GRB201024A

This page lists all entries on GRB201024A in GRBweb

Summary IPN Swift GCN 28760 GCN 28761 GCN 28762 GCN 28763 GCN 28764 GCN 28766 GCN 28770 GCN 28771 GCN 28774 GCN 28775 GCN 28777 GCN 28778 GCN 28779 GCN 28780 GCN 28782

Summary table
Variable Value Source
T0 2:48:59 UTC GCN_circulars,Swift Det
ra 125.9523° Swift
decl 3.3540° Swift
pos_error 8.03e-05° Swift
T90 5.0 s Swift
T90_start 2:48:59 UTC Swift
fluence 8.10e-07 erg/cm² Swift
redshift 0.9990 GCN_circulars,Other
T100 5.0 s
GBM_located False
mjd 59146.11734953704 GCN_circulars,Swift Det
IPN table
GRB_name GRB201024A
ra 125.9458°
decl 3.3833°
pos_error 5.00e-02°
redshift 0.9990
Swift table
GRB_name GRB201024A
t_trigger 2:48:59 UTC
ra 125.9523°
decl 3.3540°
pos_error 8.03e-05°
T90 5.0 s
fluence 8.10e-07 erg/cm²
redshift 0.9990
GCN 28760 table
GRB_name GRB201024A
GCN_number 28760
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 28760 SUBJECT: Swift GRB201024A: Global MASTER-Net OT detection DATE: 20/10/24 03:09:25 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, N.Tyurina, E. Gorbovskoy, V.Kornilov, 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. 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), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB201024A (trigger 1001514) 36 sec after notice time and 66 sec after trigger time at 2020-10-24 02:51:20 UT. On our first (10s exposure) set we found 1 optical transient within Swift error-box (ra=125.95 dec=3.35444 r=0.05) brighter than 16.5. T-Tmid Date Time Expt. Ra Dec Mag ---------|---------------------|-------|-----------------|-----------------|----- 229 2020-09-25 21:54:16 40 (08h 23m 48.58s, +03d 21m 13.8s) 14.9 The 5-sigma upper limit has been about 17mag The message may be cited.
GCN 28761 table
GRB_name GRB201024A
GCN_number 28761
Detection_method Swift Det
t_trigger 2:48:59 UTC
ra 125.9480°
decl 3.3770°
Circular_text TITLE: GCN CIRCULAR NUMBER: 28761 SUBJECT: GRB 201024A: Swift detection of a burst with an optical afterglow DATE: 20/10/24 03:10:12 GMT FROM: David Palmer at LANL F. E. Marshall (NASA/GSFC), M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), J.D. Gropp (PSU), N. J. Klingler (PSU), N. P. M. Kuin (UCL-MSSL), S. Laha (GSFC/UMBC/CRESST), A. Melandri (INAF-OAB), D. M. Palmer (LANL), T. Sbarrato (INAF-OAB) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team: At 02:48:59 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 201024A (trigger=1001514). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 125.948, +3.377 which is RA(J2000) = 08h 23m 47s Dec(J2000) = +03d 22' 38" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak structure with a duration of about 5 sec. The peak count rate was ~1200 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 02:50:14.0 UT, 74.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source with an enhanced position: RA, Dec 125.9521, 3.3537 which is equivalent to: RA(J2000) = 08h 23m 48.50s Dec(J2000) = +03d 21' 13.4" with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 85 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 consistent with the Galactic value of 3.64 x 10^20 cm^-2 (Willingale et al. 2013). The initial flux in the 2.5 s image was 6.41e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 495 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 08:23:48.55 = 125.95229 DEC(J2000) = +03:21:14.5 = 3.35403 with a 90%-confidence error radius of about 0.62 arc sec. This position is 0.7 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.85 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03. Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.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/)
GCN 28762 table
GRB_name GRB201024A
GCN_number 28762
Detection_method correction
Circular_text TITLE: GCN CIRCULAR NUMBER: 28762 SUBJECT: GRB 201024A: MASTER correction to GCN 28760 DATE: 20/10/24 03:18:40 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs Due to a typo, the OT datetime data in the table(GCN 28760) was wrong Here are the correct values T-Tmid Date Time Expt. Ra Dec Mag ---------|---------------------|-------|-----------------|-----------------|----- 66 2020-10-24 02:51:20 10 (08h 23m 48.58s, +03d 21m 13.8s) 14.9 The OT position is coincident with UVOT and XRT position. The afterglow appears to be fading rapidly.
GCN 28763 table
GRB_name GRB201024A
GCN_number 28763
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 28763 SUBJECT: GRB 201024A: BOOTES-2/TELMA early optical observation and 1.5m OSN follow-up DATE: 20/10/24 04:10:24 GMT FROM: Youdong HU at IAA-CSIC E. Fernandez-Garcia, Y.-D. Hu, A. J. Castro-Tirado, A. Sota (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), R. Fernandez-Munoz (IHSM/UMA-CSIC), M.D. Caballero-Garcia and M. Jelinek (ASU-CAS), on behalf of a larger collaboration, report: The 0.6m BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain) automatically responded to the Swift trigger of GRB 201024A (Marshall et al. GCNC 28761). A series of images were taken starting on Oct 24 at Oct 02:50:07 UT (~68 s after trigger). A bright optical source is detected on the first image (10s, clear filter) with r= 14.1 mag, at a position consistent with the optical afterglow reported by UVOT/Swift (Marshall et al. GCNC 28761) and MASTER (Lipunov et al. GCNC 28760). Furthermore, from a deeper image gathered at the 1.5m OSN telescope in Observatorio de Sierra Nevada at 03:16 UT we measure R = 18.9, thus confirming the rapid fading of the optical afterglow brightness as pointed out on GCNC 28762. Additional observations are ongoing. We thank the staff at La Mayora and OSN for their excellent support.
GCN 28764 table
GRB_name GRB201024A
GCN_number 28764
Detection_method Other
redshift 0.9990
Circular_text TITLE: GCN CIRCULAR NUMBER: 28764 SUBJECT: GRB 201024A: Redshift from GTC/OSIRIS DATE: 20/10/24 04:28:55 GMT FROM: Alexander Kann at IAA-CSIC A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann, M. Blazek, J. F. Agui Fernandez, C. C. Thoene (all HETH/IAA-CSIC), S. Geier, and M. Rivero (both GRANTECAN) report: We observed the afterglow (Lipunov et al., GCN#28760, Marshall et al., GCN#28761, Fernandez-Garcia et al., GCN#28763) of GRB 201024A (Marshall et al., GCN#28761) with the 10.4m GTC telescope, at Roque de los Muchachos Observatory (La Palma, Spain) equipped with OSIRIS. The observation started on 24 October 2020 at 03:28:47 UT (0.663 hrs after the GRB onset) and consisted of 3 x 900 s with the R1000B grism, covering the wavelength range between 3700 and 7800 AA. Observations were taken under good conditions but high airmass. At the afterglow position, a clear source is detected. We measure r' ~ 19.3 mag (AB) vs. nearby PanSTARRS field stars. This indicates the source has faded rapidly vs. the early MASTER/BOOTES detection, as Lipunov et al., GCN#28760 and Fernandez-Garcia et al., GCN#28763 stated. A preliminary reduction of the spectrum shows a clear continuum, with MnII, FeII, FeII*, MgII, and MgI absorption lines, as well as the [OII] doublet in emission, all at a common redshift of z = 0.999, which we identify as the redshift of the GRB. We furthermore note that there is an underlying galaxy at the OT position visible in SDSS and PanSTARRS, at r ~ 21.15 mag. We also see a second galaxy offset by a few arcsec in our finding chart. We thank P. D'Avanzo and L. Izzo for pointing out the galaxy.
GCN 28766 table
GRB_name GRB201024A
GCN_number 28766
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 28766 SUBJECT: GRB 201024A: FRAM-ORM afterglow detection DATE: 20/10/24 08:56:09 GMT FROM: Martin Jelinek at Astro.Inst-AVCR,Ondrejov Martin Jelinek and Jan Strobl (ASU CAS Ondrejov, CZ), Sergey Karpov, Martin Masek, Petr Janecek, Jakub Jurysek, Jan Ebr, Ronan Cunniffe, Petr Travnicek and Michael Prouza (Institute of Physics, Prague, CZ) report: The 25cm robotic telescope FRAM-ORM at La Palma (Spain) reacted robotically to the alert of GRB201024A (Marshall et al GCNC 28761), obtaining a series of 20 s unfiltered images starting at 02:49:34.4 UT, i.e. 35.3s post trigger. We clearly detect the source reported by other telescopes (Lipunov et al. GCN 28760, Fernandez-Garcia et al. GCN 28763, de Ugarte Postigo et al GCN 28764 and others). As reported before, the brightness of the object reaches a maximum of about R(Vega) = 14.0 and then decays relatively steeply with a power law index alpha = ~1.5.
GCN 28770 table
GRB_name GRB201024A
GCN_number 28770
Detection_method Swift-XRT Det
ra 125.9522°
decl 3.3544°
Circular_text TITLE: GCN CIRCULAR NUMBER: 28770 SUBJECT: GRB 201024A: Enhanced Swift-XRT position DATE: 20/10/24 11:13:17 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 890 s of XRT Photon Counting mode data and 3 UVOT images for GRB 201024A, 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 = 125.95224, +3.35444 which is equivalent to: RA (J2000): 08h 23m 48.54s Dec (J2000): +03d 21' 16.0" with an uncertainty of 2.7 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 28771 table
GRB_name GRB201024A
GCN_number 28771
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 28771 SUBJECT: GRB 201024A: VIRT optical observations DATE: 20/10/24 15:49:18 GMT FROM: Priyadarshini Gokuldass at U. of the Virgin Islands P. Gokuldass (UVI), R. Strausbaugh (UVI), N. Orange (OrangeWave Innovative Science, LLC), D. Morris (UVI), A. Cucchiara (UVI/College of Marin) report: We observed the field of GRB201024A (F. E. Marchall et al., GCN 28761) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 10-24-2020 starting at 06:39:34.2 UT (T+3.3 hrs). We performed a series of exposures in R filter with a total exposure of 1430 s. The weather conditions were partly cloudy during the hours of observation with an average arimass of 1.5. We find no new source within the enhanced XRT position error circle (P. A. Evans et al., 28770) and report the following 3-sigma upper limit: T_mid ||Exposure ||Filter ||Limit T+ 5 hrs ||1430s ||R ||>18.9 The limit is estimated from comparison to nearby USNO B1 stars and is not corrected for Galactic extinction. The VIRT is still in the commissioning phase. This work is supported by NASA-MUREP-MIRO grant NNX15AP95A, NSF EiR AST Award 1901296, and NSF HBCU-UP AST Award 1831682. This message can be cited.
GCN 28774 table
GRB_name GRB201024A
GCN_number 28774
Detection_method Swift-UVOT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 28774 SUBJECT: GRB 201024A: Swift/UVOT Detection DATE: 20/10/25 00:02:46 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 201024A 495 s after the BAT trigger (Marshall et al., GCN Circ. 28761). A source consistent with the XRT position (Evans et al. GCN Circ. 28770) is detected in the initial UVOT exposures. 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 495 645 148 17.94 +/- 0.05 v 653 845 39 17.39 +/- 0.30 b 750 1348 58 18.65 +/- 0.32 u 726 1151 39 17.86 +/- 0.29 w1 702 1471 78 17.46 +/- 0.30 m2 677 2140 117 >18.4 w2 801 2091 117 >17.7 The observations show a rapid decay as reported by MASTER (Lipunov et al, GCN Circ. No. 28762). The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).
GCN 28775 table
GRB_name GRB201024A
GCN_number 28775
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 28775 SUBJECT: GRB 201024A: Swift-XRT refined Analysis DATE: 20/10/25 01:18:16 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), J. D. Gropp (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto) and F.E. Marshall report on behalf of the Swift-XRT team: We have analysed 6.0 ks of XRT data for GRB 201024A (Marshall et al. GCN Circ. 28761), from 450 s to 48.0 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 28770). The light curve can be modelled with a power-law decay with a decay index of alpha=0.98 (+0.07, -0.06). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.08 (+0.19, -0.18). The best-fitting absorption column is 1.7 (+0.6, -0.5) x 10^21 cm^-2, in excess of the Galactic value of 3.6 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 3.3 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.7 (+0.6, -0.5) x 10^21 cm^-2 Galactic foreground: 3.6 x 10^20 cm^-2 Excess significance: 4.1 sigma Photon index: 2.08 (+0.19, -0.18) If the light curve continues to decay with a power-law decay index of 0.98, the count rate at T+24 hours will be 5.7 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x 10^-13 (2.6 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/01001514. This circular is an official product of the Swift-XRT team.
GCN 28777 table
GRB_name GRB201024A
GCN_number 28777
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 28777 SUBJECT: GRB201024A: rebrightening after initial steep decline DATE: 20/10/25 15:33:11 GMT FROM: Paul Kuin at MSSL Paul Kuin (UCL/MSSL) reports on behalf of the Swift UVOT Team: We now have the light curve of GRB 201024A in the seven UVOT filters from the start of our observations T0+495s until T0+100ks. After a steep decline a rebrightening is seen starting around T0+1400s which then peaks between 20 and 70 ks.
GCN 28778 table
GRB_name GRB201024A
GCN_number 28778
Detection_method Swift-BAT Det
ra 125.9590°
decl 3.3570°
Circular_text TITLE: GCN CIRCULAR NUMBER: 28778 SUBJECT: GRB 201024A: Swift-BAT refined analysis DATE: 20/10/25 23:46:04 GMT FROM: Sibasish Laha at GSFC T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), F. E. Marshall (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+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 201024A (trigger #1001514) (F. E. Marshall et al., GCN Circ. 28761). The BAT ground-calculated position is RA, Dec = 125.959, 3.357 deg which is RA(J2000) = 08h 23m 50.3s Dec(J2000) = +03d 21' 24.6" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 22%. The BAT light curve showed a single peak structure with a duration of about 6 sec. T90 (15-350 keV) is 5.00 +- 2.24 sec (estimated error including systematics). The time-averaged spectrum from T+0.01 to T+6.01 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.10 +- 0.18. The fluence in the 15-150 keV band is 8.1 +- 0.9 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+1.01 sec in the 15-150 keV band is 3.7 +- 0.6 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/1001514/BA/
GCN 28779 table
GRB_name GRB201024A
GCN_number 28779
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 28779 SUBJECT: GRB 201024A: MITSuME Akeno optical upper limits DATE: 20/10/26 09:38:09 GMT FROM: Katsuhiro L. Murata at Nagoya U M. Niwano, K. L. Murata, R. Hosokawa, R. Adachi, F. Ogawa, N. Nakamura, N. Ito, S. Ogata, H. Takamatsu, H. Hara, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration: We observed the field of GRB 201024A (F. E. Marshall et al.,GCN Circular #28761) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. We observed for two nights. The observation with a series of 60 sec exposures started at 2020-10-24 16:04:04UT for the first night and 2020-10-25 15:56:17UT for the second night. We stacked the images with good conditions each night. We did not detect the point source reported by other telescopes (Lipunov et al. GCN Circular #28760, Fernandez-Garcia et al. #28763, de Ugarte Postigo et al. #28764, Martin Jelinek et al. #28766). We obtained the 5-sigma limits of the stacked images as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits ------------------------------------------------------------------------------------------------ 13.78 2020-10-24T18:27:11 11520 g'>20.2, Rc>20.4, Ic>19.7 38.48 2020-10-25T17:17:59 1980 g'>19.4, Rc>19.6, Ic>18.8 ------------------------------------------------------------------------------------------------ T0+: Elapsed time after the burst T-EXP: Total Exposure time We used the PS1 catalog for flux calibration. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al., accepted for publication in PASJ, https://arxiv.org/abs/2008.11486; https://github.com/MNiwano/Eclaire).
GCN 28780 table
GRB_name GRB201024A
GCN_number 28780
Detection_method correction
Circular_text TITLE: GCN CIRCULAR NUMBER: 28780 SUBJECT: GRB201024A: correction to GCN28777 - there was no rebrightening DATE: 20/10/26 11:23:46 GMT FROM: Paul Kuin at MSSL Paul Kuin (UCL/MSSLL) reports: Due to an incorrect background subtraction in the later exposures of GRB201024A, an incorrect 'rebrightening' was found in the Swift-UVOT photometry. In actuality the source had faded away. My sincere apologies if this has caused any problems.
GCN 28782 table
GRB_name GRB201024A
GCN_number 28782
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 28782 SUBJECT: GRB 201024A: 1.3m DFOT optical observations DATE: 20/10/26 20:10:16 GMT FROM: Rahul Gupta at ARIES, India Rahul Gupta (ARIES), Amit Kumar (ARIES), Dimple (ARIES), Ankur Ghosh (ARIES), Amar Aryan (ARIES), Shashi B. Pandey (ARIES), and Kuntal Misra (ARIES) report: We observed the optical afterglow ( Lipunov et al., GCN 28760; Marshall et al., GCN 28761; Fernandez-Garcia et al., GCN 28763; de Ugarte Postigo et al., GCN 28764; Jelinek et al., GCN 28766; and Kuin et al., GCN 28774 ) of Swift triggered GRB 201024A (Marshall et al., GCN 28761) using the 1.3m Devasthal Fast Optical Telescope (DFOT) at Devasthal observatory of Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2020-10-24 at 21:03:09 UT . Multiple frames having an exposure time of 120 s were taken in R and I filters. We clearly detected the optical counterpart in the stacked images. The preliminary photometric estimate of the afterglow in the stacked images is the following : Date Start_UT T_start-T0 (hrs) Filter Exp time (s) Magnitude Mag_err ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------------------------ 2020-10-24 21:03:09 18.24 I 30*120 20.12 0.07 ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------------------------ The magnitude is not corrected for the Galactic and Host extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalog. This circular may be cited.