Nova in Sgr: V7993 Sgr = N Sgr 2025 No. 3 = TCP J18022164-3310319
Abstract:
V7993 Sgr (N Sgr 2025 No. 3 = TCP J18022164-3310319) was independently discovered by the NMW survey (Stanislav Korotkiy, Kirill Sokolovsky, Vladimir Belousov reporting for NMW team, Nizhnii Arkhyz, Karachay-Cherkessia, Russia) and by Tadashi Kojima (Tsumagoi, Gunma-ken, Japan). NMW DETAILS: 2025 Mar. 24.0555 UT, 12.2 unfiltered CCD. Second NMW camera on Mar. 24.0714 UT, 12.8 unfiltered +/-0.2. Mar. 15.081 UT image <13. KOJIMA DETAILS: 2025 Mar. 23.7635 UT, 13.5 unfiltered. Mar. 09.794 UT images <14.2. ADDITIONAL PHOTOMETRY: Mar 24.834 UT, 12.15B, 11.02V, 9.28Ic (K. Yoshimoto, Yamaguchi, Japan); Mar. 25.713, 11.91B, 10.62V, 9.83R, 8.94Ic (A. Pearce, Nedlands, Western Australia). Pearce notes no catalog star found within 2.6". For more data see Notes. SPECTROSCOPY by Y. Tampo (SAAO, U. Capetown) using SAAO 1-m Lesedi telescope on Mar 24.990 UT shows a classical nova (ATel #17108). NOTES: Located near dark nebula LDN 1762. Information from CBET 5530. Additional notes see Justification.
Justification:
The AAVSO is requesting coverage of this nova with observations of all types (visual, CCD/CMOS, DSLR, spectroscopy) and in all filters as it evolves. All novae are worthy of as good coverage as possible for as long as possible to support research on novae being carried out now and in the future. Spectroscopy is also encouraged where possible. See sections below for cadence and other observing recommendations. ADDITIONAL NOTES: There is a very nearby 14.1 star; see Comparison and check stars below. E. Kazarovets (Inst. of Astronomy, Moscow) reports assignment of the GCVS name V7993 Sgr. Instrumentation: NMW cameras used (135-mm+unfiltered ST-8300M CCD). Kojima used Canon EOS 6D+300mm f/2.8 lens. Images: NMW - http://scan.sai.msu.ru/$kirx/img/TCPJ18022164-3310319/ ; Yoshimoto - http://orange.zero.jp/k-yoshimoto/TCP_J18022164-3310319_20250324.jpg. ATel #17108 link: https://www.astronomerstelegram.org/?read=17108 . Except for spectroscopy, information in this observing campaign was taken from IAU CBET 5530 (Daniel W. E. Green, editor); additional details may be found there. More photometry reported to the AAVSO (all F.-J. Hambsch, Mol, Belgium): 2025 Mar. 26.41628 UT, 8.792 I +/-0.006; 26.41645, 8.810 I +/-0.006; 26.41672, 12.042 B +/-0.005; 26.41700, 12.036 B +/-0.005; 26.41729, 10.651 V +/-0.003; 26.41751, 10.636 V +/-0.003.
Requested Data Types:
Spectroscopy, Photometry
Targets
| Name | Magnitude | Variability Type | Photometry Notes | Spectroscopy Notes |
|---|---|---|---|---|
| TCP J18022164-3310319 | 11.02 | N |
Cadence: Custom Precision: 100 |
Cadence: Custom Resolution: 250 Desired SNR: 100 |
Spectroscopy Lines:
H-beta (4861.0 Å), H-alpha (6563.0 Å)
Photometry Filters:
B (Johnson), V (Johnson), R (Cousins), u (Sloan), r (Sloan), i (Sloan), z (Sloan), Other (Please Specify)
Comparison Stars:
Finder charts with comparison stars may be created using the AAVSO Variable Star Plotter (VSP, https://apps.aavso.org/vsp/). NOTE: There is a 14.1 star extremely close to the position of the nova. The AAVSO 'F' scale chart most clearly shows the relative positions. Observers are recommended to have a copy of this chart on hand (in addition to whatever scales are needed for their instrumentation) so as to clearly identify the two stars, especially as the nova fades. Observers are also reminded that the nova is located near the dark nebula LDN 1762.
Co-Authorship
Observers are not eligible for co-authorship.
Additional Observer Input:
Frequency of observation depends on the rate of decline, but Dr. Fred Walter (Stony Brook University) recommends a minimum of one observation per night per band. For spectroscopy, Dr. Walter recommends spectra in blue to observe He II 4686, H-beta, and the Bowen blend (4640A), in addition to H-alpha. Cadence for spectra depends on how fast the nova continues to evolve, but, he adds, "you can't go wrong with a spectrum every clear night." Former AAVSO Spectroscopy Section co-leader Lauren Herrington adds: "Slitless spectra would also be valuable; spectra with resolution as low as R=100 are useful to track broad changes in emission as the nova evolves."
Additional Submission Location:
Not provided
Notes:
No public notes