January 2026 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 41579] GRB 260120C: Fermi GBM Final Real-time Localization
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43482 SUBJECT: GRB 260120C: Fermi GBM Final Real-time Localization DATE: 26/01/20 23:15:26 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely SHORT GRB At 23:07:06 UT on 20 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260120C (trigger 790643231.34709 / 260120963). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 262.0, Dec = 3.4 (J2000 degrees, equivalent to J2000 17h 27m, 3d 23'), with a statistical uncertainty of 9.3 degrees. The angle from the Fermi LAT boresight is 108.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120963/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120963/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120963/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43482. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41578] GRB 260101A: 239Alferov CubeSat detection
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43481 SUBJECT: GRB 260101A: 239Alferov CubeSat detection DATE: 26/01/20 20:52:27 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin (Ioffe), D. Frederiks (Ioffe), D. Kapshtan (Geoscan), M. Orlov (Geoscan), V. Bazunova (Geoscan), E. Shchepin (Geoscan), E. Meltsov (Geoscan), K. Starikov (Geoscan, SPbSU), A. Khogoev (Geoscan), A. Razdobarin (SPbAU), and D. Dolmatov (SPbSU), on behalf of the 239Alferov team, report: The long-duration GRB 260101A (Fermi-GBM detection: The Fermi GBM team, GCN 43284; Hristov and Meegan, GCN 43297; Swift-BAT detection: Cenko et al., GCN 43285; Markwardt et al., GCN 43354; SVOM-GRM detection: Yu et al., GCN 43292; GECAM-B detection: Wang et al., GCN 43294; Konus-Wind detection: Svinkin et al., GCN 43389) was detected by 239Alferov 3U CubeSat at about 00:56:30 UT. The burst light curve, as measured by 239Alferov detector, shows a multipeaked structure very similar to that observed by other IPN instruments. The total burst duration duration is ~28 s. The emission is seen up to ~500 keV. The light curve recorded by 239Alferov is available at: http://www.ioffe.ru/LEA/GRBs/GRB260101_T03419/239Alferov/ 239Alferov is an educational 3U CubeSat mission at SSO combining amateur radio and space research objectives. The gamma-ray detector onboard 239Alferov contains a 64x72x15 mm NaI(Tl) scintillator read out by a SiPM array and covers the energy range from ~20 keV to ~1000 keV. The spacecraft is now at a commissioning stage, with scientific observations started in December 2025. Currently, the instrument records count rates in five energy bands: ~20-50 keV, ~50-100 keV, ~100-500 keV, 500-1000 keV, and > 1000 keV, with 1 s temporal resolution. The surveys span a couple of days with about a day-long analysis and maintenance intervals between the observations. The ground segment of the mission utilizes the SONIKS open ground station network. View this GCN Circular online at https://gcn.nasa.gov/circulars/43481. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41577] EP260116a: COLIBRÍ observations of a tentative optical rebrightening
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43480 SUBJECT: EP260116a: COLIBRÍ observations of a tentative optical rebrightening DATE: 26/01/20 18:36:58 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Alan M. Watson (UNAM), Noémie Globus (UNAM), Nathaniel R. Butler (ASU), Antonio de Ugarte Postigo (LAM) Jean-Luc Atteia (IRAP), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Asuka Kuwata (UNAM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), and Benjamin Schneider (LAM) report: We observed the field of EP260116a (Wang et al., GCN Circ. 43424) with the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope from 2026-01-20 03:54 to 08:25 UTC (from 99.7 to 104.3 hours after the trigger) and obtained 142 and 198 minutes of exposure in the r and z filters, respectively. Conditions were poor with variable transparency. The data were reduced, coadded, calibrated, and analyzed with the COLIBRÍ ASU pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. Compared to our observations on the previous night (Butler et al., GCN Circ 43459), we measure an apparent rebrightening of Delta r = -0.17 +/- 0.11 Delta z = -0.30 +/- 0.21 Individually, these apparent rebrightenings are only at the level of about 1.5 sigma. However, together they point to a possibly more significant result, minimally that the decay seen previously appears to have slowed. Further observations are planned and encouraged. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/43480. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41576] GRB 260120B: Swift detection of a burst
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43479 SUBJECT: GRB 260120B: Swift detection of a burst DATE: 26/01/20 18:16:31 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> M. Ferro (INAF-OAB), R. Gupta (NASA GSFC), A. Y. Lien (U Tampa), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 18:00:26 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 260120B (trigger=1442454). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 284.666, +61.912 which is RA(J2000) = 18h 58m 40s Dec(J2000) = +61d 54' 42" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 10 sec. The peak count rate was ~1700 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 18:02:51.6 UT, 145.5 seconds after the BAT trigger. No source was detected in the 2.5-s promptly available image. We are waiting for the full dataset to detect and localise the XRT counterpart. No UVOT data are available at this time. Burst Advocate for this burst is M. Ferro (matteo.ferro AT inaf.it). 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/) View this GCN Circular online at https://gcn.nasa.gov/circulars/43479. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41575] Swift GRB260120.75: Global MASTER-Net observations report
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43478 SUBJECT: Swift GRB260120.75: Global MASTER-Net observations report DATE: 26/01/20 18:16:28 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB260120.75 (trigger No 1442454,18h 58m 39.84s , +61d 54m 43.2s, R=0.05) errorbox 277 sec after notice time and 308 sec after trigger time at 2026-01-20 18:05:34 UT, with upper limit up to 17.0 mag. The observations began at zenith distance = 72 deg. The sun altitude is -43.2 deg. The galactic latitude b = 23 deg., longitude l = 92 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3109829 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 399 | MASTER-Kislovodsk | C | 180 | 12.3 | 399 | MASTER-Kislovodsk | C | 180 | 17.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/43478. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41574] GRB 260120B: Fermi GBM Final Real-time Localization
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43477 SUBJECT: GRB 260120B: Fermi GBM Final Real-time Localization DATE: 26/01/20 18:10:48 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 18:00:26 UT on 20 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260120B (trigger 790624831.046372 / 260120750). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 282.2, Dec = 64.2 (J2000 degrees, equivalent to J2000 18h 48m, 64d 12'), with a statistical uncertainty of 1.5 degrees. The angle from the Fermi LAT boresight is 11.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120750/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120750/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120750/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43477. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41573] EP260119A: Mondy I-Band Observations
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43476 SUBJECT: EP260119A: Mondy I-Band Observations DATE: 26/01/20 18:05:21 GMT FROM: Nicolai Pankov at IKI <colinsergesen(a)gmail.com> N. Pankov (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the EP260119a (Jiang et al., GCN 43447; Cheng et al., GCN 43449) at the redshift of z ~ 5.47 (Corcoran et al., GCN 43469) with the AZT-33IK 1.5-meter telescope of the Mondy observatory. We obtained 45x120 sec total exposure in the I-band, starting on 2026-01-19 at 17:18:42 UT. The afterglow (Fortin et al., GCN 43450; GCN 43455; Eyles-Ferris et al., GCN 43452; Moskvitin & Spiridonova, GCN 43463; Liu et al., GCN 43464; Ma et al., GCN 43466; Zheng et al., GCN 43468; Corcoran et al., GCN 43469; Bochenek & Perley, GCN 43472) is clearly detected in the stacked image. The preliminary photometry and observation details are provided below: Date UT start t-T0 Exp. Filter Mag MagErr. UL (mid,days) (n*s) (3sigma) 2026-01-19 17:18:42 0.74299 45*120 I 20.87 0.11 22.2 The photometry is based on the same stars used by (Moskvitin & Spiridonova, GCN 43463) and has not been corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43476. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41572] Fermi trigger No 790601190: Global MASTER-Net observations report
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43475 SUBJECT: Fermi trigger No 790601190: Global MASTER-Net observations report DATE: 26/01/20 17:16:02 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB260120.48 (trigger No 790601190,02h 33m 50.40s , +52d 51m 00.0s, R=2.66) errorbox 18094 sec after notice time and 18127 sec after trigger time at 2026-01-20 16:28:32 UT, with upper limit up to 18.0 mag. The observations began at zenith distance = 15 deg. The sun altitude is -25.6 deg. The galactic latitude b = -7 deg., longitude l = 139 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3109139 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 18157 | 2026-01-20 16:28:32 | MASTER-Kislovodsk | (02h 09m 49.63s , +52d 59m 30.1s) | C | 60 | 18.0 | 18566 | 2026-01-20 16:35:21 | MASTER-Kislovodsk | (02h 24m 49.14s , +48d 54m 14.6s) | C | 60 | 12.7 | 18566 | 2026-01-20 16:35:21 | MASTER-Kislovodsk | (02h 17m 56.92s , +49d 13m 20.4s) | C | 60 | 18.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/43475. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41571] Fermi trigger No 790570272: Global MASTER-Net observations report
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43474 SUBJECT: Fermi trigger No 790570272: Global MASTER-Net observations report DATE: 26/01/20 17:15:40 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB260120.12 (trigger No 790570272,03h 14m 19.20s , -35d 09m 36.0s, R=1.41) errorbox 133 sec after notice time and 170 sec after trigger time at 2026-01-20 02:53:57 UT, with upper limit up to 20.9 mag. The observations began at zenith distance = 41 deg. The sun altitude is -32.2 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB260120.12 errorbox 50498 sec after notice time and 50534 sec after trigger time at 2026-01-20 16:53:22 UT, with upper limit up to 13.0 mag. The observations began at zenith distance = 78 deg. The sun altitude is -30.1 deg. The galactic latitude b = -58 deg., longitude l = 236 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3108498 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 185 | 2026-01-20 02:53:57 | MASTER-OAFA | (02h 59m 50.02s , -35d 32m 29.5s) | C | 30 | 18.5 | 226 | 2026-01-20 02:54:33 | MASTER-OAFA | (02h 59m 50.06s , -35d 32m 29.0s) | C | 40 | 20.7 | 277 | 2026-01-20 02:55:19 | MASTER-OAFA | (02h 59m 50.12s , -35d 32m 29.0s) | C | 50 | 20.8 | 338 | 2026-01-20 02:56:15 | MASTER-OAFA | (02h 59m 50.21s , -35d 32m 29.0s) | C | 60 | 20.9 | 50565 | 2026-01-20 16:53:22 | MASTER-Kislovodsk | (03h 10m 05.18s , -34d 42m 45.9s) | C | 60 | 13.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/43474. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41570] GRB 260114A: Swift/UVOT Upper Limits
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43473 SUBJECT: GRB 260114A: Swift/UVOT Upper Limits DATE: 26/01/20 17:04:02 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M.H. Siegel (PSU) and R. A. J. Eyles-Ferris (U Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 260114A 164 s after the BAT trigger (Eyles-Ferris et al., GCN Circ. 43396). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ 43412) or the faint red counterpart (Li et al., GCN Circ. 43398; Volnova et al, GCN Circ. 43401) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 164 848 102 >20.50 v 705 1100 52 >18.44 b 631 824 38 >19.22 u 507 799 136 >19.56 uvw1 755 774 19 >17.70 uvm2 730 750 19 >17.28 uvw2 681 1080 58 >18.59 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.069 in the direction of the burst (Schlegel et al. 1998) View this GCN Circular online at https://gcn.nasa.gov/circulars/43473. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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