The results of raw data tapes on lunar motion recorded at McDonald Observatory from January 1 through June 30, 1975 are presented. The direct use of laser pulse shape information in the filtering of return photon data is suggested, together with an extensive revision of the environment record. The absence of archive parameters, including clock epoch offset, atmospheric seeing, and shot-by-shot resolution is noted. Programming problems involving photoelectric occultation observations are also examined

Mulholland, J. D.

English

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https://ntrs.nasa.gov/search.jsp?R=19750019908 2020-03-22T20:08:47+00:00Z
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THE UNIVERSITY OF TEXAS AT AUSTIN
(NASA-CR-143175)	 LUNAR MOTION ANALYSIS 	 N75-279BG
Semiannual Status Report, 1 Jan. - 30 Jun.
1975 (ricDonald Observatory, Austin, Tex.)
7 p K' $3. 25 	CSCL 03A	 Uncles
63/89 29799
DEPARTMENT OF ASTRONOMY
	
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McDON ALD OBSERN'ATOBY
Austin, Texas 78712
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Semi-Annual Status Report
NASA Grant NGR 44-012-219
(Lunar Motion Analysis)
for the period 1975 January 1 - June 30
University of Texas at Austin
Department of Astronomy
Austin, Texas 78712
1975 July
Derral lho and
Principal Investigator
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9.8
12.3
7.9
7.8
10.1
20.7
14.2
Data Management`
The processing of raw data tapes from McDonald Observatory
continued throughout the report period. The results were as follows:
TAPE ID LUNATION PHOTONS OBSERVATIONS
MCD73 19741,11 1819 178
74 1974L12 252 31
75 1975L1 1310 103
76 1975L2 2822 220
77 1975L3 2109 212
78 1975L4 1954 404
79 1975L5 2385 338
Machine readable observations and residuals for McDonald observations
for the period 1974 August 30 through 1975 March 31 were distributed
to those requesting them and residual listings for the same period were
provided to all LURE team members. Note that the distribution of
observations from McDonald tapes MCD70, MCD71 and MCD72 covering the
period 1974 August 30 through 1974 November 30 had been delayed
until Silverberg's analysis of electronic calibration problems during
that period was completed. Also the distribution of McDonald observa-
tions for tie period 1974 December - 1975 January was delayed because
of "firing epoch" problems during that period. Beginning with the
data distribution for 1974 December, residuals are now computed with
respect to LURE-2 parameters. See Table II.
Three lunations worth of data was transmitted to Austin by the
LURE observatory on Mt. Haleakala, Maui, covering a data span 2442463-
2442561. Soft-ware was prepared at Austin to process this data, which
was written in temporary format. Our data filtering systems did not
reveal any obvious lunar returns, although one group of observations
z	
`9
TABLE II
LURE-2 MODEL
McDonald Telescope coordinates:
• r	 = 6374.66466 km
X(2440400.5)
	 = 2S5.978012SE
m	 = 30°5032425
Principal axis reflector coordinates:
0 2 3 4
r	 1735.48452 1736.34715 1735.50073 1734.66115
23.411748 -17.538819 3.567223 30.86S756
0.69453 -3.624102 26.155946 25.851806
f=
Ephemeris: LURE-2
Librations: JPL Lunar Libration Tape 5 (extended)
8 = 631.26 x 10 -6	C30 = -10.44 x 10-6
y = 227.37 x 10-6	C31 = 28.6 x 10-6
C32 = 4.82 x 10-6
-6
C 33 = 2.7 x 10
T o = 1.2451723 x 10-3	To = -2.6562663 x 10-5
p o = -7.0228562 x 10
-5
	po = -1.94824643 x 10-5
(IQ) o = 1.703917 x 10-4	(IQ)o = -1.65123951 x 10 -5
Other relevant parameters:
(
	
c = 299792.458 km/sec
M^/M^ = 81.3007
t
AI1KM = 149597870.95869 km/A. U.
I 
S31 = 8.8 x 10-6
S 32 = 1.71 x 10-6
S 33 = -1.14 x 10-6
J
3proved to be statistically significant. The spread of these suspected
returns and the size of their residuals lend very little weight to their
•
being accepted as true signal returns.
	
'	 With the multiple pulsing which has been produced by the McDonald
laser during early 1975 and with the desire to obtain greater accuracy
with the McDonald observations it appears to be quite appropriate to
directly use laser pulse shape information in the filtering of return
photon data. A first generation cross-correlation analysis routine
has been written and debugged. The initial application of this
technique to the McDonald data has been favorable when the number of
returns are sufficient for proper statistical analysis. Since this
i
technique is still in the check-out stage, until further notice all
1	 data distributions will be made using our original filtering system,
not the new cross-correlation routines. It is anticipated that these
new filtering routines will result in greater accuracy for earlier
McDonald data since more accurate electronic calibration results should
be obtainable.
As would be expected, most of the activity related to data	
;m
management and distribution was directed toward the processing of the
Hawaiian data tapes. All data so far received have been written in
temporary format. The correction of this formatting D roblem was the
primary reason for Shelus' trip to Maui in May. The following
items were discussed:
It was agreed that the present formatting of shot records (which
	
i	 provide shot by shot start and stop times, reflector identifications,
acid range gate and ephemeris prediction information) should remain intact.
1
1
4It was agreed that extensive revision of the environment record
was necessary for several reasons:
n L._
1) many archive p
a)
b)
C)
d)
e)
f)
g)
h)
i)
J)
k)
1)
M)
n)
o)
P)
q)
arameters were lacking. Among these were:
clock epoch offset
atmospheric seeing
electronic calibration accuracy code
laser energy
laser frequency
pulse width
shot-by-shot resolution
dark count
site count
star count
star identifier
spectral filter width
spatial diaphram width
no. of shots fired
uncertainty estimate
electronic delay
clock frequency offset
2) Due to a desire to keep all data numerical we agreed that the
largest negative number which could be written would be used
for a "no information" indicator on transmitted records.
3) At the present time environmental and calibration data are
only written once at the beginning of a day's observations and
then once again at the end of that day's observations,
regardless of how much time might have intervened. This would
require unrealistic linear interpolation over as much as 8-10
hours resulting in faulty information, especially during the
central portion of an observing period. An informal definition
of an observing "run" was agreed upon in an attempt to overcome
this difficulty. It is hoped that this will also provide the
means of subdividing a long run of observations into logical
sub-units which can be realistically formed into "normal points."
4) Wong will supply us with a list of identification numbers to
be used with bright stars which are used to obtain photo-cell
readings. Again, this is an attempt to elim'nate all BDC or
ASCII types of representations.
5) Still to be decided is the manner in which clock epoch and clock
frequency offset information is to be transmitted to Austin.
At the present time McDonald Observatory reduces its own LORAN-C
information to provide us with epoch and frequency offsets for
each set of observations directly. Carter wishes only to
transmit LORAN-C information and have epoch and frees y offsets
be computed therefrom in Austin. Arguments were pr'-e3ed on
^y
5
both sides with no agreement reached. Since many similar
stations are planned throughout the world, it was decided to
seek advice from the LURE, team as to the most cost-effective
and meaningful manner of transmitting this type of information
to Austin. Presently Hawaii is not providing epoch or frequency
offsets nor is enough LORAN-C information provided to us in
order to compute these quantities in Austin.
6) An observatory identification code must still be obtained
for the LURE observatory at Haleakala.
Three Dimensional Lunar Ephemeris
At the end of the last report period an apparent ephemeris had
been supplied to USNO covering a portion of the interval for which there
are photoelectric occultation observations. Similar information was
provided for the rest of the interval early in this report period. Our
inability to provide all of this information last December was, after
some effort, traced to a logical flaw in one of our programs, which caused
no difficulty under ordinary conditions but which would occasionally
cause the execution to transfer into an infinite loop. This problem has
been overcome.
As it turned out th;_s was not the last of our programming problems,
despite the fact that the c-nti:,e software system for the occultation
analysis had been debugged add c(^rtified as operating in principle, by
means of test cases. As it turned out, however, some of the test cases
were unrealistic, and some of the programming was tailored to the
test cases rather than to the general problem. The situation is now
believed to be well in hand. Solutions on the occultation data were
underway at the end of the report period.
Simultaneously with this effort, we have continued to improve the
mathematical modelling of the range data and the mechanics of the solution
i
7
6
process. This has included the coding of better orbit partial derivatives,
the introduction of a number of additional solution parameters, and refine-
ment of the computation of such small magnitude but significant modelling
factors as the Universal time and atmospheric refraction. Current solutions
to laser only data, depending on the observations used and the parameters
solved for, are on the order of a meter if one uses the numerically inte-
grated librations. We will defer a more detailed discussion at this
time, because the drafting of the final report on this task will begin
soon, and we expect it to be delivered in final form not more than 30
days following the nominal grant termination date (1975 August 31).
FL	 Mobile Staticn Sensitivity Study
The previous semi-annual status report gave a brief description of
this study, which was not a proposed task, but rather one that was
requested of us by the project monitor. Some preliminary results were
giver at that time. Since that time, portions of this work have been
used in presentations by the principal investigator, by Dr. Eric Silverberg,
(U.T. McDonald Observatory), and by Dr. Gary Latham (U.T. Galveston).
This study is now finished, but we omit a discussion of the results here,
due to the fact that the final report on this task is already in prepara-
tion. It is expected to be delivered by 1975 August 15.
Staff, Publications and Travel
IDuring the report period, the project staff consisted of J. I).
Mulholland (P. I. 3 man months) , S. Killen (3 112 mm) , G. I.oumos (2 112 mm) ,
i
	
	 N. Otto (2 mm) and P. J. Shelus (6 mm). Loumos terminated his connection
with the project on May 31, while Killen joined it January 1.
7No manuscripts were submitted for publication during the report
+	 interval, although three of those submitted during the previous period and
noted in the previous status report as accepted fo: , publication have
•	 since appeared in the open literature. These are Mulholland, "The Rotation
	 I
of the Moon," Acad. Roy. Belgique, 5th series LX, 1088, 1974, Shelus,
Mulholland and Silverberg "Laser Observations of the Moon: Normal
Points for 1972" Astron. J. 80, 174, 1975, and Shelus and Jefferys
"A Note on an Attempt at More Efficient Poisson Series Evaluation"
Cel. Mech. 11, 75, 1975.
Travel supported under this grant during the report period
included attendance by Mulholland and Shelus at the February and June
LI TRE Team meetings in Washington and a trip to the Haleakala Observatory
by Shelus to facilitate the solution of the problems disci,ssed in the
data management section of this report.


Lunar motion analysis

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