- GCN/BACODINE POSITION NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 27 Apr 19 04:34:29 UT
NOTICE_TYPE: Swift-BAT GRB Position
TRIGGER_NUM: 900730, Seg_Num: 0
GRB_RA: 280.213d {+18h 40m 51s} (J2000),
280.370d {+18h 41m 29s} (current),
279.805d {+18h 39m 13s} (1950)
GRB_DEC: +40.322d {+40d 19' 20"} (J2000),
+40.342d {+40d 20' 29"} (current),
+40.274d {+40d 16' 26"} (1950)
GRB_ERROR: 3.00 [arcmin radius, statistical only]
GRB_INTEN: 542 [cnts] Image_Peak=90 [image_cnts]
TRIGGER_DUR: 0.032 [sec]
TRIGGER_INDEX: 10318 E_range: 25-100 keV
BKG_INTEN: 14420 [cnts]
BKG_TIME: 16441.19 SOD {04:34:01.19} UT
BKG_DUR: 8 [sec]
GRB_DATE: 18600 TJD; 117 DOY; 19/04/27
GRB_TIME: 16454.95 SOD {04:34:14.95} UT
GRB_PHI: 148.52 [deg]
GRB_THETA: 24.57 [deg]
SOLN_STATUS: 0x20000003
RATE_SIGNIF: 54.54 [sigma]
IMAGE_SIGNIF: 11.10 [sigma]
MERIT_PARAMS: +1 +0 +0 -5 +2 +1 +0 +0 +14 +0
SUN_POSTN: 34.32d {+02h 17m 16s} +13.73d {+13d 44' 02"}
SUN_DIST: 98.44 [deg] Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN: 312.34d {+20h 49m 22s} -19.44d {-19d 26' 32"}
MOON_DIST: 66.78 [deg]
MOON_ILLUM: 48 [%]
GAL_COORDS: 69.25, 19.05 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 287.41, 63.15 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT-BAT GRB Coordinates.
COMMENTS: This is a rate trigger.
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
COMMENTS: This trigger occurred at longitude,latitude = 88.92,-16.71 [deg].
COMMENTS:
COMMENTS: NOTE: This BAT event is temporally(1.0<100sec) coincident with the FERMI_GBM event (trignum=578032460).
- red DSS finding chart
ps-file
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sat 27 Apr 19 04:34:44 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 49
TRIGGER_NUM: 578032460
GRB_RA: 272.517d {+18h 10m 04s} (J2000),
272.650d {+18h 10m 36s} (current),
272.173d {+18h 08m 41s} (1950)
GRB_DEC: +46.833d {+46d 49' 60"} (J2000),
+46.838d {+46d 50' 17"} (current),
+46.822d {+46d 49' 19"} (1950)
GRB_ERROR: 3.50 [deg radius, statistical plus systematic]
GRB_INTEN: 3851 [cnts/sec]
DATA_SIGNIF: 25.80 [sigma]
INTEG_TIME: 0.032 [sec]
GRB_DATE: 18600 TJD; 117 DOY; 19/04/27
GRB_TIME: 16455.08 SOD {04:34:15.08} UT
GRB_PHI: 97.00 [deg]
GRB_THETA: 110.00 [deg]
DATA_TIME_SCALE: 0.0320 [sec]
HARD_RATIO: 0.35
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 62% Distant Particles
2nd_MOST_LIKELY: 31% GRB
DETECTORS: 0,1,1, 0,0,0, 0,0,0, 1,1,1, 0,0,
SUN_POSTN: 34.32d {+02h 17m 16s} +13.73d {+13d 44' 02"}
SUN_DIST: 100.12 [deg] Sun_angle= 8.1 [hr] (West of Sun)
MOON_POSTN: 312.34d {+20h 49m 22s} -19.44d {-19d 26' 30"}
MOON_DIST: 75.31 [deg]
MOON_ILLUM: 48 [%]
GAL_COORDS: 74.32, 26.22 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 275.09, 70.23 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190427190/quicklook/glg_lc_medres34_bn190427190.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 52.95,-25.57 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=900730).
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 27 Apr 19 04:37:47 UT
NOTICE_TYPE: Swift-BAT GRB Lightcurve
TRIGGER_NUM: 900730, Seg_Num: 0
GRB_RA: 280.213d {+18h 40m 51s} (J2000),
280.370d {+18h 41m 29s} (current),
279.805d {+18h 39m 13s} (1950)
GRB_DEC: +40.322d {+40d 19' 20"} (J2000),
+40.342d {+40d 20' 29"} (current),
+40.274d {+40d 16' 26"} (1950)
GRB_DATE: 18600 TJD; 117 DOY; 19/04/27
GRB_TIME: 16455.07 SOD {04:34:15.07} UT
TRIGGER_INDEX: 10318
GRB_PHI: 148.52 [deg]
GRB_THETA: 24.57 [deg]
DELTA_TIME: 52.00 [sec]
TRIGGER_DUR: 0.032 [sec]
SOLN_STATUS: 0x3
RATE_SIGNIF: 54.54 [sigma]
IMAGE_SIGNIF: 11.10 [sigma]
LC_URL: sw00900730000msb.lc
SUN_POSTN: 34.32d {+02h 17m 17s} +13.73d {+13d 44' 04"}
SUN_DIST: 98.44 [deg] Sun_angle= 7.6 [hr] (West of Sun)
MOON_POSTN: 312.37d {+20h 49m 29s} -19.44d {-19d 26' 13"}
MOON_DIST: 66.79 [deg]
MOON_ILLUM: 48 [%]
GAL_COORDS: 69.25, 19.05 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 287.41, 63.15 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT-BAT GRB Lightcurve.
COMMENTS:
COMMENTS: The next comments were copied from the BAT_POS Notice:
COMMENTS: This is a rate trigger.
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
COMMENTS: This trigger occurred at longitude,latitude = 88.92,-16.71 [deg].
- GCN Circular #24261
A. Tohuvavohu (PSU), N. J. Klingler (PSU), A. Y. Lien (GSFC/UMBC),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:
At 04:34:15 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 190427A (trigger=900730). Swift's slew will be delayed
due to an observing constraint.
The BAT on-board calculated location is
RA, Dec 280.213, +40.322 which is
RA(J2000) = 18h 40m 51s
Dec(J2000) = +40d 19' 20"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single short
structure with a duration of about 0.5 sec. The peak count rate
was ~6000 counts/sec (15-350 keV), at ~0 sec after the trigger.
Due to an observing constraint, Swift will not slew until T0+43.4
minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is A. Tohuvavohu (aaronb AT swift.psu.edu).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)
- GCN Circular #24263
V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa,
A.Kuznetsov, V.V.Chazov, D. Vlasenko
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk
Irkutsk State University
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 and Carlos Saffe
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
D. Buckley, S. Potter, A. Kniazev, M. Kotze
South African Astronomical Observatory
MASTER-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010,
Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) was pointed to the
Swift GRB190427.19 ( 18h 40m 51.12s , +40d 19m 19.20s, R=0.05) errorbox 40 sec after trigger time
at 2019-04-27 04:34:54 UT, with upper limit up to 18.6 mag. The observations began at zenit
distance = 16 deg. The sun altitude is -23.5 deg.
MASTER-SAAO robotic telescope located in South Africa (South African Astronomical Observatory) was
pointed to the Swift GRB190427.19 errorbox 44 sec after trigger time at 2019-04-27 04:34:58 UT,
with upper limit up to 13.2 mag. Observations started at twilight. The observations began at
zenit distance = 75 deg. The sun altitude is -7.5 deg.
The galactic latitude b = -60 deg., longitude l = 98 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1004408
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
45 | MASTER-IAC | P- | 10 | 16.8 |
45 | MASTER-IAC | P| | 10 | 17.1 |
50 | MASTER-SAAO | P\ | 10 | 13.3 |
77 | MASTER-SAAO | P\ | 10 | 13.2 |
100 | MASTER-IAC | P- | 20 | 17.4 |
100 | MASTER-IAC | P| | 20 | 17.6 |
108 | MASTER-SAAO | P\ | 20 | 13.1 |
160 | MASTER-IAC | P- | 30 | 17.7 |
160 | MASTER-IAC | P| | 30 | 17.9 |
212 | MASTER-IAC | P- | 40 | 17.9 |
212 | MASTER-IAC | P| | 40 | 18.2 |
274 | MASTER-IAC | P- | 50 | 18.1 |
274 | MASTER-IAC | P| | 50 | 18.3 |
346 | MASTER-IAC | P- | 60 | 18.3 |
346 | MASTER-IAC | P| | 60 | 18.6 |
The observation and reduction will continue.
The message may be cited.
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 27 Apr 19 05:36:59 UT
NOTICE_TYPE: Swift-XRT Nack-Position
TRIGGER_NUM: 900730, Seg_Num: 0
POINT_RA: 280.198d {+18h 40m 48s} (J2000)
POINT_DEC: +40.325d {+40d 19' 29"} (J2000)
IMG_START_DATE: 18600 TJD; 117 DOY; 19/04/27
IMG_START_TIME: 20190.67 SOD {05:36:30.67} UT, 3735.7 [sec] since BAT Trigger Time
COUNTS: 10 Min_needed= 20
STD_DEV: 0.00 Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER: 1 Max_iter_allowed= 4
ERROR_CODE: 1
COMMENTS: SWIFT-XRT Nack Position.
COMMENTS: No source found in the image.
- GCN Circular #24264
S. Campana (INAF-OAB), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU) and G. Tagliaferri
(INAF-OAB) report on behalf of the Swift-XRT team:
The XRT began observing the field of GRB 190427A at 05:36:30.6 UT,
3735.8 seconds after the BAT trigger. No source was detected in 142 s
of promptly downlinked data. We are waiting for the full dataset to
detect and localise the XRT counterpart.
- GCN Circular #24265
L. Izzo (HETH/IAA-CSIC), D. B. Malesani (DAWN/NBI and DARK/NBI), D. Xu
(NAOC/CAS), and N. Jannsen (NOT), report:
We observed the field of the Swift GRB 190427A (Tohuvavohu et al., GCN
24261; Campana et al., GCN 24264) using the Nordic Optical Telescope
(NOT) located in La Palma (Canary Islands, Spain), equipped with the
ALFOSC camera. We have obtained a series of 2 exposures of 300 s each in
the SDSS r’, i’ and z’ filters.
The first r'-band image was acquired starting on 2019 Apr 27.19742 UT
(602 s after the GRB). Visual comparison with the Pan-STARRS archival
images reveals no new sources inside the BAT error circle, down to a
limiting magnitude r = 23.5 AB (calibrated against Pan-STARRS sources).
Further analysis is ongoing.
- GCN Circular #24272
Y.-D. Hu, X.-Y.Li, E. Fernandez-Garcia, A. Ayala, and A. J.
Castro-Tirado (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), S. Jeong and
I. H. Park (SKKU), I. Carrasco, A. Castellon, C. Perez del Pulgar (Univ.
de Malaga), S. B. Pandey (ARIES) and M. D. Caballero-Garcia (ASU-CAS,
CZ) on behalf of a larger collaboration, report:
Following the detection of the short-duration GRB 190427A (Tohuvavohu et
al. GCNC 24261), both the 30cm BOOTES-1 robotic telescope in Mazagon
(Huelva, southern Spain) and the BOOTES-5/JGT robotic telescope at
Observatorio Astronomico Nacional in San Pedro Martir (Mexico),
automatically responded at 04:35:01 UT (~46 s after trigger) and
04:55:00 UT (~0.33 hr after trigger) respectively. No optical afterglow
is detected down to 17 mag and 20 mag respectively. This is consistent
with the no-detection reported by Lipunov et al. (GCNC 24263) and Izzo
et al. (GCNC 24265). Further analysis is ongoing.
- GCN Circular #24282
Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM),
Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB),
Antonino Cucchiara (UVI), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), Jesús González (UNAM), Carlos Roman-Zuniga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.),
and Vicki Toy (UMD) report:
We observed the field of GRB 190427A (Tohuvavohu, et al., GCN 24261)
with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
Astronomico Nacional on Sierra San Pedro Martir from 2019/04 27.28 to
2019/04 27.30 UTC (2.22 to 2.53 hours after the BAT trigger), obtaining
a total of 0.20 hours exposure in the r and i bands and 0.06 hours
exposure in the Z, Y, J, and H bands.
In comparison with the SDSS DR9 catalog, we detect no new source brighter
than r~22 AB mag within the BAT error circle.
We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Martir.
- GCN Circular #24287
Alan M. Watson (UNAM), Eleonora Troja (GSFC), Nat Butler (ASU), Rosa L.
Becerra (UNAM), Diego González (UNAM), William H. Lee (UNAM), Margarita
Pereyra (UNAM), Carlos Román-Zúñiga (UNAM) and Alexander Kutyrev (GSFC)
report:
We observed the field of GRB 190427A (Tohuvavohu et al., GCN Circ.
24261) with the COATLI 50-cm telescope and interim imager at the
Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir
(http://coatli.astroscu.unam.mx) from 2019-02-04 05:28:30 to 06:36:27
(from 0.9 to 2.0 hours after the trigger), obtaining a total of 3000
seconds of exposure in the w filter.
Comparing to the USNO and Pan-STARRS1 catalogs, we do not detect any new
sources brighter than w = 21 in the BAT error region.
Our w magnitudes are calibrated against the Pan-STARRS1 catalog, are on
an approximate AB system, and are not corrected for Galactic extinction
in the direction of the GRB.
We thank the COATLI technical team and the staff of the Observatorio
Astronómico Nacional.
- GCN Circular #24288
K. L. Murata, M. Oeda, K.Shiraishi, K. Iida, M. Niwano, R. Adachi, Y.
Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME
collaboration:
We searched for the optical counterpart of GRB 190427A (Tohuvavohu et al.,
GCN Circular #24261) 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 13:16:48 UT. We did not find any new point
sources within the BAT circle (Tohuvavohu et al., GCN Circular #24261) in
all three bands.
We obtained the following 5-sigma limits for the magnitudes.
T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
~8.7 13:35:08 1620(g'),1560(Rc),1980(Ic) g'>17.8,Rc>18.2,Ic
>18.6
------------------------------------------------------------------------------------------------
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 AB system.
- GCN Circular #24290
Keto Zhang, Shaunak Modak, WeiKang Zheng and Alexei V. Filippenko
(UC Berkeley) report on behalf of the KAIT GRB team:
We observed the field of GRB 190427A (Tohuvavohu et al., GCN 24261) with
the 1-m Nickel telescope located at Lick observatory, California.
Observations started about 4.31 hours after the burst. A total of
5 image in R band were taken with each exposure time of 600s.
No viable counterparts were identified in our images. The limiting
magnitude of our 5 combined image is R~22.0 mag calibrated to the
Pan-STARRS1 catalog.
- GCN Circular #24293
C. Malacaria (NASA-MSFC/USRA), A. von Kienlin (MPE)
and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 04:34:15.08 UT on 27 04 2019, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 190427A (trigger 578032460 / 190427190).
The event was also detected by the Swift/BAT
(Tohuvavohu et al. 2019, GCN 24261)
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time
is 106 degrees.
The GBM light curve consists of a dominant pulse with following
structure and a duration (T90) of about 0.37 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.384 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.05 +/- 0.18 and
the cutoff energy, parameterized as Epeak, is 246.40 +/- 78.20 keV.
The event fluence (10-1000 keV) in this time interval is
(4.855 +/- 0.717)E-07 erg/cm^2. The 64-msec peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band
is 18.8 +/- 1.1 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 #24294
V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa,
A.Kuznetsov, V.V.Chazov, D. Vlasenko
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk
Irkutsk State University
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 and Carlos Saffe
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
D. Buckley, S. Potter, A. Kniazev, M. Kotze
South African Astronomical Observatory
MASTER-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB190427.19 ( 18h 10m 04.08s , +46d 49m 58.80s, R=3.5) errorbox 45378 sec after trigger time at 2019-04-27 17:10:33 UT, with upper limit up to 19.8 mag. The observations began at zenit distance = 36 deg. The sun altitude is -25.2 deg.
The galactic latitude b = -60 deg., longitude l = 98 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1004400
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
45468 | 2019-04-27 17:10:33 | MASTER-Tunka | ( 17h 57m 43.43s , +46d 10m 42.11s) | C | 180 | 19.4 |
45468 | 2019-04-27 17:10:33 | MASTER-Tunka | ( 18h 7m 26.47s , +45d 59m 55.38s) | C | 180 | 19.8 |
46124 | 2019-04-27 17:21:29 | MASTER-Tunka | ( 17h 57m 41.81s , +46d 10m 55.77s) | C | 180 | 19.2 |
46124 | 2019-04-27 17:21:29 | MASTER-Tunka | ( 18h 7m 25.60s , +46d 0m 08.49s) | C | 180 | 19.8 |
46415 | 2019-04-27 17:26:19 | MASTER-Tunka | ( 17h 57m 42.87s , +46d 11m 01.93s) | C | 180 | 19.4 |
46415 | 2019-04-27 17:26:19 | MASTER-Tunka | ( 18h 7m 26.54s , +46d 0m 14.87s) | C | 180 | 19.8 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
- GCN Circular #24330
T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), A. Tohuvavohu (PSU)
(i.e. the Swift-BAT team):
Using the data set from T-61 to T+242 sec from the recent telemetry
downlink,
we report further analysis of BAT GRB 190427A (trigger #900730)
(Tohuvavohu et al., GCN Circ. 24261). The BAT ground-calculated position is
RA, Dec = 280.217, 40.304 deg which is
RA(J2000) = 18h 40m 52.0s
Dec(J2000) = +40d 18' 15.6"
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 68%.
The mask-weighted light curve shows a double-peaked structure that starts
from ~ T0 and ends at ~T+0.3. The main peak occurs at ~T0, followed by a
weaker peak at ~T+0.2 s. T90 (15-350 keV) is 0.3 +- 0.1 sec
(estimated error including systematics).
The time-averaged spectrum from T-0.0 to T+0.3 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.17 +- 0.21. The fluence in the 15-150 keV band is 1.3 +- 0.2 x 10^-7
erg/cm2.
The 1-sec peak photon flux measured from T-0.33 sec in the 15-150 keV band
is 1.6 +- 0.3 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/900730/BA/
- GCN Circular #24333
N. P. M. Kuin (UCL-MSSL) and A. Tohuvavohu (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 190427A
3737 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 24261).
No optical afterglow consistent with the BAT position (Ukwatta et al.,
GCN Circ. 24330) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
u 3737 3936 197 >19.9
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.06 in the direction of the burst
(Schlegel et al. 1998).
- GCN Circular #24339
N. Cannady (LSU),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka, S. Ozawa, S. Torii (Waseda U),
T. Tamura, Y. Shimizu (Kanagawa U), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena)
and the CALET collaboration:
The short GRB 190427A (Swift-BAT trigger #900730:
Tohuvavohu et al., GCN Circ. 24261, Ukwatta et al., GCN Circ. 24330;
Fermi GBM detection: Malacaria, von Kienlin and Meegan, GCN Circ. 24293)
was detected in ground analysis of the CALET Gamma-ray Burst Monitor (CGBM)
data near the Swift-BAT trigger time at T0=04:34:14.95 UT on 27 April 2019.
The burst signal was seen only by the SGM detector.
The source location (Ukwatta et al., GCN Circ. 24330) was out
of the HXM detectors' FOVs and likely blocked by the ISS structures.
The burst light curve shows a single bin (125 ms) spike
with a signal-to-noise ratio of 9.0 in the 40-1000 keV range.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1240374828/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.
Previous IAU Circulars 