//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27172 SUBJECT: Swift GRB200224.14: Global MASTER-Net observations report DATE: 20/02/24 03:34:37 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs 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), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), 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 GRB200224.14 (trigger No 958141,16h 35m 10.56s , +41d 40m 30.0s, R=0.05) errorbox 17 sec after notice time and 90 sec after trigger time at 2020-02-24 03:26:19 UT, with upper limit up to 13.8 mag. Observations started at twilight. The observations began at zenith distance = 2 deg. The sun altitude is -6.3 deg. The galactic latitude b = 42 deg., longitude l = 66 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1295946 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 95 | MASTER-Kislovodsk | P- | 10 | 13.8 | 95 | MASTER-Kislovodsk | P| | 10 | 13.0 | The observation and reduction will continue. The message may be cited. [GCN OPS NOTE(24feb20): This is the beginning Circular in the sequence of 8 circulars which were all labeled A because of the sequence assigner being offline. In particular, this circular is using the .dd fractional time format instead of the letter A, but the A is equivalent for this event.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27173 SUBJECT: GRB 200224A: Swift detection of a burst DATE: 20/02/24 03:41:23 GMT FROM: David Palmer at LANL T. N. Ukwatta (LANL), E. Ambrosi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), J. A. Kennea (PSU), N. J. Klingler (PSU), S. Laha (GSFC/UMBC/CRESST), A. Y. Lien (GSFC/UMBC) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 03:24:49 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 200224A (trigger=958141). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 248.794, +41.675 which is RA(J2000) = 16h 35m 11s Dec(J2000) = +41d 40' 31" 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 30 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~3 sec after the trigger. The XRT began observing the field at 03:26:26.9 UT, 97.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 248.7668, 41.6123 which is equivalent to: RA(J2000) = 16h 35m 04.04s Dec(J2000) = +41d 36' 44.1" with an uncertainty of 2.9 arcseconds (radius, 90% containment). This location is 237 arcseconds from the BAT onboard position. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 8.91 x 10^19 cm^-2 (Willingale et al. 2013). UVOT results will be reported later. Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta AT gmail.com). 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 OPS NOTE(24feb20): This is the second Circular in the sequence of 8 circulars which were all labeled A because of the sequence assigner being offline. This circular was correctly labelled A.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27176 SUBJECT: GRB 200224A: BOOTES-1 and 1.5m OSN optical observations DATE: 20/02/24 06:37:24 GMT FROM: Alberto J. Castro-Tirado at IAA-CSIC A. Sota, E. Fernandez-Garcia, Y.-D. Hu and A. J. Castro-Tirado (IAA-CSIC), A. Castellon, I. Carrasco-Garcia and C. Perez del Pulgar (UMA), on behalf of a larger collaboration, report: Following the detection of GRB 200224A by Swift (Ukwatta  et al., GCNC 27173), the 0.3cm robotic telescope at the BOOTES-1 astronomical station at INTA-CEDEA in Huelva (Spain) started gathering images at 03:26:27 UT, 40s after the alert and 118s after the onset of the burst. No optical transient is detected in the single images with a limiting magnitude of 14 (consistent with the MASTER upper limit, Lipunov et al., GCNC 27172). Further data reduction is ongoing. Deeper exposures were obtained with the 1.5m telescope at Observatorio de Sierra Nevada starting at 05:35 UT (i.e. 2.1 h post burst).  We find an optical source consistent with the Swift/XRT position,  at coordinates (RA & Dec, J2000)  = 16:35:04.11 +41:36:42 (+/- 1”). The preliminary magnitude is R = 22. Further observations are planned to confirm whether this is the optical afterglow to GRB 200224A. This message can be quoted. [GCN OPS NOTE(24feb20): This is the fifth Circular in the sequence of 8 circulars which were all labeled A because of the sequence assigner being offline. This circular was correctly labelled A.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27177 SUBJECT: GRB 200224A: Tautenburg observations DATE: 20/02/24 07:37:12 GMT FROM: Sylvio Klose at TLS Tautenburg B. Stecklum, S. Klose, A. Nicuesa Guelbenzu, and S. Melnikov (all Tautenburg) report: We observed the field of GRB 200224A (T0=03:24:49 UT; Ukwatta et al., GCN 27173) with the Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6k x 6k CCD camera and the wide V-band filter (VB). The transmission curve of this filter closely follows the Gaia GBP filter. Observations started at 04:09:53 UT and consisted of 5x3 min exposures. Based on several Gaia DR2 stars in the field within 1 arcmin radius about the afterglow position, we measure for the optical transient (Sota et al., GCN 27176) at RA, DEC (J2000) = 16:35:04.11, +41:36:42.4 (+/- 0.5 arcsec) the following preliminary Vega magnitude: mean time t = Feb 24, 04:18:01 UT; t-T0 = 53m 12s; VB = 21.83 +/- 0.10. [GCN OPS NOTE(24feb20): This is the sixth Circular in the sequence of 8 circulars which were all labeled A because of the sequence assigner being offline. This circular was correctly labelled A.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27179 SUBJECT: GRB 200224A: Swift-XRT refined Analysis DATE: 20/02/24 16:21:20 GMT FROM: Phil Evans at U of Leicester J. D. Gropp (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), A. Tohuvavohu (U. Toronto), and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team: We have analysed 12 ks of XRT data for the Swift-detected burst GRB 200224A, from 105 s to 34.0 ks after the Swift trigger. The data are entirely in Photon Counting (PC) mode. Using 4055 s of PC mode data and 4 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 248.76655, +41.61133 which is equivalent to: RA (J2000): 16h 35m 03.97s Dec(J2000): +41d 36' 40.8" with an uncertainty of 1.7 arcsec (radius, 90% confidence). This position is 4.0 arcmin from the Swift position. The light curve can be modelled with a power-law decay with a decay index of alpha=0.86 (+0.10, -0.09). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.09 (+0.39, -0.29). The best-fitting absorption column is 3.2 (+7.4, -2.3) x 10^20 cm^-2, consistent with the Galactic value of 8.9 x 10^19 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.0 x 10^-11 (3.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.2 (+7.4, -2.3) x 10^20 cm^-2 Galactic foreground: 8.9 x 10^19 cm^-2 Excess significance: <1.6 sigma Photon index: 2.09 (+0.39, -0.29) If the light curve continues to decay with a power-law decay index of 0.86, the count rate at T+24 hours will be 9.9 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x 10^-14 (3.3 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00958141. This circular is an official product of the Swift-XRT team. [GCN OPS NOTE(24feb20): This is the eighth Circular in the sequence of 8 circulars which were all labeled A because of the sequence assigner being offline. This circular was correctly labelled A.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27182 SUBJECT: GRB 200224A: Swift/UVOT Detection DATE: 20/02/24 21:40:15 GMT FROM: Frank Marshall at Swift/UVOT F. E. Marshall (NASA/GSFC) and T. N. Ukwatta (LANL) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 200224A 101 s after the BAT trigger (Ukwatta et al., GCN Circ. 27173). A source consistent with the enhanced XRT position (Gropp et al., GCNC 27179) and the optical positions reported by Sota et al. (GCNC 27176) and Stecklum et al. (GCNC 27177) is detected in the initial UVOT exposures. The source is very close to the edge of the image in the first exposure at 101 s after the BAT trigger, and further analysis is required to determine an accurate intensity for that exposure. The preliminary UVOT position is: RA (J2000) = 16:35:04.14 = 248.76727 (deg.) Dec (J2000) = +41:36:42.3 = 41.61174 (deg.) with an estimated uncertainty of 0.43 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 u 259 509 246 18.75 +/- 0.10 white 861 1011 147 20.57 +/- 0.20 w1 5978 19265 1098 >20.7 m2 5772 18542 1279 >21.4 w2 5363 30092 1953 >21.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.005 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27189 SUBJECT: GRB 200224A: RATIR Optical Observations and Confirmation of the Afterglow DATE: 20/02/25 00:49:46 GMT FROM: Rosa Leticia Becerra Godinez at Inst. de Astronoma,UNAM Rosa L. Becerra (UNAM), Margarita Pereyra (UNAM), Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report: We observed the field of GRB 200224A (Palmer D., et al., GCN 27173) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2020/02 24.36 to 2020/02 24.54 UTC (5.33 to 9.66 hours after the BAT trigger), obtaining a total of 3.44 hours exposure in the r and i bands. For a source within the Swift-XRT error circle, in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following upper limits (3-sigma): r > 23.88 i > 23.84 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. Castro-Tirado et al. (GCN 27176) and Stecklum et al. (GCN 27177) report an afterglow candidate at roughly magnitude 22 at about 1 and 2 hours after the burst. Our observations show subsequent fading of this source and confirm that it is the afterglow. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27191 SUBJECT: GRB 200224A: LCO Upper Limits DATE: 20/02/25 04:02:07 GMT FROM: Robert Strausbaugh at U. of the Virgin Islands R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration: We observed Swift GRB 200224A (Ukwatta et al., GCN 27173) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on February 24, from 12:01 to 12:18 UT (corresponding to 8.62 to 8.90 hours from the GRB trigger time) with the Bessel I and R filters. We performed a series of 5x120s exposures in I and 3x120s in R. We do not detect any sources in the individual frames (nor in stacked images) in the Swift error region. Using the USNO-B.1 catalog as reference, we obtain the following 3-sigma upper limits: R > 19.85 I > 19.05 R.S. is funded by NSF AST grant #1831682 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27194 SUBJECT: GRB 200224A: Swift-BAT refined analysis DATE: 20/02/25 06:53:49 GMT FROM: Amy Lien at GSFC A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (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-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 200224A (trigger #958141) (Ukwatta et al., GCN Circ. 27173). The BAT ground-calculated position is RA, Dec = 248.743, 41.666 deg which is RA(J2000) = 16h 34m 58.4s Dec(J2000) = +41d 39' 57.2" with an uncertainty of 3.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a weak pulse from ~T0 to ~T+5 s, followed by some weaker emission that lasts till ~T+50 s. T90 (15-350 keV) is 45.0 +- 9.2 sec (estimated error including systematics). The time-averaged spectrum from T-0.79 to T+49.21 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.69 +- 0.51. The fluence in the 15-150 keV band is 2.9 +- 0.9 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+2.21 sec in the 15-150 keV band is 0.4 +- 0.1 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/958141/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27222 SUBJECT: GRB 200224A: Calar Alto 2.2m optical afterglow detection DATE: 20/02/26 10:47:39 GMT FROM: Alexander Kann at IAA-CSIC J. F. Agui Fernandez, M. Blazek, D. A. Kann (all HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. C. Thoene (HETH/IAA-CSIC), E. Gallego-Cano, and A. Guijarro (both CAHA) report: We observed the field of the Swift-detected GRB 200224A (Ukwatta et al., GCN #21173) with the 2.2m telescope at CAHA, Almeria, Spain. We obtained 5 x 120 s each in Rc and Ic. At the position of the optical afterglow reported by Sota et al. (GCN #27176), Stecklum et al. (GCN #21177), and Marshall & Ukwatta (GCN #27182), we clearly detect a source in each stack image. We measure Rc = 21.60 +/- 0.06 mag at 0.03702 days after the GRB, and Ic = 21.31 +/- 0.09 mag at 0.05794 days after the GRB (Vega magnitudes), in good agreement with the measurements of Tautenburg at an earlier time (GCN #27177) and OSN at a later time (GCN #27176). We note the optical afterglow is very faint (see also Becerra et al., GCN #27189), but the clear detection in u by Swift/UVOT (GCN #27182) as well as the blue Rc-Ic color we find indicates this GRB is neither at high redshift nor particularly extinguished (see also the XRT results, Gropp et al., GCN #27179), it is likely just intrinsically faint. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27240 SUBJECT: GRB 200224A: Mondy optical upper limit DATE: 20/02/27 16:28:46 GMT FROM: Alexei Pozanenko at IKI, Moscow S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We observed the field of GRB 200224A (Ukwatta et al., GCN 27173; Fermi GBM team GCN 27174) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Feb. 26 (UT) 17:24:49. We did not detect the optical afterglow (Sota et al., GCN 27176; Stecklum et al., GCN 27177; Marshall et al., GCN 27182; Becerra et al., GCN 27182; Fernandez et al., GCN 27222). Preliminary photometry of the field is following. Date UT start, t-T0 Filter Exp. OT UL(3sigma) (mid, days) (s) 2020-02-26 17:24:49 2.60348 R 29*120 n/d 22.6 Photometry is based on the USNO-B1.0 nearby stars.