Gamma-ray Burst 220403C

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 03 Apr 22 10:10:44 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     670673407
GRB_RA:           66.850d {+04h 27m 24s} (J2000),
                  67.086d {+04h 28m 21s} (current),
                  66.320d {+04h 25m 17s} (1950)
GRB_DEC:         -23.350d {-23d 21' 00"} (J2000),
                 -23.302d {-23d 18' 05"} (current),
                 -23.461d {-23d 27' 37"} (1950)
GRB_ERROR:       6.89 [deg radius, statistical only]
DATA_SIGNIF:     5.00 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        19672 TJD;    93 DOY;   22/04/03
GRB_TIME:        36602.66 SOD {10:10:02.66} UT
GRB_PHI:         316.00 [deg]
GRB_THETA:        16.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:        12.56d {+00h 50m 13s}   +5.38d {+05d 22' 58"}
SUN_DIST:         60.43 [deg]   Sun_angle= -3.6 [hr] (East of Sun)
MOON_POSTN:       37.04d {+02h 28m 10s}  +13.44d {+13d 26' 28"}
MOON_DIST:        47.05 [deg]
MOON_ILLUM:      5 [%]
GAL_COORDS:      221.10,-41.38 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       59.67,-44.38 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220403424/quicklook/glg_lc_medres34_bn220403424.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_670673407.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
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 03 Apr 22 10:10:27 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      44
TRIGGER_NUM:     670673407
GRB_RA:           54.267d {+03h 37m 04s} (J2000),
                  54.464d {+03h 37m 51s} (current),
                  53.823d {+03h 35m 18s} (1950)
GRB_DEC:         -41.067d {-41d 04' 00"} (J2000),
                 -40.995d {-40d 59' 39"} (current),
                 -41.230d {-41d 13' 48"} (1950)
GRB_ERROR:       28.70 [deg radius, statistical plus systematic]
GRB_INTEN:       47 [cnts/sec]
DATA_SIGNIF:     5.10 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        19672 TJD;    93 DOY;   22/04/03
GRB_TIME:        36602.66 SOD {10:10:02.66} UT
GRB_PHI:          40.00 [deg]
GRB_THETA:        15.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.29
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      94%  GRB
2nd_MOST_LIKELY:   4%  Solar Flare
SUN_POSTN:        12.56d {+00h 50m 13s}   +5.38d {+05d 22' 58"}
SUN_DIST:         60.15 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
MOON_POSTN:       37.04d {+02h 28m 10s}  +13.44d {+13d 26' 24"}
MOON_DIST:        56.77 [deg]
MOON_ILLUM:      5 [%]
GAL_COORDS:      246.17,-53.40 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       34.29,-57.80 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220403424/quicklook/glg_lc_medres34_bn220403424.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 03 Apr 22 10:20:17 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     670673407
GRB_RA:           56.500d {+03h 46m 00s} (J2000),
                  56.684d {+03h 46m 44s} (current),
                  56.086d {+03h 44m 21s} (1950)
GRB_DEC:         -44.260d {-44d 15' 35"} (J2000),
                 -44.192d {-44d 11' 29"} (current),
                 -44.415d {-44d 24' 51"} (1950)
GRB_ERROR:       15.32 [deg radius, statistical only]
GRB_DATE:        19672 TJD;    93 DOY;   22/04/03
GRB_TIME:        36602.66 SOD {10:10:02.66} UT
GRB_PHI:          54.00 [deg]
GRB_THETA:        14.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:        12.56d {+00h 50m 15s}   +5.39d {+05d 23' 07"}
SUN_DIST:         63.45 [deg]   Sun_angle= -2.9 [hr] (East of Sun)
MOON_POSTN:       37.12d {+02h 28m 29s}  +13.47d {+13d 28' 27"}
MOON_DIST:        60.36 [deg]
MOON_ILLUM:      5 [%]
GAL_COORDS:      250.83,-51.22 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       34.37,-61.39 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220403424/quicklook/glg_lc_medres34_bn220403424.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220403424/quicklook/glg_locplot_all_bn220403424.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:        In the LAT Field-of-view.  
COMMENTS:        This is likely a Long GRB.

GCN Circular #31824
Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), James DeLaunay (UAlabama), Jamie A. Kennea (PSU), report:
Swift/BAT did not localize GRB 220403C onboard (T0: 2022-04-03T10:13:50 UTC, INTEGRAL SPI/ACS trig #9822 CALET trig #1333015963).
The INTEGRAL and CALET notices, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 90 seconds of BAT event-mode data from [-45,+45] seconds around the time of the burst. All the requested event mode data was delivered to the ground.
The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu, arXiv:2111.01769), detects the burst with a sqrt(TS) of 224.4 in a 8.192 s analysis time bin. The burst episode as seen by BAT is ~15s long.
NITRATES results strongly indicate a burst coming from outside the coded FoV, with DeltaLLHOut of -1614.
See Section 9.1 and Figure 20 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.
GUANO was also triggered by notice of GRB 220403A, detected by Fermi/GBM with T0: 2022-04-03T10:10:02 UTC (GCN 31818). GUANO retrieved 200s of event data from [-50,+150] seconds around the time of the burst. This Fermi/GBM trigger was 228 seconds before the emission episode reported above.
This burst is not detected by NITRATES running on the BAT-GUANO data.
The peak flux of the first emission episode in Fermi/GBM is substantially weaker compared to that seen for the second in BAT, and its non-detection in the BAT data is not necessarily indicative of a different progenitor object, especially considering the OFOV origin.
GRB 220403A could be a weak precursor episode to GRB 220403C, produced by the same object. Enhanced localizations for both bursts will be required to determine their relationship, if any.
GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/
GCN Circular #31860
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Fermi/GBM GRB 220403C. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021484
Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Fermi/GBM event. 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 #31866
M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of GRB 220403C, detected outside the BAT coded FOV by GUANO NITRATES (Aaron Tohuvavohu et al. GCN Circ. 31824), as well as by Fermi-GBM, INTEGRAL, CALET and ISS-ASIM, collecting 3.2 ks of Photon Counting (PC) mode data between T0+497.7 ks and T0+528.5 ks.
Six uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below:
Source 1:

  RA (J2000.0):  19.7120  =  01:18:50.87
  Dec (J2000.0): -56.4530  =  -56:27:10.8
  Error: 11.4 arcsec (radius, 90% conf.)
  Count-rate: (3.7 [+3.1, -2.2])e-3 ct s^-1   
  Distance: 515 arcsec from ASIM position.

Source 2:

  RA (J2000.0):  19.6293  =  01:18:31.04
  Dec (J2000.0): -56.3726  =  -56:22:21.5
  Error: 8.4 arcsec (radius, 90% conf.)
  Count-rate: (3.8 [+3.0, -2.2])e-3 ct s^-1   
  Distance: 530 arcsec from ASIM position.

Source 3:

  RA (J2000.0):  19.7466  =  01:18:59.17
  Dec (J2000.0): -56.4578  =  -56:27:28.0
  Error: 9.1 arcsec (radius, 90% conf.)
  Count-rate: (6.2 [+3.7, -2.8])e-3 ct s^-1   
  Distance: 484 arcsec from ASIM position.

Source 4:

  RA (J2000.0):  19.7142  =  01:18:51.41
  Dec (J2000.0): -56.2603  =  -56:15:37.1
  Error: 6.7 arcsec (radius, 90% conf.)
  Count-rate: (4.3 [+1.7, -1.3])e-3 ct s^-1   
  Distance: 479 arcsec from ASIM position.
  Flux: (2.90 [+1.13, -0.91])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 5:

  RA (J2000.0):  19.7189  =  01:18:52.53
  Dec (J2000.0): -56.2878  =  -56:17:16.2
  Error: 6.8 arcsec (radius, 90% conf.)
  Count-rate: (1.17 [+1.01, -0.72])e-3 ct s^-1	 
  Distance: 411 arcsec from ASIM position.

Source 6:

  RA (J2000.0):  19.9526  =  01:19:48.63
  Dec (J2000.0): -56.2605  =  -56:15:37.7
  Error: 6.8 arcsec (radius, 90% conf.)
  Count-rate: (2.13 [+1.25, -0.92])e-3 ct s^-1	 
  Distance: 344 arcsec from ASIM position.

The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00021484.
This circular is an official product of the Swift-XRT team.

GCN Circular #31877
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the MGNS/BepiColombo and HEND/Mars Odyssey teams,
J. Benkhoff on behalf of the BepiColombo team,
D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko, and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi GBM team,
E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on behalf of the GRS-Odyssey GRB team, report:
The bright, long-duration GRB 220403C (Swift/BAT-GUANO detection: Tohuvavohu et al. GCN Circ. 31824) was detected by Konus-Wind, Fermi (GBM in the trigger 670673407), INTEGRAL (SPI-ACS), BepiColombo (MGNS), Mars-Odyssey (HEND), Swift (BAT), CALET (CGBM), and ISS (ASIM) at about 36830 s UT (10:13:50). The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:
```
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    17.570 (01h 10m 17s) -56.225 (-56d 13' 31")
  Corners:
    17.411 (01h 09m 39s) -56.347 (-56d 20' 48")
    17.548 (01h 10m 12s) -56.349 (-56d 20' 56")
    17.728 (01h 10m 55s) -56.104 (-56d 06' 13")
    17.591 (01h 10m 22s) -56.101 (-56d 06' 05")
  ---------------------------------------------
```
The error box area is 68 sq. arcmin, and its maximum dimension is 18 arcmin (the minimum one is 4.3 arcmin). The Sun distance was 62 deg.
This box may be improved.
The box is inconsistent with the GRB 220403A Konus-GBM annulus centered at RA(2000)=355.082 deg (23h 40m 20s) Dec(2000)=-4.166 deg (-4d 09' 56"), whose radius is 23.380 +/- 23.380 deg (3 sigma). Thus GRB 220403C and GRB 220403A (GCN 31818) are unrelated.
A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB220403_T36829/IPN/
The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
GCN Circular #31907
D. Svinkin, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, report:
The bright, long-duration GRB 220403C (Swift/BAT-GUANO detection: Tohuvavohu et. al, GCN Circ. 31824; IPN triangulation: Kozyrev et al., GCN Circ. 31877) triggered Konus-Wind at T0=36829.998 s UT (10:13:49.998).
The burst light curve shows multipeaked structure which starts at ~T0-3 s and has a total duration of ~66 s. The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB220403_T36829/
As observed by Konus-Wind, the burst had a fluence of 1.45(-0.20,+0.17)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+3.456 s, of 2.81(-0.48,+0.47)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+64.512 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.12(-0.09,+0.10), the high energy photon index beta = -1.86(-0.25,+0.11), the peak energy Ep = 540(-130,+254) keV (chi2 = 86/82 dof).
The spectrum near the maximum count rate (measured from T0+3.328 to T0+4.096 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.86(-0.09,+0.11), the high energy photon index beta = -2.38(-0.97,+0.31), the peak energy Ep = 835(-200,+240) keV (chi2 = 60/56 dof).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #31924
A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed a second follow-up observation of GRB 220403C, detected outside the BAT coded FOV by GUANO NITRATES (Aaron Tohuvavohu et al. GCN Circ. 31824), and later triangulated by IPN (GCN Circ. 31877). This time the XRT pointed at the centre of the IPN error region, collecting 2.5 ks of Photon Counting (PC) mode data between T0+1311.3 ks and T0+1324.1 ks.
Two uncatalogued X-ray sources have been detected, however neither of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if either, is the afterglow. Details of these sources are given below:
Source 1:
```
  RA (J2000.0):  17.5547  =  01:10:13.12
  Dec (J2000.0): -56.2345  =  -56:14:04.2
  Error: 5.5 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (5.7 [+2.0, -1.6])e-3 ct s^-1   
  Distance: 46 arcsec from IPN position.
  Flux: (6.8 [+2.4, -2.0])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
```
Source 2:
```
  RA (J2000.0):  17.9074  =  01:11:37.77
  Dec (J2000.0): -56.1775  =  -56:10:38.9
  Error: 9.7 arcsec (radius, 90% conf.)
  Count-rate: (5.0 [+3.2, -2.3])e-3 ct s^-1   
  Distance: 695 arcsec from IPN position.
```
We note that neither of these sources is consistent with the location of the galaxy LEDA 3080270 which lies within the IPN error box.
The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00021485.
This circular is an official product of the Swift-XRT team.

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Jochen Greiner, last update: 20-Apr-2022 [Disclaimer]