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Photoelectric observations of band strengths in Comet Kohoutek (1973f)
IcARus 23, 630-631 (1974)
Photoelectric Observations of Band Strengths in Comet Kohoutek (1973f) M I C H A E L A. S E E D S A~D J A N E T
L. M I C H A E L
Joseph R. Grundy Observatory, Franklin and Marshall College, Lancaster, Pennsylvania 17604 R e c e i v e d M a y 20, 1974; r e v i s e d J u l y 29, 1974 P h o t o e l e c t r i c o b s e r v a t i o n s of t h e s t r e n g t h o f t h e CN b a n d a t 3 8 8 0 A a n d o f t h e C2 b a n d s a t 5165/~ a n d 5635_~ were o b t a i n e d o n e i g h t n i g h t s f r o m J a n u a r y 13, 1974 to F e b r u a r y 21, 1974. O b s e r v a t i o n s were l i m i t e d t o t h e n u c l e u s a n d i n n e r coma.
O b s e r v a t i o n s of C o m e t K o h o u t e k (1973f) were o b t a i n e d using t h e 40-cm reflector a t t h e G r u n d y O b s e r v a t o r y a n d a d r y ice cooled R C A 1P21 p h o t o m u l t i p l i e r . All o b s e r v a t i o n s were m a d e t h r o u g h a diap h r a g m of 29-secarc d i a m e t e r centered on the c o m e t nucleus. An 0 G - 5 3 0 ( 2 m m ) filter was used to a p p r o x i m a t e the V m a g n i t u d e . A U G - 2 ( 2 m m ) filter was used as a U filter a n d a U G - 2 ( l m m ) + W G - 9 ( 2 m m ) was used as an E filter to isolate the CN b a n d a t 3880A as described b y R a h e , Vans~sek a n d B r a n d t (1973). F o u r interference filters were used to isolate the C2 b a n d s a t 5165 a n d 5 6 3 5 A a n d to s a m p l e the c o n t i n u u m a t 5300 a n d 5780A. These s t a n d a r d interference filters are m a n u f a c t u r e d b y B a i r d - A t o m i c in t h e i r 100-A series. T h e filters h a v e a b a n d p a s s o f 100/k a t 5 0 % transmission. D a t a for these filters is g i v e n in T a b l e I. F i l t e r Y has b e e n t i p p e d 6.8 ° to m o v e its p e a k f r o m 5600 to 5592 A. T h e X - Z m a g n i t u d e difference is a m e a s u r e of the slope o f the c o n t i n u u m . TABLE
I
I n t e r p o l a t i o n to correct the W - X a n d Y - Z m e a s u r e s for this slope gives N 1 = ( W - X) - 0 . 4 1 7 ( X - Z), N 2 = ( Y - - Z ) - 0 . 4 1 2 ( X - - Z). T h u s N l a n d N 2 are m e a s u r e s of t h e s t r e n g t h s of the C2 features, a n d are i n d e p e n d e n t o f extinction. This s y s t e m as applied to a b s o r p t i o n f e a t u r e s in c a r b o n s t a r s has b e e n discussed b y Seeds (1972). E x t i n c t i o n was o b t a i n e d for all s e v e n filters on each night, a n d U - E, N 1 a n d N 2 were f o r m e d a f t e r corrections for e x t i n c t i o n were m a d e . O b s e r v a t i o n s o f a n u m b e r o f c o m p a r i s o n s t a r s were also o b t a i n e d a n d are listed in T a b l e I I . C o m e t o b s e r v a t i o n s are listed in T a b l e I I I . T a b l e I I I contains the Greenwich d a t e of each o b s e r v a t i o n a n d t h e geocentric a n d heliocentric distances in a s t r o n o m i c a l units b a s e d on t h e orbital solution b y M a r s d e n TABLE
II
COMPARISON OBSERVATIONS Star
U-E
NI
N2
Cet 0 Aqr And ~ Cet X Gas Pse •~ P e g y Tau
-0.339 -0.266 --0.300 --0.299 -0.33: --0.223 --0.409 --0.261
0.260 0.302 0.296 0.265 0.290 0.216 0.292 0.259
0.255 0.292 0.309 0.307 0.290 0.386 0.252 0.268
Sp. T.
CARBON BAND FILTERS Filter
Central wavelength
Feature
W X Y Z
5100A 5300 5592 5780
C2 5 1 6 5 ~ Continuum C2 5 6 3 5 A Continuum
Copyright © 1974by AcademicPress,
Inc. All rights o f reproduction in any form reserved. Printed in Great Britain
630
G5 G8 G8 G8 G8 A7 G8 K0
V III-IV IIIp II III V II-III III
BAND STRENGTHS IN COMET KOHOUTE]~ TABLE
631
III
COMET OBSERVATIONS D a t e 1974
A
r
V
U-E
N,
N2
Jan. 13.98
0.816 0.822 0.832 0.853 0.977 0.998 1.360 1.498
0.601 0.708 0.762 0.835 1.017 1.039 1.358 1.455
7.227 -8.536 8.956 10.346 9.90 : 12.131 12.52 :
0.019 0.24 : 0.06 : 0.153 0.035 0.02 : 0.228 -0.01 :
--1.713 --1.876 --1.801 --1.823 --1.700 --1.588 --1.124 --1.63 :
--0.992 --0.913 --0.892 --0.759 --0.802 --0.723 --0.508 --0.02 :
JazL Jan. Jan. Jan. Jan. Feb. Feb.
17.97 19.97 23.00 31.02 31.99 16.04 21.03
(1973). The N 1 and negative for stronger magnitude difference e m i s s i o n a n d is m o r e emission.
N 2 indices are more emission. The U - E is a measure of CN positive for stronger
REFERENCES ~ARSDEI~, B. G. (1973). C o m e t K o h o u t e k (1973f). I . A . U . Circular No. 2577.
I:~A.~E, d., VAN@SEK, V., AND BRANDT, J . C. (1973). R e p o r t o n p l a n n e d o b s e r v i n g p r o g r a m s for C o m e t K o h o u t e k (1973f). N A S A - G o d d a x d Space F l i g h t Center, G r e e n b e l t , M a r y l a n d . SEEDS, )]I. (1972). P h o t o m e t r i c o b s e r v a t i o n s o f t h e C2 b a n d s i n c a r b o n stars. I n " P r o c e e d i n g s o f t h e Conference o n R e d G i a n t S t a r s " (H. R . J o h n s o n , J . P. M u t s c h l e c n e r , a n d B. F. P e e r y , J r . , Eds.), I n d i a n a U n i v e r s i t y , B l o o m i n g t o n , I n d i a n a , pp. 192-203.
Photoelectric Observations of Band Strengths in Comet Kohoutek (1973f) M I C H A E L A. S E E D S A~D J A N E T
L. M I C H A E L
Joseph R. Grundy Observatory, Franklin and Marshall College, Lancaster, Pennsylvania 17604 R e c e i v e d M a y 20, 1974; r e v i s e d J u l y 29, 1974 P h o t o e l e c t r i c o b s e r v a t i o n s of t h e s t r e n g t h o f t h e CN b a n d a t 3 8 8 0 A a n d o f t h e C2 b a n d s a t 5165/~ a n d 5635_~ were o b t a i n e d o n e i g h t n i g h t s f r o m J a n u a r y 13, 1974 to F e b r u a r y 21, 1974. O b s e r v a t i o n s were l i m i t e d t o t h e n u c l e u s a n d i n n e r coma.
O b s e r v a t i o n s of C o m e t K o h o u t e k (1973f) were o b t a i n e d using t h e 40-cm reflector a t t h e G r u n d y O b s e r v a t o r y a n d a d r y ice cooled R C A 1P21 p h o t o m u l t i p l i e r . All o b s e r v a t i o n s were m a d e t h r o u g h a diap h r a g m of 29-secarc d i a m e t e r centered on the c o m e t nucleus. An 0 G - 5 3 0 ( 2 m m ) filter was used to a p p r o x i m a t e the V m a g n i t u d e . A U G - 2 ( 2 m m ) filter was used as a U filter a n d a U G - 2 ( l m m ) + W G - 9 ( 2 m m ) was used as an E filter to isolate the CN b a n d a t 3880A as described b y R a h e , Vans~sek a n d B r a n d t (1973). F o u r interference filters were used to isolate the C2 b a n d s a t 5165 a n d 5 6 3 5 A a n d to s a m p l e the c o n t i n u u m a t 5300 a n d 5780A. These s t a n d a r d interference filters are m a n u f a c t u r e d b y B a i r d - A t o m i c in t h e i r 100-A series. T h e filters h a v e a b a n d p a s s o f 100/k a t 5 0 % transmission. D a t a for these filters is g i v e n in T a b l e I. F i l t e r Y has b e e n t i p p e d 6.8 ° to m o v e its p e a k f r o m 5600 to 5592 A. T h e X - Z m a g n i t u d e difference is a m e a s u r e of the slope o f the c o n t i n u u m . TABLE
I
I n t e r p o l a t i o n to correct the W - X a n d Y - Z m e a s u r e s for this slope gives N 1 = ( W - X) - 0 . 4 1 7 ( X - Z), N 2 = ( Y - - Z ) - 0 . 4 1 2 ( X - - Z). T h u s N l a n d N 2 are m e a s u r e s of t h e s t r e n g t h s of the C2 features, a n d are i n d e p e n d e n t o f extinction. This s y s t e m as applied to a b s o r p t i o n f e a t u r e s in c a r b o n s t a r s has b e e n discussed b y Seeds (1972). E x t i n c t i o n was o b t a i n e d for all s e v e n filters on each night, a n d U - E, N 1 a n d N 2 were f o r m e d a f t e r corrections for e x t i n c t i o n were m a d e . O b s e r v a t i o n s o f a n u m b e r o f c o m p a r i s o n s t a r s were also o b t a i n e d a n d are listed in T a b l e I I . C o m e t o b s e r v a t i o n s are listed in T a b l e I I I . T a b l e I I I contains the Greenwich d a t e of each o b s e r v a t i o n a n d t h e geocentric a n d heliocentric distances in a s t r o n o m i c a l units b a s e d on t h e orbital solution b y M a r s d e n TABLE
II
COMPARISON OBSERVATIONS Star
U-E
NI
N2
Cet 0 Aqr And ~ Cet X Gas Pse •~ P e g y Tau
-0.339 -0.266 --0.300 --0.299 -0.33: --0.223 --0.409 --0.261
0.260 0.302 0.296 0.265 0.290 0.216 0.292 0.259
0.255 0.292 0.309 0.307 0.290 0.386 0.252 0.268
Sp. T.
CARBON BAND FILTERS Filter
Central wavelength
Feature
W X Y Z
5100A 5300 5592 5780
C2 5 1 6 5 ~ Continuum C2 5 6 3 5 A Continuum
Copyright © 1974by AcademicPress,
Inc. All rights o f reproduction in any form reserved. Printed in Great Britain
630
G5 G8 G8 G8 G8 A7 G8 K0
V III-IV IIIp II III V II-III III
BAND STRENGTHS IN COMET KOHOUTE]~ TABLE
631
III
COMET OBSERVATIONS D a t e 1974
A
r
V
U-E
N,
N2
Jan. 13.98
0.816 0.822 0.832 0.853 0.977 0.998 1.360 1.498
0.601 0.708 0.762 0.835 1.017 1.039 1.358 1.455
7.227 -8.536 8.956 10.346 9.90 : 12.131 12.52 :
0.019 0.24 : 0.06 : 0.153 0.035 0.02 : 0.228 -0.01 :
--1.713 --1.876 --1.801 --1.823 --1.700 --1.588 --1.124 --1.63 :
--0.992 --0.913 --0.892 --0.759 --0.802 --0.723 --0.508 --0.02 :
JazL Jan. Jan. Jan. Jan. Feb. Feb.
17.97 19.97 23.00 31.02 31.99 16.04 21.03
(1973). The N 1 and negative for stronger magnitude difference e m i s s i o n a n d is m o r e emission.
N 2 indices are more emission. The U - E is a measure of CN positive for stronger
REFERENCES ~ARSDEI~, B. G. (1973). C o m e t K o h o u t e k (1973f). I . A . U . Circular No. 2577.
I:~A.~E, d., VAN@SEK, V., AND BRANDT, J . C. (1973). R e p o r t o n p l a n n e d o b s e r v i n g p r o g r a m s for C o m e t K o h o u t e k (1973f). N A S A - G o d d a x d Space F l i g h t Center, G r e e n b e l t , M a r y l a n d . SEEDS, )]I. (1972). P h o t o m e t r i c o b s e r v a t i o n s o f t h e C2 b a n d s i n c a r b o n stars. I n " P r o c e e d i n g s o f t h e Conference o n R e d G i a n t S t a r s " (H. R . J o h n s o n , J . P. M u t s c h l e c n e r , a n d B. F. P e e r y , J r . , Eds.), I n d i a n a U n i v e r s i t y , B l o o m i n g t o n , I n d i a n a , pp. 192-203.