Alert Notice 739: Nova in Sagittarius: N Sgr 2021 No. 2 = PNV J17581670-2914490 [V6595 Sgr]

Note:  N Sgr 2021 No. 2 has been given the permanent GCVS name V6595 Sgr. 

April 6, 2021

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Time Sensitive Alerts: https://www.aavso.org/pnv-j17581670-2914490-possible-nova-sagittarius
- Novae: https://www.aavso.org/n-sgr-2021-no-2-pnv-j17581670-2914490

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: N Sgr 2021 No. 2 = PNV J17581670-2914490

Discovered by: Andrew Pearce (Nedlands, W. Australia)

Discovery magnitude: 8.4 unfiltered CCD, using Canon 1100D digital camera + 100-mm f/2.8 lens

Discovery date: 2021 April 04.825 UT

Coordinates (2000.0): R.A. 17 58 16.08   Decl. -29 14 56.6  (from VSX page for N Sgr 2021 No. 2)

Spectra: Spectra indicating the object to be a classical nova have been obtained by multiple researchers, including:
 - K. Taguchi et al. (ATel #14513), on 2021 Apr. 05.828 UT using the fiber-fed integral field spectrograph mounted on the 3.8-m Seimei telescope at Okayama Observatory (Kyoto University). They report the spectrum resembles that "of the slow nova V1280 Sco [N Sco 2007] in the early stage".
 - Global Jet Watch project team, on 2021 Apr. 05.317 UT using its telescope in Chile and confirmed by later observations at its telescope in India (TOCP).

Observing recommendations: Please observe N Sgr 2021 No. 2 as it continues to evolve, with observations of all types (visual, CCD, DSLR, PEP, spectroscopy) and multiple bands as instrumentation permits. Dr. Fred Walter (Stony Brook University) recommends observations every few hours in the early stages as the nova continues to brighten. Frequency of observation once past peak depends on the rate of decline, but should be 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, with a cadence of one spectrum per clear night.

Observations reported to the AAVSO:
2021 Mar. 30.251 UT, <14.9 g (ASAS-SN Sky Patrol, via P. Schmeer, Saarbruecken-Bischmisheim, Germany, via TOCP; saturated due to reddening);
Apr. 02.657, <13.0 unfiltered CCD (R. McNaught, Coonabarabran, NSW, Australia, TOCP);
02.715, <12.0 unfiltered CCD (McNaught);
02.776, <11.0 unfiltered CCD (McNaught);
04.639, 8.9 unfiltered CCD (McNaught, confirming image);
04.717, 9.0 unfiltered CCD (McNaught);
04.799, 9.1 unfiltered CCD (McNaught);
04.825, 8.4 unfiltered CCD (Pearce, discovery image);
04.85694, 8.8 (Pearce);
04.88264, 8.8 (Pearce);
05.12431, 8.4 (C. Adib, Porto Alegre, Brazil);
05.13194, 8.1 (L. Araujo, Pelotas, Brazil);
05.13889, 8.3 (W. De Souza, Sao Paulo, Brazil);
05.14236, 8.2 (A. Padilla Filho, Rio de Janeiro, Brazil);
05.1577, 8.3 unfiltered CCD (F. Kugel, Banon, France, TOCP);
05.16785, 8.3 unfiltered CCD (BraTS team, SONEAR Observatory, via Oliveira, Brazil (TOCP);
05.21042, 8.2 (J. De Souza Aguiar, Campinas, Brazil);
05.292, 8.98 g (ASAS-SN, via Schmeer; saturated due to reddening);
05.35406, 8.081 V +/-0.01 (C. Colesanti, Sao Paulo, Brazil);
05.36875, 8.0 (A. Amorim, Florianopolis, Brazil);
05.4188, 6.82 Ic (Kiyota);
05.4188, 8.02 V (Kiyota;
05.4188, 9.03 B (S. Kiyota, Kamagaya, Japan, with 0.25m Reflector + ST-10XME CCD at Mayhill, USA (T5, iTelescope.NET), via TOCP);
05.460, 9.01 g (ASAS-SN, via Schmeer; saturated due to reddening);
05.4747, 8.02 V (R. Fidrich, Budapest, Hungary, using a 0.25m reflector 0.25m Reflector + ST-10XME CCD at Mayhill, USA (T5, iTelescope.NET));
05.4772, 9.07 B (Fidrich);
05.48262, 8.083 V +/-0.014 (Pearce);
05.48355, 9.158 B +/-0.022 (Pearce);
05.48420, 6.503 I +/-0.078 (Pearce);
05.48479, 8.035 V +/-0.004 (Pearce);
05.48551, 9.188 B +/-0.025 (Pearce);
05.679, 8.1 unfiltered CCD (McNaught);
05.74792, 8.0 (Pearce);
05.769, 7.8 unfiltered CCD (McNaught);
05.81250, 7.7 (F. Romanov, Yuzhno-Morskoy, Nakhodka, Russia);
05.81796, 7.97 TG +/- 0.05 (Romanov);
06.12153, 8.0 (Padilla Filho);
06.16944, 8.0 (C. da Silva, Minas Gerais, Brazil);
06.22222, 7.9 (De Souza);
06.35694, 7.9 (Araujo);
06.40625, 7.9 (L. Shotter, Uniontown, PA);

Charts: Charts with comparison stars for N Sgr 2021 No. 2 may be created using the AAVSO Variable Star Plotter (VSP). Comparison stars are available for use now, when the nova is bright; fainter comparison stars are being selected and will be available when the nova fades.

Submit observations: Please submit observations using the name N SGR 2021 NO. 2. Be sure to include spaces in the name as shown. When a GCVS permanent name is assigned to the nova, please use that when submitting observations.
 - Submit optical observations to the AAVSO International Database using WebObs (see below).
 - Submit spectra to the AAVSO Spectroscopy Database (AVSpec).

Notes:
a. Designated PNV J17581670-2914490 when posted to the IAU Central Bureau for Astronomical Telegrams Transient Object Confirmation Page (TOCP).

b. Pearce reports that nothing is visible down to magnitude 11.5 at this location on six frames taken on 2021 Mar. 27.794 UT or Apr. 1.791 UT (TOCP).

c. P. Schmeer (Saarbruecken-Bischmisheim, Germany) reports that ASAS-SN Sky Patrol images show no previous brightening since 2016 March 10 (TOCP).

d. Position end figures:
 - F. Kugel (2021 Apr. 05.1577 UT, via TOCP): 16.14s, 55.9"
 - BraTS team (2021 Apr. 05.16785 UT, via TOCP): 16.08s, 56.6"
 - R. Fidrich (2021 04 05.4747) UT: 16.09s, 56.6"
 - A. Pearce (2021 04 05.482 UT): 16.06s, 56.5"

e. Images:
 - L. Araujo (2021 Apr. 05.1285 UT): https://www.aavso.org/sites/default/files/users/user63588/IMG_7787%20cort.jpg
 - F. Romanov (2021 Apr. 05.81796 UT):  https://www.flickr.com/photos/filipp-romanov/51097567569

Congratulations to Andrew Pearce on his discovery!

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