Analysis BLLac Aug 2021 Emery
Main page for the analysis of the observations of BL Lacertae of August 2021 by the LST1 using the likelihood reconstruction method.
LST data analysis responsible : Gabriel Emery using the LH fit reconstruction pipeline.
Other analysis : See the common page for links to each analysis BLLac
Context : BL Lacertae is a know blazar (and more precisely an IBL) located at a redshift of 0.069 with relatively low luminosity in quiescent state. It was active on multiple occasion in 2021 and in particular in July and August. An elevated state was reported in optical, X-rays and at high energy (see e.g. ATel #14773 , ATel #14774 and ATel #14777). This was followed in July by a detection of the source by LST reported in an astronomer telegram ATel #14783. Further observations of a new flux increase at the end of July/start of August (ATel #14820) lead to additional MAGIC follow up (ATel #14826), along with piggyback observations with LST-1.
Contents
Analysis results -- lstchain v0.9.x LHfit PR ongoing, for LST general meeting April 2022
Analysis performed in the BL lac paper TF before the LST general meeting. https://www.lst1.iac.es/wiki/index.php/BLLac_paper_meeting#collaborator_meeting
August 8th
Group strategy :
Run list 5552--5559
SED on the night of Aug 8
- w/ intensity cut(>50 pe), LogParabolaSpectralModel
- w/ intensity cut(>50 pe), SmoothBrokenPowerLawSpectralModel
- w/o intensity cut, LogParabolaSpectralModel
- w/o intensity cut, SmoothBrokenPowerLawSpectralModel
Light curve on the night of Aug 8 (>0.037, 0.057, 0.089 0.039, 0.063, 0.1 TeV) (runwise)
Light curve on the night of Aug 8 (>0.037, 0.057, 0.089 0.039, 0.063, 0.1 TeV) with short time scale, each observation time divided by 3
DL3 tools config :
LP w/ intensity > 50 pe
sBPL w/ intensity > 50 pe
LP w/o intensity cut
sBPL w/o intensity cut
July and August
Group strategy :
Run list
daily light curve above 100 GeV (for each SED?)
LP w/ intensity > 50 pe
sBPL w/ intensity > 50 pe
LP w/o intensity cut
sBPL w/o intensity cut
Previous analysis status
The dataset analysed in below is the August dataset from August 2nd to August 13th.
Clear detection and variability are obtained. The brightest night allows for the extraction of a spectrum with a threshold around 20-30 GeV.
Both a source independent and source dependent analysis are used with the likelihood method (and standard reconstruction crosscheck).
Run list
August 2nd to 13th :
5443,5444,5447,5448,5449,5450, 5454,5455,5456,5457,5458,5460,5466, 5481,5482, 5486,5488, 5546,5547, 5552,5553,5554,5555,5556,5557,5558,5559, 5592,5593,5594,5595, 5688,5689,5690, 5705,5706, 5732,5733,5734,5735,5736
August 8th : 5552,5553,5554,5555,5556,5557,5558,5559
LH-fit analysis (Shown at the LST general meeting Fall 2021)
| MC | it-cluster : /fefs/aswg/data/mc/DL0/20200629_prod5_trans_80/particle/zenith_20deg/south_pointing/ |
|---|---|
| Code | https://github.com/gabemery/cta-lstchain/tree/lhfit_wl_less1_and_numexpr |
| Config r0-dl1 | it-cluster : /home/gabriel.emery/cta/lstchaindev/cta-lstchain-lhfit/lstchain/data/lstchain_lhfit_config_data_v15.json |
| Processed DL1 files | it-cluster : /fefs/aswg/workspace/gabriel.emery/lhfit_withasymetry_rebasemaster17052021/data/DL1/v15/merged/ |
Analysis results -- lstchain v0.7.3
Presentation at LST general meeting (19/11/2021) https://indico.cta-observatory.org/event/3671/contributions/31294/attachments/20338/28385/LHfit_BLlac_flare_analysis_LSTGeneralMeetingFall2021.pdf
Main results :
Nice spectra extending to quite low energy (down to a couple of tens of GeV depending on the time window and analysis) and connecting, even if imperfectly, with the contemporaneous data from Fermi-LAT. MWL lightcurves display common and independent variability features. Analysis in source independent/dependent mode with LHfit/standard shown compatible spectra and similar light curves on the 8th. The spectra are also compatible with the simultaneous MAGIC data. Only in slides : ~3 minutes binned LC of the LST-1 LHfit analysis of the 8th shows similar variability as the run wise LC. LC below and above 100 GeV don't differ significantly.
- 2-13th of August MWL :
- 8th of August MWL:
- Multiple LST analysis and MAGIC comparison (AUg 8th):
