A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2019 Jan 2, 09:43 -0800
Don Seltzer, you wrote:
"long by obs. The last seems to be longitude by lunars."
It's a little ambiguous, right? I've seen cases where "long by obs" was used every day in which case it couldn't be lunar-based, unless it's a running lon with a lunar starting longitude (but in the specific case I recall, it was late in the 19th century and appeared to be nothing more than an "ordinary" celestial longitude ...which in an earlier decade would have been specified as "lon by chro"). Do you happen to have a list of some of the dates when Capt Stewart noted a "long by obs"? There's a distinct pattern that would fit lunars and might prove the case. For example, if the "long by obs" notations were typically found around First Quarter and Last Quarter moon phases then that would be good evidence. It doesn't work the other way: if the pattern isn't present they could still be lunar-based longitudes.