Tables 541-542. 

 ASTRONOMICAL DATA- 

 TABLE 541. — The First-magnitude Stars. 



415 



No. 



Star. 



Achemar 



Aldebaran J. . . . 



Capella ft 



Rigel *t 



Betelgeuse t § • • 



Canopus 



Sirius* 



Procyon * 



PoUux§ 



Regulus t- .... . 



a Crucis * 



/3 Crucis t 



Spica t 



j3 Centauri t . . . 



Arcturus 



a Centauri * 



Antares 1 1 • • . ■ 



Vega § 



Altair§ 



Deneb § 



Fomalhaut 



R.A. 



igoo. 



I* 34.0™ 

 4 30.2 

 9-3 

 9-7 

 49.8 

 21. 7 

 40.7 

 34- 1 

 39-2 

 3 



10 



12 21.0 

 12 41.9 

 19.9 

 S6.8 

 II. I 

 32.8 

 23-3 

 33-6 

 45-9 

 38.0 



52.1 



Dec. 

 1900. 



-57° 4S' 



+16 18 



+45 54 



-8 19 



+7 23 



-52 38 



-16 35 



+5 29 



+28 16 



-i-12 27 



—62 33 



-59 9 



-10 38 



-59 53 



+ 19 42 



-60 25 



— 26 13 



+38 41 



+8 36 



+44 55 



-30 9 



Annual 

 proper 

 motion, 



0.094 

 0.203 

 0.437 



O.OOI 



0.029 

 0.018 

 1. 316 

 1.242 

 0.62s 

 0.247 



0.048 

 0.056 

 0.055 



0.041 



2. 282 



3 680 



0.034 

 0.346 

 0.655 



O.OOI 



0.365 



P.A. 

 of 

 1^ 



108° 

 160 

 168 

 135 

 74 

 56 

 204 

 214 

 264 

 269 

 240 

 240 

 229 

 219 

 209 

 281 

 192 

 36 

 54 

 180 

 117 



Parallax. 



+0.051" 



+0 . 062 



+0.07S 



+0.007 



+0.019 



+0.007 



+0.376 



+0.309 



+0.064 



+0.033 



+0.047 



+0.008 



—0.012 



+0.037 



+0.075 



+0.759 



+0.029 



+0.091 



+0.214 



+0.002 



+0.138 



Abs. 

 mag. 



—0.9 



—0.0 

 -0.5 

 -5-5 

 -2.7 

 -6.7 

 +1.2 

 +30 

 +0.2 

 — i.i 

 -0.5 

 -4.0 



-1.3 

 -o.S 

 +4.7 

 -1.5 

 —0.1 

 +2.5 

 -7.2 

 +2.0 



Radial 



velocity 



km. 



+55 



+30 



+22 



+21 



+ 20 



-7 



-3 



+3 



-9 



+7 



+13 



+1 



-7 



-3 



— 21 



-3 



-13 



-33 



—4 



+6 



* Visual binary. t Spectroscopic binary, t Pair with common proper motion. 



§ Wide pair probably optical. 



Mass relative to sun of (7) is 3.1; of (8), 1.5; of (16), 2.0. For description of types, see Table 534 or Annals of 

 Harvard College Observatory, 28, p. 146, or more concisely 56, p. 66, and 91, p. 5. The light ratio between successive 

 stellar magnitudes is y/ioo or the number whose logarithm is 0.4000, viz., 2.512. The absolute magnitude of a star 

 is its magnitude reduced to a distance corresponding to 0.1" parallax. 



TASLE 542. — Wolfs Observed Sun-spot Numbers. Annual Means. 



Sun-spot number = /^(ro X number of groups and single spots observed + total number of spots in groups and 

 single spots), k depends on condition of observation and telescope, equaling unity for Wolf with 3-in. telescope and 

 power of 64. Wolf's numbers are closely proportional to spotted area on sun. 100 corresponds to about 1/500 of 

 visible disk covered (umbras and penumbras). Periodicity: mean, 11.13, extremes, 7.3 and 17.1 years. Monthly 

 Weather Review, 30, p. 171, 1902; monthly means, revised, 1749-1901; see A. Wolfer in Astronomische Mitteilungen 

 and Zeitschrift fiir Meteorologie, daily and monthly values. 



Note: The sun's apparent magnitude is — 26.5, sending the earth 90,000,000,000 times as much light as the star 

 Aldebaran. Its absolute magnitude is +4.8. 



Ratio of total radiation of sun to that of moon about 100 000 to i 

 " " " " " 400,000 to 



light 



1 1 Langley 



Smithsonian Tables. 



