30*120 21.67 0.19 22.5 AZT-33IK
2020-11-11 13:59:54 7.84871 R 29*120 21.60 0.25 21.8 AZT-33IK
The photometry is based on the same stars used in GCNs 28862, 28875.
GCN Circular 28886
Subject
ZTF20acozryr/AT2020yxz (GRB 201103B): CrAO/ZTSh optical observations
Date
2020-11-14T12:26:46Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), V. Rumyantsev (CrAO), N. Pankov
(HSE) report on behalf of GRB IKI FuN:
We continued observations of the ZTF20acozryr/AT2020yxz (Coughlin et
al., GCN 28841) with ZTSh 2.6m telescope of CrAO observatory starting
on Nov., 13 (UT) 22:58:04. We detect the optical transient (Coughlin et
al., GCN 28841; Xu et al., GCN 28846; Zhu et al., GCN 28854; Mao et
al., GCN 28861; Belkin et al., GCNs 28862, 28875, 28883; Mao et al.,
GCN 28863; Kumar et al., GCN 28876; SungHak et al., GCN 28880) at
redshift z = 1.105 (Xu et al., GCN 28847) associated with afterglow of
GRB 201103B (Ursi et al., GCN 28831; Svinkin et al., GCN 28844; Evans et
al., GCN 28858).
Preliminary photometry of the afterglow is following
Date UT start t-T0 Filter Exp. OT Err. UL. Telescope
(mid, days) (s)
2020-11-13 22:58:04 10.21897 R 24*120 21.67 0.16 22.1 ZTSh
The photometry is based on the same stars used in GCNs 28862, 28875, 28883.
GCN Circular 28925
Subject
ZTF20acozryr/AT2020yxz (GRB 201103B): correction to the GCN #28883 CrAO/ZTSh optical observations
Date
2020-11-19T23:02:08Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (IKI), S. Belkin (IKI), A. Pozanenko (IKI), V. Rumyantsev
(CrAO), N. Pankov (HSE) report on behalf of GRB IKI FuN:
Below is a correction of the photometry reported in GCN 28883 after
CrAO/ZTSh optical observations on Nov., 13 (UT) 22:58:04.
Preliminary photometry of the afterglow is following
Date UT start t-T0 Filter Exp. OT Err. UL.
(mid, days) (s)
2020-11-13 22:58:04 10.21897 R 24*120 22.45 0.14 23.6
The photometry is based on the same stars used in GCNs 28862, 28875, 28883.
We apologize for a possible confusion after erroneously reported
photometry in GCN 28883.
GCN Circular 28926
Subject
ZTF20acozryr/AT2020yxz (GRB 201103B): SAO RAS optical observations
Date
2020-11-20T09:52:20Z (5 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
A. S. Moskvitin (SAO RAS) on behalf of GRB follow-up team report.
We observed the field of the ZTF20acozryr/AT2020yxz (Coughlin et al.,
GCN 28841) associated with the GRB 201103B (Ursi et al., GCN 28831;
Svinkin et al., GCNs 28844, 28872; Evans et al., GCN 28858)
with Zeiss-1000 telescope of SAO RAS equipped with CCD photometer
on November 14, 20:58:48 -- 23:02:42 UT, t_mid - T0 = 11.1625 days.
We obtained 8 x 300 sec. images in Rc band.
The OT (Coughlin et al., GCN 28841; Xu et al., GCNs 28846, 28847;
Zhu et al., GCN 28854; Evans et al., GCN 28858; Mao et al.,
GCNs 28861, 28863; Belkin et al., GCNs 28862, 28875, 28883, 28886;
Sharma et al., GCN 28876; Paek et al., GCN 28880; Volnova et al.,
GCN 28925) is clearly detected in the stacked image with the
brightness of R = 22.8 +/- 0.2. This preliminary photometry is
based on R2 magnitudes of nearby USNO-B1 stars.
GCN Circular 29181
Subject
ZTF20acozryr/AT2020yxz (GRB 201103B): Maidanak optical observations
Date
2020-12-28T00:05:21Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Pozanenko (IKI), O. Burhonov (UBAI), R. Ya.
Inasaridze (AbAO), P. Levkina (INASAN), N. Pankov (HSE, IKI), A. Volnova
(IKI), Sh. Ehgamberdiev (UBAI) report on behalf of GRB IKI FuN:
We finished observations of the ZTF20acozryr/AT2020yxz (Coughlin et al.,
GCN 28841) with AZT-22 telescope of Maidanak observatory, AS-32
telescope of Abastumani observatory, and Zeiss-2000 telescope of Terskol
observatory. The optical transient (Coughlin et al., GCN 28841; Xu et
al., GCN 28846; Zhu et al., GCN 28854; Mao et al., GCN 28861; Belkin et
al., GCNs 28862, 28875, 28883, 28886; Mao et al., GCN 28863; Kumar et
al., GCN 28876; Paek et al., GCN 28880; Moskvitin et al., GCN 28926) at
redshift z = 1.105 (Xu et al., GCN 28847) associated with afterglow of
GRB 201103B (Ursi et al., GCN 28831; Svinkin et al., GCN 28844; Evans et
al., GCN 28858).
The photometry reported early in Volnova et al., GCN 28925 must
corrected the GCN 28886. We apologize for inconvenience and thank to
D.A. Kann who pointed out for typo in the GCN 28925.
We repeat corrected photometry of our CrAO/ZTSh optical observation on
2020-11-13 22:58:04 below. We also add photometry of positive detections
and meaningful upper limit. the photometry below is still preliminary.
The photometry is based on the same reference stars of USNO-B1.0 stars.
Date UT start t-T0 Filter Exp. OT Err. UL. Telescope
(mid, days) (s)
2020-11-12 20:20:48 9.12087 R 80*60 21.70 0.35 21.7 AS-32
2020-11-13 22:58:04 10.21897 R 24*120 22.45 0.14 23.6 ZTSh
2020-11-23 19:29:37 12.07213 R 14*180 22.80 0.13 24.1 AZT-22
2020-11-23 19:26:37 20.08671 R 30*180 n/d n/d 23.2 AZT-22
A full light curve and upper limits obtained in our observations
(R-filter) can be found in
http://grb.rssi.ru/GRB201103B/GRB201103B_LC_R.png
A typical power law light curve (index of ~1.12) can be suggested based
on our observations and photometry gathered from GCNs, see
http://grb.rssi.ru/GRB201103B/GRB201103B_LC_GCN.png
One can suggest overlay bumps (or plateau) on the light curve of at 2-3
days, and 5-9 days after burst trigger.
If we extrapolate the power law curve backward to the 200 seconds the
afterglow brightness could have ~12m. If so, one can look for data in
all sky cameras or wide field surveys to search early phase of the
afterglow of the GRB 201103B (trigger time (UT) 2020-11-03 18:06:45.36,
Ursi et al., GCN 28831).