文件操作 - 1760512288.M551402P23931.mail.planetcloud-host.com,S=7671,W=7802:2,

文件: /var/vmail/bicar.it/stefano/cur/1760512288.M551402P23931.mail.planetcloud-host.com,S=7671,W=7802:2,

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  17443, 17444
Message-Id: <20251015071125.4ADED288052D@server.astronomerstelegram.org>
Date: Wed, 15 Oct 2025 03:11:25 -0400 (EDT)

------------------------------------------------------------------------------ 
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 #17443							     ATEL #17443

Title:	NGC 1346 broadband polarization returns to its pre-changing-look
		level
Author:	Frederic Marin (ObAS/France), Svetlana Jorstad (BU/USA), and
		Damien Hutsemekers (AGO/Blegium)
Queries:	frederic.marin@astro.unistra.fr
Posted:	14 Oct 2025; 07:45 UT
Subjects:Optical, AGN, Transient

The radio-quiet active galactic nucleus (AGN) NGC 1346 is known for its
optical spectral evolution, that transitioned from a type-1 (broad and
narrow emission lines observed in its total flux spectrum) to a type-2
classification (narrow emission lines only) somewhere between 2001 and
2018 (Senarath et al. 2019). The exact moment the source "changed of look"
was, unfortunately, not caught by any telescope. In November 23, 2022,
1.83 m Perkins polarimetric measurements revealed that the source was still
in a type-2 spectral state, based on its R-band polarization level : P_debiased
= 2.95% +/- 0.86% and Theta = 155.6deg +/- 8.0deg (Perkins Telescope Observatory,
Flagstaff, AZ, USA). VLT/FORS2 observations carried out on August 12 and
September 4, 2024, discovered that NGC 1346 changed back to its former
type-1 classification: broad Balmer lines reappeared in its total flux
spectrum and its continuum polarization drastically diminished (P_debiased
= 0.15% +/- 0.01% and Theta = 165.7deg +/- 2.6deg in August, and P_debiased
= 0.09% +/- 0.01% and Theta = 175.8deg +/- 4.1deg in September). Perkins
polarimetric measurements on March 25, 2025 confirmed, based on the observed
R-band polarization (P_debiased = 0.42% +/- 0.35%, Theta = 168.1deg +/-
18.2deg) that the source stayed in a type-1 state (Marin, Hutsemékers
& Jorstad 2025).

Here, we report new Perkins polarimetric measurements obtained on September
24 and 25, 2025 in the R-band, showing that NGC 1346's polarization returned
to its pre-changing-look level, indicating that the AGN most certainly
transitioned back to its type-2 spectral classification. The Perkins telescope
used the PRISM camera equipped with a polaroid (POL-HN38) and a R-band
filter (lambda_eff = 6407 Angs). The polarimetric observations involved
four series of Stokes parameters (I, Q, and U measurements). A series consists
of four observations of the polaroid at instrumental position angles of
0deg, 90deg, 45deg, and 135deg, with an exposure of 120 seconds at each
position angle. The Q and U parameters were averaged over the series to
calculate the degree of polarization, P, and position angle of polarization,
Theta, and their uncertainties. The images were corrected for bias and
flat field. We used field stars to perform both interstellar and instrumental
polarization corrections. During the observations, the seeing was 2.5 arcseconds
at an airmass of 1.3.

The observed R-band magnitude is 14.285 +/- 0.006 on both September 24
and 25. The debiased polarization (following Simmons & Stewart 1985) is
3.72% +/- 0.14% at Theta = 142.5 +/- 1.0deg on September 24, and 3.13%
+/- 0.77% at Theta = 120.0deg +/- 6.1deg on September 25. Such high values
correspond to the 2022's polarization, when the source was still classified
as a type-2. We thus conclude that NGC 1346 has likely undergone another
changing-look event that would require swift new spectropolarimetric observation
to understand what is the underlying phenomenon at work.

------------------------------------------------------------------------------
Password Certification: Frederic Marin (frederic.marin@astro.unistra.fr)
https://www.astronomerstelegram.org/?read=17443
==============================================================================
ATEL #17444							     ATEL #17444

Title:	A descriptive title
Author:	 G. J. M. Luna (UNAHUR/CONICET/Argentina), K. L. Page (U.
		Leicester), K. Sokolovsky (TTU)
Queries:	CorrespondingAuthor&#39;sEmailAddress
Posted:	14 Oct 2025; 14:05 UT
Subjects:Ultra-Violet, X-ray, Nova

Nova Cen 2025 (V1935 Cen/PNV J14372177-5847400) was reported in outburst
when it reached magnitude 6.2 on 2025-09-22.396 UT (discovered by John
Seach). Fermi-LAT detected the nova on 2025-09-21.50, prior to the optical
discovery (ATel #17414). An early Swift/XRT observation reported by Sokolovsky
et al. (Atel #17418) detected bright, hot and hard X-ray emission that
most likely arose from shocks between the fast ejecta and the red giant
wind of the cold companion.

The recent observation with Swift/XRT in PC mode on October 9th yielded
not only the detection of the aforementioned hard X-ray emission but also
a soft component. The composite spectrum can be modeled with a blackbody-like
component with kT = 40 +9/-7 eV plus a single optically thin thermal plasma,
APEC, with kT = 1.06 +/- 0.07 keV, both absorbed through a column NH =
(7.2 +2.4-2.5)e21 cm^-2. The observed flux in the 0.3-10 keV energy range
was 1.4e-11 erg cm^-2 s^-1. The UVOT telescopes measure a UVW2 magnitude
of 11.06+/-0.06.

We thank the Swift PI, Brad Cenko, and his deputies for approving the time,
as well as the Swift planning and operations teams for their continuing
support.

------------------------------------------------------------------------------
Password Certification: Gerardo Juan Manuel Luna (juan.luna@unahur.edu.ar)
https://www.astronomerstelegram.org/?read=17444
==============================================================================

==============================================================================
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 - 1760512288.M551402P23931.mail.planetcloud-host.com,S=7671,W=7802:2,

文件: /var/vmail/bicar.it/stefano/cur/1760512288.M551402P23931.mail.planetcloud-host.com,S=7671,W=7802:2,

编辑文件内容

修改文件时间

删除文件