(10-02-2017, 10:36 PM)c_davidson Wrote:(10-01-2017, 07:03 AM)Rumata Wrote: Gentlemen,
I just tried to use Sight reduction Astron spreadsheet / manual option and can't locate Altitude correction for Sextant sight. Also, Index error shows only minus option. But if it is (-) should I add it instead of subtracting it from Hs? . When I entered the Height of eyes in meters the spreadsheet calc simply subtracted this number from Hs, not the data I saw in Nautical Almanac ( hard copy). Anyway, I got a little bit different results for azimuth and intercept.
My question is: should I blindly trust the spreadsheet or paper/pencil approach? Yes it is much faster.
Again, difference about +/- 1.5 deg. in azimuth and tolerable in the intercept results. Thank you.
Rumata,
Astron does a good job and I've not found it inaccurate so far. Compared to the USNO's site- [/url]
Celestial Navigation Data for Assumed Position and Time
...it's very good and equivalent. However, electronics and computers, like anything that's complex will fail you when you need them the most. That's why I tend to use paper only and not electronics. But, Astron is useful and helpful for many purposes and good in helping to verify your paper based sight reductions.
Astron is good is when experimenting using hypothetical data from different latitude and longitudes so one can get a good idea of how to reduce a sight from a Contrary latitude and Eastern hemisphere. Those of us in Northern latitudes and Western longitudes often think that there is no other part of the world except ours. Astron helped answer several problems I had when attempting a hypothetical sight reduction based on Eastern longitudes;
Remember- to obtain the LHA in Eastern longitudes- round up the GHA figure to the next higher degree
figure and add the whole degree DR. Longitude to it.
The italicized text is from- [url=https://www.thenauticalalmanac.com/Complete%20Sun%20Sight%20Reduction%20Procedure-%20Ocean%20horizon.pdf#page=6]Eastern Longitude LHA rules
There is no virtue or vice in using electronics for sight reduction. We're looking to get the correct answers. While "on the hard" it's often easiest to use the method you're most comfortable with and when using Astron you can reduce a lot of sights quickly. But....paper is much more enjoyable.
Clen
Thanks, Clen. Agree. As you 've mentioned, I also tried to use Astron for hypothetical calculations. Yes, East longitude, Southern Hemisphere, crossing Date Line back and forth and so on. And yes, it is a very good tool to check paper-written calcls for the sanity. I wasn't too attentive in input for manual almanac calc and therefore asked for the advice. Thank you, Clen, and to Ed for the fast response. I found it very satisfying when my humble result is very similar to the Astron's. It means some patches of the grey matter in my brain are still functioning. ;>