Stippvisite im Sonnensystem II. Duncan Lunan, "Der Komet, der Cairn und die Kapsel" (1972)

Oha. Preprint auf arXiv vom 17. Juli.

[Submitted on 17 Jul 2025] "NSF-DOE Vera C. Rubin Observatory Observations of Interstellar Comet 3I/ATLAS (C/2025 N1)"

Abstract:

Zitat
We report on the observation and measurement of astrometry, photometry, morphology, and activity of the interstellar object 3I/ATLAS, also designated C/2025 N1 (ATLAS), with the NSF-DOE Vera C. Rubin Observatory. The third interstellar object, comet 3I/ATLAS, was first discovered on UT 2025 July 1. Serendipitously, the Rubin Observatory collected imaging in the area of the sky inhabited by the object during regular commissioning activities. We successfully recovered object detections from Rubin visits spanning UT 2025 June 21 (10 days before discovery) to UT 2025 July 7. Facilitated by Rubin's high resolution and large aperture, we report on the detection of cometary activity as early as June 21st, and observe it throughout. We measure the location and magnitude of the object on 37 Rubin images in r, i, and z bands, with typical precision of about 20 mas (100 mas, systematic) and about 10 mmag, respectively. We use these to derive improved orbit solutions, and to show there is no detectable photometric variability on hourly timescales. We derive a V-band absolute magnitude of H_V = (13.7 +/- 0.2) mag, and an equivalent effective nucleus radius of around (5.6 +/- 0.7) km. These data represent the earliest observations of this object by a large (8-meter class) telescope reported to date, and illustrate the type of measurements (and discoveries) Rubin's Legacy Survey of Space and Time (LSST) will begin to provide once operational later this year.

36 pages, 16 figures, 4 tables; collaboration between the NSF-DOE Vera C. Rubin Observatory and the LSST Solar System Science Collaboration (SSSC)

https://arxiv.org/html/2507.13409v1

Aber worauf ich hinaus will: für diese 36 Seiten werden insgesamt 114 Autoren aufgelistet.

Unter Punkt 4.9.3., "Tail analysis," finde ich dies - bevor das die UFO-Gläubigen à la Avi Loeb mal wieder unter "Aliens!" abheften.

Zitat
As noted by several observers (Jewitt & Luu, 2025; Alarcon et al., 2025; Seligman et al., 2025; Opitom et al., 2025; Bolin et al., 2025), 3I/ATLAS is observed to exhibit a short sunward-pointing tail in imaging data obtained since its discovery. While such a morphology is certainly unusual—given that dust tails are typically directed antisolar due to radiation pressure acting on dust grains—it is not without precedent among distant active bodies. Notably, Farnham et al. (2021) reported a similar sunward enhancement in comet C/2014 UN271 (Bernardinelli–Bernstein), which they interpreted as the result of the slow ejection of relatively large dust particles predominantly from the sunlit hemisphere.