arXiv subjects

J. Good

Publications and source records attributed to J. Good.

12 recordsLinked to original sources

arXiv2024

Observers' Data Access Portal: Realtime Streaming for Astronomical Data

The W. M. Keck Observatory Archive (KOA) has released the Observers Data Access Portal (ODAP), a web-application that delivers astronomical data from the W. M. Keck Observatory to the scheduled program's principal investigator and their collaborators anywhere in the world in near real-time. Data files and their associated metadata are streamed to a user's desktop machine moments after they are written to disk and archived in KOA. The ODAP User Interface is built in React and uses the WebSocket protocol to stream data between KOA and the user. This document describes the design of the tool, challenges encountered, shows how ODAP is integrated into the Keck observing model, and provides an analysis of usage metrics.

astro-ph.IM↗

arXiv2024

First high peak and average power single-pass THz FEL based on high brightness photoinjector

Advanced experiments using THz pump and X-ray probe pulses at modern free-electron lasers (FELs) like the European X-ray FEL require a frequency-tunable, high-power, narrow-band THz source maintaining the repetition rate and pulse structure of the X-ray pulses. This paper reports the first results from a THz source, that is based on a single-pass high-gain THz FEL operating with a central wavelength of 100 micrometers. The THz FEL prototype is currently in operation at the Photo Injector Test facility at DESY in Zeuthen (PITZ) and uses the same type of electron source as the European XFEL photo injector. A self-amplified spontaneous emission (SASE) FEL was envisioned as the main mechanism for generating the THz pulses. Although the THz FEL at PITZ is supposed to use the same mechanism as at X-ray facilities, it cannot be considered as a simple scaling of the radiation wavelength because there is a large difference in the number of electrons per radiation wavelength, which is five orders of magnitude higher for the THz case. The bunching factor arising from the electron beam current profile contributes strongly to the initial spontaneous emission starting the FEL process. Proof-of-principle experiments were done at PITZ using an LCLS-I undulator to generate the first high-power, high-repetition-rate single-pass THz FEL radiation. Electron bunches with a beam energy of ~17 MeV and a bunch charge of up to several nC are used to generate THz pulses with a pulse energy of several tens of microjoules. For example, for an electron beam with a charge of ~2.4 nC, more than 100 microjoules were generated at a central wavelength of 100 micrometers. The narrowband spectrum was also demonstrated by spectral measurements. These proof-of-principle experiments pave the way for a tunable, high-repetition-rate THz source providing pulses with energies in the millijoule range.

physics.acc-ph↗

arXiv2024

The Observers' Data Access Portal at the Keck Observatory Archive

For all active instruments, the Keck Observatory Archive (KOA) now ingests raw data from the Keck Telescopes within 1 minute of acquisition, quick-look reduced data within 5 minutes of creation, and science ready reduced data for four instruments as they are created by their automated pipelines. On August 1, 2023, KOA released the Observers Data Access Portal (ODAP), which enables observers at the telescope and their collaborators anywhere in the world to securely monitor and download science, calibration, and quick-look data as they are ingested into the archive. The portal is built using Python Socket IO.WebSockets that ensure metadata appear in the portal as the data themselves are ingested. The portal itself is a dynamic web interface built with React. It enables users to view and customize metadata fields, filter metadata according to data type, and download data as they are ingested or in bulk through wget scripts. Observers have used the ODAP since its release and have provided feedback that will guide future releases.

astro-ph.IM↗

arXiv2016

Studies on charge production from Cs2Te photocathodes in the PITZ L-band normal conducting radio frequency photo injector

This paper discusses the behavior of electron bunch charge produced in an L-band normal conducting radio frequency cavity (RF gun) from Cs2Te photocathodes illuminated with ps-long UV laser pulses when the laser transverse distribution consists of a flat-top core with Gaussian-like decaying halo. The produced charge shows a linear dependence at low laser pulse energies as expected in the quantum efficiency limited emission regime, while its dependence on laser pulse energy is observed to be much weaker for higher values, due to space charge limited emission. However, direct plug-in of experimental parameters into the space charge tracking code ASTRA yields lower output charge in the space charge limited regime compared to measured values. The rate of increase of the produced charge at high laser pulse energies close to the space charge limited emission regime seems to be proportional to the amount of halo present in the radial laser profile since the charge from the core has saturated already. By utilizing core + halo particle distributions based on measured radial laser profiles, ASTRA simulations and semi-analytical emission models reproduce the behavior of the measured charge for a wide range of RF gun and laser operational parameters within the measurement uncertainties.

physics.acc-ph↗

arXiv2013

The NASA Exoplanet Archive: Data and Tools for Exoplanet Research

We describe the contents and functionality of the NASA Exoplanet Archive, a database and tool set funded by NASA to support astronomers in the exoplanet community. The current content of the database includes interactive tables containing properties of all published exoplanets, Kepler planet candidates, threshold-crossing events, data validation reports and target stellar parameters, light curves from the Kepler and CoRoT missions and from several ground-based surveys, and spectra and radial velocity measurements from the literature. Tools provided to work with these data include a transit ephemeris predictor, both for single planets and for observing locations, light curve viewing and normalization utilities, and a periodogram and phased light curve service. The archive can be accessed at http://exoplanetarchive.ipac.caltech.edu.

astro-ph.IM↗

arXiv2011

The NStED Periodogram Service and Interface for Public CoRoT Data

As part of the NASA-CNES agreement, the NASA Star and Exoplanet Database (NStED) serves as the official US portal for the public CoRoT data products. NStED is a general purpose archive with the aim of providing support for NASA's planet finding and characterization goals. Consequently, the NASA Exoplanet Science Institute (NExScI) developed, and NStED adapted, a periodogram service for CoRoT data to determine periods of variability phenomena and create phased photometric light curves. Through the NStED periodogram interface, the user may choose three different period detection algorithms to use on any photometric time series product, or even upload and analyze their own data. Additionally, the NStED periodogram is remotely accessed by the CoRoT archive as part of its interface. NStED is available at {\bf http://nsted.ipac.caltech.edu}.

astro-ph.IM↗

arXiv2009

The LAEX and NASA portals for CoRoT public data

* Aims. We describe here the main functionalities of the LAEX (Laboratorio de Astrofisica Estelar y Exoplanetas/Laboratory for Stellar Astrophysics and Exoplanets) and NASA portals for CoRoT Public Data. The CoRoT archive at LAEX was opened to the community in January 2009 and is managed in the framework of the Spanish Virtual Observatory. NStED (NASA Star and Exoplanet Database) serves as the CoRoT portal for the US astronomical community. NStED is a general purpose stellar and exoplanet archive with the aim of providing support for NASA planet finding and characterisation goals, and the planning and support of NASA and other space missions. CoRoT data at LAEX and NStED can be accessed at http://sdc.laeff.inta.es/corotfa/ and http://nsted.ipac.caltech.edu,respectively. * Methods. Based on considerable experience with astronomical archives, the aforementioned archives are designed with the aim of delivering science-quality data in a simple and efficient way. * Results. LAEX and NStED not only provide access to CoRoT Public Data but furthermore serve a variety of observed and calculated astrophysical data. In particular, NStED provides scientifically validated information on stellar and planetary data related to the search for and characterization of extrasolar planets, and LAEX makes any information from Virtual Observatory services available to the astronomical community.

astro-ph.SR↗

arXiv2009

The NASA/IPAC/NExScI Star and Exoplanet Database

The NASA/IPAC/NExScI Star and Exoplanet Database (NStED) is a general purpose stellar archive which supports NASA planet-finding and planet-characterization goals, stellar astrophysics, and the planning of NASA and other space missions. There are two principal components of NStED: a database of 140,000 nearby stars and exoplanet-hosting stars, and an archive dedicated to high precision photometric surveys for transiting exoplanets (NStED-ETSS). We present summaries of these components. The NStED stellar database currently serves published parameters for 140,000 stars. These parameters include coordinates, multiplicity, proper motion, parallax, spectral type, multiband photometry, radial velocity, metallicity, chromospheric and coronal activity index, rotation velocity/period, infrared excess. NStED-ETSS currently serves data from the TrES survey of the Kepler field as well as dedicated photometric surveys of four stellar clusters. NStED-ETSS aims to serve both the surveys and the broader astronomical community by archiving these data and making them available in a homogeneous format.

astro-ph.EP↗

arXiv2008

The NStED Stellar and Exoplanet Hosting Star Service

The NASA Star and Exoplanet Database (NStED) is a general purpose stellar archive with the aim of providing support for NASA's planet finding and characterization goals, stellar astrophysics, and the planning of NASA and other space missions. There are two principal components of NStED: a database of (currently) 140,000 nearby stars and exoplanet-hosting stars, and an archive dedicated to high precision photometric surveys for transiting exoplanets. We present a summary of the NStED stellar database, functionality, tools, and user interface. NStED currently serves the following kinds of data for 140,000 stars (where available): coordinates, multiplicity, proper motion, parallax, spectral type, multiband photometry, radial velocity, metallicity, chromospheric and coronal activity index, and rotation velocity/period. Furthermore, the following derived quantities are given wherever possible: distance, effective temperature, mass, radius, luminosity, space motions, and physical/angular dimensions of habitable zone. Queries to NStED can be made using constraints on any combination of the above parameters. In addition, NStED provides tools to derive specific inferred quantities for the stars in the database, cross-referenced with available extra-solar planetary data for those host stars. NStED can be accessed at http://nsted.ipac.caltech.edu

astro-ph↗

arXiv2008

The NStED Exoplanet Transit Survey Service

The NASA Star and Exoplanet Database (NStED) is a general purpose stellar archive with the aim of providing support for NASA's planet finding and characterization goals, stellar astrophysics, and the planning of NASA and other space missions. There are two principal components of NStED: a database of (currently) 140,000 nearby stars and exoplanet-hosting stars, and an archive dedicated to high-precision photometric surveys for transiting exoplanets. We present a summary of the latter component: the NStED Exoplanet Transit Survey Service (NStED-ETSS), along with its content, functionality, tools, and user interface. NStED-ETSS currently serves data from the TrES Survey of the Kepler Field as well as dedicated photometric surveys of four stellar clusters. NStED-ETSS aims to serve both the surveys and the broader astronomical community by archiving these data and making them available in a homogeneous format. Examples of usability of ETSS include investigation of any time-variable phenomena in data sets not studied by the original survey team, application of different techniques or algorithms for planet transit detections, combination of data from different surveys for given objects, statistical studies, etc. NStED-ETSS can be accessed at \tt{http://nsted.ipac.caltech.edu}

astro-ph↗

arXiv2004

The First HET Planet: A Companion to HD 37605

We report the first detection of a planetary-mass companion to a star using the High Resolution Spectrograph (HRS) of the Hobby-Eberly Telescope (HET). The HET-HRS now gives routine radial velocity precision of 2-3 m/s for high SNR observations of quiescent stars. The planetary-mass companion to the metal-rich K0V star HD37605 has an orbital period of 54.23 days, an orbital eccentricity of 0.737, and a minimum mass of 2.84 Jupiter masses. The queue-scheduled operation of the Hobby-Eberly Telescope enabled us to discovery of this relatively short-period planet with a total observation time span of just two orbital periods. The ability of queue-scheduled large-aperture telescopes to respond quickly to interesting and important results demonstrates the power of this new approach in searching for extra-solar planets as well as in other ares of research requiring rapid response time critical observations.

astro-ph↗

arXiv2000

The Digital Sky Project: Prototyping Virtual Observatory Technologies

Astronomy is entering a new era as multiple, large area, digital sky surveys are in production. The resulting datasets are truly remarkable in their own right; however, a revolutionary step arises in the aggregation of complimentary multi-wavelength surveys (i.e., the cross-identification of a billion sources). The federation of these large datasets is already underway, and is producing a major paradigm shift as Astronomy has suddenly become an immensely data-rich field. This new paradigm will enable quantitatively and qualitatively new science, from statistical studies of our Galaxy and the large-scale structure in the universe, to discoveries of rare, unusual, or even completely new types of astronomical objects and phenomena. Federating and then exploring these large datasets, however, is an extremely challenging task. The Digital Sky project was initiated with this task in mind and is working to develop the techniques and technologies necessary to solve the problems inherent in federating these large databases, as well as the mining of the resultant aggregate data.

astro-ph↗