Fast Offline Analysis GRB 240912A September 2024 P068

General information

• Name of the source: GRB 240912A
• Brief description of the source:
  • Object type :
  • Redshift (z) : z = 1.234
  • Other relevant information
  • RA: 8h18m32.62s (hh mm ss), Dec: 33d59m54.96s (dd mm ss)
  • RA, Dec in deg (ICRS): 124.64, 34.00

• Analysis by:
  • Helena Luciani (University of Trieste - helena.luciani@phd.units.it)

Data-taking information

• Dates of data-taking: 2024-09-11
  • • time of observations: 0.28 hours
    • ZD range (deg): 50 - 70
    • Observations:

20240911 : [19036]

• Data quality selection:

• Joint observations with MAGIC?: No
• Information on data-taking (observations summaries): Observation interrupted due to low CAM.H.LOW and go to Standby. (https://www.lst1.iac.es/datacheck/observation_overview/2024/09/run_summary_2024_09_11.pdf)

General analysis information

• source-independent analysis
• lstchain version: v0.10.11
• DL1b standard production (v0.10/tailcut84), run-wise merged files in:

/fefs/aswg/data/real/DL1/20240911/v0.10/tailcut84/dl1_LST-1.Run19036.h5 

Monte Carlo information

• All-sky MC production used: 20240131_allsky_v0.10.5_all_dec_base
• Declination line (training): dec_3476

Random forest

Path to the models used:

/fefs/aswg/data/models/AllSky/20240131_allsky_v0.10.5_all_dec_base/dec_3476/

DL2 data

Config file:

/fefs/aswg/data/models/AllSky/20240131_allsky_v0.10.5_all_dec_base/dec_3476/lstchain_config_2024-01-31.json

Files in:

/fefs/aswg/workspace/helena.luciani/fast_offline_analysis/grb_alert_1253910/DL2

DL3 data & IRF

Files in:

/fefs/aswg/workspace/helena.luciani/fast_offline_analysis/grb_alert_1253910/DL3

Configuration used for producing IRF/DL3 files (you can leave standard settings):

 "EventSelector": {
   "filters": {
     "intensity": [50, Infinity],
     "width": [0, Infinity],
     "length": [0, Infinity],
     "r": [0, 1],
     "wl": [0.01, 1],
     "leakage_intensity_width_2": [0, 1],
     "event_type": [32, 32]
   }
 },
 "DL3Cuts": {
   "min_event_p_en_bin": 100,
   "min_gh_cut": 0.1,
   "max_gh_cut": 0.95,
   "min_theta_cut": 0.0,
   "max_theta_cut": 0.2,
   "fill_theta_cut": 0.2,
   "allowed_tels": [1]
 },

• Standard cuts: Intensity > 50 p.e., 70 % efficiency for both gammaness and theta gamma-ray selection energy-dependent cuts.
• Point-like IRF.

High-level analysis and results

Analysis settings

• Gammapy version: 1.1
• 1D analysis (point-like IRF)

Theta2 plot

Settings:

• Theta2 cut for signal extraction: 0.04 deg2
• Energy range: 10 GeV - 10 TeV

• Non-homogeneities found across the field of view for E>500 GeV, causing a mismatch in the on/off normalization for wobble positions 180, 270.
  

Possible explanation: very large zenith observations (60-70 deg)

Significance and Excess sky maps

• High ZD observation - energy threshold increased to 500 GeV