3,733 research outputs found
OPTICON: EC Optical Infrared Coordination Network for Astronomy
OPTICON, the ICN Optical Infrared Coordination Network for Astronomy, brings
together for the first time the operators of all Europe's medium to large
optical-infrared telescopes, the largest corresponding data archives, and
several user representatives. The OPTICON partners work with their communities
to identify those major challenges for the future development of European
optical-infrared astronomy which require Europe-wide collaboration. OPTICON
sponsors and coordinates developments towards these goals, involving the entire
astronomical community through workshops and meetings targeted towards these
agreed common goals of general importance.Comment: to appear in Organizations and Strategies in Astronomy II, Ed. A.
Heck, Kluwer Acad. Pub
Search for transient optical counterparts to high-energy IceCube neutrinos with Pan-STARRS1
In order to identify the sources of the observed diffuse high-energy neutrino
flux, it is crucial to discover their electromagnetic counterparts. IceCube
began releasing alerts for single high-energy ( TeV) neutrino
detections with sky localisation regions of order 1 deg radius in 2016. We used
Pan-STARRS1 to follow-up five of these alerts during 2016-2017 to search for
any optical transients that may be related to the neutrinos. Typically 10-20
faint ( mag) extragalactic transients are found within the
Pan-STARRS1 footprints and are generally consistent with being unrelated field
supernovae (SNe) and AGN. We looked for unusual properties of the detected
transients, such as temporal coincidence of explosion epoch with the IceCube
timestamp. We found only one transient that had properties worthy of a specific
follow-up. In the Pan-STARRS1 imaging for IceCube-160427A (probability to be of
astrophysical origin of 50 %), we found a SN PS16cgx, located at 10.0'
from the nominal IceCube direction. Spectroscopic observations of PS16cgx
showed that it was an H-poor SN at z = 0.2895. The spectra and light curve
resemble some high-energy Type Ic SNe, raising the possibility of a jet driven
SN with an explosion epoch temporally coincident with the neutrino detection.
However, distinguishing Type Ia and Type Ic SNe at this redshift is notoriously
difficult. Based on all available data we conclude that the transient is more
likely to be a Type Ia with relatively weak SiII absorption and a fairly normal
rest-frame r-band light curve. If, as predicted, there is no high-energy
neutrino emission from Type Ia SNe, then PS16cgx must be a random coincidence,
and unrelated to the IceCube-160427A. We find no other plausible optical
transient for any of the five IceCube events observed down to a 5
limiting magnitude of mag, between 1 day and 25 days after
detection.Comment: 20 pages, 6 figures, accepted to A&
The 2010 M 87 VHE flare and its origin: the multi-wavelength picture
The giant radio galaxy M 87, with its proximity (16 Mpc) and its very massive
black hole ((3 - 6) \times 10^9 M_solar), provides a unique laboratory to
investigate very high energy (E>100 GeV; VHE) gamma-ray emission from active
galactic nuclei and, thereby, probe particle acceleration to relativistic
energies near supermassive black holes (SMBH) and in relativistic jets. M 87
has been established as a VHE gamma-ray emitter since 2005. The VHE gamma-ray
emission displays strong variability on timescales as short as a day. In 2008,
a rise in the 43 GHz Very Long Baseline Array (VLBA) radio emission of the
innermost region (core; extension of < 100 Rs ; Schwarzschild radii) was found
to coincide with a flaring activity at VHE. This had been interpreted as a
strong indication that the VHE emission is produced in the direct vicinity of
the SMBH. In 2010 a flare at VHE was again detected triggering further
multi-wavelength (MWL) observations with the VLBA, Chandra, and other
instruments. At the same time, M 87 was also observed with the Fermi-LAT
telescope at MeV/GeV energies, the European VLBI Network (EVN), and the
Liverpool Telescope (LT). Here, preliminary results from the 2010 campaign will
be reported.Comment: 6 pages, 2 figures; Procceedings of the workshop "High Energy
Phenomena in Relativistic Outflows III" (HEPRO III), Barcelona, June 27 -
July 1, 201
Astrophysicists and physicists as creators of ArXiv-based commenting resources for their research communities. An initial survey
This paper conveys the outcomes of what results to be the first, though
initial, overview of commenting platforms and related 2.0 resources born within
and for the astrophysical community (from 2004 to 2016). Experiences were
added, mainly in the physics domain, for a total of 22 major items, including
four epijournals, and four supplementary resources, thus casting some light
onto an unexpected richness and consonance of endeavours. These experiences
rest almost entirely on the contents of the database ArXiv, which adds to its
merits that of potentially setting the grounds for web 2.0 resources, and
research behaviours, to be explored.
Most of the experiences retrieved are UK and US based, but the resulting
picture is international, as various European countries, China and Australia
have been actively involved.
Final remarks about creation patterns and outcome of these resources are
outlined. The results integrate the previous studies according to which the web
2.0 is presently of limited use for communication in astrophysics and vouch for
a role of researchers in the shaping of their own professional communication
tools that is greater than expected. Collaterally, some aspects of ArXiv s
recent pathway towards partial inclusion of web 2.0 features are touched upon.
Further investigation is hoped for.Comment: Journal article 16 page
Looking before leaping: Creating a software registry
What lessons can be learned from examining numerous efforts to create a
repository or directory of scientist-written software for a discipline?
Astronomy has seen a number of efforts to build such a resource, one of which
is the Astrophysics Source Code Library (ASCL). The ASCL (ascl.net) was founded
in 1999, had a period of dormancy, and was restarted in 2010. When taking over
responsibility for the ASCL in 2010, the new editor sought to answer the
opening question, hoping this would better inform the work to be done. We also
provide specific steps the ASCL is taking to try to improve code sharing and
discovery in astronomy and share recent improvements to the resource.Comment: 11 pages; submission for WSSSPE2. Revised after review for
publication in the Journal of Open Research Softwar
Usage Bibliometrics
Scholarly usage data provides unique opportunities to address the known
shortcomings of citation analysis. However, the collection, processing and
analysis of usage data remains an area of active research. This article
provides a review of the state-of-the-art in usage-based informetric, i.e. the
use of usage data to study the scholarly process.Comment: Publisher's PDF (by permission). Publisher web site:
books.infotoday.com/asist/arist44.shtm
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Design and performance of the first IceAct demonstrator at the South Pole
In this paper we describe the first results of IceAct, a compact imaging air-Cherenkov telescope operating in coincidence with the IceCube Neutrino Observatory (IceCube) at the geographic South Pole. An array of IceAct telescopes (referred to as the IceAct project) is under consideration as part of the IceCube-Gen2 extension to IceCube. Surface detectors in general will be a powerful tool in IceCube-Gen2 for distinguishing astrophysical neutrinos from the dominant backgrounds of cosmic-ray induced atmospheric muons and neutrinos: the IceTop array is already in place as part of IceCube, but has a high energy threshold. Although the duty cycle will be lower for the IceAct telescopes than the present IceTop tanks, the IceAct telescopes may prove to be more effective at lowering the detection threshold for air showers. Additionally, small imaging air-Cherenkov telescopes in combination with IceTop, the deep IceCube detector or other future detector systems might improve measurements of the composition of the cosmic ray energy spectrum. In this paper we present measurements of a first 7-pixel imaging air Cherenkov telescope demonstrator, proving the capability of this technology to measure air showers at the South Pole in coincidence with IceTop and the deep IceCube detector
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