Electronic Telegram No. 5603
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
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Prepared using the Tamkin Foundation Computer Network


V4371 OPHIUCHI = NOVA OPHIUCHI 2025 = TCP J17301230-2753488
     Tadashi Kojima, Tsumagoi, Gunma-ken, Japan, reports his discovery of an
apparent nova (mag 12.5) on three unfiltered 4-s exposures taken on Sept.
5.433 UT with a Canon EOS 6D digital camera (+ 300-mm-f.l. f/3.2 lens).  His
measured position is R.A. = 17h30m12s.30, Decl. = -27d53'48".8 (equinox
J2000.0), and when he posted it to the Central Bureau's TOCP webpage, the
variable was automatically designated TCP J17301230-2753488.  Nothing is
visible at this position on Kojima's imaging on Aug. 30.461 with the same
instrument (limiting mag 13.0).
     A pre-discovery CCD image taken of TCP J17301230-2753488 on Sept. 5.406
UT by K. Itagaki (Yamagata, Japan) with a 180-mm-f.l. f/2.8 camera lens shows
the variable at mag 10.9.  Itagaki has posted an image taken on Sept. 5.438 at
website URL http://k-itagaki.jp/images/Oph-25-09.jpg.
     K. Yoshimoto, Yamaguchi, Japan, reports the following magnitudes for TCP
J17301230-2753488 from CCD images obtained on Sept. 8.126 UT with a 0.43-m
f/6.8 reflector located at the Utah Desert Remote Observatory (near Beryl
Junction, UT, USA):  B = 12.85, V = 10.83, I = 8.31.  Yoshimoto has posted an
image at http://orange.zero.jp/k-yoshimoto/TCP_J17301230-2753488_20250908.jpg.
     A. Pearce, Nedlands, Western Australia, reports position end figures
12s.28, 49".3 from CCD imaging obtained on Sept. 8.617 UT with a 0.35-m f/6
RCOP telescope at Perth Observatory (Gaia DR2 catalogue comparison-star
positions).  He notes that TCP J17301230-2753488 is located 0".4 from the
Pan-STARRS DR1 catalogue star 74522625511123781 (which has no magnitude given
but is presumably fainter than 20th magnitude); the variable is laos 1".4 from
the star Gaia DR3 4061213018095504128 (G magnitude 20.6).  Pearce provides
the following magnitudes for TCP J17301230-2753488 from Sept. 8.617:  B =
12.63, V = 11.04, R = 9.80, I = 8.60.
     Kojima adds that Mitugu Fujii (Okayama, Japan) obtained spectroscopy of
TCP J17301230-2753488 on Sept. 6.423 UT at the Fujii Kurosaki Observatory
using a 0.4-m telescope (+ NLS-II spectrograph; resolution ~ 1000).  Emission
lines of H-alpha and H-beta with P-Cyg profiles are present, with the H-alpha
absorption component showing a blueshift of 1600 km/s.  In addition, diffuse
interstellar bands at 578.0, 579.7, and 628.3 nm are detected, and the
continuum is strongly reddened.  These features are characteristic of a nova.
The spectrum has been posted at the following website URL:
https://otobs.org/FBO/fko/n/tcp_j1730123-2753488/tcp_j17301230-2753488.htm.
     E. Kazarovets writes that the permanent GCVS designation V4371 Oph has
been assigned to TCP J17301230-2753488.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2025 CBAT
2025 September 8                 (CBET 5603)              Daniel W. E. Green