//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28841 SUBJECT: ZTF20acozryr/AT2020yxz: Zwicky Transient Facility discovery of a fast optical transient with no associated GRB DATE: 20/11/05 21:01:37 GMT FROM: Michael Coughlin at U of Minnesota 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 2020-11-04 08:47 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,...".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28844 SUBJECT: IPN triangulation of GRB 201103B (consistent with ZTF20acozryr/AT2020yxz) DATE: 20/11/06 00:20:30 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team, A. Ursi, N. Parmiggiani, F. Verrecchia, A. Bulgarelli, A. Trois, M. Marisaldi, C. Pittori, M. Tavani, Y. Evangelista, I. Donnarumma, M. Cardillo, G. Piano, G. Minervini, A. Argan, F. Lucarelli, A. Zoli, V. Fioretti, F. Fuschino, M. Pilia, F. Longo, A. Giuliani on behalf of the AGILE team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report: The long-duration, bright GRB 201103B (AGILE detection: Ursi et al., GCN Circ. 28831) has been detected by AGILE, Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), and Swift (BAT), so far, at about 65207 s UT (18:06:47). The burst was outside the coded field of view of the BAT. We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 42.089 (02h 48m 21s) +12.441 (+12d 26' 29") Corners: 41.830 (02h 47m 19s) +14.128 (+14d 07' 41") 42.595 (02h 50m 23s) +11.069 (+11d 04' 07") 42.244 (02h 48m 59s) +10.759 (+10d 45' 32") 41.511 (02h 46m 03s) +13.781 (+13d 46' 52") --------------------------------------------- The error box area is 1.24 sq. deg, and its maximum dimension is 3.4 deg (the minimum one is 23.8 arcmin). The Sun distance was 175 deg. This box may be improved. The distance between the optical transient ZTF20acozryr/AT2020yxz (Coughlin et al., GCN Circ. 28841) and the IPN box center is 19 arcmin, thus confirming the association of the burst and the OT. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB201103_T65207/IPN The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28846 SUBJECT: GRB 201103B (ZTF20acozryr/AT2020yxz): Nanshan/NEXT-0.6m optical observations DATE: 20/11/06 02:36:07 GMT FROM: Dong Xu at NAOC/CAS D. Xu (NAOC), Z.P. Zhu (NAOC, HUST), S.Y. Fu, X. Liu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report: We observed the optical transient, ZTF20acozryr/AT2020yxz, an likely orphan GRB optical afterglow when discovered by ZTF (Coughlin et al., GCN 28841) and later confirmed by the IPN localisation as the optical afterglow of GRB 201103B (Svinkin et al., GCN 28844), using the NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. Observations started at 17:33:06 UT on 2020-11-05 and a series of 120s exposures were obtained in the Sloan r-filter. Considering the IPN trigger time, 18:06:47 UT on 2020-11-03, as the onset of the burst, preliminary photometry results are as follows: T_mid_obs (UT) T_mid_grb(day) Mag MagErr 2020-11-05T17:43:35 1.984 20.5 0.3 2020-11-05T18:31:28 2.017 20.8 0.2 calibrated with nearby PS1 stars. Compared with the ZTF photometry, such a decay is consistent with that of a conventional GRB optical afterglow. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28847 SUBJECT: GRB 201103B (ZTF20acozryr/AT2020yxz): VLT/X-shooter redshift DATE: 20/11/06 04:58:38 GMT FROM: Dong Xu at NAOC/CAS D. Xu (NAOC), J.-B. Vielfaure (APC, Paris University), D. A. Kann (HETH/IAA-CSIC), D. B. Malesani (DTU Space), D. A. Perley (LJMU), A. J. Levan (Radboud U. Nijmegen), S. Klose (TLS Tautenburg), K. Wiersema (Univ. Warwick), and A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI) report on behalf of the Stargate Consortium: We observed the transient ZTF20acozryr/AT2020yxz (Coughlin et al., GCN 28841), which has been proposed to be the optical afterglow of GRB 201103B (Svinkin et al., GCN 28844) using the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph. Our spectra cover the wavelength range 3000-21000 AA, and consist of 4 exposures of 1200 s each. The observation mid-time was 2020 Nov 6.116 UT (56.66 hr/2.361 days after the GRB). In a 60 s image taken with the acquisition camera on Nov 6.0771 UT, we detect the optical afterglow, for which we measure a preliminary magnitude r ~ 20.7 mag (AB magnitude, calibrated against a nearby galaxy from the Pan-STARRS catalog; Chambers et al. 2016, arXiv:1612.05560). We clearly detect continuum over the entire wavelength range. From detection of multiple absorption features, which we interpret as due to CII, MgII, and multiple FeII lines, we infer a redshift z = 1.105. We suggest this to be the redshift of the transient, which we hereby confirm spectroscopically to be the afterglow of GRB 201103B. We acknowledge excellent support from the ESO observing staff in Paranal, in particular Ivan Aranda and Matias Jones. [GCN OPS NOTE(04nov2020): Per author's request, Ivan Aranda and Matias Jones were added to the last sentence.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28849 SUBJECT: Correcton to GCN 28848: Swift observes ZTF20acozryr DATE: 20/11/06 07:58:44 GMT FROM: Phil Evans at U of Leicester 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28854 SUBJECT: GRB 201103B (ZTF20acozryr/AT2020yxz): Xinglong-2.16m optical observations DATE: 20/11/06 16:03:42 GMT FROM: Dong Xu at NAOC/CAS Z.P. Zhu (NAOC, HUST), S.Y. Fu, X. Liu, L.P. Xin, J.Y. Wei, D. Xu (NAOC) report on behalf of a larger collaboration: We observed the field of ZTF20acozryr/AT2020yxz (Coughlin et al. GCN 28841), likely the optical afterglow of GRB 201103B (Svinkin et al., GCN 28844), using the 2.16m telescope equipped with the BFOSC camera at Xinglong, Hebei, China. Observations started at 14:12:36 UT on 2020-11-06, and 8x180s R-band frames were obtained. The source is clearly detected in our stacked image, with R = 20.36 +/- 0.05 mag at Tmid-T0 = 2.8373 days post-burst, calibrated with nearby Pan-STARRS1. We acknowledge excellent support from the Xinglong-2.16m observing staff, in particular Jie Zheng. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28858 SUBJECT: Swift XRT and UVOT detection of ZTF20acozryr/AT2020yxz/GRB201103B DATE: 20/11/06 17:44:52 GMT FROM: Boris Sbarufatti at PSU P. A. Evans (U Leicester), N. P. M. Kuin (UCL-MSSL) and B. Sbarufatti (PSU) report on behalf of the Swift team: Swift-XRT has performed follow-up observations of the ZTF-detected afterglow candidate ZTF20acozryr/AT2020yxz, (Coughlin et al., GCN 28841) proposed to be associated with the AGILE and IPN-detected GRB 201103B (Ursi et al., GCN Circ. 28831, Svinkin et al., GCN Circ. 28844), collecting 1.2 ks of Photon Counting (PC) mode data between T0+199.5 ks and T0+206.0 ks. An uncatalogued X-ray source is detected, at RA, Dec=42.1842, +12.1382 which is equivalent to: RA (J2000): 02:48:44.21 Dec(J2000): +12:08:17.6 with an uncertainty of 5.3 arcsec (radius, 90% confidence). This position is 3.8 arcsec from the ZTF position, consistent with that source. We cannot determine at the present time whether the source is fading. The mean count-rate of the source is (1.5 +/- 0.5) x 10^-3 ct/sec, and we cannot yet confirm any variability. This location has been previously observed by Swift in 2014 November, and these observations are in the 2SXPS catalogue (Evans et al., 2020): https://www.swift.ac.uk/2SXPS/doSimpleSearch.php?searchpos=42.18421+12.1382&searchrad=750&getWhat=1&subset=1&dssubset=0&coordType=0&retType=0&searchWhat=1 The stacked image (field 10000005379) created from the 2014 observation contained about 2043 s of exposure at this position, and contained only 2 events at the ZTF location, giving a 3-sigma upper limit of 5.4 x 10^-3 ct/sec. Thus the XRT source reported above is a transient event, and we identify it as the X-ray afterglow to GRB 201103B. It has been pointed out to us that we incorrectly stated in GCN 28849 that the nature of the object had not been confirmed, whereas Xu et al (GCN Circ. 28847) has in fact confirmed the associated with the GRB via their spectroscopy. We apologize for the confusion. The automated analysis of this object is available at https://www.swift.ac.uk/xrt_products/00021039 A source is also detected in UVOT data with magnitude B=20.25+-0.26 at ~T+205 ks. A weak signal is also detected in the V band at less than 3 sigma significance (V > 19.6) with some evidence of fading. This circular is an official product of the Swift XRT and UVOT teams. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28862 SUBJECT: ZTF20acozryr/AT2020yxz (GRB 201103B): Assy optical observations DATE: 20/11/07 13:47:08 GMT FROM: Alexei Pozanenko at IKI, Moscow 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 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28875 SUBJECT: ZTF20acozryr/AT2020yxz (GRB 201103B): Mondy, Kitab, TSHAO optical observations DATE: 20/11/09 23:22:50 GMT FROM: Alexei Pozanenko at IKI, Moscow 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 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28876 SUBJECT: ZTF20acozryr (GRB 201103B): GROWTH-India Telescope optical observations DATE: 20/11/10 15:25:55 GMT FROM: Harsh Kumar at Indian Inst of Tech,Bombay 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). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28880 SUBJECT: ZTF20acozryr/AT2020yxz (GRB 201103B): Flattening of the optical light curve DATE: 20/11/11 11:54:49 GMT FROM: Gregory SungHak Paek at SNU 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28883 SUBJECT: ZTF20acozryr/AT2020yxz (GRB 201103B): Mondy continued optical observations DATE: 20/11/12 11:36:35 GMT FROM: Alexei Pozanenko at IKI, Moscow 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28886 SUBJECT: ZTF20acozryr/AT2020yxz (GRB 201103B): CrAO/ZTSh optical observations DATE: 20/11/14 12:26:46 GMT FROM: Alexei Pozanenko at IKI, Moscow 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28925 SUBJECT: ZTF20acozryr/AT2020yxz (GRB 201103B): correction to the GCN #28883 CrAO/ZTSh optical observations DATE: 20/11/19 23:02:08 GMT FROM: Alexei Pozanenko at IKI, Moscow 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28926 SUBJECT: ZTF20acozryr/AT2020yxz (GRB 201103B): SAO RAS optical observations DATE: 20/11/20 09:52:20 GMT FROM: Moskvitin Alexander at SAO RAS 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29181 SUBJECT: ZTF20acozryr/AT2020yxz (GRB 201103B): Maidanak optical observations DATE: 20/12/28 00:05:21 GMT FROM: Alexei Pozanenko at IKI, Moscow 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).