Passbands and Theoretical Colors for the Washington System
The passbands of the Washington system (C, M, T1,T2) have been checked through synthetic photometry of theVilnius spectra and comparison of observed and synthetic color-colorrelations. Using the derived passbands, theoretical colors were computedusing the grid of ATLAS no-overshoot models of Castelli. These can beused for calibration of the Washington system.
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Washington CCD standard fields
Twenty-two new Washington system standards have been established in fourfields suitable for observation with a CCD. Each field includes starswith a wide color range sufficiently faint to be observed with largetelescopes. The fields are (mostly) equatorial, and spaced approximatelyevery 6 hours in right ascension. All observations were obtainedphotoelectrically to ensure that they were on the standard system. Themean number of observations per star is 18, and the mean colors andmagnitudes are determined to about 0.005 mag. The existence of anextremely red star near the Landolt standard SA 98-682 is noted. Inaddition, (M-51) observations are presented for 13 traditionalCMT(1)T(2) standards that allow their use as standards for this colorindex as well.
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Empirical temperature calibrations for early-type stars
Three temperature calibrations of suitable photometric quantities havebeen derived for O and B stars. A sample of 120 stars with reliableT(eff.) determinations has been used for establishing each calibration.The different calibrations have been critically discussed and compared.Temperature determinations for 1009 program stars have been obtainedwith an accuracy of the order of 10 percent.
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Transformation equations and other aids for VRI photometry
Transformations among VRI systems are commonly beset by Paschen-jumpeffects, for which fully satisfactory allowance has not previously beenmade. This paper describes two new techniques which are based on thework of Gutierrez-Moreno, and which allow fully for the effects of thePaschen jump. Values of E(V-R)/E(B-V) and E(R-I)/E(B-V) are also givenfor the Cousins system for a wide range of temperatures. These and thenew techniques contribute to a set of new transformation relations whichapply for most VRI systems; the status of the remaining systems isreviewed, and future work needed for them is described. Two majorsources of Cousins VRI data underlie the new relations; the consistencyof these sources is reviewed and found to be generally satisfactory,although more work on this question is needed. Finally, three tables oftransformed standard-star and other data are given for the Cousins andJohnson systems, and a description of ways to reproduce the latter ispresented.
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UBV Photometry of Equatorial Stars
Not Available
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Standardization of Broadband Photometry of Equatorial Standards
Not Available
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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.
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The Washington system - Photometric properties and standard stars
Observations on the Washington Photometric System (C,M,T1,T2), leadingto an expanded set of 79 standards, are presented. This primary standardlist extends to a V magnitude of approximately 12.0. A V filter has beenadded to the system, which permits V-T1 colors and V magnitudes on theJohnson system. Revised primary and secondary extinction values fromfour observatories are presented. The extent of errors in the standardcolors is discussed. Reddening effects are also discussed.
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Interaction between the Barnard Loop Nebula and the interstellar magnetic field
New observations of the linear interstellar polarization of starlightare used to study the geometric structure of the interstellar magneticfield in the vicinity of the Barnard Loop Nebula in Orion. The observedcomplex field structure cannot be explained by a simple radial expansionof a conducting gaseous shell into an initially parallel field. Asatisfactory fit of the observations can be obtained by assuming thatthe interstellar gas in Orion is suspended in an interstellar 'magneticpocket'. It is suggested that the formation of the observed denseinterstellar clouds and very young stars in the Orion aggregate is aresult of the local structure of the interstellar magnetic field.
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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
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