NavList:

Mauritius Island, April 01, 2012

Dear Alex,

Thank you very much for disclosing to our NavList Community your Mar 29, 2012 Lunars raw data. Your "environment details" about the way you were holding your sextant, and the way you were oriented are also a very good point.

I took the time to process your data and to compare results with Frank's Computer.

Some data are recalled here-under, and they have been corrected for instrument errors, and for these only. For each Lunar, I used averaged values, in order to reduce the number of computations. I am using your geographical position, Alex, with an altitude of 210 meters above WGS 84 Ellipsoid as check'd on Google Earth (BTW, you live in a nice area, don't you).

I also trust that I am computing Apparent Coordinates to an accuracy of +/- 0.05 arc Minute, and I am using TT-UT = 67.7 seconds of time. Still, do not overly trust the published trailing digits which are displayed here just to limit round off errors if and when subtracting close numbers which can be compared.

1 *** 1st Jupiter Lunar with UT=00h33m43.0s and Sextant Distance = 35°21'66667

1.1 - If we assume that both UT and position are correct, then you should have observed a Sextant Distance of 35°21'834, which yields an observational error of -0'167 . In comparison, Frank's results give an observational "Error in Lunar" equal to -0'2 (-0'177 actually).
1.2 - If we assume that both Sextant Distance and Position are correct, then Watch correction is to be -20.2 seconds of time with UT = 00h33m12.2s . From such "reprocessed" data, Frank's Computer Results differ by 0'013 as regards observed sextant angular values.

*******

2 *** Venus Lunar with UT=00h38m39.66667s and Sextant Distance = 23°49'76667

2.1 - If we assume that both UT and position are correct, then you should have observed a Sextant Distance of 23°50'078, which yields an observational error of -0'311 . In comparison, Frank's results give an observational "Error in Lunar" equal to -0'2 (-0'226 actually).
2.2 - If we assume that both Sextant Distance and Position are correct, then Watch correction is to be -40.2 seconds of time with UT = 00h37m39.5s . From such "reprocessed" data, Frank's Computer Results differ by 0'073 as regards observed sextant angular values.

*******

3 *** Mars Lunar with UT=00h58m48.0s and Sextant Distance = 77°14'0333 (far Limb)

3.1 - If we assume that both UT and position are correct, then you should have observed a Sextant Distance of 77°14'025 (Far Limb), which yields an observational error of 0'008 . In comparison, Frank's results give an observational "Error in Lunar" equal to 0.0' (0.010' actually).
3.2 - If we assume that both Sextant Distance and Position are correct, then Watch correction is to be -1.5 seconds of time with UT = 00h58m46.5s . From such "reprocessed" data, Frank's Computer Results differ by 0'000 as regards observed sextant angular values.

*******

4 *** 2nd Jupiter Lunar with UT=01h14m28.3333s and Sextant Distance = 35°35'3

4.1 - If we assume that both UT and position are correct, then you should have observed a Sextant Distance of 35°35'221, which yields an observational error of +0'079 . In comparison, Frank's results give an observational "Error in Lunar" equal to 0'1 (0'063 actually).
4.2 - If we assume that both Sextant Distance and Position are correct, then Watch correction is to be +14.4 seconds of time with UT = 01h14m42.7s . From such "reprocessed" data, Frank's Computer Results differ by 0'013 as regards observed sextant angular values.

*******

DISCUSSION OF RESULTS

First of all, I am extremely impressed at the quality of your Lunars ! You definitely deserve Captain Cook's Lunars Commendation Medal.

Second, this has been the first time I have processed Lunars in months : ans actually I kept playing with Lunars almost all day long. I have thus discovered version 4 of Frank's Lunar Computer. Frank, @ one year ago it used to be V. 3, no ? I have checked its accuracy through random Lunars Computation back to 1753 and got results fully reliable as regards your claimed accuracy. Frank, you have perfected your On-Line Computer into a most Wonderful Tool ! Congratulations again !

So, thank you to both of you, Alex and Frank for such a revival of the Ancient Grand Art of Lunars.

Best Regards to you all

Kermit

Antoine M. "Kermit" Couëtte

**********************************************************************************

[NavList] Re: Lunar weather in Indiana
From: Alexandre Eremenko
Date: 29 Mar 2012 00:06
Dear Kermit,

Yes I used Frank's calculator:-)
I cannot publish ALL row data (I have to much) but here is the data for
tonight.
My place: N40d 27.2, W86d55.8 Termometer: 60 Barometer 740mm
(sorry: 29.13 inches, my barometer is German:-) GMT March 29.
SNO-T, IC=-0'3 from Sun, 6x Kepler scope. Watch (set on GMT) 3 sec fast.
Row data (GMT watch reading; sextant reading):
1. Moon (Near limb)-Jupiter:
00:31:50 35d21'1
00:34:03 35d22'
00:35:25 35d22'8
2. Moon (Near limb)-Venus:
00:37:24 23d50'
00:38:31 23d50'
00:40:13 23d50'2
Break for a cup of tea.
3. Moon (Far limb)-Mars:
00:57:09 77d14'9
00:59:24 77d14'4
01:00:00 77d13'7
4. Break. Index check: Rigel, IC= -0'2 or -0'3 (not sure).
Some small star, IC=-0'3.
Reduced the sights with Frank's calculator using IC=-0.3.
5. Moon (Far limb)-Jupiter, again, using stopwatch instead of wrist watch
stopwatch is exact, started from Internet GMT:

01:12:33 35d35'0
01:14:52 35d35'7
01:16:00 35d36'1

Remarks. Sitting in a chair, in the case of Mars, facing Mars.
Holding the sextant with two hands. Adjust and look, adjust
and look...
Stopwatch more convenient (don't need to put eyeglasses on and off;
stopwatch has a hudge dial (2.3 inches),
and I use a microlight from Celestaire to
read the time and sextant. Native SNO illuminator is not enough for my
eyes, but magnifier helps a lot, so I can read without eyeglasses.
Stopwatch has two second hands: one can be stopped another continues.
Then I read the time, press a button, and the stopped hand joins the
running hand. Very convenient for Cel nav. Russian Molnia stopwatch,
dial reads to 1/10 of a second, but I don't care of course about 1/10
when taking Lunars, in fact one can safely round to 5 seconds:-)

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