Spectrum of Nova Cassiopeiae 2021

The Nova Cassiopeiae 2021 (=V1405 Cas = PNV J23244760+6111140) is a bright galactic nova in constellation Cassiopeia. The discovery magnitude was 9.6 mag (unfiltered CCD) [1]. The nova peaked around 20th March with a brightness of V=7.4 mag (see light curve). With this brightness it is easy reachable with the Alpy600 spectrograph. Up to now I took an image and a spectrum:

2021-03-24 Image, the sky was clear with good transparency, low humidity and avarage seeing, at temperature of 6° C
2021-03-24 Spectrum, the sky was clear with good transparency, low humidity and avarage seeing, at temperature of 5° C
2021-04-04 Spectrum, the sky was clear with good transparency, low humidity and avarage seeing, at temperature of 2° C

Data about Nova Cas 2021

Position:	RA 23h 24m 47.73s, DEC +61° 11' 14.8"
Progenitor:	V1405 Cas, CzeV3217
Discovery:	2021 March 18.4236 UT by Yuji Nakamura (Kameyama, Mie, Japan)
Brightness:	V=9.6 mag (unfiltered, at discovery date), V=7.9 mag (2021-03-24.792 UT), see light curve of Nova Cas 2021

Image and spectra of Nova Cas 2021

2021-03-24 18:56 - 19:03 UT, Roof Observatory Kaufering, Meade 14" ACF telescope on Taurus GM-60 mount, CCD: Moravian G2-8300FW, 3x3 binning, L-filter, exposures: 31x1 sec; magnitude measured with Astrometrica: V=7.9 mag; click to uncrop image;

For other images see

Here are my spectra of this nova:

Spectrum of Nova Cas 2021, Mar 24th
2021-03-24 19:38 - 20:10 UT, Roof Observatory Kaufering, Meade 14" ACF telescope on Taurus GM-60 mount, Astro Physics reducer CCDT67, Alpy600 with guiding unit, CCD camera: Atik 428EX, guiding camera: ASI 120 MM; recording software: AstroArt, guiding software: PHD2;
Wavelength calibration: Hg lines from energy saving lamp and Ne lines from flicker flame light bulbs, instrumental response calibration: with reference star HIP 114904 (=HD 219634), B0 Vn, data reduction: with Integrated Spectrographic Innovative Software from Christian Buil;
The spectral type of HIP 114904 may be unprecise in Simbad (character D). I achieved the best fit with a type of B2 IV database spectrum.

calibrated spectrum: _ncas21_202103242038_cal.fit

Spectrum of Nova Cas 2021, Apr 4th
2021-04-04 19:42 - 20:44 UT, Roof Observatory Kaufering, Meade 14" ACF telescope on Taurus GM-60 mount, Astro Physics reducer CCDT67, Alpy600 with guiding unit, CCD camera: Atik 428EX, guiding camera: ASI 120 MM; recording software: AstroArt, guiding software: PHD2;
Wavelength calibration: Hg lines from energy saving lamp and Ne lines from flicker flame light bulbs, instrumental response calibration: with reference star HIP 114904 (=HD 219634), B2 IV, data reduction: with Integrated Spectrographic Innovative Software from Christian Buil;

calibrated spectrum: _ncas21_202104042142_cal.fit

Line identification and discussion

Here is the labeled spectrum:
labelled spectrum of Nova Cas 2021, Mar 24th
There are strong emission lines of Hydrogen and Helium indicating a classical nova. Strong P-Cygni profiles are a sign of a fast expanding shell. This is also shown in ATELs #14471 [2] and #14472 [3].

Spectra evolution of Nova Cas 2021

Here are the spectra for comparison, they are shifted in y-direction by 5 units each for better distinction:
Nova Cas 2021 spectra evolution

References:
[1] Nova Cas 2021 in AAVSO alert notice 735
[2] Nova Cas 2021 in ATel#14471
[3] Nova Cas 2021 in ATel#14472

My other spectroscopic observations: Spektroskopie (German)

[ updated: 2021-04-07 | Email icon Gregor Krannich | Gregors astronomy page ]