arXiv subjects

Victor Zabalza

Publications and source records attributed to Victor Zabalza.

3 recordsLinked to original sources

arXiv2016

Open high-level data formats and software for gamma-ray astronomy

In gamma-ray astronomy, a variety of data formats and proprietary software have been traditionally used, often developed for one specific mission or experiment. Especially for ground-based imaging atmospheric Cherenkov telescopes (IACTs), data and software are mostly private to the collaborations operating the telescopes. However, there is a general movement in science towards the use of open data and software. In addition, the next-generation IACT instrument, the Cherenkov Telescope Array (CTA), will be operated as an open observatory. We have created a Github organisation at https://github.com/open-gamma-ray-astro where we are developing high-level data format specifications. A public mailing list was set up at https://lists.nasa.gov/mailman/listinfo/open-gamma-ray-astro and a first face-to-face meeting on the IACT high-level data model and formats took place in April 2016 in Meudon (France). This open multi-mission effort will help to accelerate the development of open data formats and open-source software for gamma-ray astronomy, leading to synergies in the development of analysis codes and eventually better scientific results (reproducible, multi-mission). This write-up presents this effort for the first time, explaining the motivation and context, the available resources and process we use, as well as the status and planned next steps for the data format specifications. We hope that it will stimulate feedback and future contributions from the gamma-ray astronomy community.

astro-ph.IM↗

arXiv2013

Astropy: A Community Python Package for Astronomy

We present the first public version (v0.2) of the open-source and community-developed Python package, Astropy. This package provides core astronomy-related functionality to the community, including support for domain-specific file formats such as Flexible Image Transport System (FITS) files, Virtual Observatory (VO) tables, and common ASCII table formats, unit and physical quantity conversions, physical constants specific to astronomy, celestial coordinate and time transformations, world coordinate system (WCS) support, generalized containers for representing gridded as well as tabular data, and a framework for cosmological transformations and conversions. Significant functionality is under active development, such as a model fitting framework, VO client and server tools, and aperture and point spread function (PSF) photometry tools. The core development team is actively making additions and enhancements to the current code base, and we encourage anyone interested to participate in the development of future Astropy versions.

astro-ph.IM↗

arXiv2011

Search for VHE signals from microquarsars with MAGIC

Microquasars are accreting binary systems displaying relativistic radio jets where very high energy gamma rays might be produced via Inverse Compton scattering. The detection of the microquasar Cygnus X-3 above 100 MeV by both Fermi/LAT and AGILE satellites, together with the short flares from Cygnus X-1 reported by AGILE, confirmed that this class of astrophysical objects are interesting candidates for very high energy gamma-ray observations. The stand-alone imaging atmospheric Cherenkov MAGIC telescope, and later on the recently inaugurated stereoscopic system, made a significant effort to search for signals from microquasars. This paper reviews all MAGIC results of Cygnus X-3, Cygnus X-1, Scorpius X-1, and SS 433 observations. The stand-alone MAGIC telescope observed Cygnus X-3 for almost 60 hrs from March 2006 until August 2009 in many different X-ray spectral states where a very high energy emission is predicted and also simultaneously with a flux enhancement at high energies detected by Fermi/LAT. No significant signal was found in any of the observed conditions. The MAGIC stereoscopic system pointed at the Z-type low-mass X-ray binary Scorpius X-1 in May 2010 for ~8 hrs. Simultaneous soft X-ray measurements allowed to define the X-ray spectral state of the source which could emit very-high-energy photons in the horizontal branch. MAGIC did not detect the source and put some constraints on the maximum TeV luminosity to jet power ratio. Further observations of Cygnus X-1 were also carried out with the new and twice as sensitive stereoscopic system in Autumn 2009 for a total amount of 30 hrs. Finally, we also report on SS 433 observations obtained during two periods of minimum absorption processes from the accretion disk.

astro-ph.HE↗