Ahir vaig rebre una nota de l'AAVSO sobre una nova a Sagitari, aquí la teniu:

AAVSO Alert Notice 829
Nova in Sagittarius - V6598 Sgr = N Sgr 2023 No. 3 (= TCP J17525020-2024150)
July 17, 2023

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Time Sensitive Alerts: www.aavso.org/n-sgr-2023-no-3-V-6598-sgr
- Novae: www.aavso.org/n-sgr-2023-no-3-V-6598-sgr-01

Please subscribe to these threads if you are observing this nova so you can be updated as to its behavior and any observing campaigns on it. Join in the discussion or ask questions there!

Event: Nova in Sagittarius - V6598 Sgr = N Sgr 2023 No. 3 (= TCP J17525020-2024150)

Discovered independently by:
- Andrew Pearce (Nedlands, W. Australia)
- Yuji Nakamura (Kameyama, Mie, Japan; reported to CBAT via the National Observatory of Japan)

Discovery magnitude:
- Pearce: 10.3 unfiltered CCD, using Canon 800D digital camera + 85-mm f/1.2 lens
- Nakamura: 9.6: does not give filter, using 135-mm F/4.0 lens +CMOS camera

Discovery date:
- Pearce: 2023 July 15.4590 UT
- Nakamura: 2023 July 15.522 UT

Coordinates (2000.0): R.A. 17 52 49.31 Decl. -20 24 15.4 (from VSX page for V6598 Sgr)

Spectra: Spectroscopy indicating the object to be a nova was obtained by:
- O. Garde et al. (ATel #16135) on 2023 Jul. 15.95 and 16.04 UT using the 2SPOT Alpy600 and eShel spectrographs in Chile. They report that "the source is a classical nova in the early, optically thick stage of expansion."

- G. Masi, on 2023 Jul. 16.867 UT (low resolution) using a 200 lines/mm grating on the 14” robotic unit part of the Virtual Telescope Project facility in Manciano, Italy (CBET 5278).

Observing recommendations: Generally, please observe V6598 Sgr as it continues to evolve, with observations of all types (visual, CCD/CMOS, DSLR, spectroscopy) and multiple bands as instrumentation permits. 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, he 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."

Observations reported to the AAVSO: (selected from 100+ observations submitted)
2023 Jul. 12.455 UT, <12.0 unfiltered CCD (Andrew Pearce, Nedlands, W. Australia);
14.45694, <12.0 unfiltered CCD (Pearce);
14.7775, 13.5 CV +/-0.1 (S. Korotkiy, K. Sokolovsky, and S. Ostapenko, CBET 5278);
14.7929 13.1 CV +/- 0.2 (Korotkiy, et al., CBET 5278);
15.4590, 10.3 unfiltered CCD (discovery image, Pearce);
15.49792, 10.3 (visual confirmation, Pearce);
15.5, 10.5 L filter CMOS (E. Guido, M. Rocchetto, and A. Valvasori, remotely using a Telescope Live instrument in Yess, NSW, Australia, CBET 5278);
15.5215, 9.6: (independent discovery image, Y. Nakamura, does not give filter, 135-mm F/4.0 lens +CMOS camera, CBET 5278);
15.52778, 10.3 (Pearce);
15.53839, 11.872 B +/-0.001 (Pearce);
15.53936, 10.222 V +/-0.023 (Pearce);
15.54015, 9.077 R +/-0.045 (Pearce);
15.54079, 7.821 I +/-0.001 (Pearce);
15.58333, 10.4 (Pearce);
15.59068, 12.116 B +/-0.003 (Pearce);
15.59133, 10.336 V +/-0.002 (Pearce);
15.59183, 9.120 R +/-0.005 (Pearce);
15.59226, 8.227 I +/-0.003 (Pearce);
15.86111, 10.64 TG +/-0.05 (V. Cseh, Debrecen, Hungary);
15.90690, 11.4 (A. Amorim, Florianopolis, Brazil);
16.01662, 12.794 B +/-0.002 (Pearce);
16.01764, 11.399 V +/-0.002 (Pearce);
16.01846, 9.799 R +/-0.001 (Pearce);
16.01921, 8.359 I +/-0.001 (Pearce);
16.11174, 11.530 V +/-0.065 (E. Gomez, Sylva, NC);
16.17458, 8.599 I +/-0.015 (F.-J. Hambsch, remotely in Atacama, Chile)
16.17502, 11.350 V +/-0.008 (Hambsch);
16.17528, 12.898 B +/-0.010 (Hambsch);
16.17597, 10.000 R +/-0.005 (Hambsch);
16.3048, 11.97 B (S. Kiyota, Kamagaya, Japan, remotely using T72, iTelescope.NET (0.5m, F:6.8 CDK) at Deep Sky Chile at Rio Hurtado Valley, Chile, CBET 5278);
16.3048, 10.94 V (Kiyota);
16.3048, 9.58 Rc (Kiyota);
16.3048, 8.35 Ic (Kiyota);
16.46181, 11.9 (Pearce);
16.46890, 13.362 B +/-0.006 (Pearce);
16.46963, 11.782 V +/-0.002 (Pearce);
16.47022, 9.987 R +/-0.001 (Pearce);
16.47064, 8.845 I +/-0.084 (Pearce);
16.65188, 13.419 B +/-0.005 (Pearce);
16.65284, 11.975 V +/-0.003 (Pearce);
16.65363, 10.132 R +/-0.005 (Pearce);
16.65424, 8.812 I +/-0.002 (Pearce);
16.8603, 9.4 R (G. Masi, remotely using CCD+14” robotic unit part of the Virtual Telescope Project facility in Manciano, Italy, CBET 5278);
16.92360, 11.8 (Amorim);
17.06228, 12.628 V +/-0.065 (Gomez);
17.07797, 13.754 B +/-0.004 (Pearce);
17.07892, 12.611 V +/-0.004 (Pearce);
17.07971, 10.518 R +/-0.001 (Pearce);
17.08045, 9.168 I +/-0.001 (Pearce);
17.46870, 13.0 (N. Brown, Yanchep, W. Australia);
17.51156, 13.988 B +/-0.007 (Pearce);
17.51253, 12.680 V +/-0.002 (Pearce);
17.51333, 10.632 R +/-0.001 (Pearce);
17.51398, 9.432 I +/-0.002 (Pearce);

Charts: Charts with comparison stars for V6598 Sgr may be created using the AAVSO Variable Star Plotter (VSP).

Submit observations: Please submit observations using the name V6598 SGR.
- Submit optical observations to the AAVSO International Database using WebObs.
- Submit spectra to the AAVSO Spectroscopy Database (AVSpec).

Notes:
a. Designated TCP J17525020-2024150 when posted to the IAU Central Bureau for Astronomical Telegrams Transient Object Confirmation Page (TOCP). Designated N Sgr 2023 No. 3 in CBAT Central Bureau Electronic Telegram 5278.

b. The progenitor, whose position matches that of the nova, appears to be IGR J17528-2022, an object identified earlier by J. Hare et al. (ApJ, 914, 85 (2021)) as a candidate magnetic cataclysmic variable.

c. Images
- E. Guido, M. Rocchetto, and A. Valvasori (2023 Jul. 15.6422 UT, CBET 5278): tinyurl.com/novasgranim

d. Assigned the permanent GCVS designation V6598 Sgr by E. Kazarovets (CBET 5278).

Congratulations to Andrew Pearce and Yuji Nakamura on their latest discoveries!

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.

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SUBMIT OBSERVATIONS TO THE AAVSO

Information on submitting observations to the AAVSO may be found at:
- Photometry/visual observations: www.aavso.org/webobs
- Spectroscopy: www.aavso.org/apps/avspec/

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