GRB210321A

This page lists all entries on GRB210321A in GRBweb

Summary IPN Swift GCN 29677 GCN 29678 GCN 29679 GCN 29680 GCN 29681 GCN 29683 GCN 29684 GCN 29685 GCN 29686 GCN 29687 GCN 29689 GCN 29691 GCN 29692 GCN 29694 GCN 29696 GCN 29697 GCN 29725

Summary table
Variable Value Source
T0 7:13:51 UTC GCN_circulars,Swift Det
ra 87.8948° Swift
decl 70.1305° Swift
pos_error 6.34e-05° Swift
T90 8.21 s Swift
T90_start 7:13:51 UTC Swift
fluence 6.70e-07 erg/cm² Swift
redshift 1.4870
T100 8.21 s
GBM_located False
mjd 59294.30128472222 GCN_circulars,Swift Det
IPN table
GRB_name GRB210321A
ra 87.8750°
decl 70.1167°
pos_error 5.00e-02°
redshift 1.4870
Swift table
GRB_name GRB210321A
t_trigger 7:13:51 UTC
ra 87.8948°
decl 70.1305°
pos_error 6.34e-05°
T90 8.21 s
fluence 6.70e-07 erg/cm²
redshift 1.4870
GCN 29677 table
GRB_name GRB210321A
GCN_number 29677
Detection_method Swift Det
t_trigger 7:13:51 UTC
ra 87.8740°
decl 70.1190°
Circular_text TITLE: GCN CIRCULAR NUMBER: 29677 SUBJECT: GRB 210321A: Swift detection of a burst DATE: 21/03/21 07:22:33 GMT FROM: David Palmer at LANL S. Dichiara (NASA/GSFC/UMCP), C. Gronwall (PSU), H. A. Krimm (NSF), 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 07:13:51 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210321A (trigger=1037828). Swift did not immediately slew due to an observing constraint. The BAT on-board calculated location is RA, Dec 87.874, +70.119 which is RA(J2000) = 05h 51m 30s Dec(J2000) = +70d 07' 09" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 15 sec. The peak count rate was ~1300 counts/sec (15-350 keV), at ~1 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+43.3 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is S. Dichiara (dichiara AT umd.edu). 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/)
GCN 29678 table
GRB_name GRB210321A
GCN_number 29678
Detection_method Swift-XRT Other
ra 87.8963°
decl 70.1304°
Circular_text TITLE: GCN CIRCULAR NUMBER: 29678 SUBJECT: GRB 210321A: Swift-XRT observations DATE: 21/03/21 08:24:08 GMT FROM: Phil Evans at U of Leicester M. Perri (SSDC & INAF-OAR), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU) and G. Cusumano (INAF-IASF PA) report on behalf of the Swift-XRT team: The XRT began observing the field of GRB 210321A at 07:59:21.6 UT, 2730.6 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 87.89627, 70.13042 which is equivalent to: RA(J2000) = 05h 51m 35.10s Dec(J2000) = +70d 07' 49.5" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 49 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 https://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 (1.13 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 4 (+3.35/-2.86) x 10^21 cm^-2 (90% confidence).
GCN 29679 table
GRB_name GRB210321A
GCN_number 29679
Detection_method Swift-UVOT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 29679 SUBJECT: GRB 210321A: Swift/UVOT Detection DATE: 21/03/21 13:35:49 GMT FROM: Mike Siegel at PSU/Swift MOC M.. H. Siegel (PSU) and S. Dichiara (NASA/GSFC/UMCP) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 210321A 2735 s after the BAT trigger (Dichiara et al., GCN Circ. 29677). A source consistent with the XRT position (Perri et al., GCN Circ. 29678) is detected in the initial UVOT exposures. 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 2735 2837 100 18.76 +/- 0.11 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.116 in the direction of the burst (Schlegel et al. 1998).
GCN 29680 table
GRB_name GRB210321A
GCN_number 29680
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 29680 SUBJECT: GRB 210321A: DDOTI Afterglow Confirmation DATE: 21/03/21 14:54:00 GMT FROM: Nat Butler at Az State U Nat Butler (ASU), Alan M. Watson (UNAM), Rosa L. Becerra (UNAM), Simone Dichiara (GSFC/UMD), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl Lopez (UNAM), Diego Gonzalez (UNAM), Margarita Pereyra (UNAM), Srihari Ravi (ASU), and Eleonora Troja (GSFC/UMD) report: We observed the field of the Swift/BAT GRB 210321A (Dichiara et al., GCN Circ. 29677) with the DDOTI wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Martir ( http://ddoti.astroscu.unam.mx) starting at 2021-03-21 08:56 UTC (from 1.7 hours after the trigger). We observed a region covering approximately 7 degrees in RA and 10 degrees in declination (about 70 square degrees) centered on the XRT position (Perri et al., GCN 29678) in the w filter. Compared to the USNO-B1, Pan-STARRS DR1, and APASS DR10 catalogs, we detect a bright source at 08:39:50.04 +60:12:18.9 (J2000) fading from about w = 18. This confirms the afterglow reported in UVOT observations by Siegel et al. (GCN Circ. 29679). We thank the staff of the Observatorio Astronomico Nacional in San Pedro Martir.
GCN 29681 table
GRB_name GRB210321A
GCN_number 29681
Detection_method Swift-XRT Det
ra 87.8958°
decl 70.1306°
Circular_text TITLE: GCN CIRCULAR NUMBER: 29681 SUBJECT: GRB 210321A: Enhanced Swift-XRT position DATE: 21/03/21 15:54:59 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 1720 s of XRT Photon Counting mode data and 5 UVOT images for GRB 210321A, 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 = 87.89579, +70.13057 which is equivalent to: RA (J2000): 05h 51m 34.99s Dec (J2000): +70d 07' 50.1" with an uncertainty of 1.7 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.
GCN 29683 table
GRB_name GRB210321A
GCN_number 29683
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 29683 SUBJECT: GRB 210321A: MASTER optical observation DATE: 21/03/21 20:49:00 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy,N.Tiurina,P.Balanutsa,F.Balakin, V.Vladimirov, A.Kuznetsov,K.Zhirkov,D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, A.Chasovnikov,A.Pozdnyakov,V.Topolev, D.Cheryasov(Lomonosov Moscow State University, SAI, Physics Department), D. Buckley (South African Astronomical Observatory), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico FelixAguilar OAFA), R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity) MASTER Global robotic net (MASTER-Net:http://observ.pereplet.ru Lipunov et al.,2010,Advances in Astronomy,2010,30L) started Swift GRB 210321A (BAT:Dichiara et al. GCN 29677,Ttrig=07:13:51; XRT:Perri et al. GCN 29678,Beardmore et al. GCN29681; UVOT: Siegel GCN29679), optical observations at MASTER-Tavrida at 2021-03-21 16:55:20UT, ~9.7h after trigger time, with mlim=20.8m. Swift optical counterpart (87.8947 +70.1305) isn't visible yet. This message may be cited.
GCN 29684 table
GRB_name GRB210321A
GCN_number 29684
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 29684 SUBJECT: GRB 210321A: NOT optical afterglow detection and redshift limit DATE: 21/03/21 22:41:10 GMT FROM: Kasper Elm Heintz at Univ. of Iceland and DAWN/NBI Kasper E. Heintz (Univ. of Iceland, DAWN/NBI), Johan P. U. Fynbo (DAWN/NBI), and Tapio Pursimo (NOT), report on behalf of a larger collaboration: We observed the field of the Swift/BAT-detected GRB 210321A (Dichiara et al., GCN #29677), using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Starting at 20:26:25.6 UTC on March 21, we obtained 3x300 sec exposures in the Sloan r-band. The observations were carried out under good conditions, with seeing around 0.8". We confirm the optical afterglow reported by Siegel et al. (GCN #29679), and measure r = 21.6 +/- 0.15 mag at 13.5 hr post-burst, calibrated against nearby field stars in the Pan-STARRS catalog. Following the imaging sequence, we obtained spectroscopy of the afterglow with ALFOSC using grism 4 (320 to 960 nm) and for 4x1200 sec total integration. A faint trace is detected but we do not identify any particular absorption or emission features to infer the redshift from. However, since the continuum is detected down to 380 nm, we put a limit on the redshift of z < 2.
GCN 29685 table
GRB_name GRB210321A
GCN_number 29685
Detection_method Other
redshift 1.4870
Circular_text TITLE: GCN CIRCULAR NUMBER: 29685 SUBJECT: GRB 210321A: Redshift from OSIRIS/GTC DATE: 21/03/21 22:57:51 GMT FROM: Antonio de Ugarte Postigo at IAA-CSIC A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D.A. Kann, C. Thoene, M. Blazek, J.F. Agui Fernandez (all HETH/IAA-CSIC), S. Geier (GTC, IAC), A. Tejero (GTC) report: We observed the afterglow of GRB 210321A (Dichiara et al. GCN 29677; Perri et al. GCN 29678; Siegel et al. GCN 29679; Butler et al. GCN 29680; Heintz et al. GCN 29684) with OSIRIS at the 10.4m GTC telescope at Roque de los Muchachos Observatory, in La Palma (Spain). The observation started at 20:28 UT (0.5517 days after the burst), and consisted in 3x900s with grism R1000B, covering the spectral range from 3700 to 7800 AA. The 30s acquisition image, with a seeing of 0.75“, shows the afterglow at a magnitude of r’ = 21.39+/-0.03, using a nearby PanSTARRS field star as photometric reference. The spectral continuum is well detected above 3900 AA, and shows very weak lines consistent with several features of FeII, MgII and MgI at a common redshift of z = 1.487, which we assume to be the likely redshift of the GRB. However, we note that strictly speaking this would be a lower limit, with the upper limit being z ~< 2, as already noted by the NOT spectroscopy (Heintz et al. GCN 29684).
GCN 29686 table
GRB_name GRB210321A
GCN_number 29686
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 29686 SUBJECT: GRB 210321A: Swift-XRT refined Analysis DATE: 21/03/21 23:16:40 GMT FROM: Phil Evans at U of Leicester K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU) and S. Dichiara report on behalf of the Swift-XRT team: We have analysed 6.7 ks of XRT data for GRB 210321A (Dichiara et al. GCN Circ. 29677), from 2.7 ks to 44.2 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 29681). The light curve can be modelled with a power-law decay with a decay index of alpha=1.59 (+0.13, -0.11). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.99 (+0.20, -0.19). The best-fitting absorption column is 2.3 (+0.8, -0.7) x 10^21 cm^-2, in excess of the Galactic value of 1.1 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.3 (+0.8, -0.7) x 10^21 cm^-2 Galactic foreground: 1.1 x 10^21 cm^-2 Excess significance: 2.9 sigma Photon index: 1.99 (+0.20, -0.19) If the light curve continues to decay with a power-law decay index of 1.59, the count rate at T+24 hours will be 2.2 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.0 x 10^-14 (1.1 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/01037828. This circular is an official product of the Swift-XRT team.
GCN 29687 table
GRB_name GRB210321A
GCN_number 29687
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 29687 SUBJECT: GRB 210321A: Xinglong GWAC-F60A optical observation DATE: 21/03/22 03:41:33 GMT FROM: Liping Xin at NAOC, SVOM L. P. Xin(NAOC), C. Gao(GXU), X. H. Han(NAOC), J. Y. Wei(NAOC), J. Wang(GXU), G. W. LI(NAOC), L. H. Li(NAOC), C. Wu(NAOC), X. G. Wang(GXU), E. W. Liang (GXU), Y. L. Qiu(NAOC), and J. S. Deng(NAOC) report: We began to observe GRB 210321A (Dichiara et al. GCN 29677; Perri et al. GCN 29678; Siegel et al. GCN 29679; Butler et al. GCN 29680; Heintz et al. GCN 29684; Ugarte Postigo et al., GCN 29685) with Xinglong GWAC-F60A telescope, China, at 11:30:49 (UT), 21th. Mar. 2021, about 4.28 hours after the burst. A series of R, I images were obtained. The optical counterpart ( Siegel et al. GCN 29679; Butler et al. GCN 29680; Heintz et al. GCN 29684; Ugarte Postigo et al., GCN 29685) was clearly detected in the stacked R-band image observed during 11:30:49 and 12:48:17 UT. The brightness was estimated to be 18.98 +/-0.13 mag at the mean time of 4.88 hours after the burst, calibrated to USNO B1.0 R2 mag, This result is consistent with the previous report (Zhu et al., GCN 29530).
GCN 29689 table
GRB_name GRB210321A
GCN_number 29689
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 29689 SUBJECT: GRB 210321A: Mondy optical observations DATE: 21/03/22 11:15:29 GMT FROM: Alexei Pozanenko at IKI, Moscow N. Pankov (HSE), A. Pozanenko (IKI), E. Klunko (ISTP), S. Belkin (IKI) report on behalf of GRB IKI FuN: We observed the field of GRB 210321A (Dichiara et al., GCN 29677) with AZT-33IK telescope of Sayan observatory (Mondy) starting on 2021-03-21 (UT) 14:20:37. The optical afterglow (Siegel et al., GCN 29679; Butler et al., GCN 29680; Lipunov et al., GCN 29683; Heintz et al., GCN 29684; de Ugarte Postigo et al., GCN 29685; Xin et al. GCN 29687) is clearly detected in a combined image. Preliminary photometry of the afterglow in the combined image is following Date UT start t-T0 Filter Exp. OT Err. UL(3sigma) (mid, days) (s) 2021-03-21 14:20:37 0.31199 R 45*60 20.1 0.14 20.5 The photometry is based on the nearby USNO-B1.0 stars USNO-B1.0_id R2 1601-0068003 15.84 1600-0068970 16.18 1601-0068018 16.54 1601-0067995 16.23
GCN 29691 table
GRB_name GRB210321A
GCN_number 29691
Detection_method Swift-BAT Det
ra 87.8870°
decl 70.1090°
Circular_text TITLE: GCN CIRCULAR NUMBER: 29691 SUBJECT: GRB 210321A: Swift-BAT refined analysis DATE: 21/03/22 18:12:52 GMT FROM: Hans Krimm at NSF/NASA-GSFC T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), S. Dichiara (NASA/GSFC/UMCP), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), (i.e. the Swift-BAT team): Using the data set from T-240 to T+700 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210321A (trigger #1037828) (Dichiara, et al., GCN Circ. 29677). The BAT ground-calculated position is RA, Dec = 87.887, 70.109 deg which is RA(J2000) = 05h 51m 32.8s Dec(J2000) = +70d 06' 33.4" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 30%. The mask-weighted light curve shows a single, fairly symmetrical peak from approximately T-8 to T+4 sec. T90 (15-350 keV) is 8.21 +- 0.50 sec (estimated error including systematics). The time-averaged spectrum from T-7.00 to T+1.84 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.15 +- 0.20. The fluence in the 15-150 keV band is 6.7 +- 0.8 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-6.99 sec in the 15-150 keV band is 1.7 +- 0.4 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/1037828/BA/
GCN 29692 table
GRB_name GRB210321A
GCN_number 29692
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 29692 SUBJECT: GRB 210321A: CrAO optical upper limit DATE: 21/03/22 19:02:33 GMT FROM: Alexei Pozanenko at IKI, Moscow N. Pankov (HSE), S. Nazarov (CrAO), A. Pozanenko (IKI), S. Belkin (IKI) report on behalf of GRB IKI FuN: We observed the field of GRB 210321A (Dichiara et al., GCN 29677) with AZT-8 telescope of CrAO observatory starting on 2021-03-21 (UT) 19:04:11. The optical afterglow (Siegel et al., GCN 29679; Butler et al., GCN 29680; Lipunov et al., GCN 29683; Heintz et al., GCN 29684; de Ugarte Postigo et al., GCN 29685; Xin et al. GCN 29687; Pankov et al., GCN 29689) is not detected in a combined image. Preliminary photometry of the field is following Date UT start t-T0 Filter Exp. OT Err. UL(3sigma) (mid, days) (s) 2021-03-21 19:04:11 0.51238 R 55*60 n/d n/d 20.8 The photometry is based on the nearby USNO-B1.0 stars USNO-B1.0_id R2 1601-0068003 15.84 1600-0068970 16.18 1601-0068018 16.54 1601-0067995 16.23
GCN 29694 table
GRB_name GRB210321A
GCN_number 29694
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 29694 SUBJECT: GRB 210321A: DDOTI Position Correction DATE: 21/03/22 19:42:51 GMT FROM: Nat Butler at Az State U The afterglow position quoted by Butler et al. (GCN 29680) was typed incorrectly. The correct position is 05:51:34.82, +70:07:50.4 (J2000).
GCN 29696 table
GRB_name GRB210321A
GCN_number 29696
Detection_method Konus-Wind Det
t_trigger 7:13:51.023 UTC
redshift 1.4870
Circular_text TITLE: GCN CIRCULAR NUMBER: 29696 SUBJECT: Konus-Wind detection of GRB 210321A DATE: 21/03/23 12:37:30 GMT FROM: Dmitry Frederiks at Ioffe Institute D. Frederiks, S. Golenetskii, A.Lysenko, D. Svinkin, A. Ridnaya, A. Tsvetkova, M. Ulanov, and T. Cline, report: The long GRB 210321A (Swift-BAT trigger #1037828, T0(BAT)= 07:13:51.023 UT: Dichiara, et al., GCN 29677; Ukwatta, et al., GCN 29691) was detected by Konus-Wind (KW) in the waiting mode. A Bayesian block analysis of the KW waiting mode data in the 20-400 keV band reveals a ~10 sigma count rate increase over background in the interval from ~T0(BAT)-6.430 s to ~T0(BAT)+2.402 s. A fit to the KW 3-cannel waiting mode spectrum with by a power law with an exponential cutoff (CPL) yields alpha~-2 and doesn't constrain Ep. A fit with a simple power law (PL) gives a photon index of (2.19 ± 0.17), chi^2 = 0.78/ 1 dof. This result is consistent with the Swift-BAT refined analysis (GCN 29691). In the 10 keV-10 MeV band, standard for the KW spectral analysis, the total burst fluence, estimated from the PL model, is (1.6 ± 0.3)x10^-6 erg/cm^2, and the 2.944 s peak energy flux is (2.2 ± 0.4)x10^-7 erg/cm^2. Assuming the redshift z=1.487 (de Ugarte Postigo, et al., GCN 29685) and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the burst isotropic energy release E_iso to ~9.7x10^51 erg and the isotropic luminosity L_iso to ~3.2x10^51 erg/s. The KW light curve of this burst is available at http://www.ioffe.ru/LEA/GRBs/GRB210321A/
GCN 29697 table
GRB_name GRB210321A
GCN_number 29697
Detection_method Swift-UVOT Det
ra 87.8948°
decl 70.1305°
Circular_text TITLE: GCN CIRCULAR NUMBER: 29697 SUBJECT: GRB 210321A: Swift/UVOT Detection DATE: 21/03/23 14:17:59 GMT FROM: Sam LaPorte at PSU GRB 210321A: Swift/UVOT Detection S. J. Laporte (PSU) and S. Dichiara (NASA/GSFC/UMCP) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 210321A 2735 s after the BAT trigger (Dichiara et al., GCN Circ. 29677). A source consistent with the XRT position (Beardmore et al. GCN Circ. 29681) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 05:51:34.75 = 87.89479 (deg.) Dec (J2000) = +70:07:49.8 = 70.13051 (deg.) with an estimated uncertainty of 0.49 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 2735 2885 147 18.69 +/- 0.09 v 2892 4465 331 18.44 +/- 0.16 b 3713 3913 197 18.64 +/- 0.11 u 3507 3706 197 18.29 +/- 0.12 w1 3302 3502 197 18.48 +/- 0.17 m2 3097 3296 197 >18.9 w2 4124 4324 197 >19.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.118 in the direction of the burst (Schlegel et al. 1998).
GCN 29725 table
GRB_name GRB210321A
GCN_number 29725
Detection_method Swift Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 29725 SUBJECT: GRB 210321A: OSN Upper Limit DATE: 21/03/24 23:41:30 GMT FROM: Alexander Kann at IAA-CSIC D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. C. Thoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC), and F. Aceituno (IAA-CSIC) report: We observed the optical afterglow (Perri et al. GCN #29678; Siegel et al. GCN #29679; Butler et al. GCN #29680; Heintz et al. GCN #29684; Xin et al., GCN #29687; Pankov et al., GCNs #29689, #29692; Laporte et al., GCN #29697) of GRB 210321A (Swift detection: Dichiara et al., GCN #29677) with the 1.5m T150 telescope of the Observatorio de Sierra Nevada (OSN), Granada, Spain. Observations could not be taken due to high winds in the first night after the GRB. We obtained 11 x 180 s exposures in Rc starting at 2021-03-22 19:59:44.93 UT, before high winds shut the telescope down again. The afterglow is not detected in the combined image. We determine an upper limit Rc > 23.3 mag (AB mag, vs. a nearby Pan-STARRS star converted to Rc following the Lupton transformations, then transformed back to AB mag) at 1.5437 days after the GRB.