//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26982 SUBJECT: GRB 200205A: Swift detection of a burst with a possible UV counterpart DATE: 20/02/05 07:14:19 GMT FROM: Kim Page at U.of Leicester P. A. Evans (U Leicester), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), K. K. Simpson (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team: At 06:35:51 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 200205A (trigger=954304). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 130.171, -35.245 which is RA(J2000) = 08h 40m 41s Dec(J2000) = -35d 14' 39" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual with an image trigger, the available BAT light curve shows no significant structure. The XRT began observing the field at 06:38:07.9 UT, 136.3 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 130.1717, -35.2715 which is equivalent to: RA(J2000) = 08h 40m 41.21s Dec(J2000) = -35d 16' 17.4" with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 95 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 3.00e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 250 seconds with the UVW2 filter starting 139 seconds after the BAT trigger. There is a possible UVOT counterpart close to the XRT position, but we cannot provide precise coordinates at this time. Burst Advocate for this burst is P. A. Evans (pae9 AT star.le.ac.uk). 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/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26983 SUBJECT: Swift GRB 200205A: Global MASTER-Net observations report DATE: 20/02/05 07:36:11 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB 200205A ( P. A. Evans et al., GCN 26982) errorbox 24 sec after notice time and 916 sec after trigger time at 2020-02-05 06:51:08 UT, with upper limit up to 18.9 mag. The observations began at zenith distance = 32 deg. The sun altitude is -34.4 deg. The galactic latitude b = 4 deg., longitude l = 257 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1278043 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 1007 | MASTER-OAFA | C | 180 | 18.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26984 SUBJECT: GRB 200205A: MASTER Ot detection DATE: 20/02/05 08:17:29 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, N.Tiurina, V.Kornilov, P.Balanutsa,A.Kuznetsov, V. Vladimirov, O.Gress, D. Vlasenko, F.Balakin, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D. Kuvshinov, V.Shumkov (Lomonosov Moscow State University, SAI, Physics Department), D. Buckley(South African Astronomical Observatory), R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), 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), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), V. Yurkov, A. Gabovich, Yu. Sergienko(Blagoveschensk Educational State University) MASTER Global Robotic Net (http://observ.pereplet.ru, Lipunov et al., 2010,Advances in Astronomy,v. 2010, 30L) observed Swift GRB 200205A (Evans et al. GCN 26982, Lipunov et al GCN 26983) MASTEr auto-detection system detected new variable OT MASTER OT J084040.87-351625.3 at RA,Dec2000= 08 40 40.87 -35 16 25.3 with m_OT=15.8 observation and reduction will be continued //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26985 SUBJECT: MAXI GRB200205.29: Global MASTER-Net observations report DATE: 20/02/05 08:34:08 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the MAXI GRB200205.29 (trigger No 884222838,08h 40m 11.04s , -35d 21m 43.2s, R=1) errorbox 8 sec after trigger time at 2020-02-05 06:54:39 UT, with upper limit up to 19.2 mag. The observations began at zenith distance = 33 deg. The sun altitude is -34.0 deg. The galactic latitude b = 4 deg., longitude l = 257 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1278160 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 99 | 2020-02-05 06:54:39 | MASTER-OAFA | (08h 39m 57.54s , -35d 09m 42.9s) | C | 180 | 19.1 | 310 | 2020-02-05 06:58:10 | MASTER-OAFA | (08h 39m 50.71s , -35d 10m 45.6s) | C | 180 | 19.1 | 521 | 2020-02-05 07:01:42 | MASTER-OAFA | (08h 39m 56.58s , -35d 10m 21.2s) | C | 180 | 19.2 | 732 | 2020-02-05 07:05:13 | MASTER-OAFA | (08h 39m 53.86s , -35d 09m 01.6s) | C | 180 | 19.2 | 944 | 2020-02-05 07:08:44 | MASTER-OAFA | (08h 39m 53.89s , -35d 10m 49.8s) | C | 180 | 19.2 | 1155 | 2020-02-05 07:12:15 | MASTER-OAFA | (08h 39m 57.46s , -35d 09m 19.0s) | C | 180 | 19.1 | 1652 | 2020-02-05 07:20:32 | MASTER-OAFA | (08h 39m 53.68s , -35d 11m 24.3s) | C | 180 | 18.9 | 1864 | 2020-02-05 07:24:04 | MASTER-OAFA | (08h 39m 49.82s , -35d 12m 26.6s) | C | 180 | 19.1 | 2075 | 2020-02-05 07:27:36 | MASTER-OAFA | (08h 39m 57.19s , -35d 12m 13.6s) | C | 180 | 19.1 | 2286 | 2020-02-05 07:31:06 | MASTER-OAFA | (08h 39m 53.81s , -35d 10m 35.3s) | C | 180 | 19.1 | 2497 | 2020-02-05 07:34:38 | MASTER-OAFA | (08h 39m 53.88s , -35d 12m 01.5s) | C | 180 | 19.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26986 SUBJECT: GRB 200205A: REM optical observations DATE: 20/02/05 09:32:24 GMT FROM: Andrea Melandri at INAF-OAB A. Melandri, S.Covino, D. Fugazza, P. D'Avanzo (INAF/OAB), on behalf of the REM team, report: We observed the field of GRB200205A (Evans et al. GCN 26982) with the REM 60cm robotic telescope located at the ESO premise of La Silla (Chile). The observations were performed starting from about 6 min after the event and were carried in the g, r, i, z bands. The optical counterpart (Lipunov et al. GCN 2698) is detected in all the optical bands. A preliminary photometry gives: R = 16.3 +/- 0.1 I = 16.8 +/- 0.1 at 19 min from the GRB time. Magnitudes are calibrated against the USNO-B1 catalogue. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26987 SUBJECT: GRB 200205A: MAXI/GSC detection DATE: 20/02/05 11:00:12 GMT FROM: Motoko Serino at RIKEN/MAXI M. Niwano (Tokyo Tech), T. Mihara (RIKEN), M. Nakajima (Nihon U.), M. Serino (AGU), H. Negoro, W. Maruyama, M. Aoki, K. Kobayashi, R. Takagi (Nihon U.), C. Guo, Y. Zhou, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, S. Sugita, H. Nishida, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.), M. Shidatsu (Ehime U.), N. Kawai, M. Oeda, K. Shiraishi (Tokyo Tech), S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, R. Shimomukai, M. Tominaga (JAXA), Y. Ueda, A. Tanimoto, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake (Kyoto U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.), M. Yamauchi, S. Iwahori, Y. Kurihara, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC) report on behalf of the MAXI team: The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at UT 2020-02-05T06:54. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (130.230 deg, -35.413 deg) = (08 40 55, -35 24 46) (J2000) with a 90% C.L. statistical error of 0.17 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius). This position is consistent with that of GRB 200205A triggered by Swift (GCN#26982) on 2020-02-05T06:35. The X-ray flux in 4.0-10.0 keV energy band rapidly incrased, 72 mCrab (2020-02-05T06:54) to 262 mCrab (2020-02-05T07:16). In the next transit at 2020-02-05T08:27, the source was detected only in the 2.0-4.0 keV energy band with the flux of 66 +- 18 mCrab. There was no significant excess flux in the previous transit at UT 05:43 and in the next transit at 08:49 UT with an upper limit of 20 mCrab for each. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26989 SUBJECT: GRB 200205A / Swift trigger 954304: VLT optical observations DATE: 20/02/05 18:32:10 GMT FROM: Daniele B Malesani at DTU Space D. B. Malesani (DTU Space), L. Izzo (DARK/NBI), J. Palmerio (GEPI - Paris Observatory), N. R. Tanvir (Univ. Leicester), A. J. Levan (Radboud Univ.), D. A. Kann (HETH-IAA/CSIC), report on behalf of the Stargate consortium: We observed the optical counterpart of GRB 200205A / Swift trigger 954304 (Evans et al., GCN 26982), with the ESO VLT UT2 (Kueyen) equipped with the X-shooter instrument. Unfortunately, observations could be started only late in twilight and no spectroscopy was secured. We confirm the presence of an optical counterpart just outside the currently available (unenhanced) XRT position (Evans et al., GCN 26982; Lipunov et al., GCN 26984; Melandri et al., GCN 26986). Its coordinates are (calibrated to the Gaia catalog; 0.2" uncertainty): RA = 08:40:40.94 Dec = -35:16:25.1 In a 60-s image taken in the SDSS r filter at a mid time Feb 5.385 UT (2.63 hr after the BAT trigger), we measure for it r = 17.7+-0.1 AB, where the error is dominated by the scatter of the calibrators, chosen from the SkyMapper catalog (Wolf et al. 2018, PASA, 35, 010; https:doi.org/10.4225/41/593620ad5b574). We note that the MAXI detection for a prolonged time at X-ray energies (Niwano et al., GCN 26987), the unusually large optical/gamma-ray brightness ratio, and the low Galactic latitude (4 deg above the plane) may indicate that this source is not a GRB but a Galactic transient. Further analysis of the high-energy data, or ground-based spectroscopic observations, will be necessary to distinguish among these options. We acknowledge support from the ESO observing staff in Paranal, in particular Elyar Sedaghati, Eleonora Sani, and Ditte Slumstrup. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26991 SUBJECT: Swift GRB200205.81: Global MASTER-Net OT detection DATE: 20/02/05 19:32:33 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs D. Buckley, S. Potter, A. Kniazev, M. Kotze South African Astronomical Observatory V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, F. Balakin Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk Irkutsk State University A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory V. Yurkov, A. Gabovich, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk R. Podesta, Carlos Lopez and F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) Hugo Levato Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the GRB200205.81 21 sec after notice time and 300 sec after trigger time at 2020-02-05 19:26:44 UT. On our first (60s exposure) set we found 1 optical transient within Swift error-box (ra=107.8 dec=-56.4808 r=0.05) brighter than 15.7. T-Tmid Date Time Expt. Ra Dec Mag ---------|---------------------|-------|-----------------|-----------------|------- 330 2020-02-05 19:26:44 60 (07h 11m 09.07s , -56d 29m 14.6s) 16.3 The 5-sigma upper limit has been about 15.7mag The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26992 SUBJECT: Swift GRB200205.81: Global MASTER-Net observations report DATE: 20/02/05 19:44:55 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB200205.81 (trigger No 954519,07h 11m 12.72s , -56d 28m 51.6s, R=0.05) errorbox 21 sec after notice time and 300 sec after trigger time at 2020-02-05 19:26:44 UT, with upper limit up to 18.0 mag. The observations began at zenith distance = 28 deg. The sun altitude is -21.2 deg. The galactic latitude b = -20 deg., longitude l = 267 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1278994 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 331 | MASTER-SAAO | P\ | 60 | 16.2 | 411 | MASTER-SAAO | P\ | 220 | 16.8 | Coadd 419 | MASTER-SAAO | P\ | 70 | 16.6 | 521 | MASTER-SAAO | P\ | 90 | 16.9 | 642 | MASTER-SAAO | P\ | 110 | 17.5 | 797 | MASTER-SAAO | P\ | 420 | 18.0 | Coadd 789 | MASTER-SAAO | P\ | 140 | 17.5 | 966 | MASTER-SAAO | P\ | 170 | 17.6 | The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26996 SUBJECT: GRB 200205A: Enhanced Swift-XRT position DATE: 20/02/05 21:59:52 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 2012 s of XRT Photon Counting mode data and 5 UVOT images for GRB 200205A, 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 = 130.17006, -35.27366 which is equivalent to: RA (J2000): 08h 40m 40.81s Dec (J2000): -35d 16' 25.2" with an uncertainty of 1.9 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27000 SUBJECT: GRB 200205A = Swift J0840.7-3516, A newly discovered transient X-ray Pulsar DATE: 20/02/06 08:12:46 GMT FROM: Phil Evans at U of Leicester J. A. Kennea (Penn State), D. M. Palmer (LANL), M. H. Siegel (Penn State), F. E. Marshall (NASA/GSFC), P. A. Evans (U Leicester), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), K. K. Simpson (Penn State), S. Campana (INAF-OAB) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team: Swift trigger 954304 was initialy reported as GRB 200205A (Evans et al., GCN Circ. 26982). The source was localized by XRT, and did not match any previously known cataloged object. MAXI also reported a detection of this source (Niwano et al., GCN Circ. 26987). The enhanced XRT position was reported by Osborne et al (GCN Circ. 26996). Examination of the downlnked Swift data shows that the source light-curve is not behaving like a GRB, the flux over the three orbits of Windowed Timing XRT data show no signs of overall fading, however the light-curve is highly variable, showing both short and longer term variations. The mean flux over the first three windows is 2.2 x 10^-9 erg/s/cm^2 (0.5 - 10 keV). However, in subsequent observations starting ~3.3 hours after the trigger, the source fades significantly, with PC mode flux measured at 3.7 x 10^-11 erg/s/cm^2 (0.5 - 10 keV). A Z^2_1 period search of the WT event data reveals a possible detection of coherent pulsations at P=8.96s, suggesting that this source is an accreting pulsar, although longer periods (e.g. ~55s) cannot be ruled out due to aliasing and the relatively short exposure this periodicity is based upon (754s). A longer/more sensitive observation is needed in order to determine the periodicity of this transient. We note that the fitted spectrum of this source is hard, with a photon index of 1.06 +/- 0.05, which is typical of accreting pulsars. Due to the presence of a bright star in the field, UVOT only took data in the UV filters. The preliminary UVOT position is: RA (J2000) = 08:40:40.96 = 130.17068 (deg.) Dec (J2000) = -35:16:25.0 = -35.27362 (deg.) with an estimated uncertainty of 0.47 arc sec. (radius, 90% confidence). 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 w2 139 389 246 17.09 +/- 0.09 w2 4611 6293 661 16.69 +/- 0.07 Follow-up observations are encouraged in order to determine the source type. This circular, a cross-posting of ATEL 13452, is an official product of the Swift team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27003 SUBJECT: GRB 200205A = Swift J0840.7-3516: optical photometry in Chilescope observatory DATE: 20/02/06 18:31:31 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Pozanenko (IKI), M. Krugov (AFIF), A. Volnova (IKI), S. Belkin (IKI) report on behalf of IKI-FuN follow-up collaboration: We observed the newly discovered transient X-ray pulsar Swift J0840.7-3516 (Kennea et al., GCN 27000) initially classified as GRB 200205A (Evans et al., GCN 26982; Niwano etal., GCN 26987; Osborne et al., GCN 26996). Observation of Chilescope RC-1000 started on Feb. 6 (UT) 02:13:56 in r'-filter. We detect optical transient (Evans et al., GCN 26982; Lipunov et al., GCN 26984; Melandri et al., GCN 26986; Malesani et al., GCN 26989). Preliminary photometry is following. Date UT start MJD_mid Filter Exp. OT(AB) Err. UL (mid, days) (s) 2020-02-06 02:13:56 58885.11255 r' 5*600 19.70 0.06 22.1 The photometry is based on nearby stars of APASS catalog Ref.stars APASS_id r’ err 45257574 15.130 0.014 45257540 14.807 0.061 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27010 SUBJECT: Swift J0840.7-3516 (AKA GRB 200205A): Swift-BAT refined analysis DATE: 20/02/07 15:48:03 GMT FROM: Sibasish Laha at GSFC M. Stamatikos (OSU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), P. A. Evans (U. Leicester), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-239 to T+255 sec from the recent telemetry downlink, we report further analysis of BAT source Swift J0840.7-3516 (trigger #954304) (Evans et al., GCN Circ. 26982). The BAT ground-calculated position is RA, Dec = 130.168, -35.275 deg which is RA(J2000) = 08h 40m 40.4s Dec(J2000) = -35d 16' 30.9" with an uncertainty of 3.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 94%. The mask weighted light curve shows some weak emission which started before the source came into BAT field of view (which is ~ T-100 sec). Kennea et al. 2020 (Atel #13452) discuss the properties of this newly discovered X-ray transient. The lower limit of the duration of the burst as detected by BAT is ~ 200 sec. The source went out of BAT field of view at ~T+260 sec, with a possibility of continuing emission which may be detected by other telecopes. The time-averaged spectrum from -81.88 to 132.86 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.84 +- 0.91, and Epeak of 31.5 +- 8.4 keV (chi squared 67.17 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is (1.3 +- 0.1) x 10^-06 erg/cm2 and the 1-sec peak flux measured from T-81.90 sec in the 15-150 keV band is 0.3 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.26 +- 0.17 (chi squared 77.17 for 57 d.o.f.). 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/954304/BA/