The blazar 3C 279, one of the brightest identified extragalactic objects in the γ-ray sky, underwent a large (factor of ∼10 in amplitude) flare in γ-rays towards the end of a 3-week pointing by CGRO, in 1996 January-February. The flare peak represents the highest γ-ray intensity ever recorded for this object. During the high state, extremely rapid γ-ray variability was seen, including an increase of a factor of 2.6 in ∼8 hr, which strengthens the case for relativistic beaming. Coordinated multifrequency observations were carried out with RXTE, ASCA, ROSAT and IUE and from many ground-based observatories, covering most accessible wavelengths. The well-sampled, simultaneous RXTE light curve shows an outburst of lower amplitude (factor of ≃3) well correlated with the γ-ray flare without any lag larger than the temporal resolution of ∼1 day. The optical-UV light curves, which are not well sampled during the high energy flare, exhibit more modest variations (factor of ∼2) and a lower degree of correlation. The flux at millimetric wavelengths was near an historical maximum during the γ-ray flare peak and there is a suggestion of a correlated decay. We present simultaneous spectral energy distributions of 3C 279 prior to and near to the flare peak. The γ-rays vary by more than the square of the observed IR-optical Stanford, CA 94305

The γ-ray blazar 3C 279 was monitored on a nearly daily basis with IUE, ROSAT and EGRET for three weeks between December 1992 and January 1993. During this period, the blazar was at a historical minimum at all wavelengths. Here we present the UV data obtained during the above multiwavelength campaign. A maximum UV variation of ∼50% is detected, while during the same period the X-ray flux varied by no more than 13%.At the lowest UV flux level the average spectrum in the 1230-2700Å interval is unusually flat for this object ( α U V ∼ 1). The flattening could represent the lowest energy tail of the inverse Compton component responsible for the X-ray emission, or could be due to the presence of a thermal component at ∼20000 K possibly associated with an accretion disk. The presence of an accretion disk in this blazar object, likely observable only in very low states and otherwise hidden by the beamed, variable synchrotron component, would be consistent with the scenario in which the seed photons for the inverse Compton mechanism producing the γ-rays are external to the relativistic jet.We further discuss the long term correlation of the UV flux with the X-ray and γ-ray fluxes obtained at various epochs. All UV archival data are included in the analysis. Both the X-and γ-ray fluxes are generally well correlated with the UV flux, approximately with square root and quadratic dependences, respectively.

No abstract

ABSTRACTgPhoton is a new database product and software package that enables analysis of GALEX ultraviolet data at the photon level. The project's stand-alone, pure-Python calibration pipeline reproduces the functionality of the original mission pipeline to reduce raw spacecraft data to lists of time-tagged, skyprojected photons, which are then hosted in a publicly available database by the Mikulski Archive at Space Telescope (MAST). This database contains approximately 130 terabytes of data describing approximately 1.1 trillion sky-projected events with a timestamp resolution of five milliseconds. A handful of Python and command line modules serve as a front-end to interact with the database and to generate calibrated light curves and images from the photon-level data at user-defined temporal and spatial scales. The gPhoton software and source code are in active development and publicly available under a permissive license. We describe the motivation, design, and implementation of the calibration pipeline, database, and tools, with emphasis on divergence from prior work, as well as challenges created by the large data volume. We summarize the astrometric and photometric performance of gPhoton relative to the original mission pipeline. For a brief example of short time domain science capabilities enabled by gPhoton, we show new flares from the known M dwarf flare star CR Draconis. The gPhoton software has permanent object identifiers with the ASCL (ascl:1603.004) and DOI (doi:10.17909/T9CC7G). This paper describes the software as of version v1.27.2.

The Simple Spectral Access (SSA) Protocol (SSAP) defines a uniform interface to remotely discover and access one-dimensional spectra. SSA is a member of an integrated family of Status of This Document This document has been produced by the IVOA Data Access Layer Working Group. It has been reviewed by IVOA Members and other interested parties, and has been endorsed by the IVOA Executive Committee as an IVOA Recommendation. It is a stable document and may be used as reference material or cited as a normative reference from another document. IVOA's role in making the Recommendation is to draw attention to the specification and to promote its widespread deployment. This enhances the functionality and interoperability inside the Astronomical Community. This document is an update to the earlier SSA V1.04 IVOA Recommendation (February 2008). Changes from the earlier version are summarized in section 9.1. Note from the V1.0 document (this is still planned for a future version): a getCapabilities operation returning service metadata will be added which will eventually obsolete the Many of the ideas in this document originated from others involved in developing Virtual Observatory concepts and standards. In particular, the idea of using association in the query response to group similar datasets grew out of an idea originally proposed by Roy Williams. Arnold Rots originated the idea of ranking query results via a score heuristic, and helped put the coordinate systems used in SSA on firm theoretical foundation via the development of STC. Francois Bonnarel, Mireille Louys, Alberto Micol, and others contributed to the representation of astronomical metadata and in particular the Characterization data model. Laszlo Dobos contributed early implementations of the access protocol using the spectral archive at JHU.