Hi All, not sure where to put this or if this is an "Issue", but advise if this shouldn't be here.
We had a clear night last night so I did a couple lunars using Procyon and Sirius, that aren't one of nine stars historically used and had large LDs.
I did four shots each and averaged their four LDs and times. Normally I am pretty sloppy on my lunars because I know they are not going to be close, but this time I was more careful.
The errors are large. Procyon time/long are off by 3 minutes/0.75° and Sirius is off by 10 minutes/2.49°. See my attached chart.
I'm bring this up, not to claim that I'm a poor observer (there is obviously some of that!), but to point out lunar sights/calcs are not going to be very exact, and to bolster my opinion that we shouldn't get carried away on doing multiple calcs (like longitude) that are going to be so far off. Sure, this is fun, but the results are often poor, for lots of reasons, not just my poor sextant usage... More on that in next post.
Note that I made a correction to these number after I noticed I used the IC from the wrong sextant (made it look better, but still way off....
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| body |
actual UTC WWV |
actual Long |
measured LD |
CelNav calc time |
error UTC |
CelNav calc long |
error long |
distance from ecliptic |
ΔLD |
| Procyon |
"1/8/2025 4:40:14 AM |
92° 13' W |
55° 43.8' |
"1/8/2025 04:37:13 |
0:02:59 |
91° 28' |
0° 45' |
15° 16' |
30.4 arc-minutes/hr |
| Sirius |
"1/8/2025 4:56:00 AM |
92° 13' W |
71° 17.7' |
"1/8/2025 5:06:20 |
0:10:20 |
89° 24' |
2° 49' |
38° 42' |
22.0 arc-minutes/hr |
Hi All, not sure where to put this or if this is an "Issue", but advise if this shouldn't be here.
We had a clear night last night so I did a couple lunars using Procyon and Sirius, that aren't one of nine stars historically used and had large LDs.
I did four shots each and averaged their four LDs and times. Normally I am pretty sloppy on my lunars because I know they are not going to be close, but this time I was more careful.
The errors are large. Procyon time/long are off by 3 minutes/0.75° and Sirius is off by 10 minutes/2.49°. See my attached chart.
<style> </style>I'm bring this up, not to claim that I'm a poor observer (there is obviously some of that!), but to point out lunar sights/calcs are not going to be very exact, and to bolster my opinion that we shouldn't get carried away on doing multiple calcs (like longitude) that are going to be so far off. Sure, this is fun, but the results are often poor, for lots of reasons, not just my poor sextant usage... More on that in next post.
Note that I made a correction to these number after I noticed I used the IC from the wrong sextant (made it look better, but still way off....