Interferometry observations from 90-in. and 61-in. telescopes tracking the Comet Kohoutek are summarized. Laboratory reflection studies of ices potentially useful for future cometary work were conducted. The frosts studied included: H2O, CO2 NH3, H2S, CH4, NH4HS, and ammonia polysulfide. The frost spectra show remarkable changes with the temperatures, particularly in the case of hydrogen sulfide. Additional analysis found the variation in the H2S ice spectrum to be due to a phase change from a low temperature tetragonal unit cube to a higher temperature face-centered cubic structure. The spectra data indicate that if frost spectra are required for comparison with observed cometary or planetary absorption, the temperature of the frost must be matched

Fink, U.

English

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Produced by the NASA Center for Aerospace Information (CASI) 
https://ntrs.nasa.gov/search.jsp?R=19750016525 2020-03-22T22:03:39+00:00Z
Lunar and Planetary Laboratory
University of Arizona
Tucson, Arizona 85721
Final Report
NASA Grant NGR 03-002-392
Infrared Spectroscopy of Comet Kohoutek
Gv' C"^9 ^v
2
Submitted May 15, 1975
ryAn,
Pa
Uwe Fink
Principal Investigator
(NASA-CR-142809) INFRARED SPECTROSCOPY OF
COMET KOHOUTEK Final Report (firizona Univ.,
Tucson.) 14 p HC $3.25 	 CSCL 03A
N75-24597
Unclas	 11
G3/89	 21803	 1,41
NSur°nary
This grant was obtained to make infrared spectral observations of Comet
Kohoutek during its apparition in Dec. 1973-Jan 1974. Unfortunately, due to
the faintness of the comet, a factor of one hundred or so below the predic-
tions, and the inclement weather in Tucson during the time of its brightest
intensity, we were not able to obtain any spectra of the comet. A list of
attempted observations is given in Table I.
We therefore asked in a letter to Dr. Steve Maran (see Appendix 1)
whether we could use the money that wea not spent on the comet work to do
laboratory reflection studies of ices that could be useful in future cometary
work. This request was granted in a letter of April 8, 1974 by Genevieve ;t
Wiseman (Appendix 2). All the laboratory work on the ices has been completed,
but the computer reduction and analysis is not quite complete. However, since
the final report on this grant is now overdue, vie are presenting the data that
was obtained. We are planning two publications from this work:
Near infrared spectra and analysis of H S frost as a function of
temperature - John R. Ferraro and Uwe F?nk
Infrared laboratory spectra of frosts for comparison with planetary
observations - Utve Fi.K, J. R. Ferraro, H. P. Larson, N. Gautier,
and W. Wisniewski.
The results of our ice analysis that have been reduced are described
further below, and the spectra are shown in the Appendix.
I. Comet Kohoutek observations
The observations attempted for Comet Kohoutek are listed in Table I.
Unfortunately before perihelion we simply could not track the comet into
daytime. During our effort at the 90", Dec 15-18, we picked the comet up
every morning but could not track it more than half,an hour into dawn. With
M
our broad bandpass of about 100-50Q cps, which is necessary for our inter-
ferometer, we could not detect a signal.
3
We were hoping that during our run from Dec 21 to Dec 24 at the 60"
the comet's brightness would improve sufficiently that we could track it.
The morning of Dec. 22 was especially quite clear with good seeing and we
could pick up 5th magnitude stars routinely during the daytime, but we could
not find the comet,	 A search for the comet by means of its signal was ser-
iously hampered by a large signal from scattered sunlight, since by nov/ the
comet was quite close to the sun.
Conditions after perihelion should have been much more favorable with
the comet somewhat brighter, higher in the sky and farther from the sun.
For this reason we scheduled two interferometers on two telescopes: 	 the
Block interferometer at the Steward Observatory 90" telescope and the Idea-
lab interferometer at the LPL 61" 	 telescope. Unfortunately three successive
winter storms moved in, and it was cloudy during all of our scheduled tele-
scope time to about Jan 10th.
We feel that if the weather had been favorable after perihelion we
would have stood a good chance of getting some data. 	 Since the intensity
of the comet was far below predictions, our observing window, during which
we felt we could get reasonable data, was narrowed down to a short time
G
period around perihelion and conditions were simply not in our favor, even
though we had spent all of December and a good part of January solely on
the comet.
ii
II.	 Laboratory frost observations
The frosts that were studied in the laboratory were: H 2O, CO 25 MH30 H2 S,
CH4 , MH4HS and ammonia polysulfide. 	 Spectra of all these frosts except the y
last two have been reduced, and are shown in the figures. 	 All the spectra show ry
remarkable changes with the temperatures that can be seen in the figures.
It is quite clear from these data that if frost spectra are required for
-3-
comparison with observed cometary or planetary absorption, the temperature 	 ^.
of the frost must be matched. Conversely if these frosts are detected, their
temperature dependence can be used to determine the ice temperature of the
frost responsible for the absorptions. Since the frost data described above
are not available from the literature, we plan to publish these shortly,
as mentioned in the Summary, as soon as the last two frosts are reduced.
Hydrogen sulfide frost changed its appearance so drastically between
113.9
 K and 1250
 K that a special effort for its anal.vsis was undertaken.
This was carried out mainly by Dr. John R.Ferraro, a distinguished visit-
Ing scientist from the Argonne National Laboratory. We found that the change
in the ice's spectrum is due to a phase change from a low temperature
tetragonal unit cube to a higher temperature face centered cubic structure.
Table II shows the selection rules for the internal and external
modes of the low temperature phase (phase III). Table III summarizes the
selection rules and compares them with experimental results. With the
assignment of the combination bands made in this study, the first complete
vibrational assignment that has been made for phase III of H 2S including
the near, mid, and far infrared regions, has become possible.
L
-1.0
-1.7
-1.2
-1.2
-0.7
-0.3
0.1
1973 Dec. 24	 Block IF 61"
1974 Jan. 1	 Idealab IF 61"
Block IF 90"
1974 Jan. 2	 Idealab IF 61"
Block	 IF 90"
1974 Jan.	 3 Idealab IF 61"
Block	 IF 61"
1974 Jan.
	
4 Idealab IF	 61"
Block	 IF 90"
1974 Jan.	 5 Idealab IF 61"
Block	 IF 90"
3.0	 cloudy
	
2.3	 top of Mtn. was in clouds.
	
2.8	 high winds, could not open
telescope
	
2.8	 cloudy
n
	
3.3	 see.note d
top of Mtn. was in cloud;
	
3.7	 cloudy
cloudy
	
4.6	 cloudy
cloudy
a
TableiI
i
Summary Comet Kohoutek Observations -- Interferometey
bPredicted
ca
InterFerometer r Total Nuclear
MST Date Telescope used Magnitude Magnitude Comments
1973 Dec. 15 Idealab	 IF 90" 2.5 6.5 615 dawn, 630 found comet and
1973 Dec. 16 it" 2,2 6.2
start telescope drive (7° above
horizon), 700	 los" comet	 in sky,;
1973 Dec. 17 " 1.9 5.9 720 sunrise.	 Did not see a
1973 Dec 18 „ 1.6 5.6
signal	 from the interferometer.
1973 Dec. 21 Idealab	 IF 61" 0.5 11.5 could not find comet in daytime
1973 Dec. 22
sky,	 either by eye or by signal;'''
could find 5th magnitude stars
routinely
Notes:	 (a)	 61" -- 61" LPL telescope in the Catalina Mtns., Tucson, Ariz.
90'' -- 90" Steward Observatory telescope on Kitt Peak, Ariz.
(b) Total predicted magnitude taken from ephemeris by D. K.
Yeomans. His weaker estimates,which seemed to be close
but still a little too bright, were used.
(c) Nuclear magnitude estimated by subtracting 1; magnitudes
from table.
(d) Jan. 3 partially cloudy till noon. Then tclesc o pe could
not be o ened because of dripping water from dome. From
about 308 it was clear but night assistant was scheduled
to work only till 4 o'clock and refused to work thereafter.
Saw comet with the naked eye after sunset and using
binoculars by comparison with nearby B Cap estimated nuclear
magnitude to be about -1-11.0.
(vl'lV2rv3)
(vlrV2rv3)
:Vlrv2rV3)(v1'v21v3)
(vlrv2rv3)
---(vlrV2'V3)
Modes
TrR
3.3
3,3
3,3
313
	
3,3	
,Irk
(Tx ,Ty )	 3,3
AR
C 4
(T Z)
Table I1. Selection rules for solid H 2 S (Phase III) using the
correlation method.
Internal Modes
C 2
	 Cl	 C4h
(Point Symmetry)	 (Site Symmetry)	 Factor. Group)
8 vlrv3 Al
A2
B	 24A
8 v 2
	A2
External Modes
Degs, of Freedom	 Cl
(T/R)
(24,24)
	
A(Tx,Ty1T2)
(Rx,RyrRz)
ORIGINAL PAGE LS
OP POOR QUALPPY
Table III. Comparison of predicted and experimental results for
solid II2S (Phase III) .
Predicted Results Based	 Internal Fundamental	 External
on a C 4 Factor Group
	 Modes	 Modes
V l	 V2	 v3	 T1 R
r
w
IR
	 2
	 2
	 2	 A	 6
R
	 3	 3	 3	 9	 9
--------------------
Experimental Results	 V1;V2
	
V3
	 T	 R
IR
	 3	 2	 9	 5
R
	 6	 2	 5	 6	 {
Abbreviations: IR = infrared; R = Raman, T = translation; R =
rotation.
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V
THE UNIVERSITY OF ARIZONA
TUCSON, ARIZONA S 721
LUNAR AND PLANETARY LAwRAToitY
February 19, 1974
Dr. Steve Maran
Code 683
Goddard Space Flight•
 Center
Greenbelt, MD 20771
Dear Steve:
Now that the comet has faded away I want to tell you that
despite our every effort we were not able to obtain a spectrum
of the comet in the near infrared. There were two major reasons
for this: the lack of intensity and the bad weather in Tucson
after perihelion. We list the telescope time which vie tied scheduled,
and during which we ob rzrved the cornet, in Table 1:.
Before perihelion we simply could not track the comet inW
time. During our effort at the 90", Dec. 15-Dec. 18, we pi<s!ted
the comet up every morning but could not track it more than half-
an hour into dawn. With our broad bandpass of about 100-500 cps,
which is necessary for our interferometer operation, we could not
detect a signal.
We were hoping that during our run from Dec. 21 to Dec. 211
at the 60" the comet's brightness would improve sufficiently that
we could track it. Especially the moring of Dec. 22 was quite clear
with good seeing and we could pick up 5th magnitude stars routinely
during the daytime, but we could not find the comet. A search fur
the comet by means of its signal was seriously hampered by a large
signal from scattered sunlight, since by now the comet was quite
close to the sun.
We knew that conditions after perihelion would be much more
favorable. The comet should be somewhat brighter, higher up in
the sky and farther from the sun. For this reason we scheduled
two interferometers on two telescopes. The Block interferometer
at the Steward observatory 90" telescope and the Idea-lab interfero-
meter at the LPL 61" telescope. Unfortunately three successive
winter storms moved in, and it was cloudy during all of our
scheduled telescope time to about Jan. l0th.
I feel that if the weather had been favorable after perihelion
we would have stood a good chance of getting some data. Since the
r
Dr. Steve Maran
Pale 2
February 19, 19711
intensity of the comet was for below predictions, our observing
window, during which we felt are could get reasonable data, was
narrowed down 10 a short time period around perihelion and condi -
tions were simply not in our favor. We are very disappointed,
especially sine we had worked quite hard, and had spent all of
December and a good part of January solely on the comet. In
addition we were out at NASA Ames at the end of November to install
the Idealab interferometer aboard the NASA C1 111 in anticipation
of any possible flights for the comet.
want to ask your permission to use the money that was not
used up in the study of the comet for laboratory ice spectra.
This work should be quite appropriate for cometary studies and
will be needed for the interpretation of any future spectra. We
wish to run CHl t , iIH 3 and H 2O ices in reflection as a function of
temperature, and possibly In transmission. Dr. John Ferraro, a
distingttished visiting scientist from Argonne National laboratory,
will be helping me on that p.oject.	 "
I hope this will meet with your approval; if not, please
let me know.
With best regards,
Uwe Fink
I 0
Ge"CIMAL PAG>; IS^ i o 
I'G()R QUALI".I*y


Infrared spectroscopy of Comet Kohoutek

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