Fast Offline Analysis gw-alerts241125 November 2024 P071

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General information

• Name of the source: gw-alerts241125 or S241125n
• Brief description of the source: Swift-BAT position (GCN Circular 38308) of a gravitational wave alert(GCN Circular 38305)
  • Object type : Binary Black hole merger
  • Redshift (z) : NA
  • Other relevant information
  • RA: 03h 52m 18.96s (hh mm ss), Dec: +69d 41’ 20.4″ (dd mm ss)
  • RA, Dec in deg (ICRS): 58.079, +69.689

• Analysis by:
  • Analyzer 1 Sweta Menon (INAF-Rome - sweta.menon@inaf.it)

Data-taking information

• Dates of data-taking: 2024-11-25
  • Date (time of observation h)" 3.4
    • ZD range (deg): 40-60
    • Observations:

20241125:   [19799 19801 19802 19804 19805 19806 19807 19808 19809 19810 19811]

• Data quality selection: 0 hours of good data

Number of runs (% is w.r.t. those in Sky region & zenith range):

   In the requested Sky region and range of dates:	 13
 + zenith in requested range:				 13
 + NSB in requested range:				 13 (100.0%)

 + FF and pedestal interleaved events are present:	 13 (100.0%)
 + Stable pointing:					 13 (100.0%)
 + dR/dI fit P-value ok:				 13 (100.0%)
 + dR/dI LS periodogram ok:				 12 (92.3%)
 + dR/dI index ok:					 11 (84.6%)
 + dR/dI rate ok:					 0 (0.0%)
 + intensity threshold ok:				 0 (0.0%)

• Joint observations with MAGIC?: Yes except runs 19879, 19880
• Information on data-taking (observations summaries): Bad weather with poor transmission rates at 9km <40% (from MAGIC LIDAR). Cloudiness ~80%

General analysis information

• source-independent analysis
• lstchain version: v0.10.13
• DL1b standard production (v0.10/tailcut84), run-wise merged files in:

/fefs/aswg/data/real/DL1/20241125/v0.10/tailcut84/dl1_LST-1.Run?????.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_6676

Random forest

Path to the models used: (example below)

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

DL2 data

The config file to produce the DL2 files must be the one used to produce the RF models. Should be located together with model's files.

Files in:

/fefs/aswg/workspace/sweta.menon/FOA/S241125n/DL2/*

DL3 data & IRF

Files in:

/fefs/aswg/workspace/sweta.menon/FOA/S241125n/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.
• Recommended to produce unzipped DL3 files since the Gammapy analysis Gammapy is faster.
• You can set the max theta cut (and filling value to the same value) to e.g. 0.2 deg. In this way, you can use more off-regions in Gammapy.
• Point-like IRF.

High-level analysis and results

Analysis settings

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

Theta2 plot

• 2024-11-25

• Theta2 cut for signal extraction: 0.04 deg2
• Number of off positions: 1
• Energy range < 0.2 TeV

Excess: -124.000; Off: 51525
Gamma rate: -0.579 events / minute
Off rate: 240.482 events / minute
alpha (backg normalization): 1.000
Li & Ma Significance: 0.00 standard deviations

• Theta2 cut for signal extraction: 0.02 deg2
• Number of off positions: 3
• Energy range > 0.2 TeV

Excess: -19.333; Off: 148
Gamma rate: -0.090 events / minute
Off rate: 0.691 events / minute
alpha (backg normalization): 0.333
Li & Ma Significance: 0.00 standard deviations

Significance and Excess sky maps

• Energy range: 0.4 - 10 TeV

• Energy range: 0.3 - 10 TeV

Spectral results

Include the spectral parameters. Given the no gamma-ray excess and low-transmission conditions, these results cannot be used to claim any adequate flux limit.

type	name	value	unit	error	min	max	frozen	is_norm
spectral	index	2.8491e+00		2.000e+00	nan	nan	False	False
spectral	amplitude	1.0076e-14	TeV-1 s-1 cm-2	1.428e-14	1.000e-14	1.000e-08	False	True
spectral	reference	6.3403e-01	TeV	0.000e+00	nan	nan	True	False

Light curve