NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Non-adjustable sextant error calibrations
From: Doug Royer
Date: 2004 Feb 2, 14:57 -0800
From: Doug Royer
Date: 2004 Feb 2, 14:57 -0800
After reading Joel's post I started to think about this matter.Frank started a thread(part 1 of 2) on measuring the angles between stars to find error.I was interested in the subject but didn't persue it further untill part 2 is written.However,after Joel's post I wonder if one can calibrate the instruments' non-adjustable error useing this or some other method. Doesn't collumation error have to do with the alignment of the scope to the frame?I've read in some book also,that to check collumation one places a grid a certain distance from the sextant and scope and checks for the error in that way.I'll have to dig around in these books to find if that is what was being written about. I've read in older nav. books a procedure called "interstellar angles" or some such.There was even a table with angles between stars(such as Sirius to Spica,Spica to Aldebahran etc.)that spanded close to long angles to measure. My question is : is this the method one can use to find or calibrate the non-adjustable error that Fred states? As I posted awhile ago I took my sextant into Baker Marine years ago(when they offered this service)to have the arc error checked(for a healthy sum)only to find out it was well in spec < 10" of arc over the entire arc of 130*.So,because of the cost of this couldn't Fred or any of us use this or some technique to find the error in some of the older sextants that state the error on the certification papers inside the sextants' box?