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New aperture photometry for 217 galaxies in the Virgo and Fornax clusters.
We present photo electric multi-aperture photometry in UBVRI of 171 and46 galaxies in the Virgo and Fornax clusters, respectively. Many of thegalaxies have not been observed in at least one of these passbandsbefore. We discuss the reduction and transformation into the Cousinsphotometric system as well as the extinction coefficients obtainedbetween 1990 and 1993.
| The zero point of the Cepheid period-luminosity relation in the 1.05 micron wave band
New observations of the Cepheids in the galactic clusters and externalgalaxies LMC, NGC 6822, NGC 300, and Sex A in the 1.05-micron wave band(IV) are presented. The slope of the P-L(IV) relation derived from theCepheids in the LMC agree with that in the SMC and that obtained forGalactic Cepheids. The zero point of the relation has been determinedfrom the distances to the galactic Cepheid clusters obtained throughZAMS fitting and referenced to the Pleiades modulus of 5.57. Thebolometric P-L relations derived individually using the data in V, J, Kwave bands are found to have the same slope and the zero point asobserved in the IV wave band. The comparison of the bolometric P-Lrelation with that obtained theoretically by Becker, Iben, and Tuggleshows agreement in the value of the slope. But the theoreticalmagnitudes are brighter by 0.4 mag. The true distance moduli to the LMC,the SMC, NGC 6822, NGC 300, and Sex A have been derived from P-L(IV)data and are found to be as 18.42, 18.83, 23.18, 25.72, and 25.27,respectively.
| The distance and structure of the Coalsack. I - Photometric data
The results of UBV and H-beta photometry for 284 stars of spectral typesB to F located in the area of the dark cloud Coalsack are presented.Most of the present stars are brighter than 10.0 mag and are classifiedin the MK system of Houk and Cowley (1975). For each star, the bestvalues for the extinction and distance modulus are provided, withtypical estimated errors of + or - 0.08 mag for the extinction and + or- 0.32 mag for the distance modulus. Possible misclassifications andspectral peculiarities are noted for several of the stars.
| UBV (RI)c standard stars in the E- and F-regions and in the Magellanic Clouds - a revised catalogue.
Not Available
| UBV photometry of E region standard stars of intermediate brightness
Photometry data are given for 335 stars in the nine E regions.Observations were made using a photometer and filters on the 47 cmreflector at Cape Town. The stellar dispersions are summarized. Data arepresented in tabular form.
| Atmospheric extinction in the /U-B/ color index
Various methods for obtaining the atmospheric extinction in the (U-B)color index taking into account the dependence of extinction coefficienton the intrinsic color index of the star are examined. Numericalintegrations are performed to determine synthetic color indices for 32stars of spectral classes O9 to M0 and luminosity classes I, III and Vthrough 0, 1 and 2 air masses, resulting in three (u-b) color indicesfor each star. Photometric reduction of the color indices to the (U-B)color index was then performed by the classical method, by the methodproposed by Gutierrez-Moreno et al. (1966) and various modifications ofit, and by the method proposed by Moffat and Vogt (1977). Comparisonwith observations of 71 stars in the standard region E5, nine extinctionstandard stars and 25 Johnson standard stars in the UBV reveals that thereduction of (U-B) by the classical method gives internal errors betweentwo and three times larger than those obtained for (B-V) and V, whilethe methods of Gutierrez-Moreno et al. and Moffat and Vogt providegreatly improved accuracy.
| Southern metal-poor stars - UBVRI photometry
Considering the study of subdwarf kinematics and metallicities by Eggen,Lynden-Bell, and Sandage (1962), UBVRI photometry and normalizedultraviolet excesses are presented for 178 metal-poor stars, 144 ofwhich are contained in the kinematically unbiased list of Bidelman andMacConnell (1973). The Lowell 0.6 m telescope at Cerro Tololo was used,equipped with a single-channel photometer and a Ga-As photomultiplier.The final magnitudes and colors, number of observations, value ofdelta(U-B)0.6 (if B-V lies between 0.35 and 0.90), B and M class, andpublished spectral types for these stars are presented; severalextremely metal-poor stars are evident. In addition, sixteen nearbyvisual companions of the stars were measured, and their magnitudes andcolors are given.
| Photoelectric standards of intermediate brightness in the E-regions. I. UBV photometry.
Not Available
| Photometric standard stars for the UBV and (RI)KC systems.
Not Available
| Fainter Standards for VRI Photometry in the E Regions
Not Available
| The color-absolute magnitude relation for E and S0 galaxies. II - New colors, magnitudes, and types for 405 galaxies
Colors and magnitudes measured in the ubVr photometric system arepresented along with galaxy types and radial velocities for 405 E, S0,SB0, and Sa field galaxies. The color-aperture effect for E and S0galaxies is investigated together with the K-reddening due to redshiftand the aperture correction to V magnitudes. An average standardcorrected color reduced to an aperture ratio of 0.5 and a standard Vmagnitude corrected to an aperture ratio of 2.5 are given for eachgalaxy; the Galactic reddening as a function of latitude is derived fromthe corrected color data. The color-absolute magnitude (C-M) relationpreviously established for the Virgo cluster and nine other nearbygroups and clusters of galaxies is shown to apply equally to the presentsample of E and S0 field galaxies. It is concluded that whatever itscause, the C-M effect appears to be universal and may be useful for thedetermination of relative distances to galaxies in clusters, groups, andthe general field.
| Absolute magnitude-color relation for early type spirals
The color-magnitude (CM) relation in early-type spirals is investigatedusing narrow-band observations of (u-V) color indices and V magnitudesfor 28 early-type spirals in the Virgo cluster complex and 13 additionalgalaxies in 11 other clusters or groups. The color indices andmagnitudes of each galaxy are corrected for various systematic errorsand observational effects, and a CM relation is derived for the Virgo Icluster. This CM relation is shown to be universal and to have the sameslope, intrinsic dispersion, and absolute zero point in all examinedgroups at distances of 4 to 63 Mpc. Scatter in the CM relation isassessed, and observations of the Mg index for the galaxies in the VirgoI cluster are reported. It is suggested that the CM relation isindependent of the environment where a galaxy formed.
| The redshift-distance relation. VIII - Magnitudes and redshifts of southern galaxies in groups: A further mapping of the local velocity field and an estimate of the deceleration parameter
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975ApJ...202..563S&db_key=AST
| Six UBV photoelectric sequences in VELA (l=257 degres to 281 degres.).
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975A&AS...19...45D&db_key=AST
| Standard magnitudes in the E regions.
Not Available
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Observation and Astrometry data
| Constellation: | Κένταυρος |
| Right ascension: | 12h14m51.80s |
| Declination: | -44°06'42.1" |
| Apparent magnitude: | 7.556 |
| Distance: | 307.692 parsecs |
| Proper motion RA: | -26.8 |
| Proper motion Dec: | 2.3 |
| B-T magnitude: | 8.98 |
| V-T magnitude: | 7.674 |
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