Alert! Nova Cas 2021 mag 9

[John Coffin]

Hi everyone, here are some velocity plots from my Alpy spectrum from 22nd March.

nova cas velocity plot 2203_ balmer.png (26.01 KiB) Viewed 11984 times

nova cas velocity plot 2203.png (32.96 KiB) Viewed 11984 times

The wavelength calibration of my Alpy normally becomes more inaccurate at shorter wavelengths, this is something two other Alpy users have noticed. The error causes a 2 Angstrom blue shift at H gamma.

Best wishes, John

[Christian Buil]

A spectrum for the 23-March-2021 taken by using a Star'Ex spectrograph (600 l/mm grating + 23 microns slit) on a 8-inch Newton telescope. The exposure is 12 x 300 seconds :



A more contrasted display:



The measured resolution is R=1700 and the SNR is 240 near 6400 A. Note the high efficiency of Star'Ex, here the result for a one-shot image of 300 exposure time only:



But note the major limitation of Star'Ex (a 3D-printing spectrograph) - the acceptable spectral range is between 5400 and 7400 A for the actual version. For IR or UV, and a nearly similar spectral résolution, the solution is Alpy600, LISA,... or the powerful and very recent UVEX by Shelyak.

Christian Buil

[Christian Buil]

New processing of Star'Ex spectrum for the 23 March (the near-IR 7065A He is now visible):






Christian Buil

[Christian Buil]

A near-IR spectrum (25-March-2021) - Pashen series is in emission:



Christian Buil

[HughAllen]

A comparison of the nova spectrum on Monday and yesterday evenings with my Alpy 600 spectroscope. If the visual magnitudes are assumed to be similar on the two evenings then an increase in the Balmer emission is visible with a small decrease in the HeI emission
Cheers
Hugh

Nova Cas 2021 Mar 22 v Mar 24.png (34.46 KiB) Viewed 11871 times

[Paolo Berardi]

Hi all,

I tried to observe the nova with a very strong atmospheric turbulence, especially for the second spectrum. Near-IR regions.





Clear sky!
Paolo

[Paolo Berardi]

Hi all,

new spectra for March 26.





A couple of cloudy nights are expected here... Hope it's better for you!

Paolo

[Christophe Boussin]

Hello all,

Very impressive spectra in the near infrared Paolo and Christian !!
Here is my update for the monitoring of the nova Cas 2021.
The following spectra were obtained with my Alpy 600, respectively, the 23th of March at 20 h 10 TU (resolution of 525, JJ = 2459297.3404) with an acquisition time of 36 min (12 x 180s) and the 24th of March at 19 h 55 TU (resolution of 529, JJ = 2459298.33) with an acquisition time of 18 min (6 x 180s) :

Nova Cas 2021 on March 23th, 2021

_novacas2021_20210323_840_Christophe Boussin_3600_7395.png (96.19 KiB) Viewed 11759 times

Nova Cas 2021 on March 24th, 2021

_novacas2021_20210324_830_Christophe Boussin_3600_7395.png (84 KiB) Viewed 11759 times

Nova Cas 2021 on March 20th, 23th and 24th 2021 (identification of some lines from PlotSpectra)

Clear skies,

Christophe BOUSSIN

[Olivier GARDE]

At this time, I'm on the nova with an eShel spectrograph.

[Olivier GARDE]

Evolution of the nova in 8 days taken with an eShel spectrograph (R=11000) and an RC400

H Alpha profil




H beta profil



Velocity of the Balmer's lines



and the full spectrum cut at 4000 Å because the blue part is very noisy (many obstacles like trees)