GroRE — On Known Variable Stars. 193 



129. a Heeculis. — Yery irregular, and, according to Schonield, 

 often scarcely perceptibly variable. The period, according to Arge- 

 lander, varies from 26 to 103 days ; according to Baxendell, up to 111 

 days; according to Heis, 184"9 days, with 2 maxima and 2 minima. 

 Westphal, in 1817, thought that the observations might be represented 

 by even a period of 7 days. 



Schmidt observed Maxima in 1882, February 20, June 24, and 

 September 19 ; and Minima, 1882, April 7, August 6, and ]!^ovember 3. 



130. TJ Ophitjcii. — Discovered by E. !F. Sawyer, in 1881, to be a 

 variable of the type of Algol. It is D M 1°, 3408, and Lalande 

 31384. The period was at first supposed to be 5'^ 5^ 38'"'6, but was 

 afterwards found by S. C. Chandler to be only 20*" 7™ 4P-6, being the 

 shortest per^d known. It remains at its maximum brightness (6-0 

 or 6"1) for 16 hours ; and all the variations from maximum to mini- 

 mum, and back again to maximum, are accomplished in about four 

 hours. Schjellerup, in his Catalogue (Copenhagen : 1864), already 

 pointed out its probable variability; and he estimated it 7*7 in a clear 

 sky, 1863, June 9. The magnitudes given by other observers are 

 very discordant ; and variation of magnitude from 6'0 to 6"5 were 

 observed in 1871 by Davis at Cordoba. 



131. u (68 Fl.) Heeculis. — Eegularly observed by Schmidt since 

 1869. Period, according to Schtinfeld, 37 to 40 days, with numerous 

 anomalies, especially at the minimum, when fluctuations of a few steps 

 take place in periods of 24 to 26 hours, and last about 3 days. Schmidt 

 gives extremes of 4 m. and 6 m. ; but these are seldom reached. 



132. Nova OpHrucn. — Kepler's great new star, which suddenly 

 blazed out in October, 1604. "When first seen it was white, and 

 exceeded in brilliancy Mars, Jupiter, and was even thought to rival 

 Venus in splendour ! It gradually diminished, and in six months was 

 not equal in lustre to Saturn. In March, 1606, it had entirely dis- 

 appeared. The position given is that deduced by Schonfeld from the 

 observations of David Fabricius. There does not, however, seem to be 

 the same amount of certainty with reference to its exact position as 

 in the case of Tycho Brahe's star in Cassiopeise. The nearest star is 

 one of 12 m., a little sf. Chacornac, however, in 1861, mapped a star 

 of 10 m. about 2' preceding the spot. This star would seem to have 

 since disappeared, as it was missed by some observers in 1871 and 1872. 

 Winnecke, however, observed, in 1875 a 12 m. star very near the place 

 occupied by Chacornac's star. It has been stated that no star was dis- 

 cernible in this position, with 7 inches aperture, on several occasions in 

 1872-74. It would, therefore, appear that a variable star exists close 

 to the place of the Nova ; and its variability is, of course, evidence in 

 favour of its identity with Kepler's star. About 6' following the 

 calculated position of the Nova is a 8"9m. star — Oeltzen, 16872. This 

 star is again followed by two fainter stars, forming with it a rough 

 isosceles triangle. 



