2,953 research outputs found
Edsger Wybe Dijkstra (1930 -- 2002): A Portrait of a Genius
We discuss the scientific contributions of Edsger Wybe Dijkstra, his opinions
and his legacy.Comment: 10 pages. To appear in Formal Aspects of Computin
On the basis for ELF - An Extensible Language Facility
Computer language for data processing and information retrieva
Development of an MSC language and compiler, volume 1
Higher order programming language and compiler for advanced computer software system to be used with manned space flights between 1972 and 198
Investigation of x ray variability in highly active cool stars
Ginga x ray observations of highly active cool star coronae were obtained and analyzed in an effort to better understand the nature of their time variability. The possible types of variability studied included x ray occultations via eclipses in a binary system, rotational modulation of x ray emission, flares, and a search for microflaring. Observation of both sigma(sup 2) CrB and Algol were performed successfully by Ginga. The sigma(sup 2) CrB observations occurred on 27 to 30 June 1988, and the Algol observations on 12 to 14 January 1989. In the sigma(sup 2) CrB observation, simultaneous IUE and Very Large Array (VLA) observations were obtained during part of the Ginga observation. Flaring activity was detected on sigma(sup 2) CrB in the Ginga 1.7 to 11 KeV band and in the IUE microwave region. A large flare on Algol which lasted well over 12 hours was detected, began with a maximum temperature of 65 MK which gradually decayed to 36 MK, and evidence was shown of highly ionized Fe line emission
Kepler Eclipsing Binary Stars. VI. Identification of Eclipsing Binaries in the K2 Campaign 0 Data-set
The original {\it Kepler} mission observed and characterized over 2400
eclipsing binaries in addition to its prolific exoplanet detections. Despite
the mechanical malfunction and subsequent non-recovery of two reaction wheels
used to stabilize the instrument, the {\it Kepler} satellite continues
collecting data in its repurposed {\it K2} mission surveying a series of fields
along the ecliptic plane. Here we present an analysis of the first full
baseline {\it K2} data release: the Campaign 0 data-set. In the 7761 light
curves, we have identified a total of 207 eclipsing binaries. Of these, 97 are
new discoveries that were not previously identified. Our pixel-level analysis
of these objects has also resulted in identification of several false positives
(observed targets contaminated by neighboring eclipsing binaries), as well as
the serendipitous discovery of two short period exoplanet candidates. We
provide catalog cross-matched source identifications, orbital periods,
morphologies and ephemerides for these eclipsing systems. We also describe the
incorporation of the K2 sample into the Kepler Eclipsing Binary
Catalog\footnote{\url{keplerebs.villanova.edu/k2}}, present spectroscopic
follow-up observations for a limited selection of nine systems, and discuss
prospects for upcoming {\it K2} campaigns.Comment: Accepted for publication in MNRAS. 51 pages [20 figures, 8 tables].
Results available online in the Kepler Eclipsing Binary Star Catalog
http://keplerebs.villanova.edu/k
GIER: A Danish computer from 1961 with a role in the modern revolution of astronomy
A Danish computer, GIER, from 1961 played a vital role in the development of
a new method for astrometric measurement. This method, photon counting
astrometry, ultimately led to two satellites with a significant role in the
modern revolution of astronomy. A GIER was installed at the Hamburg Observatory
in 1964 where it was used to implement the entirely new method for the
measurement of stellar positions by means of a meridian circle, then the
fundamental instrument of astrometry. An expedition to Perth in Western
Australia with the instrument and the computer was a success. This method was
also implemented in space in the first ever astrometric satellite Hipparcos
launched by ESA in 1989. The Hipparcos results published in 1997 revolutionized
astrometry with an impact in all branches of astronomy from the solar system
and stellar structure to cosmic distances and the dynamics of the Milky Way. In
turn, the results paved the way for a successor, the one million times more
powerful Gaia astrometry satellite launched by ESA in 2013. Preparations for a
Gaia successor in twenty years are making progress.Comment: 19 pages,8 figures, Accepted for publication in Nuncius Hamburgensis,
Volume 2
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