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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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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Luminosity classification with the Washington system
The DDO 51 filter has been added to the Washington photometric system.The strong surface gravity sensitivity of the Mg I 'b' triplet and MgHbands which it monitors allows the system to easily discriminate betweendwarfs and giants of late G and K spectral type. The system isespecially suited as a membership criterion for abundance studies ofdistant cluster giants. The Mg index is insensitive to surface gravityvariations among G giants. The metallicity sensitivity among giants isalso relatively weak. Population I and II giants can be distinguishedbut no further differentiation is evident.
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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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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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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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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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