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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: A small puzzle
From: Dan Allen
Date: 2000 Sep 07, 6:38 PM
From: Dan Allen
Date: 2000 Sep 07, 6:38 PM
If Betelgeuse officially wasn't where you took the shot, and if the various lists of navigational stars show nothing in the area, could you have taken a sighting of a satellite or aircraft that happened to be moving away from you such that its visible position looked close to stationary? Just thinking "out of the box" about possible explanations... ;-) Dan -----Original Message----- From Navigation Mailing List [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]On Behalf Of Richard B. Emerson Sent: Wednesday, September 06, 2000 8:58 PM To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM Subject: A small puzzle While sailing back from New England, coasting down the New Jersey coast, I did some morning sights even though I was fairly close to my final destination. For one reason and another, I was only able to get off shots for Jupiter, the Moon, and one star. Although the angle between Jupiter and the Moon was only about 35 degrees, the lines were generally usable and confirmed my position. The reductions for the star, however, failed miserably and I have yet to figure out what went wrong. I was pretty sure I was shooting Betelgeuse but when I reduce the sights, the distance to the GP is something awful (about 80 miles, to!). Now, it was early in the morning, I'd been up much of the night and we'd been traveling fairly hard for about a week, so I was hardly the crispest cookie in the box. [g] My first thought was that I'd made a timing error. I've been using a stopwatch and writing down the hack time when I start the watch. The stopwatch is a 30 minute watch and it doesn't have a telltale for rolling over from one half hour to the next. With all of this in mind, here's the setup: The date is 22 Aug 2000, the AP is 39-04 N 74-40 W, the course and speed are 224T at 5.8 kt. He is 5' and Ic is 2.0' on. The horizon was clear and the sky was clear, too. My notes show the initial hack time was 09:20Z (05:20EDT) (the hack changes for the last two bodies; I waited for a lighter horizon). What follows are typed versions of my notes; I've added the UTC times as well as watch times. Also, it's helpful to know the bearing to Betelgeuse at the time was approximately 110T. Finally, I chose Betelgeuse because its reddish color makes it distinctive in the sextant's scope (4x). Sight No. Time (WT/UTC) Hs Betelgeuse(?) 01 08:20 09:28:20 36-23.5 02 09:34 09:29:34 36-42.0 03 10:34 09:30:34 36-52.5 NOTE! New hack time: 09:49Z Jupiter 04 02:04 09:51:04 63-10.0 05 03:09 09:52:09 63-18.0 06 04:04 09:53:04 63-25.5 Moon (Lower Limb) 07 05:48 09:54:48 63-53.0 08 07:05 09:56:05 63-58.0 09 07:56 09:56:56 63-59.5 Your mission, if you choose to accept it, is to figure out what went wrong with the star sight. Rick S/V One With The Wind, Baba 35