sep function

[xdw316]

does the seperation calculation work correctly for for two topocentric refracted positions?

[brandon-rhodes]

It should, yes. Are you getting an unexpected or worrying result?

[xdw316]

when i use ai generated python using skyfield, the seperation result, near 15 degrees, differs from the correct result using refracted topocentric alt az and the cos formulat. the ai may not fully understand the function.

[xdw316]

difference is about 3 min.

[brandon-rhodes]

To make a specific diagnosis, I would need to see the code, so that I could see what exact values the separation function is getting, versus the values going into the cos formula. Do you have a small example script that prints both values, so I could run it myself and see the 3-minute difference in results? Thanks!

[xdw316]

On Wednesday, January 21, 2026 at 04:24:18 PM EST, Brandon Rhodes ***@***.***> wrote: It should, yes. Are you getting an unexpected or worrying result? — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you authored the thread.Message ID: ***@***.***>

[xdw316]

=========== RESTART: C:\Users\daw\Desktop\dwPython\ZubenLDdeepseek.py ======================================================================Date: 17 Dec 2025, 13:30 UTCLocation: 32°30'N, 110°30'WConditions: 1010 mbar, 10°CObject: Moon near Zubenelgenubi (HIP 72622)============================================================ TRUE altitudes (minimal refraction):Moon:  10° 36.5023'Star:  25° 16.4133' APPARENT altitudes (with explicit refraction):Moon:  10° 41.6015'       (refraction: +5.099 arcmin)Star:  25° 18.5079'       (refraction: +2.095 arcmin) Skyfield apparent altitudes (for comparison):Moon:  10° 36.5023'Star:  25° 16.4133' Azimuths:Moon:  129° 12.0102'Star:  131° 43.0797' Moon angular radius: 0° 14.7464' ============================================================SEPARATION RESULTS:============================================================ Center-to-center: 14° 48.5153'NEAR limb: 14° 33.7689'FAR limb:  15° 3.2617' In arcseconds:Center separation: 53310.92"Near limb: 52426.13"Far limb: 54195.70" ============================================================SKYFIELD'S SEPARATION (for comparison):============================================================Center-to-center: 14° 51.4881'NEAR limb: 14° 36.7417'FAR limb:  15° 6.2344' No occultation. Clear separation. On Wednesday, January 21, 2026 at 04:24:18 PM EST, Brandon Rhodes ***@***.***> wrote: It should, yes. Are you getting an unexpected or worrying result? — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you authored the thread.Message ID: ***@***.***>

[xdw316]

I may be confused on which methods use refracted alt and which don't.Thanks for any help. listing attached. Dave Walden  On Sunday, February 1, 2026 at 09:12:44 AM EST, Brandon Rhodes ***@***.***> wrote: To make a specific diagnosis, I would need to see the code, so that I could see what exact values the separation function is getting, versus the values going into the cos formula. Do you have a small example script that prints both values, so I could run it myself and see the 3-minute difference in results? Thanks! — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you authored the thread.Message ID: ***@***.***>