THE FACE OF THE SKY FOR SEPTEMBER. 



By A. C. D. CROMMELIN, B.A., D.Sc, F.R.A.S. 



Table 52. 



Date. 



Greenwich 



Sept. 



Sun. 

 R.A. Dec. 



h. m. 

 1043-9 

 11 1*9 

 11 199 



11 37-9 



11 55-8 



12 13-8 



N.8'1 



6-2 



4'3 



2 '4 



N.o-s 



S.,-5 



Moon. 

 R.A. Dec. 



h. m. 



12 8-5 S. i-8 

 16 46-4 S. 27*6 

 21 18*5 S. 19*1 



° 53'4 N - 7'3 

 4 59*2 N.28'0 

 9 55'2 N.i 5 - 4 



Mercury. 

 R.A. Dec. 



9 56*5 N.i4"i 



10 33 'o u*o 



11 8-8 7-4 

 [i 43-0 N.3's 



12 15-3 S.o-5 

 12 45*0 S.4'3 



Venus. 

 R.A. Dec. 



h. m. <, 



S 13*6 N. 19*4 



8 38-0 18-3 



9 2'2 17*0 



9 26*1 15-5 

 9 49-9 13-8 

 10 13*4 N.i 1 '9 



Mars. 

 R.A. Dec. 



5 26'9 N.22"9 



5 39-7 23-1 



5 5">*i 23-3 



6 4'3 2 3'4 

 6 i6'o 23*5 

 6 27-3 23-5 



Jupiter. 

 R.A. Dec. 



h. m. 



8 34-9 S.23'4 



8 35-0 23-4 



8 35'4 2 3"4 



8 3°'i 2 3'4 



8 37'i 2 3"4 



8 38-5 S-23-4 



Saturn. 

 R.A. Dec. 



6"! N.21'2 



7't 2I'2 



7'9 2I"2 

 8'5 21-2 



8'9 21*2 

 9*2 N.2I*2 



Uranus. 

 R.A. Dec. 



h. m. 

 20 27 '1 

 20 26'5 

 20 26 'o 

 20 25*5 

 20 25' 



S.19'8 

 19-9 

 I9'9 

 19-9 

 19-9 



20 24*8 S.19'9 



Table 53. 



P is the position angle of the North end of the body's axis measured eastward from the North Point of the disc. B, L 

 are the helio-(planeto-)graphical latitude and longitude of the centre of the disc. In the case of Mars, T is the time of 

 passage of Fastigium Aryn across the centre of the disc. In the case of Jupiter, L t refers to the equatorial zone; L a to 

 the temperate zone; T lf T 2 are the times of passage of the two zero meridians across the centre of the disc ; to find inter 



mediate passages apply multiples of 9 h 50£ m , 9 h 55l m respectively. 



The letters to, e, stand for morning, evening. The day is taken as beginning at midnight. 



The asterisk indicates the day following that given in the date column. 



The Sun continues his Southward march with accelerated 

 speed. The equinox is passed 23 d 3 h 53 m e. Sunrise during 

 August changes from 5.13 to 5.59, sunset from 6.48 to 5.41. 

 Its semi-diameter increases from 15' 53" to 16' 0". Outbreaks 

 of spots in high latitudes should be watched for. 



Mercury is in Superior Conjunction 16 d 3 h e ; before that 

 it is a morning star. Illumination increases from A to Full. 

 Semi-diameter diminishes from 3" to 2i". 



Venus is a morning star, rising 3 hours before the Sun. 

 Semi-diameter diminishes from 7" to 6". At beginning of 

 month J of disc is illuminated; at end of month §. Being 

 North of Sun it is favourably placed for Northern observers. 



The Moon.— First Quarter 7 d l h 6 m e ; Full 15 d h 46 m e ; 

 Last Quarter 23 d h 30 m e. New 30 d 4 h 57 m m. Perigee 

 l d 7 h in, semi-diameter 16' 44". Apogee 15 d Noon, semi- 

 diameter 14' 44". Perigee 29 d 6 h e, semi-diameter 16' 44". 

 Maximum Librations, 7 d 8° W, 8 d 7° N., 23 d 7° E., 

 23 d 7° S. The letters indicate the region of the Moon's 

 limb brought into view by libration. E. VV. are with 

 reference to our sky, not as they would appear to an 

 observer on the Moon. 



Eclipses. — A small partial eclipse of the Sun, invisible in 

 Europe, occurs on August 31st, lasting from 8 h 2 m e to 

 9 h 42 m e ; greatest magnitude 0*15. Visible in Newfoundland, 

 Labrador, Greenland. 



A total eclipse of the Moon, invisible in Europe, occurs on 

 September 15th, lasting from 10" 53 m w to 2 h 44 m e. Visible 

 over Pacific Ocean, Australia, New Zealand, and so on. 



A partial eclipse of the Sun, invisible in Europe, occurs on 

 September 30th, lasting from 2 h 56 m m to 6 h 36 m m ; greatest 



magnitude 0*83. Visible in South Africa, Madagascar, 

 Mauritius, and South Indian Ocean. 



Mars is a morning Star, semi-diameter 4", defect of 

 illumination nearly a second. It will reach Opposition 

 early in January, so the season of observation is 

 commencing. The Earth is in the plane of Mars' Equator 

 on September 6th ; both poles are then on the edge of the 

 disc. 



Juno is in opposition September 14th, magnitude 7*6. 

 Ephemeris for midnight : — 



R.A. S.Dec. 



Sept. 



Saturn is a morning star, coming into a better position for 

 observation. Polar semi-diameter 8 i". P. is — 4°*9; ring 

 major axis 43J", minor 194". The ring is very widely open. 

 It is of interest to examine the exact amount of overlap 

 beyond the planet's pole. 



East Elongations of Tethys (every fourth given), 3 d 4 h -9e, 

 ll d 6 h -lw, 18 d 7 h -4e, 26 d 8 h -6m; Dione (every third given), 

 6 d ll h - le, 15 d 4 h -2TO, 23 d 9 h -3»» ; Rhea (every second given), 

 2 d 4 h -8-n, ll d 5 h -7m,20 d 6 h -6w, 29 d 7 h -5m. For Titan and 

 Iapetus E.W. mean East and West Elongations; I. Inferior 

 (North) Conjunctions, S. Superior (South) ones. Titan, 3 d 

 5 h -7e W., 7 d 5 h -2e S. ; ll d 8 h -4e E., 15 d 8 h -4e I., 19 d 4 h *9 d 

 W., 23 d 4 h -3e S., 27 d 7 b -4e E. ; Iapetu , 9* 5 h -3w S., 29e 

 6 h -0e E. 



Uranus was in opposition on July 29th. Semi-diameter, 

 13". At end of August, 2° S.E. of p Capricorni. 



303 



