Electronic Telegram No. 5531 Central Bureau for Astronomical Telegrams Mailing address: Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network V7993 SAGITTARII = TCP J18022164-3310319 = NOVA SAGITTARII 2025 No. 3 Stanislav Korotkiy (Astroverty, Ka-Dar astronomy foundation, Moscow), Kirill Sokolovsky (University of Illinois), and Vladimir Belousov report the discovery of a variable star (mag 12.2) on three unfiltered 20-s CCD images obtained on Mar. 24.056 UT with a wide-field camera utilizing a Canon 135-mm- f.l. f/2 telephoto lens as part of the "New Milky Way" (NMW) survey at the Astroverty astrofarm in Nizhnii Arkhyz, Karachay-Cherkessia, Russia. The variable's position was given as R.A. = 18h02m21s.64, Decl. = -33d10'31".9 (equinox J2000.0), and it was assigned the designation TCP J18022164-3310319 when posted to the Central Bureau's TOCP webpage. The variable, which is located near the dark nebula LDN 1762, also shows at mag 12.8 on an image taken with a second NMW camera of the same size on Mar. 24.071. An NMW image of the field obtained on Mar. 15.081 shows nothing at this location brighter than mag 13. An ASAS-SN image taken on Mar. 16.293 shows nothing brighter than g magnitude 15. The NMW discovery images are posted at the following website URL: http://scan.sai.msu.ru/$kirx/img/TCPJ18022164-3310319/. Tadashi Kojima (Tsumagoi, Gunma-ken, Japan) reports his independent discovery of TCP J18022164-3310319 at mag 13.5 on three 4-s frames taken on Mar. 23.764 UT with a Canon EOS 6D digital camera (+ 300-mm-f.l. f/2.8 lens). He provides position end figures 21s.65, 34".0. Nothing was visible at this location on similar images taken on Mar. 9.794 (limiting mag 14.2). K. Yoshimoto, Yamaguchi, Japan, reports that a CMOS image obtained on Mar. 24.834 UT of TCP J18022164-3310319 with a 0.20-m f/8 Ritchey-Chretien reflector yields position end figures 21s.68, 31".8 and the following magnitudes: B = 12.15, V = 11.02, I_c = 9.28. His image is posted at URL http://orange.zero.jp/k-yoshimoto/TCP_J18022164-3310319_20250324.jpg . A. Pearce, Nedlands, Western Australia, reports that CCD imaging of TCP J18022164-3310319 was obtained on Mar. 25.713 UT with the Perth Observatory RCOP 0.35-m f/6 refractor, yielding position end figures 21s.67, 31".9 (reference stars from the Gaia DR3 catalogue) and the following magnitudes: V = 10.62, B = 11.91, R = 9.83, I = 8.94. He adds that he is unable to find any catalogue star closer than 2".6 from the new variable's position. A spectrogram (resolution about 400; range 400-800 nm) obtained on Mar. 24.990 UT by Y. Tampo (South African Astronomical Observatory, University of Cape Town) with the SAAO 1-m Lesedi telescope at Sutherland shows Balmer and He I lines with P-Cyg profiles and He II 468.6-nm emission; the H-alpha absorption minimum indicates a velocity of about 700 km/s, and Tampo suggests cf. website URL http://www.astronomerstelegram.org/?read=17108) that this is indicative of a classical nova. E. Kazarovets (Institute of Astronomy, Moscow) writes that the permanent GCVS designation V7993 Sgr has been assigned to this nova. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2025 CBAT 2025 March 26 (CBET 5531) Daniel W. E. Green