Color-indices of 215 extragalactic nebulae / 215 გარეგალაქტიკური ნისლეულის კოლორ–ინდექსები

Vashakidze, M.A. and ვაშაკიძე, მ. and Вашакидзе, М.А. (1945) Color-indices of 215 extragalactic nebulae / 215 გარეგალაქტიკური ნისლეულის კოლორ–ინდექსები. აბასთუმნის ასტროფიზიკური ობსერვატორიის ბიულეტენი / Bulletin of the Abastumani Astrophysical Observatory (8). pp. 1-41.


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The determination of color-indices. The present paper is the third communication treating the color-indices of extragalactic nebulae published by us. The color-indices of nebulae given here were determined mainly in the same way as before in order to maintain homogeneity m the color-index system of oar catalogue. However the determination of color-indices, of some nebulae marked by an asterisc in Table I was done in a somewhat different way.This difference consists in the account of the sky background by reducing to the chemical fog present on the calibration films received with the tube photometer as well as on the films with the areas studied. This was done by measuring on the negatives the unexposed part of the films and the sky background and accounting for the latter. Thus formula for the determination of color-indices using the tube photometer scale becomes (1), where this is a constant containing the zero-point correction deduced from the polar sequence, the correction for zenith—distance and others. The color-indices determined in this way differ little from those found by the usual method by means of the tube photometer as described in the preceding paper. Table 1 contains the color-indices of 215 extragalactic nebulae; the integral photographic magnitudes according to Shapley and Ames are given in the second column of the table; the photovisual magnitudes derived from the photographic ones by substracting our values of color-indices in the third; the color-indices in our system - in the fourth; the types of nebulae according to Shapley and Ames in the fifth one. As will be shown our color-indices do not coincide with the international ones, thus the photovisual magnitudes related to our system. For several nebulae the types were corrected according to later data. In such cases the new type is shown beside the old one, which is in brackets. November, 1944

Item Type: Article
Subjects: Q Science > QB Astronomy
Divisions: Institutes > Evgeny Kharadze Abastumani National Astrophysical Observatory
Depositing User: თამარ ჭაღიაშვილი
Date Deposited: 16 Jul 2018 10:12
Last Modified: 16 Jul 2018 10:12

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