Alert Notice 735: Nova in Cassiopeia: N Cas 2021 = PNV J23244760+6111140 = CzeV3217

March 19, 2021

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Time Sensitive Alerts: https://www.aavso.org/pnv-j232447606111140-nova-eruption-czev3217
- Novae: https://www.aavso.org/pnv-j232447606111140-nova-eruption-czev3217-0

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 Cassiopeia: N Cas 2021 = PNV J23244760+6111140 = CzeV3217

Discovered by: Yuji Nakamura (Kameyama, Mie, Japan)

Discovery magnitude: 9.6 unfiltered CCD, using 135mm F4.0 lens + CCD

Discovery date: 2021 March 18.4236 UT

Coordinates (2000.0): R.A. 23 24 47.73  Decl. +61 11 14.8  (from VSX page for N Cas 2021)

Spectra: Spectroscopy obtained by H. Maehara et al. (ATel #14471) on 2021 March 18.820 UT with the fiber-fed integral field spectrograph mounted on the 3.8-m Seimei telescope at Okayama Observatory (Kyoto University, Japan) indicates the object is a classical nova.

K. Taguchi et al. (ATel #14472) report that a spectrum taken by O. Ohshima at the Ohshima Observatory confirms that the object is a nova.

Observing recommendations: Please observe N Cas 2021 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. Cadence for spectra depends on how fast the nova evolves, but, he adds, "you can't go wrong with a spectrum every clear night."

Observations reported to the AAVSO:
2021 Mar. 14.71 UT, 13.53 CV (S. Korotkiy et al., NMW Survey, pre-discovery, via TOCP);
17.15, <11.3 unfiltered CCD (W. Vollmann, Vienna, Austria);
18.79303, 8.844 V +-0.003 (M. Larsson, Malmoe, Sweden);
18.80532, 8.806 V +-0.003 (Larsson);
18.80551, 8.948 V +-0.034 (T. Vanmunster, Landen, Belgium);
18.80575, 9.339 B +-0.079 (Vanmunster);
18.80576, 8.816 V +-0.003 (Larsson);
18.80659, 8.939 V +-0.029 (Vanmunster);
18.80720, 8.437 R +-0.019 (Vanmunster);
18.80744, 8.116 I +-0.027 (Vanmunster);
18.80744, 8.818 V +-0.003 (Larsson);
18.80799, 9.371 B +-0.065 (Vanmunster);
18.80833, 8.450 R +-0.018 (Vanmunster);
18.80858, 8.121 I +-0.024 (Vanmunster);
18.81909, 9.185 B +-0.006 (Larsson);
18.81933, 8.738 V +-0.003 (Larsson);
18.85053, 8.632 V +-0.003 (Larsson);
18.85091, 9.009 B +-0.005 (Larsson);
18.86515, 8.968 B +-0.012 (Larsson);
18.86544, 8.454 V +-0.007 (Larsson);
18.85, 9.105 B (K. Taguchi et al. (ATel #14472));
18.85, 8.460 V (Taguchi et al. (ATel #14472));
18.85, 8.190 Rc (Taguchi et al. (ATel #14472));
18.85, 8.014 Ic (Taguchi et al. (ATel #14472));
19.37361, 8.4 (K. Sokolovsky, Moscow, Russian Fed.);
19.4544, 7.93 TG +/- 0.06 (F. Romanov, Yuzhno-Morskoy, Nakhodka, Russian Fed.);
19.468, 7.8 unfiltered CCD (T. Noguchi, Katori, Japan, via TOCP);
19.48986, 7.930 V +-0.023 (A. Pearce, Nedlands, W. Australia);
19.49079, 8.334 B +-0.014 (Pearce);
19.49155, 6.931 I +-0.004 (Pearce);
19.49616, 7.879 +- 0.001 (R. Fidrich, Budapest, Hungary);
19.76389, 8.1 (D. Heinonen, Sweden);
19.76519, 7.725 V +-0.002 (Larsson);
19.76554, 8.269 B +-0.003 (Larsson);
19.77284, 7.781 V +-0.004 (T. Tordai, Budapest, Hungary);
19.78318, 8.328 B +-0.003 (Larsson);
19.78343, 7.750 V +-0.002 (Larsson);
19.79007, 8.300 B +-0.003 (Larsson);
19.79032, 7.765 V +-0.002 (Larsson);
19.80038, 8.258 B +-0.003 (Larsson);
19.80063, 7.708 V +-0.002 (Larsson);
19.80990, 7.716 V +-0.002 (Larsson);
19.81022, 8.254 B +-0.003 (Larsson);
19.81530, 7.6 (G. Holmberg, Lund, Sweden);
19.86460, 7.7 (W. Kriebel, Schierling/Walkenstetten, Germany);

Charts: Charts with comparison stars for N Cas 2021 may be created using the AAVSO Variable Star Plotter (VSP).

Submit observations: Please submit observations using the name N CAS 2021. When a GCVS name is assigned to this nova, please use it 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 J23244760+6111140 when posted to the IAU Central Bureau for Astronomical Telegrams Transient Object Confirmation Page (TOCP).

b. Nakamura writes that nothing is visible down to magnitude 13.0 at this location on frames taken 2021 Mar. 14.4253 UT (TOCP).

c. The position of N Cas 2021 coincides with that of the W UMa-type eclipsing variable star CzeV3217 = Gaia EDR3 2015451512907540480. The variable type for CzeV3217 has been revised from EW to N+E (VSX).

d. P. Schmeer (Saarbruecken-Bischmisheim, Germany) reports that no brightenings had been recorded by the ASAS-SN Sky Patrol since 2014 Dec. 17, with the most recent ASAS-SN observation being from 2021 Feb. 12.066 UT.
 
e. Images
 - S. Korotkiy et al. (2021 Mar. 14.71 UT): http://scan.sai.msu.ru/~kirx/img/PNVJ23244760+6111140/NMW/
 - F. Romanov (2021 Mar. 19.4544 UT): https://www.flickr.com/photos/filipp-romanov/51052256002
 - T. Noguchi (2021 Mar. 19.468 UT, via TOCP): http://park8.wakwak.com/~ngc/images/PNVinCas_20210319.jpg

f. Position end figures:
 - T. Noguchi (2021 Mar. 19.468 UT, via TOCP): 47.76s, 15.0"

Congratulations to Yuji Nakamura on his discovery!

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

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