HEPRO VIII GRB221009A analysis (dark)

Dark analysis

This page explains the analysis (source independent) done to produce the high-level results from GRB 221009A for the HEPRO VIII conference. The analysis uses the dark observations of this GRB (see below)

General information

• Name of the source: GRB 221009A
• Brief description of the source:
  • Object type : GRB
  • Redshift (z) : 0.15
  • Other relevant information
  • RA, Dec in deg (ICRS): 288.26452 deg, +19.77350 deg

• Analysis by Arnau Aguasca-Cabot (UB - arnau.aguasca@fqa.ub.edu)

Data-taking information

• • 2022-10-15
    • Zenith range (deg): 23.8 -> 57.9
    • Transmission9km: n/a
    • Observation condition: dark and moon (9629,9630)
    • Observation mode: std wobble
    • Runs: 9625 - 9628
    • Joint observations with MAGIC? : Yes, except the first 2 runs
    • ELOG link: [1]
    • Important comments: Data were affected by timestamp issue. (Reprocessing is already done and results below are from reprocessed data)

• • 2022-10-16
    • Zenith range (deg): 32.1 -> 64.1
    • Transmission9km: n/a
    • Observation condition: dark
    • Observation mode: std wobble
    • Runs: 9640 - 9647
    • Joint observations with MAGIC? : No
    • ELOG link: [2]
    • Important comments: Data were affected by timestamp issue. (Reprocessing is already done and results below are from reprocessed data)

• • 2022-10-17
    • Zenith range (deg): 25.9 -> 58.6
    • Transmission9km: n/a
    • Observation condition: dark
    • Observation mode: std wobble
    • Runs: 9670 - 9677
    • Joint observations with MAGIC? : Yes
    • ELOG link: [3]
    • Important comments: Data were affected by timestamp issue. (Reprocessing is already done and results below are from reprocessed data)

• • 2022-10-18
    • Zenith range (deg): 23.1 -> 43.5
    • Transmission9km: n/a
    • Observation condition: dark
    • Observation mode: std wobble
    • Runs: 9691 - 9696
    • Joint observations with MAGIC? : No
    • ELOG link: [4]
    • Important comments: unstable rate in run 9691

• • 2022-10-21
    • Zenith range (deg): 34.6 -> 55.6
    • Observation condition: dark
    • Observation mode: std wobble
    • Runs: 9802 - 9807
    • Joint observations with MAGIC? : Yes
    • ELOG link: [5]
    • Important comments:

• • 2022-10-23
    • Zenith range (deg): 32.07 -> 59.21
    • Observation condition: dark
    • Observation mode: std wobble
    • Runs: 9829 - 9835
    • Joint observations with MAGIC? : Yes
    • ELOG link: [6]
    • Important comments:

• • 2022-10-24
    • Zenith range (deg): 49.6 -> 58.8
    • Observation condition: dark
    • Observation mode: std wobble
    • Runs: 9861 - 9863
    • Joint observations with MAGIC? : No
    • ELOG link: [7]
    • Important comments: some clouds

• • 2022-10-25
    • Zenith range (deg): 43.6 -> 56
    • Observation condition: dark
    • Observation mode: std wobble
    • Runs: 9888 - 9891
    • Joint observations with MAGIC? : Yes
    • ELOG link: [8]
    • Important comments:

• • 2022-10-26
    • Zenith range (deg): 40 -> 56
    • Observation condition: dark
    • Observation mode: std wobble
    • Runs: 9917 - 9920
    • Joint observations with MAGIC? : Only run 9919
    • ELOG link: [9]
    • Important comments: run 9918,9919 are both in W2

Monte Carlo information

• MC production reprocessed with lstMCpipe (v0.9.9) starting at DL1a level for AllSky production. NSB tuning added at the DL1 level.
• Link to lstMCpipe production: https://github.com/cta-observatory/lstmcpipe/tree/master/production_configs/20221027_v0.9.9_crab_tuned

• Link to MC files used: /fefs/aswg/data/mc/*/AllSky/20221027_v0.9.9_crab_tuned
  • Particle types: Diffuse, point-like gammas, diffuse protons
  • dec band (deg): 22.67

DL1 data

Reprocessed using DL1a files produced by LSTOSA. The files were reprocessed solving the problem with the time stamp.

• original DL1a files (real)
• lstchain v0.9.6
• real data: tailcut8-4 (with cleaning based on pedestal RMS), dynamic cleaning

/fefs/aswg/data/real/DL1/*/v0.9/tailcut84/dl1_LST-1.Run0XXXX.XXXX.h5

• MC: tailcut8-4, dynamic cleaning, NSB tuning
• lstchain v0.9.9

 "image_modifier": {
   "increase_nsb": true,
    "extra_noise_in_dim_pixels": 1.62,
    "extra_bias_in_dim_pixels": 0.655,
    "transition_charge": 8,
    "extra_noise_in_bright_pixels": 2.08,
    "increase_psf": false,
    "smeared_light_fraction": 0
 },

/fefs/aswg/data/mc/DL1/AllSky/20221027_v0.9.9_crab_tuned/*

Random forest

• lstchain-0.9.9
• source-independent analysis (diffuse gamma, disp_norm)

https://github.com/cta-observatory/lstmcpipe/tree/master/production_configs/20221027_v0.9.9_crab_tuned

DL2 data

• lstchain-0.9.9
• source-independent analysis

/fefs/aswg/workspace/arnau.aguasca/Analysis/results/LST/real/DL2/202210*/srcind/v0.9.9/tailcut84_dynclg_tNSBtoCrabPerfPaper/AllSky_20221027_v0.9.9_crab_tuned_dec_2276/

DL3 data selection

DL3 files were produced using the interpolation mode to compute the IRFs with energy-dependent cuts (both for the gammaness and theta cut). The lstchain version (and pyirf version) used to produce the DL3 files do not correctly normalise the energy dispersion matrix to 1. Then, to fix this bug, I used the script fix_edisp.py (see attached file in https://github.com/cta-observatory/pyirf/releases/tag/v0.10.0) afterwards.

• lstchain-0.9.14dev (commit: 90d0450, after IRF interpolation method merged to the main branch)

 "filters": {
   "intensity": [50, Infinity],
   "width": [0, Infinity],
   "length": [0, Infinity],
   "r": [0, 1],
   "wl": [0.01, 1],
   "leakage_intensity_width_2": [0, 0.2],
   "event_type": [32, 32]
 }
 "gh_efficiency": 0.9,
 "theta_containment": 0.7,

High-level analysis

• Science Tool: gammapy 1.0
• point-like IRF, 1D analysis
• Three OFF regions at equidistant distances
• Energy threshold based on Crab check (200 GeV)

Analysis Results

Spectral results

• 

  Spectral energy distribution using all observations in dark conditions. The Crab spectrum is shown as a dashed red line.

Light curve results

• 

  Energy flux for LST-1 dark observations (Oct. 15-18 and 21-28). The ULs from HAWC (green) and H.E.S.S. (orange) are shown. The dashed line marks the Fermi-GBM trigger time (t0).

Crab check

The quality cuts used to produce the high-level results are based on the analysis of Crab data in similar conditions to the GRB 221009A data in dark conditions

• Crab runs (2022-03-04)

• Runs: 7255, 7256

• Crab runs (2022-03-05)

• Runs: 7277, 7278, 7279, 7280, 7281, 7282

• Crab runs (2022-11-20)

• Runs: 10914, 10915, 10916, 10917, 10918

• Crab runs (2022-11-23)

• Runs: 10986, 10987, 10988, 10989

• 

  Spectral energy distribution.

• 

  Light curve above 200 GeV.

Cross-check by Kenta

The plots below show the cross-check by Kenta (source-dependent analysis, lstchain v0.10.4 with runs 9629 and 9630 included). No edisp normalisation correction was applied.

• 

  Spectral energy distribution.

• 

  Light curve.