Electronic Telegram No. 5587
Central Bureau for Astronomical Telegrams
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V691 SERPENTIS = NOVA SERPENTIS 2025 = TCP J18385851-0351482
     Kirill Sokolovsky, Department of Astronomy, University of Illinois;
Stanislav Korotkiy, Astroverty and Ka-Dar, Karachay-Cherkessia, Russia;
and Vladimir Belousov, New Milky Way Survey (NMWS), report the discovery of a
nova (mag 12.0) on July 17.9085 UT in unfiltered wide-field images obtained
with a 135-mm-f.l. f/2 telephoto lens (+ STL-8300M CCD) in the course of the
NMWS at the Astroverty astrofarm in Nizhnii Arkhyz, Karachay-Cherkessia.  The
position of the variable was given as R.A. = 18h38m58s.51, Decl. = -3d51'48".2
(equinox J2000.0), and it was automatically assigned the designation TCP
J18385851-0351482 when they posted it to the Central Bureau's TOCP website.
Nothing brighter than mag about 14 is visible at this position in the previous
NMWS image obtained on July 15.8055.  The plate-solved FITS images and finder
charts are posted at http://scan.sai.msu.ru/~kirx/img/TCPJ18385851-0351482/.
Sokolovsky adds that pre-discovery images were found via the "All-Sky
Automated Survey for SuperNovae" (ASAS-SN) and the "Zwicky Transient Facility"
(ZTF) survey with the 1.2-m Schmidt telescope at Palomar, with the variable
at the following g-band magnitudes:  July 12.174, [15.9 (ASAS-SN); 15.986,
15.8 (ASAS-SN); 17.009, 14.6 (ASAS-SN); 17.233, 14.4 (ZTF).  The ZTF imagery
yielded the following position end figures:  58s.47, 49".5.  A second NMWS
camera (with STL-11000M CCD) found TCP J18385851-0351482 at unfiltered mag
12.1 on July 18.004.
     A. Pearce, Nedlands, Western Australia, reports unfiltered mag 12.0 and
position end figure 58s.47, 49".2 (Gaia DR3 comparison stars) from a CCD image
obtained on July 19.078 UT with a Skygems Observatory 0.45-m f/4 reflector in
Namibia.  Pearce notes that there appears to be no obvious progenitor within
4".5 of that position.
     A. Amorim (Florianopolis, Brazil) reports visual mag about 12.0 for TCP
J18385851-0351482 on July 19.013 UT using a 90-mm-f.l. f/10 refractor
(Tycho-2 catalogue star magnitudes for reference from the AAVSO).
     Spectroscopy (resolution about 1300; range 355-745 nm) obtained on July
18.846 UT by the discoverers and other colleagues with the 2.5-m telescope at
the Caucasian Mountain Observatory of the Sternberg Astronomical Institute
shows a red continuum and P-Cyg lines (including H-alpha and H-beta, the
former having a peak-to-trough velocity of about 560 km/s), along with Fe II
multiplets.  The spectrum appears to be that of a classical nova before
maximum with interstellar reddening, and photometry shows the red colors;
details are possted at URL https://www.astronomerstelegram.org/?read=17292.
     E. Kazarovets (Institute of Astronomy, Moscow) writes that the permanent
GCVS designation V691 Ser has been assigned to this new nova.


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

                         (C) Copyright 2025 CBAT
2025 July 21                     (CBET 5587)              Daniel W. E. Green