- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sun 12 Apr 20 09:09:05 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 46
TRIGGER_NUM: 608375325
GRB_RA: 297.317d {+19h 49m 16s} (J2000),
297.363d {+19h 49m 27s} (current),
297.201d {+19h 48m 48s} (1950)
GRB_DEC: +64.833d {+64d 49' 60"} (J2000),
+64.885d {+64d 53' 07"} (current),
+64.706d {+64d 42' 21"} (1950)
GRB_ERROR: 25.90 [deg radius, statistical plus systematic]
GRB_INTEN: 77 [cnts/sec]
DATA_SIGNIF: 6.10 [sigma]
INTEG_TIME: 2.048 [sec]
GRB_DATE: 18951 TJD; 103 DOY; 20/04/12
GRB_TIME: 32920.71 SOD {09:08:40.71} UT
GRB_PHI: 229.00 [deg]
GRB_THETA: 50.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO: 1.04
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 96% GRB
2nd_MOST_LIKELY: 1% Generic SGR
DETECTORS: 0,0,0, 0,0,0, 1,0,1, 0,0,0, 0,0,
SUN_POSTN: 21.21d {+01h 24m 50s} +8.91d {+08d 54' 45"}
SUN_DIST: 79.33 [deg] Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN: 260.88d {+17h 23m 31s} -22.17d {-22d 10' 18"}
MOON_DIST: 91.47 [deg]
MOON_ILLUM: 76 [%]
GAL_COORDS: 97.19, 18.55 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 3.92, 78.72 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200412381/quicklook/glg_lc_medres34_bn200412381.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 23.75,3.73 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sun 12 Apr 20 09:09:17 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 58
TRIGGER_NUM: 608375325
GRB_RA: 288.867d {+19h 15m 28s} (J2000),
288.925d {+19h 15m 42s} (current),
288.721d {+19h 14m 53s} (1950)
GRB_DEC: +62.017d {+62d 01' 00"} (J2000),
+62.053d {+62d 03' 12"} (current),
+61.927d {+61d 55' 37"} (1950)
GRB_ERROR: 3.42 [deg radius, statistical plus systematic]
GRB_INTEN: 5435 [cnts/sec]
DATA_SIGNIF: 275.30 [sigma]
INTEG_TIME: 1.024 [sec]
GRB_DATE: 18951 TJD; 103 DOY; 20/04/12
GRB_TIME: 32920.71 SOD {09:08:40.71} UT
GRB_PHI: 230.00 [deg]
GRB_THETA: 55.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO: 0.47
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 90% GRB
2nd_MOST_LIKELY: 5% Cyg X-1
DETECTORS: 0,0,0, 0,0,0, 1,0,1, 0,0,0, 0,0,
SUN_POSTN: 21.21d {+01h 24m 50s} +8.91d {+08d 54' 45"}
SUN_DIST: 83.20 [deg] Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN: 260.88d {+17h 23m 32s} -22.17d {-22d 10' 19"}
MOON_DIST: 87.15 [deg]
MOON_ILLUM: 76 [%]
GAL_COORDS: 92.93, 21.04 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 339.71, 80.69 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200412381/quicklook/glg_lc_medres34_bn200412381.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 23.75,3.73 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sun 12 Apr 20 09:09:23 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 69
TRIGGER_NUM: 608375325
GRB_RA: 288.883d {+19h 15m 32s} (J2000),
288.941d {+19h 15m 46s} (current),
288.739d {+19h 14m 57s} (1950)
GRB_DEC: +62.083d {+62d 04' 60"} (J2000),
+62.120d {+62d 07' 12"} (current),
+61.994d {+61d 59' 37"} (1950)
GRB_ERROR: 3.37 [deg radius, statistical plus systematic]
GRB_INTEN: 7207 [cnts/sec]
DATA_SIGNIF: 518.00 [sigma]
INTEG_TIME: 2.048 [sec]
GRB_DATE: 18951 TJD; 103 DOY; 20/04/12
GRB_TIME: 32920.71 SOD {09:08:40.71} UT
GRB_PHI: 230.00 [deg]
GRB_THETA: 55.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO: 0.47
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 91% GRB
2nd_MOST_LIKELY: 5% Cyg X-1
DETECTORS: 0,0,0, 0,0,0, 1,0,1, 0,0,0, 0,0,
SUN_POSTN: 21.21d {+01h 24m 50s} +8.91d {+08d 54' 45"}
SUN_DIST: 83.19 [deg] Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN: 260.88d {+17h 23m 32s} -22.17d {-22d 10' 20"}
MOON_DIST: 87.22 [deg]
MOON_ILLUM: 76 [%]
GAL_COORDS: 93.00, 21.05 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 340.07, 80.72 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200412381/quicklook/glg_lc_medres34_bn200412381.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 23.75,3.73 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sun 12 Apr 20 09:09:20 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 57
TRIGGER_NUM: 608375325
GRB_RA: 266.510d {+17h 46m 02s} (J2000),
266.552d {+17h 46m 12s} (current),
266.408d {+17h 45m 38s} (1950)
GRB_DEC: +62.690d {+62d 41' 24"} (J2000),
+62.683d {+62d 40' 59"} (current),
+62.707d {+62d 42' 26"} (1950)
GRB_ERROR: 1.67 [deg radius, statistical only]
DATA_SIGNIF: 88.50 [sigma]
DATA_INTERVAL: 0.512 [sec]
GRB_DATE: 18951 TJD; 103 DOY; 20/04/12
GRB_TIME: 32920.71 SOD {09:08:40.71} UT
GRB_PHI: 221.00 [deg]
GRB_THETA: 62.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 4173 (Gnd S/W Version number)
SUN_POSTN: 21.21d {+01h 24m 50s} +8.91d {+08d 54' 45"}
SUN_DIST: 92.95 [deg] Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN: 260.88d {+17h 23m 32s} -22.17d {-22d 10' 20"}
MOON_DIST: 84.98 [deg]
MOON_ILLUM: 76 [%]
GAL_COORDS: 91.90, 31.34 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 247.29, 85.85 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200412381/quicklook/glg_lc_medres34_bn200412381.gif
POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_608375325.fits
COMMENTS: Fermi-GBM Ground-calculated Coordinates.
COMMENTS: Bright hard burst in the GBM.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: The LC_URL file will not be created/available until ~15 min after the trigger.
COMMENTS: The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sun 12 Apr 20 09:18:02 UT
NOTICE_TYPE: Fermi-GBM Final Position
RECORD_NUM: 0
TRIGGER_NUM: 608375325
GRB_RA: 279.760d {+18h 39m 02s} (J2000),
279.790d {+18h 39m 10s} (current),
279.685d {+18h 38m 44s} (1950)
GRB_DEC: +64.130d {+64d 07' 48"} (J2000),
+64.149d {+64d 08' 57"} (current),
+64.083d {+64d 04' 59"} (1950)
GRB_ERROR: 1.00 [deg radius, statistical only]
GRB_DATE: 18951 TJD; 103 DOY; 20/04/12
GRB_TIME: 32920.71 SOD {09:08:40.71} UT
GRB_PHI: 225.00 [deg]
GRB_THETA: 57.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 41731 (Gnd S/W Version number)
SUN_POSTN: 21.22d {+01h 24m 52s} +8.91d {+08d 54' 53"}
SUN_DIST: 86.90 [deg] Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN: 260.97d {+17h 23m 53s} -22.18d {-22d 11' 04"}
MOON_DIST: 87.57 [deg]
MOON_ILLUM: 76 [%]
GAL_COORDS: 94.06, 25.55 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 333.66, 85.27 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200412381/quicklook/glg_lc_medres34_bn200412381.gif
LOC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200412381/quicklook/glg_locplot_all_bn200412381.png
COMMENTS: Fermi-GBM Final Position.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: The LC_URL file should be available by the time this FINAL notice is produced.
COMMENTS: This notice was generated completely by automated pipeline processing.
COMMENTS: Bright hard burst in the GBM.
COMMENTS: This is likely a Long GRB.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(3.0<100sec) coincident with the CALET_GBM event (trignum=1270717362).
- GCN Circular #27547
The Fermi GBM team reports the detection of a likely LONG GRB
At 09:08:40 UT on 12 Apr 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200412B (trigger 608375325.70677 / 200412381).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 279.8, Dec = 64.1 (J2000 degrees, equivalent to J2000 18h 39m, 64d 05'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 57.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200412381/quicklook/glg_skymap_all_bn200412381.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200412381/quicklook/glg_healpix_all_bn200412381.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200412381/quicklook/glg_lc_medres34_bn200412381.gif
- GCN Circular #27548
J. Burgess, B. Biltzinger, F. Kunzweiler, F. Berlato & J. Greiner (all MPE Garching) report:
We note that the spectral fit from the automated pipeline appears off due to more high-energy emission than normal. We are re-running the pipeline manually to test this hypothesis. This position may be updated.
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
608375325 at 09:08:40 on 12 April 2020 were automatically fitted for spectrum
and sky location with the official BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).
The best-fit position (1 sigma statistical errors) is:
RA(2000.0) = 271.0+/-1.1 deg
Decl.(2000.0) = 64.4+/-0.3 deg
We estimate an additional systematic error of 1 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB200412381/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB200412381/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB200412381/json
- GCN Circular #27549
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-Amur robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the Fermi GRB 200412B ( Fermi GBM team, GCN 27547) errorbox 8581 sec after notice time and 8607 sec after trigger time at 2020-04-12 11:32:08 UT, with upper limit up to 18.1 mag. Observations started at twilight. The observations began at zenith distance = 62 deg. The sun altitude is -11.6 deg.
The galactic latitude b = 21 deg., longitude l = 93 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1334873
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
8638 | 2020-04-12 11:32:08 | MASTER-Amur | (18h 42m 54.00s , +64d 01m 02.2s) | C | 60 | 17.7 |
8717 | 2020-04-12 11:33:27 | MASTER-Amur | (18h 36m 40.79s , +62d 00m 23.4s) | C | 60 | 17.7 |
8876 | 2020-04-12 11:36:06 | MASTER-Amur | (18h 51m 29.33s , +66d 00m 50.1s) | C | 60 | 17.8 |
8955 | 2020-04-12 11:37:26 | MASTER-Amur | (18h 42m 48.05s , +64d 01m 55.3s) | C | 60 | 18.1 |
9036 | 2020-04-12 11:38:46 | MASTER-Amur | (19h 01m 08.17s , +64d 00m 49.8s) | C | 60 | 17.9 |
9115 | 2020-04-12 11:40:06 | MASTER-Amur | (18h 36m 35.84s , +61d 59m 55.8s) | C | 60 | 18.0 |
9195 | 2020-04-12 11:41:25 | MASTER-Amur | (18h 53m 41.44s , +62d 00m 17.0s) | C | 60 | 17.7 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
- GCN Circular #27551
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a series of observations, tiled on the sky, of the
Fermi/LAT GRB 200412C. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00089
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of
finding
serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray
source
considered to be a probable afterglow candidate will be reported via a GCN
Circular
after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
- GCN Circular #27553
Phil Evans & Kim Page (U. Leicester) report on behalf of the Swift team.
There was an error in GRB name given in GCN Circ 27551; Swift has in fact begun
observations of GRB 200412B, rather than (as yet) non-existent GRB 200412C.
We apologise for the confusion.
- GCN Circular #27555
V. Lipunov (Lomonosov MSU) and V. Yurkov, A. Gabovich, Yu. Sergienko(
[BBlagoveschensk
Educational State University)
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(Lomonosov Moscow State University, SAI, Physics Department),
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),
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),
V. Yurkov, A. Gabovich, Yu. Sergienko(Blagoveschensk Educational State
University)
MASTER OT J111012.51+274912.8 discovery - new OT inside Fermi GRB 200325B
(trigger 606840801).
MASTER-Amur auto-detection system ( located near Russia Kosmodrom
Vostochniy) discovered OT source at (RA, Dec) = 18h 33m 15.33s +62d 31m
57.0s on
2020-04-12.48156 UT in Fermi error box (GCN 27547, 27548) Lipunov et al.,
GCN 27549).
The OT unfiltered magnitude is 16.6m
(mlim18.0).
The OT is seen in 2 images. There is no minor planet at this place.
We have reference image on 2016-08-12.64123 UT with unfiltered mlim=
19.3m.
Spectral observations are required.
The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/183315.33623157.0.png
- GCN Circular #27556
V. Lipunov (Lomonosov MSU) and V. Yurkov, A. Gabovich, Yu. Sergienko(Blagoveschensk Educational State University)
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(Lomonosov Moscow State University, SAI, Physics Department),
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),
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),
V. Yurkov, A. Gabovich, Yu. Sergienko(Blagoveschensk Educational State
University)
MASTER-Amur ( located near Russian Kosmodrom Vostochniy) comeback to
MASTER OT J111012.51+274912.8 (Lipunov et al., GCN 27555)
after 2 hours and we find optical transient with limit ~ 17.5 . So this
is real afterglow:
at (RA, Dec) = 18h 33m 15.33s +62d 31m 57.0s on
The OT is seen in 2 images. There is no minor planet at this place.
We have reference image on 2016-08-12.64123 UT with unfiltered mlim= 19.3m.
Spectral observations are required.
The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/183315.33623157.0.png
- GCN Circular #27557
F. Longo (University & INFN Trieste), D.Kocesvki (NASA/MSFC),
E.Bissaldi (Politecnico and INFN, Bari), M.Ohno (Hiroshima University)
and M.Palatiello (University of Udine & INFN, Trieste)
report on behalf of the Fermi-LAT Collaboration:
On April 12, 2020, Fermi-LAT detected high-energy emission from
GRB 200412B, which was also detected by Fermi-GBM
(trigger 608375325/200412381).
The best LAT on-ground location is found to be
RA, Dec = 277.48, 61.79 (degrees, J2000)
with an error radius of 0.5 deg (90% containment, statistical error only).
This was 59 deg from the LAT boresight at the time of the GBM trigger:
T0 = 09:08:40 UT.
The data from the Fermi-LAT show a significant increase
in the event rate after the GBM trigger that is spatially correlated with the
GBM emission (2.6 degrees from the GBM position) with high significance.
The photon flux above 100 MeV in the time interval 0-1000 s after the
GBM trigger is 6.0 +/- 1.6 e-5 ph/cm2/s.
The estimated photon index above 100 MeV is -2.9 +/- 0.4
The highest-energy photon is a 1.1 GeV event which is observed 134 seconds
after the GBM trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is
Michele Palatiello (michele.palatiello@gmail.com)
The Fermi-LAT is a pair conversion telescope designed to cover
the energy band from 20 MeV to greater than 300 GeV.
It is the product of an international collaboration between
NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.
- GCN Circular #27558
B. Mailyan (Institute for Basic Science, South Korea) and R. Hamburg (UAH)
report on behalf of the Fermi GBM Team:
"At 09:08:40.71 UT on 12 April 2020, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 200412B (trigger 608375325 / 200412381),
which was also detected by the Fermi LAT (Longo et al. 2020, GCN 27557)
and observed to have a candidate optical afterglow by MASTER
(GCN 27555 & GCN 27556). The GBM on-ground location is consistent
with the LAT position.
The angle from the Fermi LAT boresight at the GBM trigger time is 59
degrees.
The GBM light curve shows a multi-peaked structure
with a duration (T90) of about 6 s (50-300 keV).
The time-averaged spectrum from T0+3.1s to T0+21.5 s is
best fit by a Band function with Epeak = 257 +/- 4 keV,
alpha = -0.54 +/- 0.01, and beta = -2.24 +/- 0.02.
The event fluence (10-1000 keV) in this time interval is
(8.00 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+9.1 s in the 10-1000 keV band
is 127.5 +/- 0.7 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support
Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
- GCN Circular #27561
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi
(INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (ASDC), A.
Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU) and
P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 200412B (Longo et al. GCN Circ. 27557) in
a series of observations tiled on the sky. The total exposure time is
4.9 ks, distributed over 7 tiles; the maximum exposure at a single sky
location was 1.5 ks. The data were collected between T0+20.1 ks and
T0+31.7 ks, and are entirely in Photon Counting (PC) mode.
Two uncatalogued X-ray sources are detected, of which one ("Source 2")
is above the RASS limit, and is therefore likely the GRB afterglow.
Using 671 s of PC mode data and 2 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 = 278.31339, +62.53253 which is
equivalent to:
RA (J2000): 18h 33m 15.21s
Dec(J2000): +62d 31' 57.1"
with an uncertainty of 2.5 arcsec (radius, 90% confidence). This
position is 30.1 arcmin from the Fermi/LAT position.
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.9 (+1.3, -1.2).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.8 (+0.6, -0.5). The
best-fitting absorption column is 1.6 (+1.8, -1.0) x 10^21 cm^-2,
consistent with the Galactic value of 5.1 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 3.1 x 10^-11 (3.8 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.6 (+1.8, -1.0) x 10^21 cm^-2
Galactic foreground: 5.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.8 (+0.6, -0.5)
If the light curve continues to decay with a power-law decay index of
1.9, the count rate at T+24 hours will be 0.015 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.7 x
10^-13 (5.8 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis of the likely afterglow
are at https://www.swift.ac.uk/xrt_products/TILED_GRB00089/Source2.php.
The results of the full analysis of the tiled XRT observations are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00089.
This circular is an official product of the Swift-XRT team.
- GCN Circular #27563
S. Gupta, V. Sharma, A. Vibhute and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data showed the detection of a long GRB 200412B, which was also detected by Fermi GBM Final Real-time (GCN #27547), BALROG (Burgess J. et al., GCN #27548), Global MASTER-Net (Lipunov V. et al, GCN #27549), Tiled Swift (Evans P. et al., GCN #27551), Fermi-LAT (Longo F. et al., GCN #27557), Fermi GBM (Mailyan B. et al., GCN #27558) and Swift-XRT (Page K. et al., GCN #27561).
The source was clearly detected in the 40-200 keV energy range. The light curve shows a single peak of emission peaking at 2020-04-12 09:08:49.5 UT. The measured peak count rate associated with the burst is 1160 +/- 40.72 cts/s above the background in the combined data of four quadrants, with a total of 3452 +/- 16.55 cts. The local mean background count rate was 519 +/- 0.87 cts/s. Using cumulative rates, we measure a T90 of 7.17 +/- 0.06 s.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
- GCN Circular #27565
Y. G. Zheng, C. Cai, Y. F. Du, W. C. Xue,
Q. Luo, S. Xiao, Q. B. Yi, Y. Huang, C. K. Li, G. Li,
X. B. Li, J. Y. Liao, S. L. Xiong,C. Z. Liu,
X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang,
X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU),
T. P. Li (IHEP/THU), F. J. Lu, L. M. Song,
M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:
At 2020-04-12T09:08:45.80 (T0), Insight-HXMT/HE detected
GRB 200412B (trigger ID: HEB200412381) in a routine search of the data,
which also triggered Fermi/GBM (GCN #27547).
The Insight-HXMT/HE light curve mainly consists of a single
pulse with a duration (T90) of 5.50 s measured from T0+0.05 s.
The 1-ms peak rate, measured from T0+4.28 s, is 14908 cnts/sec.
The total counts from this burst is 25230 counts.
URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB200412381_lc.jpg
All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (deposited energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.
Insight-HXMT is the first Chinese space X-ray telescope, which was
funded jointly by the China National Space Administration (CNSA) and
the Chinese Academy of Sciences (CAS).
More information about it could be found at:
http://www.hxmt.org.
- GCN Circular #27566
S. Belkin (IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO), V.R.
Ayvazian (AbAO), G. V. Kapanadze (AbAO), E. Mazaeva (IKI), A.
Volnova (IKI), I. Molotov (KIAM) report on behalf of GRB IKI FuN:
We observed the field of Fermi GRB 200412B (Fermi GBM team GCN 27547;
Longo et al., GCN 27557) with AS-32 (0.7m) telescope of Abastumani
Observatory starting on 2020-04-12 (UT) 18:42:21. We detected the
afterglow of GRB 200412B (Lipunov et al., GCNs 27555; Kumar et al., GCN
27564). Preliminary photometry of the afterglow is following.
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2020-04-12 18:42:21 0.41783 R 56*60 18.31 0.02 21.3
The photometry is based on nearby USNO-B1.0 stars
UUSNO-B1.0_id R2
1525-0302108 17.21
1524-0300914 17.20
1525-0301929 17.85
- GCN Circular #27567
B. Stecklum, S. Klose, S. Melnikov, and A. Nicuesa Guelbenzu (all
Tautenburg) report:
We observed the field of GRB 200412B (Fermi GBM team, GCN 27547; Mailyan
et al., GCN 27558; see also Burgess et al., GCN 27548; Longo et al., GCN
27557; Page et al., GCN 27561; Gupta et al., GCN 27563; Zheng et al., GCN
27565) 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.
The fading optical transient detected by MASTER Global Robotic Net
(Lipunov et al., GCN 27555, 27556) is clearly detected on our images (for
other optical observations see also Kumar et al., GCN 27564; Belkin et
al., GCN 27566). Using Gaia DR2 stars in the field, we measure the
following preliminary magnitudes (Vega system):
Mean time: April 12, 21:29:48 UT, VB = 18.43 +/- 0.01
Mean time: April 13, 02:22:38 UT, VB = 19.00 +/- 0.01
- GCN Circular #27570
A. Moskvitin on behalf of the larger GRB follow-up team report.
We observed the field of the GRB 200412B (The Fermi GBM team,
GCN 27547; Longo et al. GCN 27557) with the 1-m telescope
of SAO RAS, equipped with the Multi-Mode Photometer-Polarimeter.
We obtained 6 x 300 sec. images in Rc band on 2020.04.14
00:09:20--00:41:40 UT, T_mid - T0 = 1.6367 days.
The OT (Lipunov et al., GCNs 27555, 27556; Kumar et al., GCN
27564; Belkin et al., GCN 27566) is clearly visible in individual
images and stacked frame with the brightness of R = 20.8 +/- 0.1.
The photometry is based on R2 magnitudes of nearby USNO-B1 stars.
- GCN Circular #27571
L. P. Xin, X. F. Wang, J. Zheng, Y. L. Qiu, J. Y. Wei, J. Wang,
L. H. Li , C. Wu, X. H. Han and J. S. Deng, report:
We began to observe GRB 200412B (The Fermi GBM team,
GCN 27547; Longo et al. GCN 27557)
with Xinglong TNT telescope at 18:09:54 (UT), 13th. Apr. 2020,
about 33 hours after the burst.
10 x 300 sec R band images were obtained.
The optical afterglow (Lipunov et al., GCNs 27555, 27556; Kumar et al., GCN
27564; Belkin et al., GCN 27566, Stecklum et al., GCN 27567,
Moskvitin GCN 27570) is clearly detected in individual
images with the brightness of R = 20.0 +/- 0.1.
The photometry is based on R2 magnitudes of nearby USNO-B1 stars.
With the reports from (Kumar et al., GCN
27564; Belkin et al., GCN 27566, Stecklum et al., GCN 27567,
Moskvitin GCN 27570), the brightness is fading with a slope of -1.5
for a single power law (t~t^a) from 10 hours to 39 hours after the burst trigger.
- GCN Circular #27572
T. Tamura (Kanagawa U),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka, S. Torii (Waseda U), Y. Shimizu (Kanagawa U),
N. Cannady (GSFC/UMBC), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The bright GRB 200412B (BALROG localization: Burgess et al.,
GCN Circ. 27548; Fermi-LAT detection: Longo et al., GCN Circ. 27557;
Fermi GBM detection: Mailyan and Hamburg, GCN Circ. 27558;
https://gcn.gsfc.nasa.gov/other/200412B.gcn3)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 09:08:43.975 UTC
on 12 April 2020. The burst signal was seen by all CGBM detectors.
The burst light curve shows a multi-peaked structure which starts
at T-0.3 sec, peaks at T+6.2 sec and ends at T+13.1 sec. The T90 and T50
durations measured by the SGM data are 6.1 +- 0.5 sec and 1.8 +- 0.1 sec
(40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1270717362/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.
- GCN Circular #27574
S. Belkin (IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO), V.R.
Ayvazian (AbAO), G. V. Kapanadze (AbAO), E. Mazaeva (IKI), A.
Volnova (IKI), I. Molotov (KIAM) report on behalf of GRB IKI FuN:
We observed the field of GRB 200412B (Fermi GBM team, GCN 27547; Mailyan
et al., GCN 27558; see also Burgess et al., GCN 27548; Longo et al., GCN
27557; Page et al., GCN 27561; Gupta et al., GCN 27563; Zheng et al.,
GCN 27565) with AS-32 (0.7m) telescope of Abastumani Observatory
starting on 2020-04-14 (UT) 00:16:57. We clearly detected the
afterglow of GRB 200412B (Lipunov et al., GCNs 27555, 27556; Kumar et
al., GCN 27564; Belkin et al., GCN 27566, Stecklum et al., GCN 27567,
Moskvitin GCN 27570; Xin et al., GCN 27571). Preliminary photometry of
the afterglow is following.
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2020-04-14 00:16:57 1.65401 R 67*60 20.7 0.1 22.1
The photometry is based on nearby USNO-B1.0 stars
UUSNO-B1.0_id R2
1525-0302108 17.21
1524-0300914 17.20
1525-0301929 17.85
The index of power law decay of the afterglow light curve between the
two epochs of our observations (Belkin et al., GCN 27566 at 0.41793
days) and reported in this circular (at 1.65401 days) is -1.58+/-0.07
which is corroborate with the index reported by Xin et al. (GCN 27571).
- GCN Circular #27575
S. Klose, B. Stecklum, S. Melnikov, and A. Nicuesa Guelbenzu (all
Tautenburg) report:
We continued observing the field of GRB 200412B (Fermi GBM team, GCN
27547) with the Tautenburg 1.34m Schmidt telescope equipped with the
TAUKAM 6k x 6k CCD camera and the wide V-band filter (VB; Stecklum et al.,
GCN 27567).
For the optical transient (Lipunov et al., GCN 27555, 27556) at a mean
time APR 13, 21:08:59 UT (1.500 days post burst) we measure VB = 20.27 +/-
0.03. Compared to our 1st-epoch observations (dt=0.51 days; Stecklum et
al., GCN 27567) this provides a decay slope of alpha = 1.58 (F\nu \propto
t**(-\alpha)), in agreement with the results reported by Xin et al. (GCN
27571) and Belkin et al. (GCN 27574).
- GCN Circular #27576
F. Ogawa, R. Adachi, R. Hosokawa, K. L. Murata, M. Niwano, N.
Nakamura, Y. Yatsu, and N. Kawai(TokyoTech) report on behalf of the
MITSuME collaboration:
We searched for the optical counterpart of GRB 200412B (The Fermi GBM
team, GCN Circular #27547) with the optical three color (g', Rc, and
Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno
Observatory, Yamanashi, Japan.
The observation started on 2020-04-13 15:27:09 UT. We detected the
point source at the position consistent with the afterglow detected
previously (E. Gorbovskoy et al. GCN #27555).
We measured the magnitudes as follows.
T0+[hour] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
30.2 2020-04-13 17:19:02 10800 g'=20.1+/-0.2,Rc=19.6+/-0.2,Ic=19.5+/-0.2
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.
The magnitudes are expressed in the Vega system.
- GCN Circular #27581
A. Ridnaia, S. Golenetskii, R. Aptekar, D. Frederiks,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 200412B
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 27547;
Mailyan and Hamburg, GCN Circ. 27558;
BALROG localization: Burgess et al., GCN Circ. 27548;
Fermi-LAT detection: Longo et al., GCN Circ. 27557;
AstoSat CZTI detection: Gupta et al., GCN Circ. 27563;
Insight-HXMT/HE detection: Zheng et al., GCN Circ. 27565;
CALET-GRBM detection: Tamura et al., GCN Circ. 27572)
triggered Konus-Wind at T0=32924.203 s UT (09:08:44.203).
The burst light curve shows a multipeaked structure
which starts at ~T0-0.5 s and has a total duration of ~30.5 s.
The emission is seen up to ~6 MeV.
As observed by Konus-Wind, the burst
had a fluence of 1.12(-0.05,+0.05)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+5.744 s,
of 5.12(-0.43,+0.44)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+15.360 s)
is best fit in the 20 keV - 6 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.67(-0.05,+0.05),
the high energy photon index beta = -2.45(-0.12,+0.10),
the peak energy Ep = 289(-16,+16) keV
(chi2 = 66/79 dof).
The spectrum near the maximum count rate
(measured from T0+5.376 to T0+5.888 s)
is best fit in the 20 keV - 6 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.15(-0.10,+0.11),
the high energy photon index beta = -2.58(-0.17,+0.14),
the peak energy Ep = 316(-24,+24) keV
(chi2 = 56/56 dof).
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB200412_T32924/
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
- GCN Circular #27582
B. Stecklum, S. Klose, S. Melnikov, and A. Nicuesa Guelbenzu (all
Tautenburg) report:
We continued observing the field of GRB 200412B (Fermi GBM team, GCN
27547) with the Tautenburg 1.34m Schmidt telescope equipped with the
TAUKAM 6k x 6k CCD camera and the wide V-band filter (VB; Stecklum et al.,
GCN 27567; Klose et al., GCN 27575).
For the optical transient (Lipunov et al., GCN 27555, 27556) at a mean
time of 2.521 days post burst we measure VB = 21.38 +/- 0.06. This is
about 0.2 mag fainter than expected for a decay slope of alpha = 1.582 +/-
0.004 based on our previous VB-band data (see also Xin et al., GCN 27571;
Belkin et al., GCN 27574), suggesting that the light curve decay is
steepening. Additional data are required to confirm (or reject) this
conclusion.
We note that in our images there is still no evidence for an underlying
host galaxy.
- GCN Circular #27583
S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), M. Eselevich
(ISTP), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of IKI-GRB FuN:
We observed the field of GRB 200412B (Fermi GBM team, GCN 27547; Mailyan
et al., GCN 27558; see also Burgess et al., GCN 27548; Longo et al., GCN
27557; Page et al., GCN 27561; Gupta et al., GCN 27563; Zheng et al.,
GCN 27565) with AZT-33IK 1.5-m telescope of Sayan observatory (Mondy)
starting on 2020-04-14 (UT) 14:24:54.
We clearly detected the afterglow of GRB 200412B (Lipunov et al.,
GCNs 27555, 27556; see also Kumar et al., GCN 27564; Belkin et al., GCN
27566, Stecklum et al., GCN 27567, Moskvitin GCN 27570; Xin et al., GCN
27571). Preliminary photometry of the afterglow is following.
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2020-04-14 14:24:54 2.23002 R 15*120 21.22 0.08 22.8
The photometry is based on nearby USNO-B1.0 stars
UUSNO-B1.0_id R2
1525-0302108 17.21
1524-0300914 17.20
1525-0301929 17.85
- GCN Circular #27593
S. Klose, B. Stecklum, S. Melnikov, and A. Nicuesa Guelbenzu (all
Tautenburg) report:
We continued observing the field of GRB 200412B (Fermi GBM team, GCN
27547) with the Tautenburg 1.34m Schmidt telescope equipped with the
TAUKAM 6k x 6k CCD camera and the wide V-band filter (VB; Stecklum et al.,
GCN 27567, 27582; Klose et al., GCN 27575).
For the optical transient (Lipunov et al., GCN 27555, 27556) at a mean
time of 3.53 days post burst we measure VB = 22.29 +/- 0.11. This confirms
the suspected steepening of the light curve decay (Stecklum et al., GCN
27582). Our present VB-band data imply alpha2 = 2.52 +/- 0.02 and a break
time of 2.04 +/- 0.02 days.
- GCN Circular #27598
H. Kumar, M. Khandagale, K. Deshmukh, V. Bhalerao(IITB), G. C. Anupama, B. Kumar, A. Singh, A. Dutta, S. Barway(IIA), P. Dorji (IAO), U. Stanzin (IAO), report on behalf of the GROWTH collaboration:
We observed GRB200412B reported by Fermi GBM Team (GCN 27547) and Burgess J. et al, (GCN 27548) with 0.7m robotic GROWTH-India telescope. We switched from tiled observations to targeted follow-up based on the afterglow identification by Lipunov V. et al, (GCN 27555) at RA(J2000) = 18:33:15.33 Dec(J2000) = +62:31:57.0 . The field was observed multiple times in g and r filters with 550 sec exposure time, starting about 7.4 hours after the trigger. We clearly detect the afterglow emission. The decay is well-described by a power law with alpha = 1.05 +/- 0.14 for g band data and 0.85 +/- 0.17 for r band data.
We obtained the following results:
------------------------------------------------------------------
JD(Start)| Exposure(sec) | Filter | Mag | lim_Mag |
------------------------------------------------------------------
2458952.1903 | 550 | g | 18.301+/-0.034 | 20.92
2458952.3277 | 550 | g | 18.590+/-0.039 | 20.54
2458952.3601 | 550 | g | 18.761+/-0.040 | 20.52
2458952.3768 | 550 | g | 18.826+/-0.039 | 20.56
2458952.4216 | 550 | g | 18.984+/-0.041 | 20.65
2458952.1982 | 550 | r | 17.854+/-0.027 | 20.83
2458952.3356 | 550 | r | 17.998+/-0.036 | 20.32
2458952.3681 | 550 | r | 18.231+/-0.031 | 20.58
2458952.3847 | 550 | r | 18.314+/-0.039 | 20.65
2458952.4295 | 550 | r | 18.379+/-0.033 | 20.77
------------------------------------------------------------------
The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7 degree field of view, set up by the Indian Institute of Astrophysics and the Indian Institute of Technology Bombay with support from the Indo-US Science and Technology Forum (IUSSTF) and the Science and Engineering Research Board (SERB) of the Department of Science and Technology (DST), Government of India (https://sites.google.com/view/growthindia/). It is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA).
- GCN Circular #27600
B. Sbarufatti (PSU), N. P. M. Kuin (UCL-MSSL), P. A. Evans (U. Leicester), and J. D. Gropp (PSU) report on behalf of the Swift team:
Swift XRT performed follow up observations on the afterglow candidate reported by Page et al. (GCN #27561).
XRT data now comprise 6.1 ks of Photon Counting data covering times from T+20 ks to T+370 ks.
The light curve is best fit by a power-law with decay index 1.6 +/- 0.3. We thus confirm that this is indeed the afterglow of GRB 200412B.
The latest results can be viewed via: https://www.swift.ac.uk/xrt_curves/00020981/
In the initial Swift observation about 20ks after the trigger, the source was not in the UVOT field of view, which is smaller than that of the XRT. In the follow up observations around 360ks after the trigger we obtained the following 3-sigma upper limits to the source (Vega magnitudes, uncorrected for reddening):
filter exposure UL (mag)
v 374 >19.76
b 374 >20.74
u 374 >20.41
uvw1 749 >20.31
uvm2 1201 >20.48
uvw2 1499 >20.83
This circular is an official product of the Swift team.
- GCN Circular #27604
S. Belkin (IKI), A. Pozanenko (IKI), A.V. Shein (INASAN), I.A. Izvekova
(ICAMER NASU), E. Klunko (ISTP), M. Eselevich (ISTP), R. Ya.
Inasaridze (AbAO), V.R. Ayvazian (AbAO), G. V. Kapanadze (AbAO), I.
Reva (FAPHI), E. Mazaeva (IKI), A. Volnova (IKI), I. Molotov (KIAM)
report on behalf of GRB IKI FuN:
We observed the field of GRB 200412B (Fermi GBM team, GCN 27547; Mailyan
et al., GCN 27558; see also Burgess et al., GCN 27548; Longo et al., GCN
27557; Page et al., GCN 27561; Gupta et al., GCN 27563; Zheng et al.,
GCN 27565) with Zeiss-2000 of Mt.Terskol observatory, Zeiss-1000 1-m
telescope of Tien Shan Astronomical Observatory, AZT-33IK 1.5-m
telescope of Sayan observatory (Mondy) and AS-32 (0.7m) telescope of
Abastumani Observatory. We still detected the afterglow of GRB
200412B (Lipunov et al., GCNs 27555, 27556; see also e.g. Kumar et al.,
GCN 27564; Belkin et al., GCN 27566, Stecklum et al., GCN 27567,
Moskvitin GCN 27570; Xin et al., GCN 27571). Preliminary photometry of
the afterglow is following.
Date UT start t-T0 Filter OT Err. UL Observatory
(mid, days)
2020-04-13 23:10:27 1.59707 18*120 R 20.57 0.03 22.8 Terskol Z-2000
2020-04-15 14:55:11 3.25105 15*120 V 21.95 0.14 22.8 Mondy AZT-33IK
2020-04-16 17:04:23 4.33800 11*120 R n/d n/d 20.5 Mondy AZT-33IK
2020-04-16 22:30:40 4.57812 61*60 R n/d n/d 22.2 AbAO AS-32
2020-04-17 14:51:32 5.25754 28*120 R 23.22 0.28 23.4 Mondy AZT-33IK
2020-04-17 19:53:06 5.47912 91*60 R n/d n/d 22.3 TSHAO Z-1000
2020-04-17 20:12:07 5.48573 36*120 R 23.29 0.29 23.4 Terskol Z-2000
The photometry is based on nearby USNO-B1.0 stars.
The light curve based on on above photometry and photometry published
earlier (Belkin et al., GCN 27574; Belkin et al., GCN 27566; Belkin
et al., GCN 27583) can be found at
http://grb.rssi.ru/GRB200412B/GRB200412B_LC.png
(For reference, we also posted the photometric results of the Tautenburg
Observatory (Klose et al., GCN 27593; Stecklum et al., GCN 27582; Klose
et al., GCN 27575; Stecklum et al., GCN 27567).
The index of power law decay taken from our R-filter observations up to
2.3 days is -1.58+/-0.07 (see also Xin et al. GCN 27571; Klose et al.,
GCN 27575). Later we may assume a jet break previously suggested by
Klose et al. (GCN 27575) and Stecklum et al. (GCN 27567).
- GCN Circular #27605
S. Belkin (IKI), A. Pozanenko (IKI), A.V. Shein (INASAN), I.A. Izvekova
(ICAMER NASU), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of
GRB IKI FuN:
We observed the field of GRB 200412B (Fermi GBM team, GCN 27547; Mailyan
et al., GCN 27558; see also Burgess et al., GCN 27548; Longo et al., GCN
27557; Page et al., GCN 27561; Gupta et al., GCN 27563; Zheng et al.,
GCN 27565) with Zeiss-2000 of Mt.Terskol observatory. We marginally
detected the afterglow of GRB 200412B (Lipunov et al., GCNs 27555,
27556; see also e.g. Kumar et al., GCN 27564; Belkin et al., GCN 27566,
Stecklum et al., GCN 27567, Moskvitin GCN 27570; Xin et al., GCN
27571). Preliminary photometry of the afterglow is following.
Date UT start t-T0 Filter OT Err. UL Observatory
(mid, days)
2020-04-18 19:52:22 6.47687 43*120 R 23.6 0.3 23.6 Terskol Z-2000
The photometry is based on nearby USNO-B1.0 stars.
The update light curve can be found at
http://grb.rssi.ru/GRB200412B/GRB200412B_LC.png
- GCN Circular #27610
S. Belkin (IKI), A. Pozanenko (IKI), A.V. Shein (INASAN), I.A. Izvekova
(ICAMER NASU), E. Klunko (ISTP), M. Eselevich (ISTP), E. Mazaeva (IKI),
A. Volnova (IKI) report on behalf of GRB IKI FuN:
We observed the field of GRB 200412B (Fermi GBM team, GCN 27547; Mailyan
et al., GCN 27558; see also Burgess et al., GCN 27548; Longo et al., GCN
27557; Page et al., GCN 27561; Gupta et al., GCN 27563; Zheng et al.,
GCN 27565) with AZT-33IK 1.5-m telescope of Sayan observatory (Mondy)
and Zeiss-2000 of Mt.Terskol observatory. We detected the afterglow
of GRB 200412B (Lipunov et al., GCNs 27555, 27556; see also e.g. Kumar
et al., GCN 27564; Belkin et al., GCN 27566, Stecklum et al., GCN 27567,
Moskvitin GCN 27570; Xin et al., GCN 27571). Preliminary photometry of
the afterglow is following.
Date UT start t-T0 Filter OT Err. UL Observatory
(mid, days)
2020-04-19 16:10:31 7.32142 41*120 R 23.50 0.30 23.6 Mondy AZT-33IK
2020-04-19 22:23:48 7.59245 48*120 R 23.55 0.28 23.7 Terskol Z-2000
The photometry is based on nearby USNO-B1.0 stars.
The updated light curve can be found at
http://grb.rssi.ru/GRB200412B/GRB200412B_LC.png
- GCN Circular #27653
Amit Kumar, S. B. Pandey, Amar Aryan, Brijesh Kumar and Kuntal Misra (ARIES Nainital),
on behalf of a larger GRB collaboration.
Fermi-GBM triggered GRB 200412B (GCNCs 27547, 27548i, 27558) prompt emissions
and high energy observations were also carried out by Fermi-LAT (GCNC 27557) and
other space-based facilities like Konus-Wind (GCNC 27581), ASTROSAT (GCNC 27563),
CALET (GCNC 27572) and HXMT (GCNC 27567). Categorised as a long-duration GRB,
Swift-XRT triggered and found a X-ray afterglow counterpart (GCNC 27561, 27600) decaying
typical to those seen in case of other long duration bursts at the epoch of observations.
Our joint spectral analysis of the combined Fermi GBM-LAT data yields E_peak ~ 250 +/- 18
keV and spectral slope \beta ~ -2.8 +/- 0.4 above 100 MeV, similar to those reported in
GCNC 27558 and GCNC 27581. Once used with the empirical Amati relation, the estimated
value of the E_peak and the observed fluence values (GCNC 27558, GCNC 27581) place a
constrain of the redshift to be 0.3 < z < 1.5 for GRB 200412B.
The optical counterpart of the Gagarin-day burst was discovered by MASTER group of
telescopes (GCNC 27555, 27556) and follow-up observations were continued by several
ground-based facilities (GCNCs 27564, 27566, 27567, 27567, 27570, 27571, 27574, 27575,
27576, 27583, 27593, 27598, 27604, 27605 and 27610).
Late time follow-up observations of the optical counterpart were initiated using the 4Kx4K CCD
Imager (Pandey et al. 2017, arXiv:1711.05422v1) mounted at the axial port of the 3.6m
Devasthal Optical Telescope of ARIES Nainital starting on 15th April and continued till 25th April
2020. Multiple frames having exposure times of 360s each were taken in various broad-band filters
including Ic, Rc and g-bands. A fading afterglow candidate was clearly seen in single as well as in
stacked frames decayed around ~ 3 mag during our observing run. We report following preliminary
brightness of the optical afterglow seen in our stacked frames calibrated against UNSOB1 and
PanSTARRS nearby stars.
Start time, 23 April 20.61 UT, 360*12, Rc, 24.62+/-0.12, seeing ~ 0.8 arcsec
Start time, 24 April 19.71 UT, 360*10, g, 25.21+/-0.10, seeing ~ 0.9 arcsec
Once clubbed along with published GCNC values in R-band, our late time observations indicate towards
a power-law decay nature of the afterglow as seen in case of other well-monitored afterglows. The temporal
decay index between one day to the epoch of our observations demand a power-law temporal flux-decay
index of ~ 1.78+-0.15. This temporal decay is similar to those seen at XRT frequencies and might indicate
towards possible early time jet-break, if any. It is also to be cautioned that possible underlying host galaxy
contamination to our late time Rc-band stacked frames can not be ruled out. Detailed analysis of the data is
ongoing.
To decipher about late time nature of the temporal decay of the afterglow and to detect the host galaxy or
possible underlying supernova, observations using bigger optical-NIR facilities are encouraged.
This circular may be cited.
3.6m Devasthal Optical Telescope (DOT) is a recently commissioned facility in Northern Himalayan region of India
(long:79 41 04E, lat:29 21 40N, alt:2540m) owned and operated by the Aryabhatta Research Institute of
Observational Sciences (ARIES), Nainital (https://www.aries.res.in). Authors of this GCN circular thankfully
acknowledge consistent support from the staff members to run and maintain the 3.6m DOT and specially to
Director ARIES to make these observations possible during the ongoing COVID19 triggered lock-down phase.
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