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The Importance of Timing Metadata

Arnold H. Rots
2011 Proceedings of the International Astronomical Union  
FITS A FITS World Coordinate System paper (FITS WCS V) on Time is in preparation; the authors are Rots, Bunclark, Calabretta, Allen, Manchester & Thompson.  ...  For further details on Time-Scales, see (for instance) Wallace (2011) or Rots (2010) . JD 2452300.487 (TT; Geocenter) MJD 53245.964 (TDB; Barycenter) 2011-10-10T11:56:34 (UTC; Topocenter) 2.1.  ... 
doi:10.1017/s1743921312001202 fatcat:67u5idx4xrbivpeuqybryp4jgy

ChandraPublication Statistics

Arnold H. Rots, Sherry L. Winkelman, Glenn E. Becker
2012 Publications of the Astronomical Society of the Pacific  
H. Tananbaum and P. Green, and to the anonymous referee, for providing helpful suggestions.  ...  Spitzer 41 3896 96% 97% 2001-2012 D XMM 33 3629 93% 98% 2000-2011 E Fermi 45 1138 63% 91% 2005-2012 F Swift 29 820 92% 95% 2005-2012 G Suzaku 20 501 93% 98% 2006-2012 H  ...  missions and therefore recommend using "exposure time published" Table 2 . 2 Distribution of Papers for 13 Observatories over Journals (%) Journal Observatory Key (see Table 3) A B C D E F G H  ... 
doi:10.1086/665581 fatcat:2ud7k4mqeva2bkzd6bddcscxkq

HI and continuum structure of external galaxies compared to the situation in the galaxy

Arnold H. Rots
1979 Symposium - International astronomical union  
be defined: a central one which is hyperdeficient in hydrogen; a middle one which is deficient in HI, but not necessarily in total hydrogen; and an outer one which is neither deficient in HI, nor in H.  ...  Rots, 19TU, 1975) .  ...  h) . He corrected the velocity field for streaming motions and removed in that manner the steep decline around 8 kpc that caused Rots (1975) difficulties in fitting a mass model.  ... 
doi:10.1017/s0074180900014881 fatcat:n3n4cah7b5cp3dlwetgzzsjije

DETERMINING THE ABSOLUTE ASTROMETRIC ERROR INCHANDRASOURCE CATALOG POSITIONS

Arnold H. Rots, Tamás Budavári
2010 Astrophysical Journal Supplement Series  
H. Rots & T.  ...  H. Rots & T. Budavári 2010-11-24T10:40:00 Page 5 of 18 covariance for RA and Dec errors is not very important. This justifies the use of a singleaxis radial combined error.  ... 
doi:10.1088/0067-0049/192/1/8 fatcat:qm55azhyn5adpbolf5uqpnn6hy

There Goes the Neighborhood: Relational Algebra for Spatial Data Search [article]

Jim Gray, Alexander S. Szalay, Aniruddha R. Thakar, Gyorgy Fekete, William O'Mullane, Maria A. Nieto-Santisteban, Gerd Heber, Arnold H. Rots
2004 arXiv   pre-print
The intersection of a set of half-spaces {H i }, defines a convex of points. C = {x ε S | x ε H i for all H i }. A region R is the union of a set of convexes R = {x ε C i }.  ...  Figure 7 : 7 generally, any half-space H of the N dimensional space S can be expressed as H = {xε S | f(x) > 0} for some function f.  ... 
arXiv:cs/0408031v1 fatcat:dwodaxl6u5dxjprafds4t2kygq

Representations of time coordinates in FITS

Arnold H. Rots, Peter S. Bunclark, Mark R. Calabretta, Steven L. Allen, Richard N. Manchester, William T. Thompson
2015 Astronomy and Astrophysics  
H.  ...  H.  ... 
doi:10.1051/0004-6361/201424653 fatcat:w2pa5cbq5jd3rcfeuv2xhvkv6e

Using the Gregory-Loredo Algorithm for the Detection of Variability in the Chandra Source Catalog

Arnold H. Rots
2011 Proceedings of the International Astronomical Union  
In searching for a reliable variability indicator for Chandra X-ray event data, we implemented the Gregory-Loredo (G-L) algorithm to assess variability and to generate light curves for the Chandra Source Catalog. A test was performed on 118 sources detected in a single observation, spanning the intensity range 5-24,000 photons over a total observing time of 102,000 sec. We conclude that the G-L algorithm is extremely robust, yielding both a reliable variability indicator and light curves with
more » ... timal resolution, while requiring a very modest amount of CPU time. The algorithm can also work on binned data, and is capable of handling data gaps as well as variations in effective area.
doi:10.1017/s1743921312001214 fatcat:352jlam2iffjbdg6nl4jrvcfne

Absolute Timing of the Crab Pulsar with theRossi X-Ray Timing Explorer

Arnold H. Rots, Keith Jahoda, Andrew G. Lyne
2004 Astrophysical Journal  
We have reported on these results in the past (Rots et al. 1998b (Rots et al. , 2000b Rots, Jahoda, & Lyne 1998a , 2000a .  ...  The accuracy of the RXTE clock in absolute time is about 8 ms for data taken before 1997 April 29 (MJD 50,567); see Rots et al. (1998c) . After that date, the error decreased to 2 ms (C. B.  ... 
doi:10.1086/420842 fatcat:qlgaca3rzzgh7n74cpe22y7aku

Planning and developing the Chandra Source Catalog

Ian N. Evans, Janet D. Evans, Guiseppina Fabbiano, Kenny J. Glotfelty, Michael L. McCollough, Jonathan C. McDowell, Francis A. Primini, Arnold H. Rots, Roger J. Brissenden, David R. Silva
2008 Observatory Operations: Strategies, Processes, and Systems II  
The Chandra Source Catalog, presently being developed by the Chandra X-ray Center, will be the definitive catalog of all X-ray sources detected by the Chandra X-ray Observatory. The catalog interface will provide users with a simple mechanism to perform advanced queries on the data content of the archival holdings on a source-by-source basis for X-ray sources matching user-specified search criteria, and is intended to satisfy the needs of a broad-based group of scientists, including those who
more » ... y be less familiar with astronomical data analysis in the X-ray regime. For each detected X-ray source, the catalog will record commonly tabulated quantities that can be queried, including source position, dimensions, multi-band fluxes, hardness ratios, and variability statistics, derived from all of the observations that include the source within the field of view. However, in addition to these traditional catalog elements, for each X-ray source the catalog will include an extensive set of file-based data products that can be manipulated interactively by the catalog user, including source images, event lists, light curves, and spectra from each observation in which a source is detected. In this paper, we emphasize the design and development of the Chandra Source Catalog. We describe the evaluation process used to plan the data content of the catalog, and the selection of the tabular properties and file-based data products to be provided to the user. We discuss our approach for managing catalog updates derived from either additional data from new observations or from improvements to calibrations and/or analysis algorithms.
doi:10.1117/12.790526 fatcat:z5hn3f7dhfgshlytfpu5u47rde

The Chandra X-ray Observatory calibration database (CalDB): building, planning, and improving

Dale E. Graessle, Ian N. Evans, Kenny Glotfelty, X. Helen He, Janet D. Evans, Arnold H. Rots, Giuseppina Fabbiano, Roger J. Brissenden, David R. Silva, Rodger E. Doxsey
2006 Observatory Operations: Strategies, Processes, and Systems  
The calibration database implemented for the Chandra X-ray Observatory is the most detailed and extensive CalDB of its kind to date. Built according to the NASA High Energy Astrophysics Science Archive Research Center (HEASARC) CalDB prescription, the Chandra CalDB provides indexed, selectable calibration data for detector responses, mirror effective areas, grating efficiencies, instrument geometries, default source aim points, CCD characteristics, and quantum efficiencies, among many others.
more » ... e combined index comprises approximately 500 entries. A standard FTOOLS parametric interface allows users and tools to access the index. Unique dataset selection requires certain input calibration parameters such as mission, instrument, detector, UTC date and time, and certain ranged parameter values. The goals of the HEASARC CalDB design are (1) to separate software upgrades from calibration upgrades, (2) to allow multi-mission use of analysis software (for missions with a compliant CalDB) and (3) to facilitate the use of multiple software packages for the same data. While we have been able to meet the multivariate needs of Chandra with the current CalDB implementation from HEASARC, certain requirements and desirable enhancements have been identified that raise the prospect of a developmental rewrite of the CalDB system. The explicit goal is to meet Chandra's specific needs better, but such upgrades may also provide significant advantages to CalDB planning for future missions. In particular we believe we will introduce important features aiding in the development of mission-independent analysis software. We report our current plans and progress.
doi:10.1117/12.672876 fatcat:jjsy74d3wzc5hefnovemsvundq

Calibration of theRossi X‐Ray Timing ExplorerProportional Counter Array

Keith Jahoda, Craig B. Markwardt, Yana Radeva, Arnold H. Rots, Michael J. Stark, Jean H. Swank, Tod E. Strohmayer, William Zhang
2006 Astrophysical Journal Supplement Series  
The shape of the pulse is quite narrow (Rots et al. 1998) .  ...  The content of the RXTE telemetry, and the relation to absolute time, has been thoroughly documented by Rots et al. (1998) and references therein.  ... 
doi:10.1086/500659 fatcat:hrizawxqyfgqbb2qfpzxp3o4om

DIVISION XII / COMMISSON 5 / WORKING GROUP: FITS

William D. Pence, François Ochsenbein, Donald C. Wells, Steven L. Allen, Mark R. Calabretta, Lucio Chiappetti, Daniel Durand, Thierry Forveille, Carlos Gabriel, Eric Greisen, Preben J. Grosbol, Robert J. Hanisch (+10 others)
2007 Proceedings of the International Astronomical Union  
The business meeting began with a brief review of the current rules and procedures of the WG, which are documented on the WG web page. Four regional FITS committees have been established by the WG, covering North American, Europe, Japan, and Australian/New Zealand, to provide advice to the WG on pending proposals. While it is recognized that this committee structure might need to be revised to provide representation to other regions, the current system is working well, and there were no motions to make any changes at this time.
doi:10.1017/s1743921308024186 fatcat:ly3plsugbfarxi3r6kqtejd7dq

DIVISION XII / COMMISSION 5 / WORKING GROUP FITS DATA FORMAT

William D. Pence, François Ochsenbein, Donald C. Wells, Steven W. Allen, Mark R. Calabretta, Lucio Chiappetti, Daniel Durand, Thierry Forveille, Carlos Gabriel, Eric Greisen, Preben J. Grosbol, Robert J. Hanisch (+10 others)
2008 Proceedings of the International Astronomical Union  
The Working Group FITS (WG-FITS) is the international control authority for the Flexible Image Transport System (FITS) data format. The WG-FITS was formed in 1988 by a formal resolution of the IAU XX General Assembly in Baltimore (MD, USA), 1988, to maintain the existing FITS standards and to approve future extensions to FITS.
doi:10.1017/s1743921308025891 fatcat:zyriw3wtczffzfptcdau2a7b3y

THECHANDRASOURCE CATALOG

Ian N. Evans, Francis A. Primini, Kenny J. Glotfelty, Craig S. Anderson, Nina R. Bonaventura, Judy C. Chen, John E. Davis, Stephen M. Doe, Janet D. Evans, Giuseppina Fabbiano, Elizabeth C. Galle, Danny G. Gibbs (+26 others)
2010 Astrophysical Journal Supplement Series  
The Chandra Source Catalog (CSC) is a general purpose virtual X-ray astrophysics facility that provides access to a carefully selected set of generally useful quantities for individual X-ray sources, and is designed to satisfy the needs of a broad-based group of scientists, including those who may be less familiar with astronomical data analysis in the X-ray regime. The first release of the CSC includes information about 94,676 distinct X-ray sources detected in a subset of public ACIS imaging
more » ... bservations from roughly the first eight years of the Chandra mission. This release of the catalog includes point and compact sources with observed spatial extents <~ 30". The catalog (1) provides access to the best estimates of the X-ray source properties for detected sources, with good scientific fidelity, and directly supports scientific analysis using the individual source data; (2) facilitates analysis of a wide range of statistical properties for classes of X-ray sources; and (3) provides efficient access to calibrated observational data and ancillary data products for individual X-ray sources, so that users can perform detailed further analysis using existing tools. The catalog includes real X-ray sources detected with flux estimates that are at least 3 times their estimated 1 sigma uncertainties in at least one energy band, while maintaining the number of spurious sources at a level of <~ 1 false source per field for a 100 ks observation. For each detected source, the CSC provides commonly tabulated quantities, including source position, extent, multi-band fluxes, hardness ratios, and variability statistics, derived from the observations in which the source is detected. In addition to these traditional catalog elements, for each X-ray source the CSC includes an extensive set of file-based data products that can be manipulated interactively.
doi:10.1088/0067-0049/189/1/37 fatcat:lrbwlm5zpncijhsb57ydygxhhi

STATISTICAL CHARACTERIZATION OF THE CHANDRA SOURCE CATALOG

Francis A. Primini, John C. Houck, John E. Davis, Michael A. Nowak, Ian N. Evans, Kenny J. Glotfelty, Craig S. Anderson, Nina R. Bonaventura, Judy C. Chen, Stephen M. Doe, Janet D. Evans, Giuseppina Fabbiano (+26 others)
2011 Astrophysical Journal Supplement Series  
H i xy ≡ f x x i − f y y i f s s i + f m m i + f h h i , (7) To assess the success of the CSC implementation of the Park et al. (2006) algorithm, we have compared the calculated hardnesses for the simulated  ...  fluxes in three separate ranges of net h-band counts.  ... 
doi:10.1088/0067-0049/194/2/37 fatcat:j3w7t6c525fajkbtvfm5fwqr2i
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