Gamma-ray Burst 210403A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 03 Apr 21 08:27:32 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1040345,   Seg_Num: 0
GRB_RA:            2.767d {+00h 11m 04s} (J2000),
                   3.035d {+00h 12m 08s} (current),
                   2.134d {+00h 08m 32s} (1950)
GRB_DEC:         -32.999d {-32d 59' 56"} (J2000),
                 -32.881d {-32d 52' 51"} (current),
                 -33.277d {-33d 16' 37"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3507 [cnts]    Image_Peak=173 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   137     E_range: 15-50 keV
BKG_INTEN:       22667 [cnts]
BKG_TIME:        30421.22 SOD {08:27:01.22} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19307 TJD;    93 DOY;   21/04/03
GRB_TIME:        30433.95 SOD {08:27:13.95} UT
GRB_PHI:         -113.49 [deg]
GRB_THETA:        20.16 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.58 [sigma]
IMAGE_SIGNIF:    7.52 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +1  -2 -100  +0 -77  +0 
SUN_POSTN:        12.71d {+00h 50m 51s}   +5.45d {+05d 26' 53"}
SUN_DIST:         39.41 [deg]   Sun_angle= 0.6 [hr] (West of Sun)
MOON_POSTN:      270.03d {+18h 00m 07s}  -24.85d {-24d 50' 59"}
MOON_DIST:        79.15 [deg]
MOON_ILLUM:      62 [%]
GAL_COORDS:      356.57,-79.48 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      347.91,-31.05 [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 = 53.22,-12.86 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 03 Apr 21 08:31:13 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1040345,   Seg_Num: 0
GRB_RA:            2.767d {+00h 11m 04s} (J2000),
                   3.035d {+00h 12m 08s} (current),
                   2.134d {+00h 08m 32s} (1950)
GRB_DEC:         -32.999d {-32d 59' 56"} (J2000),
                 -32.881d {-32d 52' 51"} (current),
                 -33.277d {-33d 16' 37"} (1950)
GRB_DATE:        19307 TJD;    93 DOY;   21/04/03
GRB_TIME:        30433.95 SOD {08:27:13.95} UT
TRIGGER_INDEX:   137
GRB_PHI:         -113.49 [deg]
GRB_THETA:        20.16 [deg]
DELTA_TIME:      6.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.58 [sigma]
IMAGE_SIGNIF:    7.52 [sigma]
LC_URL:          sw01040345000msb.lc
SUN_POSTN:        12.71d {+00h 50m 51s}   +5.45d {+05d 26' 56"}
SUN_DIST:         39.42 [deg]   Sun_angle= 0.6 [hr] (West of Sun)
MOON_POSTN:      270.07d {+18h 00m 16s}  -24.85d {-24d 51' 10"}
MOON_DIST:        79.12 [deg]
MOON_ILLUM:      62 [%]
GAL_COORDS:      356.57,-79.48 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      347.91,-31.05 [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 = 53.22,-12.86 [deg].

GCN Circular #29748
K. L. Page (U Leicester) and A. Y. Lien (GSFC/UMBC) report on behalf of the Neil Gehrels Swift Observatory Team:
At 08:27:13 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210403A (trigger=1040345). Swift did not slew immediately to the burst due to an observing constraint. The BAT on-board calculated location is RA, Dec 2.767, -32.999 which is
```
   RA(J2000) = 00h 11m 04s
   Dec(J2000) = -32d 59' 56"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 140 sec. The peak count rate was ~1200 counts/sec (15-350 keV), at ~0 sec after the trigger.
Due to a Sun observing constraint, Swift cannot slew to the BAT position until 21:34 UT on 2021 April 14. There will thus be no XRT or UVOT data for this trigger before this time.
Burst Advocate for this burst is K. L. Page (klp5 AT leicester.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/)
GCN Circular #29751
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),
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 GRB210403.35 (trigger No 1040345,00h 11m 04.08s , -32d 59m 56.4s, R=0.05) errorbox 1478 sec after notice time and 1500 sec after trigger time at 2021-04-03 08:52:14 UT, with upper limit up to 18.8 mag. The observations began at zenith distance = 85 deg. The sun altitude is -25.4 deg.
The galactic latitude b = -80 deg., longitude l = 356 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1582518
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

    1591 |         MASTER-OAFA |   C |   180 | 16.2 |        
    2025 |         MASTER-OAFA |   C |   180 | 17.0 |        
    2205 |         MASTER-OAFA |   C |   540 | 18.0 |  Coadd 
    3222 |         MASTER-OAFA |   C |   180 | 17.8 |        
    3422 |         MASTER-OAFA |   C |   180 | 17.9 |        
    3621 |         MASTER-OAFA |   C |   180 | 18.0 |        
    3801 |         MASTER-OAFA |   C |   540 | 18.8 |  Coadd 
    3820 |         MASTER-OAFA |   C |   180 | 18.0 |        
    4020 |         MASTER-OAFA |   C |   180 | 18.1 |        
    4219 |         MASTER-OAFA |   C |   180 | 18.1 |        
    4419 |         MASTER-OAFA |   C |   180 | 18.0 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #29754
H. A. Krimm (NSF), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL), (i.e. the Swift-BAT team):
Using the data set from T-61 to T+242 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210403A (trigger #1040345) (K.Page, et al., GCN Circ. 29748). The BAT ground-calculated position is RA, Dec = 2.813, -33.024 deg which is
```
   RA(J2000)  =  00h 11m 15.2s 
   Dec(J2000) = -33d 01' 27.2" 
```
with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 80%.
The lightcurve has multiple peaks starting at T-40 sec and ending at T+140 sec. T90 (15-350 keV) is 168.3 +- 9.2 sec (estimated error including systematics).
The time-averaged spectrum from T-41.51 to T+137.18 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.93 +- 0.52, and Epeak of 37.4 +- 4.8 keV (chi squared 52.21 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.7 +- 0.2 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+0.18 sec in the 15-150 keV band is 1.1 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.13 +- 0.10 (chi squared 73.02 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/1040345/BA/

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Jochen Greiner, last update: 03-Apr-2021 [Disclaimer]