September 2021 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 28730] GRB 210912A: Swift-XRT refined Analysis
by GCN Circulars 13 Sep '21

13 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30833 SUBJECT: GRB 210912A: Swift-XRT refined Analysis DATE: 21/09/13 09:18:53 GMT FROM: Phil Evans at U of Leicester <pae9(a)leicester.ac.uk> A.P. Beardmore (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester) and E. Troja report on behalf of the Swift-XRT team: We have analysed 4.1 ks of XRT data for GRB 210912A (Troja et al. GCN Circ. 30820), from 46 s to 29.0 ks after the BAT trigger. The data comprise 32 s in Windowed Timing (WT) mode (the first 5 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 30830). The light curve can be modelled with an initial power-law decay with an index of alpha=3.4 (+/-0.4), followed by a break at T+140 s to an alpha of 0.68 (+/-0.05). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.67 (+0.25, -0.23). The best-fitting absorption column is 1.2 (+0.9, -0.7) x 10^21 cm^-2, in excess of the Galactic value of 2.4 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10^-11 (4.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.2 (+0.9, -0.7) x 10^21 cm^-2 Galactic foreground: 2.4 x 10^20 cm^-2 Excess significance: 2.2 sigma Photon index: 1.67 (+0.25, -0.23) If the light curve continues to decay with a power-law decay index of 0.68, the count rate at T+24 hours will be 0.014 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.7 x 10^-13 (6.6 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01072990. This circular is an official product of the Swift-XRT team.

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[vsnet-grb-info 28729] GRB 210912A: Swift/UVOT Detection
by GCN Circulars 13 Sep '21

13 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30832 SUBJECT: GRB 210912A: Swift/UVOT Detection DATE: 21/09/13 07:47:54 GMT FROM: Paul Kuin at MSSL <npkuin(a)gmail.com> N. P. M. Kuin (UCL-MSSL) 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 210912A 60 s after the BAT trigger (Troja et al., GCN Circ. 30820). A source consistent with the optical position (Hu et al. GCN Circ. 30823) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 08:39:34.27 = 129.89280 (deg.) Dec (J2000) = +79:13:17.1 = 79.22141 (deg.) with an estimated uncertainty of 0.47 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits 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 60 209 147 18.73 +/- 0.08 v 602 621 19 >17.8 b 528 547 19 >18.3 u 272 490 214 19.56 +/- 0.31 w2 577 597 19 >18.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.027 in the direction of the burst (Schlegel et al. 1998).

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[vsnet-grb-info 28728] Fermi GBM observation of another bright burst in the direction of SGR 1935+2154
by GCN Circulars 13 Sep '21

13 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30831 SUBJECT: Fermi GBM observation of another bright burst in the direction of SGR 1935+2154 DATE: 21/09/13 03:33:14 GMT FROM: Oliver J Roberts at USRA/NASA <oliver.roberts(a)nasa.gov> O.J. Roberts (USRA/NASA-MSFC) reports on behalf of the Fermi GBM Team: "At 20:16:10.44 UT on 12 September 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located a bright, SGR-like burst from the direction of the magnetar SGR 1935+2154 (trigger 653170575/210912845). The GBM on-ground location is consistent with the known position of the SGR. The angle from the Fermi LAT boresight at the GBM trigger time is 96 degrees. The event episode has a duration (T90) of about 1 s (10-1000 keV). During this time interval, there are several very short bursts. The first burst has a rapid risetime. The whole event is best fit with a power law function with an exponential high-energy cutoff. The power law index is 0.08 +/- 0.08 and the cutoff energy, parameterized as Epeak, is 32.1 +/- 0.3 keV. The time-integrated event fluence (10-1000 keV) from T0-0.064 to T0+0.944s is (3.545 +/- 0.038)E-6 erg/cm^2. The average photon flux in the 10-1000 keV band during this period is 84 +/- 1 ph/s/cm^2. Fermi GBM has also triggered on a further 24 bursts from the direction of SGR 1935+2154 since yesterday's GCN (Roberts and Wood, GCN 30806): Date and Time in UTC Fermi MET (s) 2021-09-12T23:19:32.08 653181577 2021-09-12T20:16:10.44 653170575 2021-09-12T15:03:50.60 653151835 2021-09-12T13:55:16.45 653147721 2021-09-12T12:19:20.44 653141965 2021-09-12T10:10:11.73 653134216 2021-09-12T07:28:07.46 653124492 2021-09-12T06:51:13.22 653122278 2021-09-12T05:14:07.84 653116452 2021-09-11T02:36:38.24 653093506 2021-09-11T20:22:59.04 653084584 2021-09-11T20:05:46.22 653083551 2021-09-11T18:54:36.05 653079281 2021-09-11T17:01:09.77 653072474 2021-09-11T16:50:03.83 653071808 2021-09-11T16:36:57.91 653071022 2021-09-11T15:26:11.55 653066776 2021-09-11T15:15:25.44 653066130 2021-09-11T15:03:00.55 653065385 2021-09-11T13:27:33.85 653059658 2021-09-11T11:53:57.29 653054042 2021-09-11T10:42:51.85 653049776 2021-09-11T05:32:38.65 653031163 2021-09-11T03:02:28.36 653022153 Fermi GBM will not report on future triggers from this event. The spectral analysis results presented above are preliminary. We encourage multi-wavelength observations to follow-up this most recent activation. For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"

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[vsnet-grb-info 28727] GRB 210912A: Enhanced Swift-XRT position
by GCN Circulars 12 Sep '21

12 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30830 SUBJECT: GRB 210912A: Enhanced Swift-XRT position DATE: 21/09/12 20:48:34 GMT FROM: Phil Evans at U of Leicester <pae9(a)leicester.ac.uk> P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 526 s of XRT Photon Counting mode data and 1 UVOT images for GRB 210912A, 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 = 129.88990, +79.22148 which is equivalent to: RA (J2000): 08h 39m 33.58s Dec (J2000): +79d 13' 17.3" with an uncertainty of 2.6 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.

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[vsnet-grb-info 28726] GRB 210912A: Host-galaxy candidate in PanSTARRS
by GCN Circulars 12 Sep '21

12 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30829 SUBJECT: GRB 210912A: Host-galaxy candidate in PanSTARRS DATE: 21/09/12 18:48:08 GMT FROM: Alexander Kann at IAA-CSIC <kann(a)iaa.es> D. A. Kann (HETH/IAA-CSIC) reports: At the afterglow position (Hu et al., GCN #30823, see also Pankov et al., GCN #30825) of the Swift GRB 210912A (Troja et al., GCN #30820), an object is visible in Pan-STARRS pre-imaging at position (J2000): RA = 129.89171813 Dec. = +79.22157927 in agreement with the position given by Hu et al., GCN #30823, with magnitudes: g' = 23.19 +/- 0.23 mag, r' = 23.09 +/- 0.36 mag, i' = 22.48 +/- 0.13 mag, z' = 22.43 +/- 0.25 mag. It is undetected in Y. We suggest this object to be the host galaxy of GRB 210912A. This may be indicative that this is a low-redshift event which may be followed by a detectable supernova. Further follow-up despite the very northerly position is warranted.

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[vsnet-grb-info 28725] Fermi trigger No 653151835: Global MASTER-Net observations report
by GCN Circulars 12 Sep '21

12 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30828 SUBJECT: Fermi trigger No 653151835: Global MASTER-Net observations report DATE: 21/09/12 17:30:33 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB210912.63 (trigger No 653151835,18h 48m 16.80s , +38d 23m 24.0s, R=11.54) errorbox 6050 sec after notice time and 6087 sec after trigger time at 2021-09-12 16:45:17 UT, with upper limit up to 17.8 mag. Observations started at twilight. The observations began at zenith distance = 6 deg. The sun altitude is -14.8 deg. The galactic latitude b = 17 deg., longitude l = 68 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1718727 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 6117 | 2021-09-12 16:45:17 | MASTER-Kislovodsk | (18h 48m 02.06s , +37d 18m 46.9s) | C | 60 | 17.7 | 6117 | 2021-09-12 16:45:17 | MASTER-Kislovodsk | (18h 42m 19.28s , +37d 41m 53.1s) | C | 60 | 17.7 | 6197 | 2021-09-12 16:46:37 | MASTER-Kislovodsk | (18h 38m 44.51s , +39d 14m 11.3s) | C | 60 | 17.8 | 6197 | 2021-09-12 16:46:37 | MASTER-Kislovodsk | (18h 32m 52.00s , +39d 37m 25.1s) | C | 60 | 17.7 | 6448 | 2021-09-12 16:50:48 | MASTER-Kislovodsk | (18h 58m 21.42s , +39d 13m 38.8s) | C | 60 | 16.1 | 6448 | 2021-09-12 16:50:48 | MASTER-Kislovodsk | (18h 52m 28.93s , +39d 37m 07.7s) | C | 60 | 15.9 | 6528 | 2021-09-12 16:52:08 | MASTER-Kislovodsk | (18h 39m 26.80s , +35d 24m 32.5s) | C | 60 | 17.2 | 6528 | 2021-09-12 16:52:08 | MASTER-Kislovodsk | (18h 33m 53.53s , +35d 47m 47.3s) | C | 60 | 17.5 | 6609 | 2021-09-12 16:53:29 | MASTER-Kislovodsk | (18h 28m 57.88s , +37d 18m 58.7s) | C | 60 | 16.4 | 6609 | 2021-09-12 16:53:29 | MASTER-Kislovodsk | (18h 23m 15.94s , +37d 42m 16.8s) | C | 60 | 16.4 | 6689 | 2021-09-12 16:54:49 | MASTER-Kislovodsk | (18h 50m 14.79s , +41d 08m 17.2s) | C | 60 | 16.4 | 6689 | 2021-09-12 16:54:49 | MASTER-Kislovodsk | (18h 44m 11.87s , +41d 31m 51.2s) | C | 60 | 16.4 | 6769 | 2021-09-12 16:56:09 | MASTER-Kislovodsk | (18h 32m 31.89s , +33d 30m 30.3s) | C | 60 | 16.0 | 6769 | 2021-09-12 16:56:09 | MASTER-Kislovodsk | (18h 27m 07.14s , +33d 53m 32.9s) | C | 60 | 16.0 | 6849 | 2021-09-12 16:57:30 | MASTER-Kislovodsk | (19h 10m 29.99s , +41d 08m 24.0s) | C | 60 | 15.8 | 6849 | 2021-09-12 16:57:30 | MASTER-Kislovodsk | (19h 04m 26.77s , +41d 31m 58.8s) | C | 60 | 15.9 | 6929 | 2021-09-12 16:58:50 | MASTER-Kislovodsk | (18h 50m 43.27s , +33d 31m 30.1s) | C | 60 | 15.0 | 6929 | 2021-09-12 16:58:50 | MASTER-Kislovodsk | (18h 45m 18.04s , +33d 54m 28.5s) | C | 60 | 15.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.

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[vsnet-grb-info 28724] Fermi trigger No 653124492: Global MASTER-Net observations report
by GCN Circulars 12 Sep '21

12 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30827 SUBJECT: Fermi trigger No 653124492: Global MASTER-Net observations report DATE: 21/09/12 17:30:21 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB210912.31 (trigger No 653124492,19h 37m 24.00s , +14d 11m 24.0s, R=5.57) errorbox 33104 sec after notice time and 33347 sec after trigger time at 2021-09-12 16:43:55 UT, with upper limit up to 16.7 mag. Observations started at twilight. The observations began at zenith distance = 26 deg. The sun altitude is -14.6 deg. The galactic latitude b = -4 deg., longitude l = 51 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1718336 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 33378 | 2021-09-12 16:43:55 | MASTER-Kislovodsk | (19h 43m 31.87s , +18d 28m 39.5s) | C | 60 | 16.4 | 33378 | 2021-09-12 16:43:55 | MASTER-Kislovodsk | (19h 48m 16.06s , +18d 04m 09.4s) | C | 60 | 16.3 | 33628 | 2021-09-12 16:48:05 | MASTER-Kislovodsk | (19h 41m 05.91s , +20d 21m 52.7s) | C | 60 | 16.3 | 33628 | 2021-09-12 16:48:05 | MASTER-Kislovodsk | (19h 45m 53.81s , +19d 57m 19.9s) | C | 60 | 15.5 | 33708 | 2021-09-12 16:49:25 | MASTER-Kislovodsk | (19h 47m 07.26s , +16d 34m 45.7s) | C | 60 | 16.5 | 33708 | 2021-09-12 16:49:25 | MASTER-Kislovodsk | (19h 51m 48.08s , +16d 10m 15.5s) | C | 60 | 16.7 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.

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[vsnet-grb-info 28723] Fermi trigger No 653122278: Global MASTER-Net observations report
by GCN Circulars 12 Sep '21

12 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30826 SUBJECT: Fermi trigger No 653122278: Global MASTER-Net observations report DATE: 21/09/12 17:30:15 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB210912.29 (trigger No 653122278,19h 38m 48.00s , +17d 55m 48.0s, R=1.33) errorbox 35039 sec after notice time and 35562 sec after trigger time at 2021-09-12 16:43:55 UT, with upper limit up to 16.5 mag. Observations started at twilight. The observations began at zenith distance = 26 deg. The sun altitude is -14.6 deg. The galactic latitude b = -2 deg., longitude l = 55 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1718305 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 35592 | 2021-09-12 16:43:55 | MASTER-Kislovodsk | (19h 43m 31.87s , +18d 28m 39.5s) | C | 60 | 16.4 | 35592 | 2021-09-12 16:43:55 | MASTER-Kislovodsk | (19h 48m 16.06s , +18d 04m 09.4s) | C | 60 | 16.3 | 35842 | 2021-09-12 16:48:05 | MASTER-Kislovodsk | (19h 41m 05.91s , +20d 21m 52.7s) | C | 60 | 16.3 | 35842 | 2021-09-12 16:48:05 | MASTER-Kislovodsk | (19h 45m 53.81s , +19d 57m 19.9s) | C | 60 | 15.5 | 35922 | 2021-09-12 16:49:25 | MASTER-Kislovodsk | (19h 47m 07.26s , +16d 34m 45.7s) | C | 60 | 16.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.

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[vsnet-grb-info 28722] GRB 210912A: Mondy optical afterglow confirmation
by GCN Circulars 12 Sep '21

12 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30825 SUBJECT: GRB 210912A: Mondy optical afterglow confirmation DATE: 21/09/12 17:21:48 GMT FROM: Alexei Pozanenko at IKI, Moscow <apozanen(a)iki.rssi.ru> N. Pankov (HSE), S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP) report on behalf of GRB IKI FuN: We observed the field of GRB 210912A (Troja et al., GCN 30820) with AZT-33IK telescope of Sayan observatory (Mondy) starting on 2021-09-12(UT) 12:57:48. We obtained 30 images in R-filter. We confirm the fading object suggested by Hu et al. (GCN 30823) as the optic afterglow of GRB 210912A. Preliminary photometry of the object in stacked images is following Date UT start t-T0 Filter Exp. OT Err. UL(3sigma) (mid, days) (s) 2021-09-12 12:57:48 0.10112 R 29*120 21.33 0.14 22.5 The photometry is based on the nearby USNO-B1.0 stars RA DEC R2 08:39:12.26208 +79:12:37.1304 15.88 08:39:10.94880 +79:16:33.8916 15.26

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[vsnet-grb-info 28721] Swift GRB 210912A: Global MASTER-Net observations report
by GCN Circulars 12 Sep '21

12 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30824 SUBJECT: Swift GRB 210912A: Global MASTER-Net observations report DATE: 21/09/12 16:40:30 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 210912A ( E. Troja et al., GCN 30820) errorbox 19826 sec after notice time and 19878 sec after trigger time at 2021-09-12 16:32:29 UT, with upper limit up to 15.0 mag. Observations started at twilight. The observations began at zenith distance = 57 deg. The sun altitude is -12.6 deg. The galactic latitude b = 32 deg., longitude l = 134 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1718486 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 5800 | MASTER- | C | 25 | 13.0 | 8423 | MASTER- | C | 20 | 17.6 | 8423 | MASTER- | C | 20 | 13.9 | 19968 | MASTER-Kislovodsk | C | 180 | 15.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.

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