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@MISC{Observatory:572892,
author = {Consortium, Cherenkov Telescope Array},
editor = {Observatory, Cherenkov Telescope Array},
title = {{CTAO} {I}nstrument {R}esponse {F}unctions - prod5 version
v0.1},
publisher = {Zenodo},
reportid = {PUBDB-2023-00798},
year = {2021},
abstract = {CTAO Instrument Response Functions - prod5 version v0.1 The
CTA Observatory (CTAO) will provide very wide energy range
and excellent angular resolution and sensitivity in
comparison to any existing gamma-ray detector. Energies down
to 20 GeV will allow CTAO to study the most distant objects.
Energies up to 300 TeV will push CTAO beyond the edge of the
known electromagnetic spectrum, providing a completely new
view of the sky. This data repository provides access to
performance evaluation and instrument response functions
(IRFs) for CTA. IRF version: prod5 v0.1 Telescope model and
site configuration: prod5-model Publication date: Sep 2021
Archived webpage with performance figures included: CTAO
Performance Description (file Website.md) Licence: this work
is licensed under a Creative Commons Attribution 4.0
International License . Please use the contact address
open-data@cta-observatory.org for any inquiries. Citation
and Acknowledgements: In cases for which the CTA instrument
response functions are used in a research project, we ask to
add the following acknowledgement in any resulting
publication: 'This research has made use of the CTA
instrument response functions provided by the CTA Consortium
and Observatory, see
https://www.ctao-observatory.org/science/cta-performance/
(version prod5 v0.1; [citation]) for more details.' Please
use the following BibTex Entry for [citation] in the
reference section of your publication:
https://zenodo.org/record/5499840/export/hx Description
Monte Carlo Simulations: The performance values are derived
from detailed Monte Carlo (MC) simulations of the CTA
instrument based on the CORSIKA air shower code (v7.71, with
the hadronic interaction models QGSjet-II-04 and URQMD, [1])
and telescope simulation tool $sim_telarray$ [2]. A power-
law gamma-ray spectrum with photon index 2.62 was assumed in
the calculations, although none of the instrument response
functions (e.g. differential flux sensitivities, effective
areas, angular or energy resolutions) depends on the assumed
spectral shape of the gamma-ray source. Background
cosmic-ray spectra of proton and electron/positron particle
types are modelled according to recent measurements from
cosmic-ray instruments. Nominal telescope pointing is
assumed, with all telescopes pointing directions parallel to
each other (performance estimation for other pointing modes,
e.g. divergent pointing will be provided in the future).
Performance estimations are available for three zenith
angles (20 deg, 40 deg, and 60 deg), and for each zenith
angle for two different azimuth angles (corresponding to
pointing towards the magnetic North and South). There are
significant performance differences found between the two
azimuthal pointing directions (especially for the Northern
site) as the impact of the geomagnetic field is large enough
to influence notably the air shower development. For general
studies, the use of the azimuth-averaged instrument response
functions is recommended. Instrument Response Functions
(IRFs): The analysis has been tuned to maximize the
performance in terms of flux sensitivity. The optimal
analysis cuts depend on the duration of the observation,
therefore the IRFs are provided for 3 different observation
times, from 0.5 to 50 h. IRFs are provided as binned
histogram or FITS tables. It should be stressed, that the
full potential of CTA in terms of angular and energy
resolution is not revealed by these IRFS, due to the focus
on the optimisation for best flux sensitivity. In general
all histograms are binned with a 0.2-binning on the
logarithmic energy axis (5 bins per decade); some selected
histograms (e.g. effective areas or energy migration
matrices) are provided with a finer binning. Effective area
and energy migration matrix are available in a double
version: one for the case in which there is no a priori
knowledge of the true direction of incoming gamma rays (e.g.
for the observation of diffuse sources), and another for
observations of point-like objects (including among the
analysis cuts one on the angle between the true and the
reconstructed gamma-ray direction). IRFs are provided in
ROOT format and as FITS tables. The FITS tables can be used
directly as input to science analysis tools. The values of
the IRFs are identical for the different file format, with
one exception: the angular point-spread function is
approximated by a Gaussian function for the FITS tables,
while the ROOT files contain the full distribution.
Telescope layouts are preliminary and subject to change. The
following array layouts (Alpha configuration) have been
assumed: CTA South with 14 MSTs and 37 SSTs (see
[figure](figures/CTA-Performance-prod5-v0.1-South-Alpha-Layout.png))
CTA North with 4 LSTs and 9 MSTs (see
[figure](figures/CTA-Performance-prod5-v0.1-North-Alpha-Layout.png))
Two zip files are uploaded: full archive with IRFs in FITS
and ROOT format: cta-prod5-zenodo-v0.1.zip partial archive
with IRFs in FITS format only:
cta-prod5-zenodo-fitsonly-v0.1.zip File Naming (examples):
Prod5-North-40deg-AverageAz-4LSTs09MSTs.18000s-v0.1.root:
IRF for CTA Northern site on La Palma, 40 deg zenith angle,
azimuth-averaged pointing, optimised for 5 hours of
observation time
Prod5-South-20deg-AverageAz-14MSTs37SSTs.180000s-v0.1.fits.gz:
IRF for CTA Southern site in Paranal, 20 deg zenith angle,
azimuth-averaged pointing, optimised for 50 hours of
observation time List of files: FITS format:
fits/CTA-Performance-prod5-v0.1-North-20deg.FITS.tar.gz
fits/CTA-Performance-prod5-v0.1-North-40deg.FITS.tar.gz
fits/CTA-Performance-prod5-v0.1-North-60deg.FITS.tar.gz
fits/CTA-Performance-prod5-v0.1-South-20deg.FITS.tar.gz
fits/CTA-Performance-prod5-v0.1-South-40deg.FITS.tar.gz
fits/CTA-Performance-prod5-v0.1-South-60deg.FITS.tar.gz ROOT
format: root/CTA-Performance-prod5-v0.1-North-20deg.tar.gz
root/CTA-Performance-prod5-v0.1-North-40deg.tar.gz
root/CTA-Performance-prod5-v0.1-North-60deg.tar.gz
root/CTA-Performance-prod5-v0.1-South-20deg.tar.gz
root/CTA-Performance-prod5-v0.1-South-40deg.tar.gz
root/CTA-Performance-prod5-v0.1-South-60deg.tar.gz IRFs for
subarrays of e.g., MSTs only are in the files named
MSTSubArray (similar for all other telescope types).
References [1] https://www.ikp.kit.edu/corsika/ [2]
Bernloehr, K. 2008, Astroparticle Physics, 30, 149
Acknowledgements We would like to thank the computing
centres that provided resources for the generation of the
Prod 5 Instrument Response Functions (IRFs): CAMK, Nicolaus
Copernicus Astronomical Center, Warsaw, Poland CIEMAT-LCG2,
CIEMAT, Madrid, Spain CYFRONET-LCG2, ACC CYFRONET AGH,
Cracow, Poland DESY-ZN, Deutsches Elektronen-Synchrotron,
Standort Zeuthen, Germany GRIF, Grille de Recherche d’Ile
de France, Paris, France IN2P3-CC, Centre de Calcul de
l’IN2P3, Villeurbanne, France IN2P3-CPPM, Centre de
Physique des Particules de Marseille, Marseille, France
IN2P3-LAPP, Laboratoire d Annecy de Physique des Particules,
Annecy, France INFN-FRASCATI, INFN Frascati, Frascati, Italy
INFN-T1, CNAF INFN, Bologna, Italy INFN-TORINO, INFN Torino,
Torino, Italy MPIK, Heidelberg, Germany OBSPM, Observatoire
de Paris Meudon, Paris, France PIC, port d’informacio
cientifica, Bellaterra, Spain $prague_cesnet_lcg2,$ CESNET,
Prague, Czech Republic praguelcg2, FZU Prague, Prague, Czech
Republic UKI-NORTHGRID-LANCS-HEP, Lancaster University,
United Kingdom},
keywords = {gamma-ray astronomy (Other) / CTA (Other)},
cin = {$Z_CTA$},
cid = {$I:(DE-H253)Z_CTA-20210408$},
pnm = {613 - Matter and Radiation from the Universe (POF4-613)},
pid = {G:(DE-HGF)POF4-613},
experiment = {EXP:(DE-H253)CTA-20150101},
typ = {PUB:(DE-HGF)32},
doi = {10.5281/zenodo.5499840},
url = {https://bib-pubdb1.desy.de/record/572892},
}
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