Садржај
Слике
Уплоадјуј своје слике
DSS Images Other Images
Везани чланци
An Atlas of Spectrophotometric Landolt Standard Stars
We present CCD observations of 102 Landolt standard stars obtained withthe Ritchey-Chrétien spectrograph on the Cerro TololoInter-American Observatory 1.5 m telescope. Using stellar atmospheremodels, we have extended the flux points to our six spectrophotometricsecondary standards, in both the blue and the red, allowing us toproduce flux-calibrated spectra that span a wavelength range from 3050Å to 1.1 μm. Mean differences between UBVRI spectrophotometrycomputed using Bessell's standard passbands and Landolt's publishedphotometry were determined to be 1% or less. Observers in bothhemispheres will find these spectra useful for flux-calibrating spectra,and through the use of accurately constructed instrumental passbands,will be able to compute accurate corrections to bring instrumentalmagnitudes to any desired standard photometric system (S-corrections).In addition, by combining empirical and modeled spectra of the Sun,Sirius, and Vega, we calculate and compare synthetic photometry toobserved photometry taken from the literature for these three stars.
| 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.
| Three-color surface photometry of a selected sample of early-type galaxies. I - Observations and data reduction
This paper presents the results of two or three color surface photometryfor a sample of 36 early-type galaxies obtained at the Canada FranceHawaii Telescope with CCD cameras. The calibration and data reductionprocedures are described. A comparison of the results with previous workis made for NGC 3379. For each galaxy the B surface brightness profilealong the major axis, as well as ellipticity and color profiles aredisplayed.
| UBV Photometry of Equatorial Stars
Not Available
| Standardization of Broadband Photometry of Equatorial Standards
Not Available
| U, B, V, R photometry of 37 galaxies
U, B, V, R photometry is reported for 37 objects selected fromArakelyan's catalog of high surface-brightness galaxies and several ofMarkaryan's lists. The distribution of the program galaxies in thetwo-color diagram suggests they are of diversified morphological type.Some occupy the Seyfert-galaxy region.
| 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.
| A UBVRI equatorial extinction star network
An equatorial-extinction star network, based on 1503 observations of 37stars, is presented. These results together with those of Crawford etal. (1971) provide a well-determined UBVRI extinction network.Identification charts are included.
| A UBV equatorial-extinction star network
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971PASP...83..652C&db_key=AST
|
Додај нови чланак
Линкови у сродству са темом
Додај нови линк
Чланови следећих група \:
|
Посматрања и Астрометриски подаци
| Сазвежђа: | Једнорог |
| Ректацензија: | 06h52m04.20s |
| Deклинација: | +01°15'05.6" |
| Apparent магнитуда: | 7.881 |
| Proper motion RA: | 2.8 |
| Proper motion Dec: | -4.6 |
| B-T magnitude: | 9.939 |
| V-T magnitude: | 8.051 |
Каталог и designations:
|
