//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23946 SUBJECT: GRB 190311A: Swift detection of a burst with optical counterpart DATE: 19/03/11 14:43:26 GMT FROM: Mike Siegel at PSU/Swift MOC E. Troja (NASA/GSFC/UMCP), S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), J. A. Kennea (PSU), N. J. Klingler (PSU), A. Y. Lien (GSFC/UMBC), M. J. Moss (George Washington University), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 14:23:33 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 190311A (trigger=892607). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 212.102, +53.519 which is RA(J2000) = 14h 08m 24s Dec(J2000) = +53d 31' 10" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). From the available data, the BAT light curve showed a single-peaked structure with duration of at least 10 sec. However, due to a data gap from ~T+10 s to ~ T+ 110 s, there might be additional emission in that time interval. The peak count rate was ~1700 counts/sec (15-350 keV), at ~ 0 sec after the trigger. The XRT began observing the field at 14:24:54.0 UT, 80.3 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 212.0649, 53.5007 which is equivalent to: RA(J2000) = 14h 08m 15.58s Dec(J2000) = +53d 30' 02.7" with an uncertainty of 2.2 arcseconds (radius, 90% containment). This location is 103 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (1.17 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 5.1 (+3.27/-2.92) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 5.45e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 85 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 14:08:15.65 = 212.06522 DEC(J2000) = +53:30:03.0 = 53.50084 with a 90%-confidence error radius of about 0.60 arc sec. This position is 0.85 arc sec. from the center of the XRT error circle. The estimated magnitude is 19.47 with a 1-sigma error of about 0.12. No correction has been made for the expected extinction corresponding to E(B-V) of 0.01. Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23947 SUBJECT: GRB 190311A: Mondy optical observations DATE: 19/03/11 15:49:37 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), E. Mazaeva (IKI), E. Klunko (ISTP), A. Volnova (IKI), S. Belkin (IKI) report on behalf of IKI-GRB-FuN: We observed the field of GRB 190311A (Troja et al. GCN 23946) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Mar. 11 (UT) 14:39:17. We clearly detected the candidate in optical afterglow (Troja et al. GCN 23946). Coordinates of the optical transient are (J2000) 14:08:15.74 +53:30:03.1 with uncertainty of 0.5 arcsec in both coordinates, which correspond to the coordinates obtained in GCN 23946. Preliminary photometry of the afterglow in R-filter is following. t-T0_mid(d) t-T0_mid(min) R_mag err 0.01111 16.0 19.22 0.11 0.01146 16.5 19.25 0.10 0.01180 17.0 19.50 0.11 0.01215 17.5 19.23 0.10 0.01250 18.0 19.47 0.12 0.01285 18.5 19.46 0.10 0.01348 19.4 19.50 0.08 0.01417 20.4 19.62 0.08 0.01487 21.4 19.55 0.09 0.01556 22.4 19.58 0.08 0.01626 23.4 19.56 0.09 0.01695 24.4 19.62 0.09 0.01765 25.4 19.79 0.10 0.01875 27.0 19.83 0.06 0.02014 29.0 19.83 0.06 Photometry is based on the SDSS-DR12 stars (Lupton transformations) SDSS-DR12_id R J140819.68+532900.1 17.09 J140818.11+532934.7 15.19 J140809.64+533055.9 16.97 J140807.35+533116.9 16.11 The optical transient is fading and we can confirm the optical afterglow of GRB 190311A. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23948 SUBJECT: GRB 190311A: NEXT-0.6m optical afterglow detection DATE: 19/03/11 15:50:36 GMT FROM: Dong Xu at NAOC/CAS Z.P. Zhu, D. Xu, B.Y. Yu (NAOC) report on behalf of larger collaboration: We observed the field of GRB 190311A (Troja et al., GCN 23946) using the robotic NEXT-0.6m telescope located at Nanshan, Xinjiang, China. Observations started at 14:25:14 UT on 2019-03-11, i.e., 101 sec after the BAT trigger. A series of 40 s, 60 s , 90 s, 300 s R-band frames were obtained, and photometry is still ongoing. An uncatalogued optical source is detected at coordinates R.A. (J2000) = 14:08:15.71 Dec. (J2000) = +53:30:01.7 with an uncertainty radius ~0.3 arcsec, being consistent with Swift/UVOT position (Troja et al., GCN 23946). The source has m(R) ~ 19.7 mag at 413 s post-burst, and is fading. We conclude that the source is the optical afterglow of the burst. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23949 SUBJECT: GRB190311A: MASTER Global Robotic Net OT optical observation DATE: 19/03/11 16:18:57 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, D.Vlasenko, V.Vladimirov, D.Zimnukhov, A.Kuznetsov, P.Balanutsa, A. Chasovnikov, D.Kuvshinov (Lomonosov Moscow State University, SAI, Physics Department), O. Gress, N.M. Budnev, O.Ershova, Yu.Ishmuhametova (Applied Physics Institute, Irkutsk State University), V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk Educational State University), R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico Felix Aguilar OAFA), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE) MASTER-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the GRB190311.6 (Troja et al., 23946) 55 sec after notice time and 66 sec after trigger time at 2019-03-11 14:24:45 UT. On our third (30 s exposure) set we found optical transient within SWIFT error-box at Swift UVOT position (Troja et al., 23946). m ~ 17.5 RA, DEC = 14:08:15.72, +53:30:02.9 err = 1 arcsec We obtain a following images with OT: Tmid-T0 | Site |Filt.| Expt. | Limit | Comment _________|_____________________|_____|_______|_______|________ 109 | MASTER-Tunka | P- | 10 | 16.82 | 109 | MASTER-Tunka | P- | 80 | 18.47 | Coadd 109 | MASTER-Tunka | P| | 10 | 16.69 | 109 | MASTER-Tunka | P| | 80 | 18.33 | Coadd 231 | MASTER-Tunka | P| | 30 | 17.60 | 231 | MASTER-Tunka | P- | 30 | 17.74 | 338 | MASTER-Tunka | P| | 40 | 17.70 | 338 | MASTER-Tunka | P- | 40 | 17.87 | 462 | MASTER-Amur | P/ | 60 | 13.12 | 465 | MASTER-Tunka | P| | 60 | 18.12 | 465 | MASTER-Tunka | P| | 250 | 19.14 | Coadd 465 | MASTER-Tunka | P- | 60 | 18.21 | 465 | MASTER-Tunka | P- | 250 | 19.24 | Coadd 593 | MASTER-Amur | P/ | 60 | 12.20 | 614 | MASTER-Tunka | P| | 80 | 18.50 | 614 | MASTER-Tunka | P- | 80 | 18.43 | 808 | MASTER-Tunka | P| | 110 | 18.65 | 808 | MASTER-Tunka | P- | 110 | 18.65 | 1032 | MASTER-Tunka | P| | 140 | 18.56 | 1032 | MASTER-Tunka | P| | 490 | 19.35 | Coadd 1032 | MASTER-Tunka | P- | 140 | 18.55 | 1032 | MASTER-Tunka | P- | 490 | 19.30 | Coadd 1305 | MASTER-Tunka | P| | 170 | 18.64 | 1305 | MASTER-Tunka | P- | 170 | 18.63 | 1622 | MASTER-Tunka | P| | 180 | 19.02 | 1623 | MASTER-Tunka | P- | 180 | 18.89 | 1949 | MASTER-Tunka | P| | 180 | 17.67 | 1949 | MASTER-Tunka | P| | 540 | 19.26 | Coadd 1949 | MASTER-Tunka | P- | 180 | 17.63 | 1949 | MASTER-Tunka | P- | 540 | 19.22 | Coadd 2284 | MASTER-Tunka | P| | 180 | 18.90 | 2284 | MASTER-Tunka | P- | 180 | 18.98 | 2616 | MASTER-Tunka | P| | 180 | 19.01 | 2949 | MASTER-Tunka | P| | 180 | 19.10 | 2949 | MASTER-Tunka | P| | 540 | 19.83 | Coadd 2949 | MASTER-Tunka | P- | 540 | 19.72 | Coadd 3959 | MASTER-Tunka | P- | 540 | 19.60 | Coadd 3959 | MASTER-Tunka | P| | 540 | 19.87 | Coadd 5650 | MASTER-Tunka | P| | 180 | 19.20 | 5650 | MASTER-Tunka | P- | 180 | 18.89 | 5979 | MASTER-Tunka | P- | 180 | 18.74 | 5979 | MASTER-Tunka | P| | 180 | 19.02 | 6312 | MASTER-Tunka | P| | 180 | 18.66 | 6312 | MASTER-Tunka | P- | 180 | 18.79 | The 5-sigma upper limit has been about 16.32mag The message may be cited. ==================================================================== The galactic latitude b = 60 deg., longitude l = 99 deg. The observations made on zenit distance = 48 deg.The moon (22 % bright part) is 14 deg. above the horizon. The distance between moon and object is 113 The sun altitude is -30.2 deg. The object can be observed till sunrise at 2019-03-12 23:26:58. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23950 SUBJECT: GRB 190311A: Enhanced Swift-XRT position DATE: 19/03/11 16:37:34 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 1682 s of XRT Photon Counting mode data and 2 UVOT images for GRB 190311A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 212.06539, +53.50037 which is equivalent to: RA (J2000): 14h 08m 15.69s Dec (J2000): +53d 30' 01.3" with an uncertainty of 1.8 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23951 SUBJECT: GRB 190311A: TSHAO optical observations DATE: 19/03/11 20:28:35 GMT FROM: Alexei Pozanenko at IKI, Moscow S. Belkin (IKI), I. Reva (FAPHI), A. Pozanenko (IKI), E. Mazaeva (IKI), A. Volnova (IKI), A. Kusakin (FAPHI), M. Krugov (FAPHI) report on behalf of IKI-GRB-FuN: We observed the afterglow of GRB 190311A (Troja et al. GCN 23946) with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory starting on Mar. 11 (UT) 15:54:08. Preliminary photometry of the afterglow detected previously (Troja et al. GCN 23946; Pozanenko et al. GCN 23947; Zhu et al. GCN 23948; Gorbovskoy et al. GCN 23949) is following. Date UT start t-T0 Filter Exp. OT Err. UL (mid, days) (s) 2019-03-11 15:54:08 0.07228 R 3240 20.87 0.24 21.4 The photometry is based the stars used for calibration in GCN 23947. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23952 SUBJECT: GRB 190311A: Swift-XRT refined Analysis DATE: 19/03/12 01:18:35 GMT FROM: Phil Evans at U of Leicester A. Tohuvavohu (PSU), S. J. LaPorte (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), J.A. Kennea (PSU) and E. Troja report on behalf of the Swift-XRT team: We have analysed 7.6 ks of XRT data for GRB 190311A (Troja et al. GCN Circ. 23946), from 86 s to 19.1 ks after the BAT trigger. The data comprise 80 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 23950). The light curve can be modelled with an initial power-law decay with an index of alpha=2.27 (+0.38, -0.19), followed by a break at T+386 s to an alpha of 0.56 (+0.12, -0.08). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.79 (+0.25, -0.24). The best-fitting absorption column is 2.1 (+1.2, -1.1) x 10^21 cm^-2, in excess of the Galactic value of 1.2 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.04 (+0.19, -0.18) and a best-fitting absorption column of 3.8 (+0.9, -0.8) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (5.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.8 (+0.9, -0.8) x 10^21 cm^-2 Galactic foreground: 1.2 x 10^20 cm^-2 Excess significance: 7.3 sigma Photon index: 2.04 (+0.19, -0.18) If the light curve continues to decay with a power-law decay index of 0.56, the count rate at T+24 hours will be 0.022 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.2 x 10^-13 (1.3 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00892607. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23953 SUBJECT: GRB 190311A: Fermi GBM observation DATE: 19/03/12 02:09:13 GMT FROM: Peter Veres at UAH P. Veres and C. Meegan (both UAH) report on behalf of the Fermi GBM Team: "At 14:23:37.601 UT on 11 March 2019, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 190311A (trigger 574007022 / 190311600), which was also detected by the Swift/BAT (Troja et al., GCN 23946). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 128 degrees. The GBM light curve consists of a single peak with a duration (T90) of about 12.5 s (50-300 keV). The time-averaged spectrum from T0-4.1 s to T0+3.1 s is adequately fit by a simple power law function with index 1.86 +/- 0.08. The event fluence (10-1000 keV) in this time interval is (1.40 +/- 0.18)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0-2.75 s in the 10-1000 keV band is 3.00 +/- 0.35 ph/s/cm^2. A power law function with an exponential high-energy cutoff fits the spectrum equally well with Epeak= 89 +/- 34 keV and alpha = -1.51 +/- 0.25. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23954 SUBJECT: GRB 190311A: GMG observation DATE: 19/03/12 05:10:29 GMT FROM: Jirong Mao at Yunnan Obs J. Mao, X.-L. Zhang, and J.-M. Bai (YNAO) report: We observed the field of GRB 190311A (Troja et al. GCN Circ. 23946) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG) station of Yunnan Observatories. The observation began at UT 16:15:07, 11, March, 2019, about 2 hours after the trigger. We clearly detected the afterglow (Pozanenko et al. GCN Circ. 23947; Zhu et al. GCN Circ 23948; Belkin et al. GCN Circ. 23951) , and the preliminary magnitude is measured to be R~20.6. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23958 SUBJECT: GRB 190311A: Mondy optical observations DATE: 19/03/12 14:34:41 GMT FROM: Elena Mazaeva at IKI, Moscow <30.v@mail.ru> E. Mazaeva (IKI), E. Klunko (ISTP), A. Pozanenko (IKI), S. Belkin (IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We continue to observe optical afterglow of GRB 190311A (Troja et al. GCN 23946; Pozanenko et al. GCN 23947; Zhu et al. GCN 23948; Gorbovskoy et al. GCN 23949; Belkin et al. GCN 23951; Mao et al. GCN 23954) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Mar. 11 (UT) 15:11:33 (31 minutes after GRB trigger). Light curve of the afterglow in R-filter (of the full set of the observations incl. reported earlier in GCNs 23947, 23951) can be found at: http://grb.rssi.ru/GRB190311A/GRB190311A_LC.png Photometry is based on the SDSS-DR12 stars (Lupton transformations) SDSS-DR12_id R J140819.68 +532900.1 17.09 J140818.11 +532934.7 15.19 J140809.64 +533055.9 16.97 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23959 SUBJECT: GRB190311A: OAO observations DATE: 19/03/12 15:13:24 GMT FROM: Alberto Fernandez-Soto at IFCA (CSIC/UC,Santander) V. Peris (OAUV-Valencia) and A. Fernandez-Soto (IFCA-Santander) report: We have observed the field of GRB190311A (Troja et al., GCN 23946) with the OAUV-0.5m telescope at the Observatorio de Aras de los Olmos (OAO) in Aras de los Olmos (Valencia, Spain). Observations began after local midnight on March 12 (UT 01:03, (t-t0) ~ 10.7 hours ~ 0.444 days). We took 23 ten-minute exposures using a Johnson R filter, out of which 15 have been selected based on best quality. The afterglow reported in GCN23946 and confirmed by Pozanenko et al. (GCN 23947) is clearly detected in our combined image, with the following magnitude and timestamp: UT(middle) (t-t0) Exposure R Error ---------- ------- -------- ----- ----- 03:41:46 0.4443d 15x10min 21.45 0.15 The image has been calibrated using 100 stars in the field, the APASS catalog (r and i mags) and the conversion equations in Lupton (2005) as given in the SDSS pages. The calibration zeropoint error is not significant in comparison with the flux uncertainty (Delta(ZP)~0.03). Our results confirm the fading of the afterglow and extend the time baseline from previous observations. We cannot at the present stage measure the fading rate within our observations. OAO is operated by the Observatori Astronomic de la Universitat de Valencia (OAUV). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23961 SUBJECT: GRB 190311A: Swift-BAT refined analysis DATE: 19/03/12 16:23:39 GMT FROM: Amy Lien at GSFC J. R. Cummings (CPI), S. D. Barthelmy (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 190311A (trigger #892607) (Troja et al., GCN Circ. 23946). The BAT ground-calculated position is RA, Dec = 212.067, 53.486 deg which is RA(J2000) = 14h 08m 16.1s Dec(J2000) = +53d 29' 09.2" with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 79%. The mask-weighted light curve shows a single-pulse structure that starts at ~T-2 s, peaks at ~T+1 s, and ends at ~T+20 s. T90 (15-350 keV) is 17.0 +- 6.8 sec (estimated error including systematics). The time-averaged spectrum from T-2.22 to T+20.78 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.80 +- 0.17. The fluence in the 15-150 keV band is 9.1 +- 0.9 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.78 sec in the 15-150 keV band is 1.8 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/892607/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23962 SUBJECT: GRB 190311A: NOT optical counterpart DATE: 19/03/12 21:47:13 GMT FROM: Jonatan Selsing at DARK/NBI J. Selsing (DAWN/NBI), Z.P. Zhu (NAOC), D. Xu (NAOC), D. Malesani  (DAWN/NBI, DARK/NBI), D. Nespral (IAC), D. Gandolfi (Univ. Turin), and  J. Telting (NOT), report on behalf of a larger collaboration: We have observed the optical afterglow of GRB 190311A (Troja et al.,  GCN 23946; Goad et al., GCN 23950; Veres & Meegan, GCN 23953) with the  2.5-m Nordic Optical Telescope (NOT). We have obtained an r+z imaging  sequence using the ALFOSC instrument, with 4x300 and 5x300 s exposure in  the r and z band, respectively. Imaging observations began 9.4 hr after  the BAT trigger. In the images we clearly detect the optical counterpart of GRB 190311A,  as previously reported (Zhu et al., GCN 23948; Pozanenko et al., GCN  23947; Gorbovskoy et al., GCN 23949; Belkin et al., GCN 23951; Mao et  al., GCN 23954; Peris & Fernandez-Soto, GCN 23959). We calibrate the photometric zeropoints against the Pan-STARRS catalog and derive the following magnitudes for the optical counterpart: r = 21.88 +- 0.03 AB mag z = 21.26 +- 0.04 AB mag The source is centred at the position: RA (J2000.0) = 14:08:15.726 DEC (J2000.0) = +53:30:02.74 with the astrometric solution calibrated against the 2MASS catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23963 SUBJECT: GRB 190311A: Liverpool Telescope observations DATE: 19/03/13 09:20:05 GMT FROM: Martin Blazek at HETH/IAA-CSIC M. Blazek, L. Izzo. D. A. Kann (all HETH/IAA-CSIC), A. de Ugarte-Postigo (HETH/IAA-CSIC, DARK/NBI) and C. C. Thoene (HETH/IAA-CSIC) report: We observed the Swift GRB 190311A (Troja et al, GCN 23946) with the 2-m Liverpool Telescope located in La Palma, Spain. The observation started at 02:19:56 UT on March 12, 2019 (t-t0 = 11.94 hours). We obtained 5x60 seconds exposures each in g', r', and i'. We clearly detected the optical afterglow inside the Swift-XRT error circle given of Goad et al. (GCN 23950). We measure the following magnitudes g' = 22.18 +- 0.24 mag, r' = 21.70 +- 0.13 mag, i' = 21.54 +- 0.18 mag. Magnitudes were derived against 9 nearby stars from the SDSS catalogue and are in the AB system. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23964 SUBJECT: GRB 190311A: Mondy optical observations DATE: 19/03/13 15:51:30 GMT FROM: Elena Mazaeva at IKI, Moscow <30.v@mail.ru> E. Mazaeva (IKI), E. Klunko (ISTP), A. Pozanenko (IKI), S. Belkin (IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We continue observations the afterglow of GRB 190311A (Troja et al. GCN 23946) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Mar. 12 (UT) 16:23:42. Preliminary photometry of the afterglow detected previously (Troja et al. GCN 23946; Pozanenko et al. GCN 23947; Zhu et al. GCN 23948; Gorbovskoy et al. GCN 23949; Belkin et al. GCN 23951; Mao et al. GCN 23954; Mazaeva et al. GCN 23958; Selsing et al. GCN 23962; Blazek et al. GCN 23963) is following. Date       UT start t-T0    Filter  Exp. OT    Err.  UL                      (mid, days)     (s) 2019-03-12 16:23:42 1.11471  R  5400 22.16 0.09  23.5 The photometry is based on several nearby SDSS-DR12 stars used in GCN 23958. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23965 SUBJECT: GRB 190311A: Swift/UVOT Detection DATE: 19/03/13 16:33:25 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 190311A 88 s after the BAT trigger (Troja et al., GCN Circ. 23946). A source consistent with the XRT position (Goad et al., GCN Circ. 23950) is detected in the initial UVOT exposures. This source is consistent with the initial transient reported by UVOT, Mondy (Pozanenko et al., GCN Circ. 23947), Next (Zhu et al., GCN Circ. 23948), MASTER (Gorbovskoy, GCN Circ. 23949), TSHAO (Belkin et al., 23951), GMG (Mao et al., GCN Circ. 23954) and OAO (Peris et al., GCN Circ. 23959). The source faded below detection by the second orbit. The preliminary UVOT position is: RA (J2000) = 14:08:15.71 = 212.06546 (deg.) Dec (J2000) = +53:30:02.9 = 53.50080 (deg.) with an estimated uncertainty of 0.49 arc sec. (radius, 90% confidence). Preliminary detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 88 238 147 19.59 +/- 0.10 white 5678 7314 393 >21.42 white 51260 58205 2454 >22.45 u 301 550 246 19.85 +/- 0.20 u 6704 18770 1081 >21.08 b 6910 19082 493 >20.89 v 6089 12525 1164 >20.42 uvw1 6500 28478 1676 >20.98 uvm2 6294 23285 1557 >20.87 uvw2 5884 7521 393 >20.16 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23966 SUBJECT: GRB 190311A: OSN optical afterglow detection DATE: 19/03/13 17:51:06 GMT FROM: Martin Blazek at HETH/IAA-CSIC M. Blazek, D. A. Kann, L. Izzo, C. C. Thoene (all HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), and A. Sota (IAA-CSIC) report: We observed the Swift GRB 190311A (Troja et al, GCN 23946) with the 1.5-m telescope of the Sierra Nevada Observatory (OSN), Spain. The observation started at 22:54:30 on March 11, 2019 (t-t0 = 8.5158 hours). We obtained 9x360 seconds exposures each in V, Rc and Ic band. We clearly detect the optical afterglow inside the Swift-XRT error circle given by Goad et al. (GCN 23950). We measure the following AB magnitudes: V = 21.94 +- 0.17 mag (23:31:10 - 1:54:18 UT) Rc = 21.7 +- 0.09 mag (23:12:50 - 1:35:58 UT) Ic = 21.27 +- 0.15 mag (22:54:30 - 1:16:14 UT) Magnitudes were derived against 11 nearby stars from the SDSS catalogue, using the transformation equations of Lupton (2005), and transformed back into AB mags. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23968 SUBJECT: GRB190311A: MITSuME Akeno optical observation DATE: 19/03/15 12:11:13 GMT FROM: Kota Iida at Tokyo Inst. of Tech. K. Iida, R. Itoh, K. L. Murata, Y. Tachibana, S. Harita, K. Morita, K. Shiraishi, M. Oeda, M. Niwano, R. Adachi, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration We searched for the optical counterpart of GRB 190311A (Troja et al., GCN Circular #23946) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started on 14:24:43.64 UT which corresponds to 70 sec after the trigger. We detected the point source at the position consistent with the afterglow detected previously (Troja et al. GCN #23946; Pozanenko et al. GCN #23947; Zhu et al. GCN #23948; Gorbovskoy et al. GCN #23949, Belkin et al. GCN #23951). The measured magnitudes are listed as follows. T0+[sec] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------------------------------------------------- ~70 14:24:46.22 540 18.9+/-0.2 18.6+/-0.2 18.2+/-0.2 ------------------------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration. The magnitudes are expressed in the Vega system.