VI/122 The Marginal Zone of the Moon - Watts' Charts (Watts, 1963)
The Marginal Zone of the Moon
Watts C.B.
<Astron. Papers for the preparation of the Nautical Almanach XVII (1963)>
ADC_Keywords: Solar system ; Occultations
Description:
The WATTS' charts provide the elevation of the limb of the moon using
1800 contour maps (step of 0.2deg) that cover all libration ranges of
the moon. The contours of the maps were digitised by H.M. Nautical
Almanac Office in the late 1960's, and then converted to a grid format
by US Naval Observatory in the early 1970's. These charts are present
in 2 forms: as an ascii file watts.dat (without carriage-return or
line-feed!), or as a 3-D FITS file watts.fit (transformed from the
ascii files with the program "make_fit.c"). More details, especially
about the transformations between the original charts and the files
stored here, and the special processing of the 36.0° map (map#181),
can be found in the "doc.txt" file.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
doc.txt 75 455 Detailed information concerning the derivation of
the file, known errors, and the order of the data
watts.dat 6 13269600 The Watts charts, in grid layout (without CR/LF)
watts.fit 2880 13825 The Watts charts, as a FITS file [91x81x1800]
photos.dat 47 503 List of photographs used in the survey
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See also:
Morrison L.V., Martin R.J., 1971Moon....2..463M 1971Moon....2..463M
Byte-by-byte Description of bulk file: watts.dat
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Bytes Format Units Label Explanations
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1- 4 I4 0.01arcsec h height of the limb, in units of 0.01"
(sign in byte 1)
5 I1 --- a [0,7] Accuracy code a (1)
6 I1 --- b [0,7] Accuracy code b (1)
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Note (1): The accuracy code has 2 parts, a and b, each with possible
values between 0 and 7. The meaning of theses codes is detailed in
the file "doc.txt", section 3. A simplified reliability code can
be derived as follows:
-- Reliable if: b=0 or b=1; or 1<b<7 and a=0; or b=7 and a=5;
-- Uncertain if: 1<b<7 and 0<a<3; or b=7 and a=6;
-- Unreliable if: b=7 and a<5; or 1<b<7 and a>2; or b=7 and a=7;
or h>3.4; or h←3.4
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Byte-by-byte Description of file: photos.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Ordinal sequence in the printed table
5- 9 I5 --- ID Identification number in the printed table
11- 14 I4 yr Obs.Y Year of the photograph
16- 18 A3 "month" Obs.M Month of the photograph
20- 26 F7.4 d Obs.D Day of the photograph
27 A1 --- Rem [#*$] Remark on photograph:
* when used as a 'standard'
# when used to test circularity of 2nd datum
$ for both the above.
28- 33 F6.2 deg l Longitude libration
34- 39 F6.2 deg b Latitude libration
40- 43 I4 deg Arc1 Start of measured arc
44- 47 I4 deg Arc2 End of measured arc
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(End) Dave Herald [Canberra, Australia] 24-Mar-2006