Context.
Traditionally, TeV-
γ
-ray astronomy has been conducted by experiments employing proprietary data and analysis software. However, the next generation of
γ
-ray instruments, such as the ...Cherenkov Telescope Array Observatory (CTAO), will be operated as open observatories. Alongside the data, they will also make the associated software tools available to a wider community. This necessity prompted the development of open, high-level, astronomical software customized for high-energy astrophysics.
Aims.
In this article, we present Gammapy, an open-source Python package for the analysis of astronomical
γ
-ray data, and illustrate the functionalities of its first long-term-support release, version 1.0. Built on the modern Python scientific ecosystem, Gammapy provides a uniform platform for reducing and modeling data from different
γ
-ray instruments for many analysis scenarios. Gammapy complies with several well-established data conventions in high-energy astrophysics, providing serialized data products that are interoperable with other software packages.
Methods.
Starting from event lists and instrument response functions, Gammapy provides functionalities to reduce these data by binning them in energy and sky coordinates. Several techniques for background estimation are implemented in the package to handle the residual hadronic background affecting γ-ray instruments. After the data are binned, the flux and morphology of one or more
γ
-ray sources can be estimated using Poisson maximum likelihood fitting and assuming a variety of spectral, temporal, and spatial models. Estimation of flux points, likelihood profiles, and light curves is also supported.
Results.
After describing the structure of the package, we show, using publicly available gamma-ray data, the capabilities of Gammapy in multiple traditional and novel
γ
-ray analysis scenarios, such as spectral and spectro-morphological modeling and estimations of a spectral energy distribution and a light curve. Its flexibility and its power are displayed in a final multi-instrument example, where datasets from different instruments, at different stages of data reduction, are simultaneously fitted with an astrophysical flux model.
SS 433 is a microquasar, a stellar binary system that launches collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.) and found an ...energy-dependent shift in the apparent position of the gamma-ray emission from the parsec-scale jets. These observations trace the energetic electron population and indicate that inverse Compton scattering is the emission mechanism of the gamma rays. Our modeling of the energy-dependent gamma-ray morphology constrains the location of particle acceleration and requires an abrupt deceleration of the jet flow. We infer the presence of shocks on either side of the binary system, at distances of 25 to 30 parsecs, and that self-collimation of the precessing jets forms the shocks, which then efficiently accelerate electrons.
In this article, we present Gammapy, an open-source Python package for the analysis of astronomical \(\gamma\)-ray data, and illustrate the functionalities of its first long-term-support release, ...version 1.0. Built on the modern Python scientific ecosystem, Gammapy provides a uniform platform for reducing and modeling data from different \(\gamma\)-ray instruments for many analysis scenarios. Gammapy complies with several well-established data conventions in high-energy astrophysics, providing serialized data products that are interoperable with other software packages. Starting from event lists and instrument response functions, Gammapy provides functionalities to reduce these data by binning them in energy and sky coordinates. Several techniques for background estimation are implemented in the package to handle the residual hadronic background affecting \(\gamma\)-ray instruments. After the data are binned, the flux and morphology of one or more \(\gamma\)-ray sources can be estimated using Poisson maximum likelihood fitting and assuming a variety of spectral, temporal, and spatial models. Estimation of flux points, likelihood profiles, and light curves is also supported. After describing the structure of the package, we show, using publicly available \(\gamma\)-ray data, the capabilities of Gammapy in multiple traditional and novel \(\gamma\)-ray analysis scenarios, such as spectral and spectro-morphological modeling and estimations of a spectral energy distribution and a light curve. Its flexibility and power are displayed in a final multi-instrument example, where datasets from different instruments, at different stages of data reduction, are simultaneously fitted with an astrophysical flux model.
THANKSGIVING IN SAIGON, 1968 Van Eldik, Jim
Vietnam (Leesburg, Va.),
12/2020, Letnik:
33, Številka:
4
Magazine Article
...Vietnam is not a typical first choice for an American Thanksgiving celebration, and an Air Force lieutenant is not normally ones first choice of a companion for such a family-oriented occasion. ...According to Mike, the only action that had occurred nearby was a nasty little firefight between two Air Force security guards who mistook each other for Viet Cong. ...there wasn't sufficient time left to shop at the Cholon PX, so we called it a day. Because the Tan Son Nhut VIP Huey flights avoided nighttime trips we needed to hustle back to the air base to make sure I caught a flight. ...after being awake for well over 24 hours, a few catnaps were in order, at least until the depot reports started streaming into our office around midnight.
SPENCERS PROVE THEIR WORTH Van Eldik, Jim
Wild west (Leesburg, Va.),
12/2020, Letnik:
33, Številka:
4
Magazine Article
Major General Philip Sheridan, commander of the Department of the Missouri, sought advice from his aide and inspector general, George Forsyth. Each of Forsyth's scouts was issued 140 rounds of ...ammunition for his Spencer and 30 pistol rounds for his Colt Army Model 1860 revolver. Scores of Indians soon milled about the island, shooting at the entrenched soldiers.
GUNPLAY Van Eldik, Jim
Wild west (Leesburg, Va.),
08/2019, Letnik:
32, Številka:
2
Magazine Article
TOY CAP GUNS MAY LOOK LIKE COLT SIX-SHOOTERS ON THE OUTSIDE, BUT THEY RESEMBLE MAYNARD REVOLVERS ON THE INSIDE Saturday morning TV Westerns of the 195 Os-think The Lone Ranger, The Roy Rogers Show, ...Annie Oakley and The Adventures of Rin Tin Tin- created a huge demand for products kids could use or wear to imitate their small-screen heroes. What many don't realize is that while the outward appearance of tire typical cap gun apes the Colt Peacemaker, its innards emulate another gun entirely-the pre-Civil War Maynard revolver. ...there is no loading lever, as commonly found on Colt percussion pistols.
