Contents
Images
Upload your image
DSS Images Other Images
Related articles
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.
| Near infrared observations of quasars with extended ionized envelopes
We have observed a sample of 15 and 8 quasars with redshifts between0.11 and 0.87 (mean value 0.38) in the J and K' bands respectively.Eleven of the quasars were previously known to be associated withextended emission line regions. After deconvolution of the image,substraction of the PSF when possible, and identification of companionswith the help of HST archive images when available, extensions are seenfor at least eleven quasars. However, average profiles are differentfrom that of the PSF in only four objects, for which a good fit isobtained with an r(1/4) law, suggesting that the underlying galaxies areellipticals. Redshifts were available in the literature for surroundingobjects in five quasar fields. For these objects, one to five companiongalaxies were found. One quasar even belongs to a richness class 1cluster. Most other quasars in our sample have nearby galaxies inprojection which may also be companions. Environmental effects aretherefore probably important to account for the properties of theseobjects. Based on data obtained at the European Southern Observatory, LaSilla, Chile. Also based on observations made with the NASA/ESA HubbleSpace Telescope, obtained from the data archive at the Space TelescopeScience Institute; STScI is operated by the Association of Universitiesfor Research in Astronomy, Inc. under NASA contract NAS 5-26555. Thisresearch has made use of the SIMBAD database, operated at CDS,Strasbourg, France and of the NASA/IPAC extragalactic database (NED),which is operated by the Jet Propulsion Laboratory, Caltech undercontract with the National Aeronautics and Space Administration.
| High-resolution imaging with bad seeing: PKS 1610-771 as a test case.
Not Available
| Fainter Southern JHK Standards Suitable for Infrared Arrays
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995MNRAS.276..734C&db_key=AST
| SANTIAGO 91, a right ascension catalogue of 3387 stars (equinox J2000).
The positions in right ascension of 3387 stars belonging to the Santiago67 Catalogue, observed with the Repsold Meridian Circle at Cerro Calan,National Astronomical Observatory, during the period 1989 to 1994, aregiven. The average mean square error of a position, for the wholeCatalogue, is +/-0.009 s. The mean epoch of the catalogue is 1991.84.
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
Catalogs and designations:
|
