NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Lunars calculator
From: Bill B
Date: 2005 Apr 9, 20:48 -0500
From: Bill B
Date: 2005 Apr 9, 20:48 -0500
> Bill wrote > "Moon was approx. 53d, and dim against the sky. Given the Sun was lower, it > might have made sense to us it in the horizon glass instead of the Moon, but > it seemed easier to have the Moon in the glass as it was difficult to see." > Frank Replied > This is probably another reason why navigators in the 19th century seem to > have avoided lunars when the Moon's elongation was less than about 50 to 60 > degrees. The contrast against the sky is just too darn low. Of course, they > could have waited until dark and used stars if really necessary. Popped out to do a lunar April 4 at noon EST, Long 86d 56.' Moon should have had an Hc about 20.5d, and bearing of approx. 217d. Blue sky, bit of haze on the horizon. For the life of me could not see it. Rechecked my calculations against Omar's Navigator Star Finder, http://www.tecepe.com.br/cgi-win/cgiasvis.exe and went out with binoculars. True I was dodging trees but changed my vantage point often, and checked the azimuth with a compass corrected for magnetic declination. Finally hiked to where the tree line was not behind me. Still nothing! Just walked away scratching my head, > Frank added > By the way, that mystery angle you were wondering about... it's the > difference in azimuth between the two bodies. Thank you. Admit I have not done due diligence on the "Easy Lunars" formulas to track the the suspect, but that is the last place I would have guessed based on angular separation and refraction correction for two bodies. Bill