Our Astronomical Column

Abstract

VARIABLE STARS.—Of the three stars to which Col. Tennant draws attention as being probably variable (“Monthly Notices R.A.S.,” June 1875), B.A.C. 740 appears more especially deserving of regular observation. The B.A.C. has adopted the magnitude assigned by Groombridge, 6; other estimates are:—Hevelius, 6; Fedorenko (Lalande, 1789 November), 8; Piazzi, 8, by seven observations; Schwerd, 81/2 Taylor, in 1834 or 1835, in vol. iii. of “Madras Observations,” 7 (he calls the star 21 Cephei); Carrington, 8.1; the Radcliffe Catalogues, 7.5; and Durchmusterung, 8.4. With regard to the observation of Hevelius, which has been assumed to refer to this star, it may be remarked that the position given in his Catalogue for 1660, where it is No. 46 in Cepheus, does not well agree with the place of the Redhill Catalogue for B.A.C. 740, the difference of position amounting to 16′; nevertheless it is not easy to identify the star observed by Hevelius with any other in the modern catalogues. In the cases of the stars B.A.C. 4166 and 4193, also noticed by Col. Tennant, the estimates of magnitude from the epoch of Schwerd's observations to the present time appear pretty accordant. [In comparing the magnitudes assigned in different catalogues to the naked-eye stars it is necessary to bear in mind that in Argelander's Uranometria, and in Heis and Behrmann, 6.5, 5.4, &c., apply to stars which are judged to be somewhat brighter than an average sixth or fifth magnitude, and are not to be understood decimally, as is the case in the “Durchmusterung.”]