Gamma-ray Burst 220310C

(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:     Thu 10 Mar 22 22:24:15 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     668643836
GRB_RA:          290.433d {+19h 21m 44s} (J2000),
                 290.593d {+19h 22m 22s} (current),
                 290.073d {+19h 20m 17s} (1950)
GRB_DEC:         +47.017d {+47d 01' 00"} (J2000),
                 +47.060d {+47d 03' 36"} (current),
                 +46.920d {+46d 55' 13"} (1950)
GRB_ERROR:       14.10 [deg radius, statistical plus systematic]
GRB_INTEN:       67 [cnts/sec]
DATA_SIGNIF:     6.80 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        19648 TJD;    69 DOY;   22/03/10
GRB_TIME:        80631.43 SOD {22:23:51.43} UT
GRB_PHI:         252.00 [deg]
GRB_THETA:        25.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.16
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      74%  GRB
2nd_MOST_LIKELY:  25%  Cyg X-1
DETECTORS:       0,0,0, 0,0,0, 1,1,0, 0,0,0, 0,0,
SUN_POSTN:       351.11d {+23h 24m 27s}   -3.83d {-03d 49' 51"}
SUN_DIST:         73.41 [deg]   Sun_angle= 4.0 [hr] (West of Sun)
MOON_POSTN:       85.02d {+05h 40m 05s}  +25.96d {+25d 57' 24"}
MOON_DIST:       103.42 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       78.61, 14.69 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      308.88, 67.72 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220310933/quicklook/glg_lc_medres34_bn220310933.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 140.20,6.47 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 10 Mar 22 22:24:33 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     668643836
GRB_RA:          292.400d {+19h 29m 36s} (J2000),
                 292.546d {+19h 30m 11s} (current),
                 292.070d {+19h 28m 17s} (1950)
GRB_DEC:         +50.390d {+50d 23' 24"} (J2000),
                 +50.437d {+50d 26' 14"} (current),
                 +50.285d {+50d 17' 05"} (1950)
GRB_ERROR:       11.13 [deg radius, statistical only]
DATA_SIGNIF:     7.30 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        19648 TJD;    69 DOY;   22/03/10
GRB_TIME:        80631.43 SOD {22:23:51.43} UT
GRB_PHI:         247.00 [deg]
GRB_THETA:        22.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       351.11d {+23h 24m 27s}   -3.83d {-03d 49' 51"}
SUN_DIST:         73.74 [deg]   Sun_angle= 3.9 [hr] (West of Sun)
MOON_POSTN:       85.03d {+05h 40m 06s}  +25.96d {+25d 57' 25"}
MOON_DIST:        99.81 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       82.34, 14.91 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      316.03, 70.27 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220310933/quicklook/glg_lc_medres34_bn220310933.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_668643836.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:     Thu 10 Mar 22 22:33:09 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     668643836
GRB_RA:          290.740d {+19h 22m 58s} (J2000),
                 290.914d {+19h 23m 39s} (current),
                 290.349d {+19h 21m 24s} (1950)
GRB_DEC:         +43.740d {+43d 44' 24"} (J2000),
                 +43.784d {+43d 47' 02"} (current),
                 +43.642d {+43d 38' 32"} (1950)
GRB_ERROR:       5.38 [deg radius, statistical only]
GRB_DATE:        19648 TJD;    69 DOY;   22/03/10
GRB_TIME:        80631.43 SOD {22:23:51.43} UT
GRB_PHI:         258.00 [deg]
GRB_THETA:        27.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       351.12d {+23h 24m 28s}   -3.83d {-03d 49' 43"}
SUN_DIST:         71.84 [deg]   Sun_angle= 4.0 [hr] (West of Sun)
MOON_POSTN:       85.10d {+05h 40m 25s}  +25.96d {+25d 57' 52"}
MOON_DIST:       106.34 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       75.64, 13.13 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      306.57, 64.57 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220310933/quicklook/glg_lc_medres34_bn220310933.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220310933/quicklook/glg_locplot_all_bn220310933.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 #31735
The Fermi GBM team reports the detection of a likely LONG GRB
At 22:23:51 UT on 10 Mar 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 220310C (trigger 668643836.426778 / 220310933).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 290.7, Dec = 43.7 (J2000 degrees, equivalent to J2000 19h 22m, 43d 42'), with a statistical uncertainty of 5.4 degrees.
The angle from the Fermi LAT boresight is 27.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220310933/quicklook/glg_skymap_all_bn220310933.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220310933/quicklook/glg_healpix_all_bn220310933.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220310933/quicklook/glg_lc_medres34_bn220310933.gif
GCN Circular #31746
Aaron Tohuvavohu (U Toronto), James DeLaunay (UAlabama), Gayathri Raman (PSU), Jamie A. Kennea (PSU), report:
Swift/BAT did not localize GRB 220310C onboard (T0: 2022-03-10T22:23:51 UTC, Fermi/GBM GCN 31735).
The Fermi notice, 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 200 seconds of BAT event-mode data from [-50,+150] 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 in a 8.192 s analysis time bin with a sqrt(TS) of 9.7. A candidate arcminute localization is found with DeltaLLHOut of 19.7 and a DeltaLLHPeak of 5.7.
For this reason we can confidently claim detection, and preference for an in FOV origin, but the best fit arcmin localization is not strongly preferred over other positions. A few burst locations with comparable DeltaLLHPeak have been previously verified with afterglow discovery (eg GRB 211106A).
See Section 9.1 and Figure 20 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.
No source is found with conventional BAT imaging. This is expected given the strength of the signal in BAT, and its position near the edge of the coded FOV.
The BAT position is RA, Dec = 290.069, +40.253 deg which is
```
   RA(J2000)  = 19h 20m 16.62s
   Dec(J2000) = +40d 15′ 12.3″
```
with an estimated uncertainty of 5 arcmin.
This independent position is consistent with the Fermi/GBM localization (GCN 31735).
XRT and UVOT follow-up has been requested. Results of follow-up observations will be reported in future circulars.
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 #31747
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Swift/BAT-GUANO GRB 220310C. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021483
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 Swift/BAT-GUANO 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 #31749
D.N. Burrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Swift/BAT-GUANO-detected burst GRB 220310C, collecting 4.6 ks of Photon Counting (PC) mode data between T0+102.8 ks and T0+120.2 ks.
Four 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):  289.9580  =  19:19:49.91
  Dec (J2000.0): +40.2093  =  +40:12:33.3
  Error: 7.9 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (4.4 +/- 1.2)e-3 ct s^-1	 
  Distance: 344 arcsec from Swift/BAT-GUANO position.
  Flux: (9.6 +/- 2.7)e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:

  RA (J2000.0):  290.2354  =  19:20:56.50
  Dec (J2000.0): +40.3333  =  +40:19:59.9
  Error: 7.6 arcsec (radius, 90% conf.)
  Count-rate: (3.7 [+1.4, -1.1])e-3 ct s^-1   
  Distance: 539 arcsec from Swift/BAT-GUANO position.
  Flux: (1.39 [+0.51, -0.42])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 3:

  RA (J2000.0):  290.1544  =  19:20:37.05
  Dec (J2000.0): +40.2064  =  +40:12:23.0
  Error: 6.3 arcsec (radius, 90% conf.)
  Count-rate: (1.92 [+0.98, -0.76])e-3 ct s^-1	 
  Distance: 288 arcsec from Swift/BAT-GUANO position.
  Flux: (4.2 [+2.2, -1.7])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 4:

  RA (J2000.0):  289.8727  =  19:19:29.46
  Dec (J2000.0): +40.2572  =  +40:15:26.0
  Error: 6.4 arcsec (radius, 90% conf.)
  Count-rate: (1.41 [+0.96, -0.69])e-3 ct s^-1	 
  Distance: 540 arcsec from Swift/BAT-GUANO 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/00021483.
This circular is an official product of the Swift-XRT team.

GCN Circular #31755
P. Veres and C. Meegan (both UAH) report on behalf of the Fermi GBM Team:
"At 22:23:51.43 UT on 10 March 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220310C (trigger 668643836 / 220310933) which was also detected by the Swift/BAT (Tohuvavohu et al., GCN 31746). The Fermi GBM Final Real-time Localization (GCN 31735) is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 30 degrees.
The GBM light curve shows a single peak with a duration (T90) of about 16.4 s (50-300 keV). The time-averaged spectrum from T0-6.1 s to T0+16.4 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.74 +/- 0.30 and the cutoff energy, parameterized as Epeak, is 180 +/- 51 keV.
The event fluence (10-1000 keV) in this time interval is (1.52 +/- 0.27)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0-1.7 s in the 10-1000 keV band is 1.28 +/- 0.18 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/"

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Jochen Greiner, last update: 14-Mar-2022 [Disclaimer]