NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Geoff Hitchcox
Date: 2023 Oct 23, 19:20 -0700
Bonjour Kermit,
When using the JPL Horizons site, the smallest time increments you can have is 0.5 seconds. So I have used the Swiss Ephemeris, to give me 0.01" increments of time - for the positions (Az,El) of Regulus and the Moon.
I'm just using High School (flat plane) Pythagoras Trig to find the separation of the two bodies, which seems to give reasonable agreement with your numbers Kermit, as follows:
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10:57:58.90 Kermit's Lunar Distances Program
10:57:59.87 Geoff's simple Pythagoras and Swiss Ephemeris using 0.01" time increments
10:58:01.6 Swiss Ephemeris using -occult function
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12:11:34.40 Kermit's Lunar Distances Program
12:11:36.04 Geoff's simple Pythagoras and Swiss Ephemeris using 0.01" time increments
12:11:33.2 Swiss Ephemeris using -occult function
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I agree that Paul_H's Lunar Software will be needed to make the FINAL judgement for "exact" timing.
Kermit, following are my solutions, I detected about a 1 second difference between AIRLESS and REFRACTION models, but I'm not at all comfortable that the Ephemeris is giving me what I wanted. Like JPL Horizons, the moon diameter stayed the same between Swiss Ephemeris models - which we know is not quite right.
An interesting challenge.
Regards, Geoff Hitchcox, Christchurch, NZ
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Seagrave Observatory at N41°50.71' / W071°35.47' elev. +107m
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Moon has just covered the Star! **** Airless Model ****
Regulus, Az = 134.0809693,Alt = 52.4914684
MOON, Az = 134.4686538,Alt = 52.5988214
23.10.1924 10:57:59.87
Separation = 0.259055554 (deg), Moon Radius = 0.259055861 (deg)
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Moon has just UNcovered the Star! **** Airless Model ****
Regulus, Az = 164.0989466,Alt = 59.6479538
MOON, Az = 163.8634819,Alt = 59.4175165
23.10.1924 12:11:36.04
Separation = 0.259529697 (deg), Moon Radius = 0.259529181 (deg)
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Ladd Observatory at N41°50'15.6" / W071°23'59.26" elev. +69 m
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Moon has just covered the Star!! **** Refrac Model ****
Regulus, Az = 134.4499811,Alt = 52.6578831
MOON, Az = 134.8401362,Alt = 52.7639156
23.10.1924 10:58:20.91
Separation = 0.259063443 (deg), Moon Radius = 0.259063625 (deg)
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Moon has just covered the Star! **** Airless Model ****
Regulus, Az = 134.4548905,Alt = 52.6476323
MOON, Az = 134.8449809,Alt = 52.7536270
23.10.1924 10:58:21.78
Separation = 0.259062962 (deg), Moon Radius = 0.259063750 (deg)
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