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Spectral Irradiance Calibration in the Infrared. XIV. The Absolute Calibration of 2MASS
Element by element, we have combined the optical components in the threecameras of the Two Micron All Sky Survey (2MASS), and incorporateddetector quantum efficiency curves and site-specific atmospherictransmissions, to create three relative spectral response curves (RSRs).We provide the absolute 2MASS attributes associated with ``zeromagnitude'' in the JHKs bands so that these RSRs may be usedfor synthetic photometry. The RSRs tie 2MASS to the``Cohen-Walker-Witteborn'' framework of absolute photometry and stellarspectra for the purpose of using 2MASS data to support the developmentof absolute calibrators for the Infrared Array Camera and pairwisecross-calibrators between all three SIRTF instruments. We examine therobustness of these RSRs to changes in water vapor within a night. Wecompare the observed 2MASS magnitudes of 33 stars (converted from theprecision optical calibrators of Landolt and Carter-Meadows intoabsolute infrared calibrators from 1.2 to 35 μm) with ourpredictions, thereby deriving 2MASS ``zero-point offsets'' from theensemble. These offsets are the final ingredients essential to merge2MASS JHKs data with our other absolutely calibrated bandsand stellar spectra, and to support the creation of faint calibrationstars for SIRTF.
| Spectral Irradiance Calibration in the Infrared. XIII. ``Supertemplates'' and On-Orbit Calibrators for the SIRTF Infrared Array Camera
We describe the technique that will be used to develop a set of on-orbitcalibrators for the Infrared Array Camera (IRAC) and demonstrate thevalidity of the method for stars with spectral types either K0-M0 III orA0-A5 V. For application to SIRTF, the approach is intended to operatewith all available optical, near-infrared (NIR), and mid-infrared (MIR)photometry and to yield complete absolute spectra from UV to MIR. Oneset of stars is picked from Landolt's extensive network of optical(UBVRI) calibrators, the other from the Carter-Meadows set of faint IRstandards. Traceability to the ``Cohen-Walker-Witteborn'' framework ofabsolute photometry and stellar spectra is assured. The method is basedon the use of either ``supertemplates,'' which represent the intrinsicshapes of the spectra of K0-M0 III stars from far-UV (1150 Å) toMIR (35 μm) wavelengths, or Kurucz synthetic spectra for A0-A5 Vstars. Each supertemplate or Kurucz model is reddened according to theindividual star's extinction and is normalized using availablecharacterized optical photometry. This paper tests our capability topredict NIR (JHK) magnitudes using supertemplates or models constrainedby Hipparcos/Tycho or precision ground-based optical data. We provideabsolutely calibrated 0.275-35.00 μm spectra of 33 Landolt andCarter-Meadows optical standard stars to demonstrate the viability ofthis technique, and to offer a set of IR calibrators 100-1000 timesfainter than those we have previously published. As an indication ofwhat we can expect for actual IRAC calibration stars, we have calculatedthe absolute uncertainties associated with predicting the IRACmagnitudes for the faintest cool giant and hot dwarf in this new set ofcalibration stars.
| VRI Light Curves of SS 433: Photometry and Model
We present the results of VRI CCD photometric observations of SS 433 andVRI light-curve modelings for SS 433. Observations were carried out inthe fall of 1995 using the 51-cm relfector at Osaka Kyoiku University.Three cycles of the binary phase were covered. The mean magnitudes andcolors during the observational periods were V = 14.0, R = 11.1, I =10.5; V - R = 2.88, V - I = 3.50, R - I = 0.62. On October 17 and 18 astrong flare was observed. Theoretical light curves were also calculatedusing a model in which SS 433 consists of a geometrically thick torusaround a compact star and a companion star filling the Roche lobe. Inthe torus picture VRI light curves were first calculated; forappropriate parameters VRI model light curves well reproduce theobservational profiles. In addition, the extinction was first derivedfrom the magnitude difference between the obervation and the model;AV ~ 6--7, AR ~ 3--4, and AI ~ 3. These values are in goodagreement with those of a previous observation.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| UBVRI photometry of FKSZ stars. IV
The paper presents UBVRI photometry, in the Kron-Cousins system, for 117stars of the Catalog of Fundamental Faint Stars in the declination zone+18-0 deg. The observations were performed from July 1988 to March 1990with the ESO 0.50-m telescope at the ESO in La Silla, Chile. The resultsof 24 nights of observations are reported.
| A radio optical reference frame. III - Additional radio and optical positions in the Southern Hemisphere
Radio and optical positions are presented for southern hemisphereextragalactic sources from the Parkes 2.7 GHz survey. Sixty-one sourceswere observed with Mark III VLBI at 8.4 GHz between Tidbinbilla,Australia, and Hartebeesthoek, South Africa. The results presented arepart of the effort to establish a global reference frame of 400extragalactic radio sources. Radio positions with about 10 milliarcsecerrors have been estimated for 39 sources not previously in the presentradio reference frame catalog, and provisional positions were obtainedfor two additional sources, bringing the total number of catalog sourcesto 276. The principal source of error is the uncalibrated ionosphere. Ofthe remaining sources five were completely undetected, six were eithertoo faint or too resolved, and nine had previous catalog positions.Optical positions on the FK5 system have also been measured for foursouthern sources using prime focus plates from the Anglo-Australian 4 mtelescope with an accuracy of 0.06 arcsec. This raises to 40 the numberof radio sources with accurately measured positions for their opticalcounterparts.
| UBV(RI)c photometry of equatorial standard stars - A direct comparison between the northern and southern systems
UBV(RI)c photometry of 212 stars from Landolt's list of equatorialstandards is presented. The observations are tied to the system definedby Cousin's E-region standards. A comparison of the present results withLandolt's reveals reasonably good agreement for (V-R)c and (V-I)c, butmarked systematic differences for (B-V) and (U-B). The UBV systems ofCousins and Landolt are evidently not the same and both probably differfrom Johnson's original system.
| The 77-81 intermediate-band photometric system
The 77-81 intermediate-band photometric color system for the study oflate-type stars is defined. The passbands are centered on a region ofTiO absorption at 7750 A (77) and on a region of CN absorption at 8100 A(81). Good agreement is found between measurements made on the 77-81system with different detectors. The 77-81 color is well correlated withM type and reasonably correlated with carbon-richness class. The 77-81,V-I color-color diagram clearly distinguishes M and C types from otherstars. It is also shown that the 77-81 color may be used to measure TiOband strength.
| Photoelectric observations of classical cepheids.
Not Available
| UBVRI photometric standard stars around the celestial equator
It is pointed out that accurate, internally consistent, and readilyaccessible standard star photometric sequences are necessary for thecalibration of the intensity and color data which astronomers obtain atthe telescope. The photometric results provided in connection with thepresent study represent the first part of an effort which is concernedwith the presentation of UBVRI photoelectric photometric standard starsin the magnitude range from 7 to 17 over as broad a range in color aspossible. All of the photometric observations were made with a 31034type photomultiplier used in a pulse counting mode. Some 15 to 25standard stars chosen from Cousins' lists (1973, 1976) in the E-regionswere observed with an 0.4-m telescope each night along with the programstars. UBVRI standard stars were observed periodically throughout thenight. Observations with a 0.9-m telescope were also conducted. TheUBVRI photoelectric observations take into account 223 stars.
| Spectral classifications for Landolt's celestial equatorial standard stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1979AJ.....84..783D&db_key=AST
| Equatorial UBVRI photoelectric sequences
From 1335 BVRI observations of 189 stars in selected areas 92-115,Landolt's (1973) network of faint UBV standards has been extended to RI. Of these stars, 173 have four or more observations. The (U-B) valuesof Landolt are adopted, and a well-observed equatorial faint-starnetwork is presented on the Johnson UBVRI photometric system.
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Dades d'Observació i Astrometria
| Constel·lació: | Aquila |
| Ascensió Recta: | 18h41m26.68s |
| Declinació: | +00°33'51.9" |
| Magnitud Aparent: | 7.474 |
| Distancia: | 234.742 parsecs |
| Moviment propi RA: | -2.7 |
| Moviment propi Dec: | -27.6 |
| B-T magnitude: | 9.327 |
| V-T magnitude: | 7.627 |
Catàlegs i designacions:
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