New Reduction of Groombridge's Circumpolar Catalogue for the Epoch 1810.0 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 edition. Excerpt: ... . Omitting stars of centennial proper 11 motion 20," and all stars within 15 of the pole, we obtain the following table of mean proper motions in zones of N.P.D. for each three hours of right ascension: The large value of the mean-1"'l4 for the zone 45-52 calls for some examination. The question arises whether it is due to systematic error in the Groombridge Catalogue at this N.P.D. or whether it may be attributed to those inequalities 111 the distribution of the stars and their proper motions to which attention was drawn in the last section. At Oh this zone is very near the Milky Way, and at 12h a long way from it, and an analysis of the mean proper motions in this zone from stars whose total proper motions lie between certain limits shows the following differences: --This table shows the irregularity in the distribution of the stars of large and small proper motion. Thus, between 211' and 3h, where the solar motion gives positive motion in right ascension, the numbers of stars are 'in the ratio 77 = 16 = 7 while between 91' and 15h, where the solar motion gives negative motion in right ascension, these numbers are in the ratio 48: 23; 20. The large negative proper motions at 12h thus have very considerable effect on the mean, and tables corresponding to the one on p. xcviii. have been formed for the other zones in which the stars chosen are limited to those with proper motions of less than 10" . century and 5" century respectively. The former appears to be a sufliciently ample limit-, but the latter is probably too small. Collecting the results we find for the mean proper motions in the four zones the following differences: --Second, basing the proper motions on the...