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Re: Technique question
From: Fred Hebard
Date: 2003 May 20, 21:02 -0400
From: Fred Hebard
Date: 2003 May 20, 21:02 -0400
I sent this to Steven instead of the list, but thought it might be relevant. Steven, That was the interesting part of Doug's lunars. Although they were taken two hours apart, they were in opposite directions. However, the error in time was -513 seconds for the first and -490 seconds for the second, subtracting the known time from the lunar time. Thus there was a systematic error of around 5' of arc, in this case a gap. In the moon-Jupiter lunar, the moon was east of Jupiter, while for the moon-Spica lunar, the moon was west of Spica. Fred On Tuesday, May 20, 2003, at 04:25 US/Eastern, Steven Wepster wrote: > Doug and other lunartics, > > Unfortunately I have done only two lunars up to now, and both were > done in > clear skies. I hope this answers part of Doug's question. > > In the old days mariners were advised to take, whenever possible, an > easterly lunar distance _and_ a westerly lunar distance. Any error in > the > computed position of the moon and also most systematic measurement > errors > cancel out by taking the mean of the aquired longitudes or times. I > have > not looked into Doug's observations; but if it happened that he made E > and > W distances then it would be interesting to compare them and see if the > error that he is worrying about is consistent in this respect. > > Steven. > > ----------------------------------------------------------- > Steven Wepster wepster@math.uu.nl > tel +31 30 253 1531 > Mathematisch Instituut +31 61 251 4380 > Universiteit Utrecht > PO Box 80.010 > 3508 TA Utrecht > The Netherlands > =========================================================== > > ------------------------------------------------------------------------ Frederick V. Hebard, PhD Email: mailto:Fred@acf.org Staff Pathologist, Meadowview Research Farms Web: http://www.acf.org American Chestnut Foundation Phone: (276) 944-4631 14005 Glenbrook Ave. Fax: (276) 944-0934 Meadowview, VA 24361
