# Annals of the Astronomical Observatory of Harvard College, Volume 9

Hetcalf and Company, 1878 - Astronomy - 181 pages

### What people are saying -Write a review

We haven't found any reviews in the usual places.

### Contents

 Section 1 5 Section 2 20 Section 3 21 Section 4 22 Section 5 23 Section 6 24 Section 7 25
 Section 8 56 Section 9 70 Section 10 88 Section 11 103 Section 12 138 Section 13 159

### Popular passages

Page 9 - Suppose that neither of two observers made any errors in his estimations and that their discrepancies arose solely from the differences of their scales of magnitudes. Then if they observed the same stars, whichever had fewer stars brighter than the 4th magnitude, for example, would have made the limit between his third and fourth magnitudes the brighter. In fact we might call these numbers a scale of magnitudes. If there were 175 stars brighter than the fourth magnitude we might say that the limit...
Page 105 - ... of a magnitude, so that we might be provided with stars at all times at every altitude with which to compare others in forming a new uranography. The plan was to observe 368 stars, but others sufficiently bright being noticed, about one hundred more have actually been measured. The stars proposed to be observed were divided into seventy groups each consisting of neighboring stars, these groups lying in two zones, and so that the boundary between two adjacent groups of either zone should have...
Page 9 - Then for the scale of equable distribution the numerical magnitude being m we have m = — 1 + 1.892958 log v (m) . In this way we shall obtain the magnitudes upon the scale of equable distribution of the limits of each class in the scales of the different observers. But we want the mean magnitude upon the our scale of the stars of each of these classes. For this purpose we may use the formula * My aid, Mr. Henry Tarquhar. has suggested this term.
Page 105 - The design of the observations was to obtain the magnitudes of all the stars in Argelander's Uranometria between 40° and 50° of North declination...
Page 142 - ... Argelander makes this star 5.8, and the DM., 4.4. Wm. Herschel makes it 0.2 fainter than o; Argelander, 0.9 fainter; Heis, equal; the DM., 0.3 fainter; and I, 0.3 fainter. 1876, Apr. 8, I find it but little than o. 53. ß Persei. This variable was always observed near its maximum. 88. 121 ip Persei. The absence of this star from the Uranometria, and the great difference between the magnitude assigned to it by Heis and me (5.8) and that of the Durchmusterung (7.7) certainly creates a suspicion...
Page 177 - In fact, a single glance at the heavens is sufficient to show that the stars are not uniformly distributed throughout space, but that there is a great concentration in the plane of the milky way.
Page 142 - I find jn > \|/ > 0. The star is orange. 201. 65 Ursae majoris. I have rejected this star from the mean of its group, not because I think it variable but because its near companion makes accordant measures very difficult to obtain. 218. 9 Canum venaticorum. The magnitudes of Argelander and Heis differ very much from that of the DM., and my measures are discordant. But I have excluded the star from the group, not so much on suspicion of variability, as because I do not feel sure that I always observed...
Page 172 - It will be seen that the results both for Zöllner and for me present great discrepancies. These are undoubtedly owing to faulty reductions of the scales, and must, I think, be ultimately ascribed to the fact that the scale of equable distribution of Chapter II is not an equiphotometric scale.
Page 9 - ... we assume that in that observer's mental subdivision of the second the fifth part was twice as long an interval as the fourth. We may extend the same idea to the comparison of scales of star-magnitudes. If one observer says there are 9 first magnitude stars in the northern heavens and another finds only 8 , clearly the latter consigns some star to the 2°d magnitude which the other considers to be of the 1st, and therefore he makes the limit between the first and second magnitudes to be brighter...
Page 91 - ... stars appear relatively brighter on fine, clear nights. If we could keep our artificial star constant in color and could easily modify the color in a known way, all difficulty in comparing stars of different color could be overcome. But since this cannot be done, and since the error in the immediate comparison of light of different colors is not great, I should prefer, in constructing a photometer, to leave the artificial star fixed in brightness and only alter the light of the real star.