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To: stefano@bicar.it
From: atel@astronomerstelegram.org
Subject: ATel  17939, 17940, 17941
Message-Id: <20260805070745.AB24E28807CA@server.astronomerstelegram.org>
Date: Wed,  5 Aug 2026 03:07:45 -0400 (EDT)

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ATEL #17939							     ATEL #17939

Title:	Multi-band photometric observations of TCP J00560713+4301406
		/  ASASSN-26dq in superoutburst
Author:	W. Skrobacz (U. Warsaw, PL), L. Wyrzykowski (U. Warsaw/NCBJ,
		PL/EASST. eu),  J. Kolar (U. Masaryk, CZ/UMK, PL), K. Siennicki (U.
		Warsaw, PL)
Queries:	weronikaskrobacz@gmail.com
Posted:	4 Aug 2026; 13:49 UT
Subjects:Optical, Cataclysmic Variable

The BHTOM.space network coordinated an observing campaign to monitor the
superoutburst of 
TCP J00560713+4301406 dwarf nova candidate, first detected on June 1, 2026,
by NMW- 
TexasTech survey (Sokolovsky et al.).

Follow-up observations were commenced on June 7, 2026, approximately six
days after initial 
discovery, and are still ongoing. The main superoutburst phase has already
ended, and now we 
are continuing to monitor the object in order to detect a rebrightening.

According to BHTOM photometric data, the superoutburst had an amplitude
of approximately 7 
mag and a duration of about one month. These features of a superoutburst
are typical for WZ 
Sge-type dwarf nova.

During the period from 7 to 27 June 2026, our follow-up campaign obtained
approximately 50 
photometric measurements with three instruments: 50-mm Seestar telescope,
MUO Ždánice 
80-cm telescope and Ostrowik 60-cm Cassegrain Telescope. Photometric data
were collected 
in B, V, R and I filters as well as in Sloan g’ and r’ bands and transformed
into Gaia

Synthetic Photometry (GaiaSP). The dataset for TCP J00560713+4301406 was

complemented by photometric observations from the ATLAS survey and. Additionally,
archival 
measurements from ATLAS, ZTF, PTF, PS1 and WISE provided coverage over
the 2012-2026 
period.

The morphological study of the superoutburst already allows us to suggest
that this object is a 
WZ Sge-type dwarf nova. Spectroscopic observations would be valuable to
confirm the 
proposed classification of this object. Photometric observations of the
object with BHTOM will 
continue until the end of the rebrightening phase.

BHTOM is based on the open-source TOM Toolkit by LCO and has been developed
with 
funding from the OPTICON-RadioNet Pilot (ORP) of the European Union's Horizon
2020 
research and innovation programme under grant agreement No 101004719 (2021-2025).
This 
project has received funding from the European Union's Horizon Europe Research
and 
Innovation programme ACME under grant agreement No 101131928 (2024-2028).

Target&#39;s page in BHTOM with all photometry: https://bhtom.space/public/targets/TCP%20J00560713+4301406
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Password Certification: Lukasz Wyrzykowski (wyrzykow@astrouw.edu.pl)
https://www.astronomerstelegram.org/?read=17939
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ATEL #17940							     ATEL #17940

Title:	Opportunities of solar astrometry with the Spanish solar eclipse
		of 12 August 2026
Author:	Costantino Sigismondi (ICRANet, Pescara and UPRA, Roma)
Queries:	sigismondi@icra.it
Posted:	4 Aug 2026; 15:00 UT
Subjects:Optical, The Sun

The Total Solar Eclipse of 12 August 2026 is an occasion to measure the
solar diameter to the nearest hundredth of arcsecond, by exploiting the
Baily's beads timing. 
The Baily's beads were discovered in 1842.  
We need to gather, as Edmond Halley did in the Total Solar Eclipse of 1715
over England, the positions and the timing of totality (nowadays continuous
videos) of the observers the forthcoming Eclipse in Spain.

Telescopic videos with 50x magnification may contain informations on tens
of Baily's beads, while through smartphones without additional optics it
is possible to record the two beads dis/appearing on t2 and t3, delimiting
the totality's darkness.

The accuracy of 0.01 arcsec allows to better understand the solar activity,
also on secular basis thanks to historical measures.

The most accurate results are obtained by making the camera fixed: steady
images video are recommended, and "street tests" can be done by exploiting
suspendend street-lamps as occultating disks (ATel#15991).

The best locations for Baily's beads are at the Northern or Southern limits
of the eclipse shadow's path. The geometrical effects are there enhanced,
and the irregularities of the lunar limb interrupt the crescent of the
photospheric light, producing a sequence of beads where the Moon grazes
the  
Sun.

The higher number of beads is expected at the southern limit of the shadow
(e.g. Madrid) because the lunar South pole is rich of craters and high
mountains. Less beads will appear at the Northern limit (e. g. Bilbao)
because of a smoother lunar North pole. The whole phenomenon encompasses
up to three minutes of time.

Very limited by geometry is the situation about the beads on the centerline
(e. g. Valladolid): they will appear suddendly just before and after the
totality for a few seconds, and they require a telescopic vision/recording.

Steady videos obtained through smartphones can be also helpful to integrate
our data, since they might be indeed better than the manual timings of
the past centuries. The Ghost Images (ATel#15991) of the eclipsing Sun
may contain some beads, and it is worth to prepare in advance the pointing
of the smartphone in order to have the ghost image, instead to avoid it.

Summarizing: we need of geolocation of the observers and a continuous video
for a trustable relative timing of all the totality and the minutes before
and after it. 
The choice of the observing location and the check if this point is expected
to be near the shadow's bands, where the beads phenomena are more enhanced.

Astronomical Observtories on the eclipse path are kindly invited to contact
the author: the recording strategies may be improved. All videos received
will be credited in the science paper after the eclipse.

Interactive eclipse map for 12 August 2026 (X. Jubier): http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2026_GoogleMapFull.html?Lat=41.00000&amp;Lng=-3.00000&amp;Zoom=3&amp;LC=1
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Password Certification: Costantino Sigismondi (sigismondi@icra.it)
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ATEL #17941							     ATEL #17941

Title:	M31N 2026-08a is the third reported eruption of the recurrent
		nova M31N 2006-11c
Author:	K. Hornoch (Ondrejov), F. Castellani (Monte Baldo Observatory,
		Italy), A. W. Shafter (SDSU), P. Zasche (Charles U.)
Queries:	k.hornoch@centrum.cz
Posted:	4 Aug 2026; 23:27 UT
Subjects:Optical, Nova, Transient

F. Castellani et al. reported the discovery of a probable nova in M31.
The nova, designated as AT 2026wvv, was detected on a co-added 3600-s unfiltered
CCD image taken with a 0.40-m f/7 Dall-Kirkham telescope at Monte Baldo
Observatory, Ferrara di Monte Baldo, Verona, Italy. F. Castellani et al.
pointed out that the object is located only 0.68" from the position of
the 
recurrent nova M31N 2006-11c (see ATel #7113, ATel #7116, ATel #7142, and
ATel #7158) and that it is likely another eruption of the known recurrent
nova.

Following the standard CBAT designation scheme we designate the object
AT 2026wvv as M31N 2026-08a.

To confirm a spatial coincidence of M31N 2026-08a with M31N 2006-11c =
2015-02b, we carefully registered a co-added 780-s R-band CMOS image of
M31N 2026-08a taken on 2026 Aug. 3.867 UT with the 0.65-m telescope at
Ondrejov with a co-added 600-s R-band CCD image of M31N 2015-02b taken
on 2015 Feb. 19.733 UT with the same telescope. The comparison image (see
the link to the image below) clearly demonstrates the spatial coincidence
of both objects to of order 0.5".

The probability of a chance positional coincidence of two unrelated novae
with observed separation s ~ 0.5" at this position in M31 (semi-major axis
of a=19.8' from the nucleus) is p=0.0003. We conclude that M31N 2026-08a
is indeed the third reported eruption of the recurrent nova M31N 2006-11c.

The interval between the first two observed eruptions was ~8.2 yr and that
between the second and the third observed eruption is ~11.5 yr. Assuming
that we did not miss any eruptions since 2006, the mean recurrence period
is ~9.9 &plusmn; 2.3 yrs.

We also report photometry of the current eruption obtained using the 0.40-m
telescope at Monte Baldo (MBO) and the 0.65-m telescope at Ondrejov (D65):

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

2026-08-02.891 |  17.1  | 0.2  | Unfiltered | MBO 
2026-08-03.867 |  18.15 | 0.1  | R          | D65 
2026-08-03.888 |  18.6  | 0.3  | Unfiltered | MBO 
2026-08-04.870 |  18.9  | 0.3  | Unfiltered | MBO 
2026-08-04.898 |  18.8  | 0.15 | R          | D65

</span>

Comparison Image: M31N 2015-02b (white); M31N 2026-08a (black): http://www.asu.cas.cz/~asteroid/M31N2015-02b_vs_M31N2026-08a.png
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