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The Peak Brightness of SN 1895B in NGC 5253 and the Hubble Constant
The light curve of the Type Ia supernova SN 1895B (in NGC 5253) isimportant because Sandage et al. have measured a distance to the hostgalaxy by means of Cepheid variables and thus have derived the Hubbleconstant. However, the last time the supernova plates were measured wasin 1923, and the resultant photometry is inconsistent at the 0.8 maglevel. In this paper, I report on the results of my remeasurement of theold supernova plates with a scanning microdensitometer. I findB-magnitudes of >11.3 +/- 0.3, 8.36 +/- 0.07, 8.51 +/- 0.06, 8.54 +/-0.05, and 9.34 +/- 0.08 on JD 2,413,359, 2,413,383, 2,413,384,2,413,385, and 2,413,393, respectively. The last plate was a prismplate, for which I present a flux-calibrated spectrum, taken ~15 daysafter maximum. Even though only loose constraints can be placed on thelight curve shape, the firm limit on the peak magnitude (<8.49 +/-0.03) will provide a firm limit on the Hubble constant. The most likelyshape is that of the average Type Ia template of Leibundgut et al., forwhich the best-fit peak B-magnitude is 8.26 +/- 0.11. The deducedprobability distribution for H0 is peaked at 51 +/- 7 km s-1 Mpc-1, withextreme limits of 61 +/- 12 and 26 +/- 5 km s-1 Mpc-1.
| 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.
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Osservazione e dati astrometrici
| Costellazione: | Centauro |
| Ascensione retta: | 13h38m10.87s |
| Declinazione: | -32°14'18.0" |
| Magnitudine apparente: | 8.585 |
| Distanza: | 395.257 parsec |
| Moto proprio RA: | -28.3 |
| Moto proprio Dec: | 4.6 |
| B-T magnitude: | 10.053 |
| V-T magnitude: | 8.707 |
Cataloghi e designazioni:
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