Comet 3I ATLAS on Dec 28, 2025


Date & Time: Dec 28 2025, from 25:37 to 26:30 JST(+0900)
Composed 14 shots with 4 minutes exposed
Optical: Meade 25cm(10") Schmidt-Cassegrain with conversion lens (f=1600mm, F6.3)
with IDAS LPS-P1 Light-pollution suppression filter
Auto-guided with Meade LX200 Equatorial & Lacerta M-GEN
Digital Camera: Nikon D810A
Location: Ooizumi, Hokuto city, Yamanashi pref.

Camera Settings: Recording Format...14bit CCD-RAW, converted to 16bit TIFF(4080×4080)
Device Size...20×20mm
Sensitivity...ISO4000, White Balance...Daylight


On this day, the interstellar comet 3I/ATLAS was moving westward about 2 degrees southwest of Regulus in Leo. Since it has receded from Earth compared with last month, the coma has faded to 11th magnitude, but a short tail-like structure extending eastward has become noticeable. Although observing conditions from Japan will remain favorable, the comet is expected to dim rapidly from now on.
View angle: 0.70×0.70°


24P Schaumasse on Dec 26, 2025
3I ATLAS on early morning of Nov 29, 2025

Copyright(c) 2025 by Naoyuki Kurita, All rights reserved.
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