Celestial Equator

2015 ◽  
pp. 400-400
Author(s):  
Daniel Rouan
Keyword(s):  
Celestial Equator

scholarly journals THE ATACAMA COSMOLOGY TELESCOPE: PHYSICAL PROPERTIES OF SUNYAEV-ZEL'DOVICH EFFECT CLUSTERS ON THE CELESTIAL EQUATOR,

2013 ◽  
Vol 765 (1) ◽  
pp. 67 ◽  
Author(s):  
Felipe Menanteau ◽  
Cristóbal Sifón ◽  
L. Felipe Barrientos ◽  
Nicholas Battaglia ◽  
J. Richard Bond ◽  
...  
Keyword(s):  
Physical Properties ◽  
Atacama Cosmology Telescope ◽  
Sunyaev Zel'dovich Effect ◽  
Celestial Equator

scholarly journals Producing a BOSS CMASS sample with DES imaging

2019 ◽  
Vol 489 (2) ◽  
pp. 2887-2906 ◽  
Author(s):  
S Lee ◽  
E M Huff ◽  
A J Ross ◽  
A Choi ◽  
C Hirata ◽  
...  
Keyword(s):  
Sloan Digital Sky Survey ◽  
Joint Analysis ◽  
Dark Energy Survey ◽  
Sky Survey ◽  
Angular Correlation Function ◽  
Galaxy Sample ◽  
Celestial Equator ◽  
The Difference ◽  
Galaxy Bias ◽  
Validation Tests

ABSTRACT We present a sample of galaxies with the Dark Energy Survey (DES) photometry that replicates the properties of the BOSS CMASS sample. The CMASS galaxy sample has been well characterized by the Sloan Digital Sky Survey (SDSS) collaboration and was used to obtain the most powerful redshift-space galaxy clustering measurements to date. A joint analysis of redshift-space distortions (such as those probed by CMASS from SDSS) and a galaxy–galaxy lensing measurement for an equivalent sample from DES can provide powerful cosmological constraints. Unfortunately, the DES and SDSS-BOSS footprints have only minimal overlap, primarily on the celestial equator near the SDSS Stripe 82 region. Using this overlap, we build a robust Bayesian model to select CMASS-like galaxies in the remainder of the DES footprint. The newly defined DES-CMASS (DMASS) sample consists of 117 293 effective galaxies covering $1244\,\deg ^2$. Through various validation tests, we show that the DMASS sample selected by this model matches well with the BOSS CMASS sample, specifically in the South Galactic cap (SGC) region that includes Stripe 82. Combining measurements of the angular correlation function and the clustering-z distribution of DMASS, we constrain the difference in mean galaxy bias and mean redshift between the BOSS CMASS and DMASS samples to be $\Delta b = 0.010^{+0.045}_{-0.052}$ and $\Delta z = \left(3.46^{+5.48}_{-5.55} \right) \times 10^{-3}$ for the SGC portion of CMASS, and $\Delta b = 0.044^{+0.044}_{-0.043}$ and $\Delta z= (3.51^{+4.93}_{-5.91}) \times 10^{-3}$ for the full CMASS sample. These values indicate that the mean bias of galaxies and mean redshift in the DMASS sample are consistent with both CMASS samples within 1σ.

scholarly journals Lunisolar Atmospheric Tides. II

1989 ◽  
Vol 42 (4) ◽  
pp. 439 ◽  
Author(s):  
R Brahde
Keyword(s):  
Phase Shift ◽  
Atmospheric Pressure ◽  
Mean Amplitude ◽  
Atmospheric Tides ◽  
The Moon ◽  
Celestial Equator

In an earlier paper (Brahde 1988) it was shown that series of measurements of the atmospheric pressure in Oslo contained information about a one�day oscillation with mean amplitude 0�17 mb. The data consisted of measurements every second hour during the years 1957-67, 1969 and 1977. In the present paper the intervening years plus 1978 and 1979 have been included, increasing the basis from 13 to 23 years. In addition the phase shift occurring when the Moon crosses the celestial equator has been defined precisely, thus making it possible to include all the data.

scholarly journals A New Approach To Traditional Chinese Astronomy

1988 ◽  
Vol 133 ◽  
pp. 23-28
Author(s):  
J. Kistemaker ◽  
Yang Zhengzong
Keyword(s):  
Systematic Investigation ◽  
New Approach ◽  
Original Meaning ◽  
Celestial Equator ◽  
Cardinal Directions ◽  
The Right ◽  
Insight Into

We have made a systematic investigation of the traditional Chinese stellar sky, using Yi-Shitong's precise stellar maps at the Amsterdam Zeiss Planetarium, reproducing the positions of pole, hour circles and equator for any epoch between 1000 and 3000 BC at the latitude of Xian.The right ascensions of the 28 boundary hour circles of the traditional lunar lodges, as well as the declinations of the various determinative stars, give insight into the possible original meaning of star names and ages. The four cardinal directions along the celestial equator (α Hya, η Tau, β Aqr and Sco) fit best with 2250±50 years BC.

scholarly journals Numerical effects of gravitational light deflection on the determination of the equinox and equator

1986 ◽  
Vol 114 ◽  
pp. 205-211
Author(s):  
J. A. Hughes ◽  
D. K. Scott ◽  
C. A. Smith
Keyword(s):  
Coordinate System ◽  
Proper Motion ◽  
Minor Planets ◽  
The Sun ◽  
Light Deflection ◽  
Proper Motions ◽  
Motion System ◽  
Celestial Equator ◽  
The Right

Observations of the sun and major and minor planets made by transit circle telescopes are used to determine positions of the equinox and the celestial equator and, by repeated observing programs, the motions of these fiducial references. Long series of such absolute observations, when combined into catalogs such as the FK5, yield a fundamental coordinate system which is an observational approximation to an ideal, dynamically defined coordinate system. In such a system the equinox, for example, is defined implicitly by the right ascensions (at mean epoch) and the proper motions of the stars included in the catalog system, together with the adopted constant of precession. It may be noted that independent, highly accurate determinations of the latter quantity thus help to improve the fundamental proper motion system.

Celestial Equator

2011 ◽  
pp. 264-264
Author(s):  
Daniel Rouan
Keyword(s):  
Celestial Equator

scholarly journals CCD scanning with a small telescope

1986 ◽  
Vol 118 ◽  
pp. 285-286
Author(s):  
Tom Gehrels
Keyword(s):  
Moving Objects ◽  
Electron Hole ◽  
Analog To Digital ◽  
Buried Channel ◽  
Visual Magnitude ◽  
Celestial Equator ◽  
Star Images ◽  
Right Ascension ◽  
Rotational Transformation ◽  
Zero Points

We use a scanning CCD for acquisition and astrometry of new and recovered comets, asteroids and other objects. The CCD is an RCA SID 53612 thinned, buried channel array of 512 × 320 30-micron square pixels that are back-illuminated and refrigerated to −60 C in a vacuum housing. The readout noise is ± 200 electron-hole pairs (ehp) per pixel per readout, the thermal dark current is 50 ehp/pixel/sec, and the scale of our 12-bit analog-to-digital converter is 25 ehp/AD unit. The Newtonian focus of a 91-cm telescope has been modified from f/5 to f/3.85 with a relay lens to give a platescale of 1.73 arcsecs per pixel, a scale chosen for efficient coverage of sky. The CCD is operated in the scanning mode with the telescope drive off, and the rate of transfer of signal charges is tuned to correspond to the rate at which the star images drift across the focal plane. The exposure time (the time the images take to transit the “512” dimension of the CCD) is 60 seconds at the celestial equator, giving a “six sigma” limiting (visual) magnitude of 19.5. A typical scan covers 30 minutes of time in right ascension by 0.156 deg in declination and is stored as a digital array of 14848 × 320 CCD pixels. A set of three 30-minute scans near the opposition point along the ecliptic nets about 5 new main-belt asteroids. Potential moving objects are revealed by determining the positions of all the stellar images in each scan and comparing the results of the three scans. Several potential reference (SAO) stars are in one scan. The reduction from pixel coordinates to apparent topo-centric equatorial coordinates of date involves only three free parameters, making our astrometric reductions simpler than the classical affine transformation of plate coordinates. There is no rotational transformation and the scale in right ascension is defined by the clock. The declination scale is determined from the reference stars. The zero points of R.A. and Dec. are given by the average differences between the pixel coordinates and catalog positions of the reference stars.

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