文件操作 - 1762845091.M718515P6559.mail.planetcloud-host.com,S=6910,W=7029:2,

文件: /var/vmail/bicar.it/stefano/cur/1762845091.M718515P6559.mail.planetcloud-host.com,S=6910,W=7029:2,

编辑文件内容

Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=174.142.199.243; helo=server.astronomerstelegram.org; envelope-from=atel@astronomerstelegram.org; receiver=stefano@bicar.it 
To: stefano@bicar.it
From: atel@astronomerstelegram.org
Subject: ATel  17487, 17488
Message-Id: <20251111071127.C47142880769@server.astronomerstelegram.org>
Date: Tue, 11 Nov 2025 02:11:27 -0500 (EST)

------------------------------------------------------------------------------ 
The Astronomer's Telegram is free to read, free to publish, free to
use.  Thanks to the support of our patrons, we can continue to
keep it free. https://www.patreon.com/astronomerstel
------------------------------------------------------------------------------ 
The Astronomer's Telegram                   http://www.astronomerstelegram.org 
------------------------------------------------------------------------------
Posted: Within the last 24 hours
==============================================================================
ATEL #17487							     ATEL #17487

Title:	C/2025 K1 (ATLAS): Multiple Fragmentation Observed
Author:	M. Serra-Ricart (Light Bridges, IAC, ULL), J. Licandro (IAC,
		ULL), M. R. Alarcon (Light Bridges, IAC, ULL)
Queries:	mserra@iac.es
Posted:	10 Nov 2025; 13:55 UT
Subjects:Optical, Comet

In response to the outburst alert of Comet C/2025 K1 (ATLAS) (telegram
#17482), the TTT3 telescope initiated a monitoring campaign of the comet.
On 2025 November 10, between 04:42 and 05:13 UT, a total of 70 individual
8-s exposures were obtained in the Luminance band, co-added along the cometary
apparent motion and centered on its optocenter. Staked images are shown
in attached figure. For each frame, the observation date and the start
and end times in UTC are shown above the panels, together with the total
number of sidereal-tracking exposures and the cumulative integration time.
The projected velocity vector (red arrow) and the antisolar direction (yellow
arrow) are marked, as well as the image scale and orientation. Red crosshairs
mark the cometary optocenter. Isophotal contours of the original (non-filtered)
images are overplotted using ten logarithmically spaced levels between
the 10th and 80th percentiles of pixel intensity in each frame.

The original non-filtered (sky) image (left panel) clearly shows two components,
corresponding to the comet’s main nucleus (red crosshairs) and a detached
fragment. A Laplace-filtered image of the inner coma (right panel), processed
following Serra-Ricart & Licandro (2015, ApJ, 814, 49), further reveals
a second, fainter fragment, confirming the presence of two distinct fragments
in the central region of C/2025 K1 (ATLAS).

TTT3 is a 2-meter f/6 Ritchey-Chretien telescope, currently in its commissioning
phase. Images were obtained with COLORS, a 2k camera mounted at the Nasmyth
2 focus, equipped with a back-illuminated BEX2-DD CCD sensor, resulting
in a field of view of 7.85 x 7.85 arcsec and a plate scale of 0.23 arcsec/pixel.

TTT (Two-meter Twin Telescope) is operated by Light Bridges in Tenerife,
Canary Islands (Spain). The observation time rights (DTO) used for this
research were consumed in the PEI PLANETIX25. This research used storage
and computing capacity in ASTRO POCs EDGE computing center at Tenerife
under the form of Indefeasible Computer Rights (ICR).

Combined images showing fragments: https://drive.google.com/file/d/12LwIgPCjxW73hBfJy5kJlT02MVJVFMox/view?usp=sharing
------------------------------------------------------------------------------
Password Certification: Miquel Serra-Ricart (mserra@iac.es)
https://www.astronomerstelegram.org/?read=17487
==============================================================================
ATEL #17488							     ATEL #17488

Title:	Fragmentation of C/2025 K1 (ATLAS)
Author:	John Noonan (Auburn University), Dennis Bodewits (Auburn University),
		Colin Snodgrass (University of Edinburgh), Kacper Wierzchos (Lunar
		and Planetary Laboratory), Michael Combi (University of Michigan)
		
Queries:	noonan@auburn.edu
Posted:	10 Nov 2025; 18:31 UT
Subjects:Optical, Comet

We report the possible fragmentation of comet C/2025 K1 (ATLAS) observed
in HST/STIS images obtained at 13:17 and 13:52 UTC on 2025 November 8 as
part of program GO-18135. At the time of observation, the comet was 0.88
au from the Sun, 0.65 au from Earth, and at a phase angle of ~80 degrees.

Following reports of two apparent outbursts between October 31 and November
4 2025 (ATel #17482) that included a smaller event of ~ -0.3 mag around
Oct 31-Nov 1 and a larger event of ~ -0.9 mag detected by Nov 4 relative
to Nov 2, we detect four fragments in the HST data obtained with the MIRVIS
Clear filter (exposure times of 10 s and 42 s). The fragments span ~5.2
arcsec along a position angle of 197 degrees relative to north. The two
leading fragments, separated by 3.6 arcsec, each display parabolic comae,
with the second fragment appearing noticeably brighter than the first.
Two additional fainter fragments are visible farther along the same orientation;
these are diffuse and lack sharply defined comae.

We encourage continued monitoring of C/2025 K1 (ATLAS) to track the evolution
of its morphology and to assess whether additional fragments or renewed
activity emerge in the coming weeks.

------------------------------------------------------------------------------
Password Certification: Dennis Bodewits (dennis@auburn.edu)
https://www.astronomerstelegram.org/?read=17488
==============================================================================

==============================================================================
This is an automatically-generated notice.  You can remove yourself permanently
from receiving both the Daily Email Digest and Instant Email Notices from
The Astronomer's Telegram by following this link:
https://www.astronomerstelegram.org?unsubscribe&confirmation=a803d34e7ea924f9a4142bac00763549&address=stefano@bicar.it

文件操作 - 1762845091.M718515P6559.mail.planetcloud-host.com,S=6910,W=7029:2,

文件: /var/vmail/bicar.it/stefano/cur/1762845091.M718515P6559.mail.planetcloud-host.com,S=6910,W=7029:2,

编辑文件内容

修改文件时间

删除文件