- ID:
- ivo://CDS.VizieR/J/other/Ser/177.109
- Title:
- Corrections to HIP proper motions
- Short Name:
- J/other/Ser/177.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the data on latitude variations obtained from observations with 10 classical photographic zenith tubes (PZT) in order to improve the Hipparcos proper motions in declinations µ<SUB>δ</SUB> for 807 stars. Part of observing programmes, carried out during the last century for the purpose of studying the Earth's rotation, were realized by using PZT instruments. These observations were performed within in the intervals (tens of years) much longer than that of the Hipparcos mission (less than 4 years). In addition, the annual number of observations for every PZT- programme star is several hundreds on the average. Though the accuracy of the star coordinates in the Hipparcos Catalogue is by two orders of magnitude better than that of the star coordinates from the PZT observations, the large number of observations performed a much longer time interval makes it possible to correct the Hipparcos proper motions and to improve their accuracy with respect to the accuracy given in the Hipparcos Catalogue. Long term examinations of latitude and time variations were used to form the Earth Orientation Catalogue (EOC-2), aimed at a more accurate determination of positions and proper motions for the stars included. Our method of calculating the corrections of the proper motions in declination from the latitude variations is different from the method used in obtaining the EOC-2 Catalogue. Comparing the results we have established a good agreement between our µ<SUB>δ</SUB> and the EOC-2 ones for the star sample used in the present paper.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/other/PASA/30.4
- Title:
- Corrections to the VV13 Catalogue
- Short Name:
- J/other/PASA/30.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Fixes are presented to be applied to the Veron-Cetty and Veron (VCV) Quasar Catalogue, 13th edition (Cat. VII/258). These are comprised of 39 deduplicati ons, 380 astrometric moves of 8+ arcseconds of which 31 are over 10 arcminutes, and 30 indicated delistings.
- ID:
- ivo://CDS.VizieR/J/ApJ/752/72
- Title:
- Correlation metallicity / eclipse depth
- Short Name:
- J/ApJ/752/72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Previous studies of the interior structure of transiting exoplanets have shown that the heavy-element content of gas giants increases with host star metallicity. Since metal-poor planets are less dense and have larger radii than metal-rich planets of the same mass, one might expect that metal-poor stars host a higher proportion of gas giants with large radii than metal-rich stars. Here I present evidence for a negative correlation at the 2.3{sigma} level between eclipse depth and stellar metallicity in the Kepler gas giant candidates. Based on Kendall's {tau} statistics, the probability that eclipse depth depends on star metallicity is 0.981. The correlation is consistent with planets orbiting low-metallicity stars being, on average, larger in comparison with their host stars than planets orbiting metal-rich stars. Furthermore, since metal-rich stars have smaller radii than metal-poor stars of the same mass and age, a uniform population of planets should show a rise in median eclipse depth with [M/H]. The fact that I find the opposite trend indicates that substantial changes in the gas giant interior structure must accompany increasing [M/H]. I investigate whether the known scarcity of giant planets orbiting low-mass stars could masquerade as an eclipse depth-metallicity correlation, given the degeneracy between metallicity and temperature for cool stars in the Kepler Input Catalog. While the eclipse depth-metallicity correlation is not yet on firm statistical footing and will require spectroscopic [Fe/H] measurements for validation, it is an intriguing window into how the interior structure of planets and even the planet formation mechanism may be changing with Galactic chemical evolution.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A66
- Title:
- Correlation of logR'HK with logIH{alpha}
- Short Name:
- J/A+A/566/A66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The re-emission in the cores of the CaII H & K and H{alpha} lines are well known proxies of stellar activity. However, these activity indices probe different activity phenomena: the first is more sensitive to plage variation, while the other is more sensitive to filaments. In this paper, we study the long-term correlation between logR'_HK_ and logI_H{alpha}_, two indices based on the CaII H & K and H{alpha} lines, respectively, for a sample of 271 FGK stars using measurements obtained over a ~9-year time span. Because stellar activity is one of the main obstacles to the detection of low-mass and long-period planets, understanding this activity index correlation further can give us some hints about the optimal target to focus on ways to correct for these activity effects. We found a great variety of long-term correlations between logR'_HK_ and logI_H{alpha}_. Around 20% of our sample has a strong positive correlation between the indices while about 3% show strong negative correlation. These fractions are compatible with those found for the case of early-M dwarfs. Stars exhibiting a positive correlation have a tendency to be more active when compared to the median of the sample, while stars showing a negative correlation are more present among higher metallicity stars. There is also a tendency for the positively correlated stars to be more present among the coolest stars, a result which is probably due to the activity level effect on the correlation. Activity level and metallicity therefore seem to be playing a role on the correlation between logR'_HK_ and logI_H{alpha}_. Possible explanations based on the influence of filaments for the diversity in the correlations between these indices are discussed in this paper. As a parallel result, we show a way to estimate the effective temperature of FGK dwarfs that exhibit a low activity level by using the H{alpha} index.
- ID:
- ivo://nasa.heasarc/cosbmaps
- Title:
- COS-B Map Product Catalog
- Short Name:
- COS-B
- Date:
- 09 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The European Space Agency's satellite COS-B was dedicated to gamma-ray astronomy in the energy range 50 MeV to 5 Gev and carried a single spark chamber telescope with approximately a 20 degree field of view. COS-B operated in a highly eccentric polar orbit with apogee around 90000 km between 17 August 1975 and 25 April 1982. During this operational lifetime, COS-B made 65 observations, 15 of which were devoted to high (>20 deg) galactic latitudes. This database is a collection of maps created from the 65 COS-B observation files. The original observation files can be accessed within BROWSE by changing to the COSBRAW database. For each of the COS-B observation files, the analysis package FADMAP was run and the resulting maps, plus GIF images created from these maps, were collected into this database. Each map is a 120 x 120 pixel FITS format image with 0.5 degree pixels. The user may reconstruct any of these maps within the captive account by running FADMAP from the command line after extracting a file from within the COSBRAW database. The parameters used for selecting data for these product map files are embedded keywords in the FITS maps themselves. These parameters are set in FADMAP, and for the maps in this database are set as 'wide open' as possible. That is, except for selecting on each of 4 energy ranges, all other FADMAP parameters were set using broad criteria. To find more information about how to run FADMAP on the raw event's file, the user can access help files within the COSBRAW database or can use the 'fhelp' facility from the command line to gain information about FADMAP. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/cosbraw
- Title:
- COS-B Photon Events Catalog
- Short Name:
- COS-Braw
- Date:
- 09 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The European Space Agency's satellite COS-B was dedicated to gamma-ray astronomy in the energy range 50 MeV to 5 Gev and carried a single spark chamber telescope with approximately a 20 degree field of view. COS-B operated in a highly eccentric polar orbit with apogee around 90000 km between 17 August 1975 and 25 April 1982. During this operational lifetime, COS-B made 65 observations, 15 of which were devoted to high (>20 deg) galactic latitudes. The COSBRAW database table is a log of the 65 COS-B observation intervals and contains target names, sky coordinates start times and other information taken from the final COS-B database produced by ESA in 1985. This final database consisted of three basic datasets: `OBSLI`, a dataset describing each observation period, typically a month; `OURLI`, a dataset describing each uninterrupted observation interval, lasting between 10 minutes and 10 hours; and `GAMLI`, a dataset containing records for each accepted gamma-ray photon. These three data sets were combined into FITS format images at NASA/GSFC. The images were formed by making the center pixel of a 1024 x 1024 pixel image correspond to the RA and DEC given in the `OBSLI` file. Each photon's RA and DEC was converted to a relative pixel in the image. This was done by using Aitoff projections. All the raw data from these three COS-B files are now stored in 65 FITS files accessible with BROWSE software in the database COSBRAW. The images can be accessed and plotted using XIMAGE and other columns of the FITS file extensions can be plotted with the FTOOL FPLOT. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJ/887/5
- Title:
- COS CGM compendium (CCC). III. z<=1 Ly{alpha} syst.
- Short Name:
- J/ApJ/887/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We characterize the metallicities and physical properties of cool, photoionized gas in a sample of 152 z<=1 strong Ly{alpha} forest systems (SLFSs, absorbers with 15<logN_HI_<16.2). The sample is drawn from our Cosmic Origins Spectrograph (COS) circumgalactic medium compendium (CCC), an ultraviolet survey of HI-selected circumgalactic gas around z<=1 galaxies that targets 261 absorbers with 15<logN_HI_<19. We show that the metallicity probability distribution function of the SLFSs at z<=1 is unimodal, skewed to low metallicities with a mean and median of [X/H]=-1.47 and -1.18dex. Very metal-poor gas with [X/H]{<}-1.4 represents about half of the population of absorbers with 15<logN_HI_<=18, while it is rare at higher N_HI_. Thus, there are important reservoirs of primitive (though not pristine) diffuse ionized gas around z<=1 galaxies. The photoionized gas around z<=1 galaxies is highly inhomogeneous based on the wide range of metallicities observed (-3<=[X/H]<=+0.4) and the fact that there are large metallicity variations (factors of 2 to 25) for most of the closely spaced absorbers ({Delta}v<=300km/s) along the same sightlines. These absorbers show a complex evolution with redshift and HI column density, and we identify subtle cosmic evolution effects that affect the interpretation of metallicity distributions and comparison with other absorber samples. We discuss the physical conditions and cosmic baryon and metal budgets of the CCC absorbers. Finally, we compare the CCC results to recent cosmological zoom simulations and explore the origins of the 15<logN_HI_<19 absorbers within the Evolution and Assembly of GaLaxies and their Environments (EAGLE) high-resolution simulations.
- ID:
- ivo://mast.stsci/candels
- Title:
- Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS)
- Short Name:
- CANDELS
- Date:
- 12 Feb 2020 21:03:03
- Publisher:
- Space Telescope Science Institute Archive
- Description:
- CANDELS is designed to document the first third of galactic evolution from z = 8 to 1.5 via deep imaging of more than 250,000 galaxies with WFC3/IR and ACS. It will also find the first Type Ia SNe beyond z greater than 1.5 and establish their accuracy as standard candles for cosmology. Five premier multi-wavelength sky regions are selected; each has multi-wavelength data from Spitzer and other facilities, and has extensive spectroscopy of the brighter galaxies. The use of five widely separated fields mitigates cosmic variance and yields statistically robust and complete samples of galaxies down to 109 solar masses out to z ~ 8.
- ID:
- ivo://CDS.VizieR/J/ApJS/100/281
- Title:
- Cosmic background anisotropies
- Short Name:
- J/ApJS/100/281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cosmic microwave background (CMB) anisotropies and density fluctuations are calculated for flat cold dark matter (CDM) models with a wide range of parameters, viz., {OMEGA}_0,h_, and {OMEGA}_B_, for standard recombination and for various epochs of reionization. Tables of the power spectrum of CMB anisotropies in the form of C_l_ values as a function of l are presented. Although the Harrison-Zeldovich initial spectrum is assumed in these tables, we present simple approximations for obtaining the C_l_ values corresponding to a tilted spectrum from those with a Harrison-Zeldovich spectrum. Values of {sigma}_8_ are derived for the matter density spectrum, with {sigma}(10deg), fixed Q_(rms-PS) and COBE Differential Microwave Radiometer (DMR) 2yr normalizations. Simple modifications of the fitting formula for the density transfer function are given which are applicable for models with high baryon density. By using both numerical results and these fitting formulae, we calculate the relation between {sigma}_8_ and Q_(rms-PS) and find good agreement. In addition, the velocity fields are calculated.
- ID:
- ivo://nasa.heasarc/skyview/cobe
- Title:
- Cosmic Background Explorer DIRBE Annual\ Average\ Map
- Short Name:
- COBE
- Date:
- 09 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The DIRBE Project Data Sets cover the whole sky and provide photometric data in 10 bands ranging in wavelength from 1.25 to 240 microns. SkyView has supported three maps: an early averaged map including including zodiacal and Galactic components (COBE DIRBE (OLD)), a more recent cleaner version of that data (COBE DIRBE/AAM) and a map with the zodaical light subtracted out (COBE DIRBE/ZSMA). The early data is no longer supported. Please contact us if you want access to these data. <P> Detailed descriptions of the DIRBE, the data processing, and the data products are given in an Explanatory Supplement. A Small Source Spectral Energy Distribution Browser can be used to assess the visibility of an unresolved or small extended source in the DIRBE data and see its spectral energy distribution. As noted in section 5.6.6 of the Explanatory Supplement, the DIRBE Time-ordered Data are required to derive definitive point source fluxes. <p> These maps provide an estimate of the infrared intensity at each pixel and wavelength band based on an interpolation of the observations made at various times at solar elongations close to 90&#176;;. <P> These COBE DIRBE maps are a combination original ten band passes with the following wavelengths: <UL> <LI>Band 1 - 1.25 &#181;;m <LI>Band 2 - 2.2 &#181;;m <LI>Band 3 - 3.5 &#181;;m <LI>Band 4 - 4.9 &#181;;m <LI>Band 5 - 12 &#181;;m <LI>Band 6 - 25 &#181;;m <li>Band 7 - 60 &#181;;m <li>Band 8 - 100 &#181;;m <li>Band 9 - 140 &#181;;m <li>Band 10 - 240 &#181;;m </ul> <p> The default two dimensional array uses Band 8 (100 &#181;;m). <P> The COBE DIRBE/Annual Average Maps (AAM) is the cumulative weighted average of the photometry. This average is calculated using the weighted number of observations from each Weekly Averaged Map ( WtNumObs from the Weekly Averaged Map) as the weight, such that annual_average =sum( weekly_average * weekly_weight )/ sum( weekly_weight ) <p> COBE DIRBE/Zodi-Subtracted Mission Average (ZSMA) Skymap represents the extra-Solar system sky brightness. It is the average residual map that results after the modelled interplanetary dust (IPD) signal is subtracted from each of the DIRBE Weekly Skymaps from the cryogenic mission. Individual weekly residual maps can be reconstructed from the data supplied in the DIRBE Sky and Zodi Atlas (DSZA). Provenance: COBE Team. This is a service of NASA HEASARC.
