NOTES ON PLATES OF NOVA GEMINORUM OF 1912 



TAKEN WITH THE BRUCE SPECTROGRAPH 



OF THE YERKES OBSERVATORY. 



By STORRS B. BARRETT. 

 {Read April 20, 1912.) 



ipi2, March 15. Displacement of sharp H and K lines indicates 

 a velocity of 17 km. recession. This velocity does not differ greatly 

 in all the photographs. Many titanium lines are represented by 

 absorption lines displaced about 7 A. toward the violet. The relative 

 brightness of the emission components of the hydrogen lines /?, 7, 8, 

 as compared with the continuous spectrum is less than in all subse- 

 quent plates. 



March 21. The centers of the bright bands are now 2 A. toward 

 the red, as compared with 10 A. on March 15. Note the sharp 

 bright line at A 4,526. A second absorption band now accompanies 

 each bright band. 



March 24. Shows marked increase in intensity of the second 

 absorption band for each hydrogen line. 



March 2p. Two bright maxima may be seen near the red edge of 

 the bright H8 band. They are also present in He. A similar line 

 near the beginning of the bands is more difficult to see on the print. 



March ^0. There are two conspicuous bright maxima near the 

 beginning of the bright Hy band and one or two near the red edge. 

 On a short-exposure plate of April i three conspicuous maxima 

 are seen near the red edge of /3, y and 8. 



April I and 2. The hydrogen bands are concentrating their 

 intensity toward the red edge. Note that there are two bright super- 

 posed bands for each hydrogen line, one much longer and fainter 

 than the other. This is first indicated plainly on March 29. The 

 broad bright band at A 4,640 has been gradually gathering intensity. 



Yerkes Observatory, 



Williams Bay, Wis., 

 April i8tli, 1912. 



568 



