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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Lunars -Venus!
From: Ken Muldrew
Date: 2004 Apr 23, 22:35 -0600
From: Ken Muldrew
Date: 2004 Apr 23, 22:35 -0600
Last night the moon was in a cloud by the time I got out, but I did get it on Wednesday. I'm at latitude 51? 5'N and 114? 0.5'W. Index error 8.3' on the arc. Venus to the moon's lower limb GMT Distance 3:13:10 15?58.2' 3:11:50 15?57.3' 3:13:10 15?57.0' 3:14:30 15?56.0' 3:15:20 15?56.2' GMT is for Apr 22, the time was 9:mm:ss local time. Sticking this into Arthur Pearson's webpage gave me a suprising -0.9' error. I also did Jupiter to the moon's LL GMT Distance 3:17:10 99?7.8' 3:20:50 99?6.5' 3:21:10 99?6.2' 3:22:30 99?4.2' 3:24:20 99?4.0' 3:26:00 99?3.4' This was also a surprising -1.4' error in observation (substantially more in longitude). Earlier in the day I tried getting a latitude from double altitudes of the sun. The artificial horizon that I built has a hood that has a bit of a lip in front of the pan. With the sun so low, I couldn't get a reflection with the hood on so I had to remove it. It was quite windy, so I had no chance of seeing one of the reflected limbs. Instead, I just tried to bring the sun over the centroid of the dancing green blob that was reflected off the water. I only took a single reading at each time since it took about 5-10 minutes just for that. At 5:54 PM local time (11:54PM GMT) I got a reading of 50?37.4' for an altitude of 25?12.5' (same index error). At 6:49:50PM I got a reading of 33?16.1' for an altitude of 16?35.1'. Reducing this to a latitude gave me 51? 24' 41". Considering the appalling accuracy of my readings, I was very surprised with the accuracy of the result. Altitudes are certainly a lot more forgiving than lunars! Ken Muldrew.