Gamma-ray Burst 240109A

(All information courtesy of the instrument teams.)

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 09 Jan 24 04:01:54 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1207446,   Seg_Num: 0
GRB_RA:          301.318d {+20h 05m 16s} (J2000),
                 301.591d {+20h 06m 22s} (current),
                 300.748d {+20h 02m 59s} (1950)
GRB_DEC:         +16.578d {+16d 34' 39"} (J2000),
                 +16.647d {+16d 38' 50"} (current),
                 +16.434d {+16d 26' 02"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       345 [cnts]    Image_Peak=48 [image_cnts]
TRIGGER_DUR:     0.064 [sec] 
TRIGGER_INDEX:   10420     E_range: 25-100 keV
BKG_INTEN:       15712 [cnts]
BKG_TIME:        14479.30 SOD {04:01:19.30} UT
BKG_DUR:         8 [sec]
GRB_DATE:        20318 TJD;     9 DOY;   24/01/09
GRB_TIME:        14494.98 SOD {04:01:34.98} UT
GRB_PHI:         -103.71 [deg]
GRB_THETA:        22.58 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     19.26 [sigma]
IMAGE_SIGNIF:    7.22 [sigma]
MERIT_PARAMS:     +1  +0  +0  -4  +2  -3 -100  +1 -76  +0 
SUN_POSTN:       289.89d {+19h 19m 35s}  -22.18d {-22d 10' 32"}
SUN_DIST:         40.48 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      255.89d {+17h 03m 33s}  -27.00d {-27d 00' 10"}
MOON_DIST:        62.22 [deg]
MOON_ILLUM:      7 [%]
GAL_COORDS:       56.27, -8.05 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      308.00, 35.98 [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 = 142.72,19.15 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 09 Jan 24 04:05:31 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1207446,   Seg_Num: 0
GRB_RA:          301.318d {+20h 05m 16s} (J2000),
                 301.591d {+20h 06m 22s} (current),
                 300.748d {+20h 02m 59s} (1950)
GRB_DEC:         +16.578d {+16d 34' 39"} (J2000),
                 +16.647d {+16d 38' 50"} (current),
                 +16.434d {+16d 26' 02"} (1950)
GRB_DATE:        20318 TJD;     9 DOY;   24/01/09
GRB_TIME:        14495.12 SOD {04:01:35.12} UT
TRIGGER_INDEX:   10420
GRB_PHI:         -103.71 [deg]
GRB_THETA:        22.58 [deg]
DELTA_TIME:      18.00 [sec]
TRIGGER_DUR:     0.064 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     19.26 [sigma]
IMAGE_SIGNIF:    7.22 [sigma]
LC_URL:          sw01207446000msb.lc
SUN_POSTN:       289.90d {+19h 19m 35s}  -22.18d {-22d 10' 31"}
SUN_DIST:         40.48 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      255.93d {+17h 03m 42s}  -27.01d {-27d 00' 28"}
MOON_DIST:        62.20 [deg]
MOON_ILLUM:      7 [%]
GAL_COORDS:       56.27, -8.05 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      308.00, 35.98 [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 = 142.72,19.15 [deg].

GCN Circular #35501
S. Dichiara (PSU), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 04:01:35 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 240109A (trigger=1207446). Due to a Sun constraint, Swift did not slew immediately to the burst. The BAT on-board calculated location is RA, Dec 301.318, +16.578 which is
```
   RA(J2000) = 20h 05m 16s
   Dec(J2000) = +16d 34' 39"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single spike structure with a duration of about 0.25 sec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~0.1 sec after the trigger.
Due to a Sun observing constraint, Swift cannot slew to the BAT position until 00:14 UT on 2024 March 01. There will thus be no XRT or UVOT data for this trigger before this time.
Burst Advocate for this burst is S. Dichiara (sbd5667 AT 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 #35519
O.J. Roberts (USRA/NASA-MSFC) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 04:01:35.21 UT on 09 January 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240109A (trigger 726465700/240109168). which was also detected by Swift-BAT (S. Dichiara et al. 2024, GCN 35501). The Fermi GBM on-ground Localization is consistent with the Swift-BAT position.
The angle from the Fermi LAT boresight is 79 degrees using the Swift-BAT position.
The GBM light curve consists of a single peak with a duration (T90) of about 0.26 s (50-300 keV). The time-averaged spectrum from T0-0.12 to T0+0.12 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.0 +/- 0.3 and the cutoff energy, parameterized as Epeak, is 305 +/- 179 keV.
The event fluence (10-1000 keV) in this time interval is (1.6 +/- 0.4)E-07 erg/cm^2. The 0.064-sec peak photon flux measured starting from T0-0.064 s in the 10-1000 keV band is 6 +/- 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 #35523
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), T. Parsotan (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU) (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 240109A (trigger #1207446) (Dichiara et al., GCN Circ. 35501). The BAT ground-calculated position is RA, Dec = 301.330, 16.566 deg which is
```
   RA(J2000)  =  20h 05m 19.1s
   Dec(J2000) = +16d 33' 58.3"
```
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 67%.
The BAT light curve shows a single peak with a duration ~0.5 sec. T90 (15-350 keV) is 0.16 +- 0.06 sec (estimated error including systematics).
The time-averaged spectrum from T-0.04 to T+0.15 sec is better fit by a blackbody. A simple power-law fit shows a photon index of 2.75 +-0.35 with a poor statistics (reduced chi2 of 1.9). Instead, the black body fit shows the temperature of 12.2 +-1.3 keV with a reasonable statistics (reduced chi2 of 1.2). So, the burst prefers a soft spectrum. The fluence in the 15-150 keV band is 1.2 +- 0.4 x 10^-08 erg/cm2. The 1-sec peak photon flux measured from T-0.44 sec in the 15-150 keV band is 0.7 +- 0.2 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/1207446/BA/

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Jochen Greiner, last update: 12-Jan-2024 [Disclaimer]