Fast Offline Analysis GRB240805B August 2024 P067

General information

• Name of the source: GRB240805B
• Brief description of the source:
  • Object type : GRB
  • Redshift (z) : ?
  • Other relevant information
  • RA, Dec in deg (ICRS): 254.2391, 18.3233

• Analysis by:
  • Irene Jiménez Martínez (MPI - irenejm@mpp.mpg.de)

Data-taking information

• Dates of data-taking:
  • Date: 2024-08-05 (3.8 h)
    • ZD range (deg): 10 - 60
    • Observations:

2024-08-05: [18438, 18439, 18440, 18441, 18442, 18443, 18444, 18445, 18446, 18447, 18448, 18449]

• Data quality selection: no run survives the data quality selection (max NSB std: 2.3).
• Joint observations with MAGIC?: yes
• Information on data-taking (observations summaries): https://www.lst1.iac.es/datacheck/observation_overview/2024/08/run_summary_2024_08_05.pdf

From Seiya Nozaki (via Slack): The last part of observations was significantly affected by MAGIC LIDAR, then rate control was not properly working and the rates were very low (~1 kHz). It seems this also affected the camera homogeneity, so I think that's why the background level is different between ON/OFF. http://www.lst1.iac.es/elog/LST+commissioning/3512

This seems to be causing spurious excess due to ON/OFF mismatch in one of the latest GRB data runs (18448)

General analysis information

• source-independent analysis
• lstchain version: v0.10.9
• DL1b standard production (v0.10/tailcut84), run-wise merged files in:

/fefs/aswg/data/real/DL1/20240805/v0.10/tailcut84/dl1_LST-1.Run18438.h5
/fefs/aswg/data/real/DL1/20240805/v0.10/tailcut84/dl1_LST-1.Run18439.h5
/fefs/aswg/data/real/DL1/20240805/v0.10/tailcut84/dl1_LST-1.Run18440.h5
/fefs/aswg/data/real/DL1/20240805/v0.10/tailcut84/dl1_LST-1.Run18441.h5
/fefs/aswg/data/real/DL1/20240805/v0.10/tailcut84/dl1_LST-1.Run18442.h5
/fefs/aswg/data/real/DL1/20240805/v0.10/tailcut84/dl1_LST-1.Run18443.h5
/fefs/aswg/data/real/DL1/20240805/v0.10/tailcut84/dl1_LST-1.Run18444.h5
/fefs/aswg/data/real/DL1/20240805/v0.10/tailcut84/dl1_LST-1.Run18445.h5
/fefs/aswg/data/real/DL1/20240805/v0.10/tailcut84/dl1_LST-1.Run18446.h5
/fefs/aswg/data/real/DL1/20240805/v0.10/tailcut84/dl1_LST-1.Run18447.h5
/fefs/aswg/data/real/DL1/20240805/v0.10/tailcut84/dl1_LST-1.Run18448.h5
/fefs/aswg/data/real/DL1/20240805/v0.10/tailcut84/dl1_LST-1.Run18449.h5

Monte Carlo information

Write below the MC production ID among the existing MC

• All-sky MC production used: 20240131_allsky_v0.10.5_all_dec_base
• Declination line (training): dec_2276

Random forest

Path to the models used:

/fefs/aswg/data/models/AllSky/20240131_allsky_v0.10.5_all_dec_base/dec_2276

DL2 data

Config file:

/fefs/aswg/data/models/AllSky/20240131_allsky_v0.10.5_all_dec_base/dec_2276/lstchain_config_2024-01-31.json

Files in:

/fefs/aswg/workspace/irene.jimenez/FOA/GRB240805B_20240805/DL2

DL3 data & IRF

"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": 0.98,
   "min_theta_cut": 0.1,
   "max_theta_cut": 0.32,
   "fill_theta_cut": 0.32,
   "allowed_tels": [1]
 }

• 70 % efficiency for both gammaness and theta gamma-ray selection 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
• Normalization range: 0.1 - 0.4 deg2
• Number of off positions: 3
• Energy range: 0.01 - 10 TeV

Daily results

• 2024-08-05: No detection

Light curve

Note: Run 18448 has excess of events in theta2 plot, likely because camera homogeneity was affected by MAGIC LiDAR and ON/OFF counts were different. See explanation here: https://www.lst1.iac.es/elog/LST+commissioning/3512 .