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To: stefano@bicar.it
From: atel@astronomerstelegram.org
Subject: ATel  17844, 17845, 17846
Message-Id: <20260616070739.3CF7228808B7@server.astronomerstelegram.org>
Date: Tue, 16 Jun 2026 03:07:39 -0400 (EDT)

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Posted: Within the last 24 hours
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ATEL #17844							     ATEL #17844

Title:	MeerKAT radio non-detection of the X-ray transient EP260531a
Author:	F. J. Cowie (University of Oxford), I. Heywood (University
		of Oxford and Rhodes University), R. Fender (University of Oxford
		and University of Cape Town), S. Motta (INAF-OAB) for the X-KAT collaboration
Queries:	fraser.cowie@physics.ox.ac.uk
Posted:	15 Jun 2026; 12:48 UT
Subjects:Radio, X-ray, Binary, Black Hole, Neutron Star, Transient

prova prova prova

ATel #17828 reported the discovery of EP260531a, a new X-ray transient
steadily increasing in flux from May 31st to June 3rd 2026. ATel #17833
reported a refined localisation and continued brightening on June 4th 2026.
ATel #17840 identified a potential NIR counterpart to the X-ray transient.
The low galactic latitude, X-ray properties, and candidate NIR counterpart
of the source suggested a potential X-ray binary nature, and so we triggered
follow-up radio observations with the MeerKAT telescope as part of the
X-KAT program.

The field of EP260531a was observed for 10 minutes on June 7th starting
at 20:12:49 UT  (MJD 61198.8422). Observations were carried out at a central
frequency of 1.28 GHz, with a total (un-flagged) bandwidth of 856 MHz.
PKS B1934-638 was used for flux and bandpass calibration, while J1830-3602
was used for complex gain calibration. No radio source was detected within
the 10 arcsecond error circle of the X-ray position (ATel #17833). Given
the RMS within this region of ~50 &mu;Jy/beam, we report a 3-sigma upper
limit of ~150 &mu;Jy for the flux density of the source at 1.28 GHz. Further
radio observations are planned.

X-KAT is a large MeerKAT open-time programme to observe X-ray binaries
in the radio band, performing weekly monitoring of bright, active systems,
with capacity for higher cadence observations, and in coordination with
large X-ray and optical monitoring programmes. For further information
on this programme contact Rob Fender.

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Password Certification: Sara Elisa Motta (sara.motta@physics.ox.ac.uk)
https://www.astronomerstelegram.org/?read=17844
==============================================================================
ATEL #17845							     ATEL #17845

Title:	Spectroscopic Classification of Astrophysical Transients with
		the Lick Shane Telescope
Author:	K. W. Davis, R. J. Foley (UCSC)
Queries:	kywdavis@ucsc.edu
Posted:	15 Jun 2026; 17:58 UT
Subjects:Optical, Supernovae

We report the classifications of astrophysical transients from spectroscopic
observations with the Kast spectrograph on the Shane telescope obtained
on 2026 June 15 UT. The targets were supplied by YSE and ATLAS. Targets
were identified using the target management platform YSE-PZ (Coulter et
al., 2023, PASP, 135, 4501). The classifications were performed with SNID
(Blondin & Tonry, 2007, ApJ, 666, 1024).

Name         | IAU Name   | RA (J2000)   | Dec (J2000)  |   z    | Type
| Phase | Notes 
PS26bdm      | AT2026kwm  | 15:36:03.770 | +49:35:13.82 | 0.0379 | SN II
| +50d  | (1) 
ATLAS26gyu   | AT2026ore  | 15:44:29.671 | +21:00:58.54 | 0.0603 | SN Ia
|  -3d  | (2)

Notes: 
When the redshift is given to 2 decimal places, it is derived from the
SN spectrum. Otherwise, the redshift is determined from the host galaxy.

(1) We Measure a H-alpha absorption velocity of -7,700 km/s. 
(2) We measure a Si II 6355 absorption velocity of -11,800 km/s.

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Password Certification: Ryan Foley (foley@ucsc.edu)
https://www.astronomerstelegram.org/?read=17845
==============================================================================
ATEL #17846							     ATEL #17846

Title:	Discovery of a Bright Probable Nova in M81, M81N 2026-06a
Author:	K. Hornoch, H. Kucakova (Ondrejov), A. W. Shafter (SDSU)
Queries:	k.hornoch@centrum.cz
Posted:	15 Jun 2026; 20:45 UT
Subjects:Optical, Nova, Transient

We report the discovery of a bright probable nova in M81 on a co-added
5220-s unfiltered CMOS frame taken on 2026 Jun. 13.933 UT with the 0.65-m
telescope at Ondrejov under poor seeing conditions.

The object designated as M81N 2026-06a = PNV J09552128+6902526 is located
at R.A. = 9h55m21s.28, Decl. = +69o02'52".6 (equinox 2000.0), which is
63.8" west and 62.5" south of the center of M81 (see link to discovery
image below).

Here we list the observing dates and corresponding photometry:

<span class="inner-pre" style="font-size: 13px"> 
Date [UT]    |  Mag   | Err  | Filter  | Telescope

2026-05-29.854 | >20.5  |      | C       | OND 
2026-06-13.933 |  18.9  | 0.1  | C       | OND

</span>

As with all extragalactic novae, follow-up spectroscopic and photometric
observations to determine the nova's spectroscopic class and rate of decline
(speed class) are encouraged. The OND 0.65-m is a reflecting telescope
at the Ondrejov observatory operated jointly by the Astronomical Institute
of ASCR and the Astronomical Institute of the Charles University of Prague,
Czech Republic. It uses a Moravian Instruments C3-61000EC PRO CMOS camera
(with a SONY IMX455 sensor and VRIH_alpha photometric filters) mounted
at the prime focus. The unfiltered OND photometry was calibrated against
R-band comparison stars from 
<a href="http://adsabs.harvard.edu/abs/1995AJ....109.1055P">Perelmuter
& Racine (1995)</a>.

Discovery image: http://www.asu.cas.cz/~asteroid/M81N2026-06a.png
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Password Certification: Allen W. Shafter (ashafter@sdsu.edu)
https://www.astronomerstelegram.org/?read=17846
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