T CrB before its new nova event

[Francois Teyssier]

The presentation I used during the SAS meeting
http://www.astronomie-amateur.fr/DocsSp ... -06-22.pdf
A summarize about T CRB and the state of our monitoring.

François

[Francois Teyssier]

The new season of observations after the solar conjunction is begining.

Since the detection of the end of the high state (2015-2023), T CrB evolves in the same way as before the high state with orbital variations of the photometry and spectroscopic appearence.

TCrB_1dayMean_cleaned.png (38.01 KiB) Viewed 4981 times

First spectra for the new season were secured by Woody Sims.
The aspect of the spectrum (continuum and emission lines) are compliant with the spectroscopic evolution of the traget before the "big active phase" 2015-2023.


We undergo the monitoring before the next nova event. One key point of this monitoring is: Are there any warning signs of the outburst?

One spectrum (both low and medium resolution) by week should be a good cadency at this state.
For spectrographs with short wavelength range the zone 4600-5100 is recommended.
Flux calibrated spectra are a must. Due to the strong flickering (especially B and V) the photometry should be acquired during the acquisition of the spectrum (some duration) and the flux calibration should use mean or median value of the magnitude V.

[Christophe Boussin]

Hello all,

The weather forecast isn't looking good for me at the moment...so when an opportunity presents itself, I can't miss it !
So here's my first T CrB spectrum for the year 2024, obtained with my Alpy 600 on February 28 (resolution of 515, JJ = 2460368.5673) and an acquisition time of 80 min (8 x 600 s) :

T CrB on February 28th, 2024 (3700-7565 A)

_tcrb_20240228_067_Christophe Boussin_3700_7565.png (113.55 KiB) Viewed 3440 times

Clear skies,

Christophe BOUSSIN

[Joan Guarro Flo]

Hello at all,

The T CrB outburst current year predictions has grown the interest for this star, as the same that the observers who targeted it I found T CrB in a really normal state until now.

Also you can see in its spectrum how the ASI294MM works, the graphic is the result of 6 x 1800 seconds integrations with this camera.

Meanwhile I took V photometry, improveable in my opinion, it was made by an old NIkon 300mm. F/4 objective, Bessel-V filter and an ATIK460EX camera. I hope to show better results from it in the future.

Regards J.Guarro.

[Joan Guarro Flo]

Hi again,

As a curiosity, I used these stars as a V photometric comparison.

J.G.

[Joan Guarro Flo]

Hello,

These are yesterday night's T CrB outcomes, its spectroscopy graphic, is only by 4 x1800 seconds integrations, due to the night becoming cloudy, despite it,  the photometric measures have one reasonably good dispersion of +/- 4 thousandths of V magnitude.

Best regards, J.Guarro.

[Joan Guarro Flo]

Hello, 
You can see here T CrB on 2024 04 23, its general situation is calmed, although its photometry shows little variations.

Cheers, J.Guarro.

[Joan Guarro Flo]

Hello,

I've attached two graphics today, in the first one you can notice the notable difference between T CrB H Alpha activity on 2022 08 18 and the current little oscillations on its weak signal nowadays.

In the second picture, there are only 10 photometric points taken in not more good conditions. The weather is changing here for the next few days.

Regards, J.Guarro.

[Joan Guarro Flo]

Hello,
Unfortunately, bad weather persists here for a lot of weeks, and the forecasts can't say how many times it will last.

Meanwhile, I attached here this graphic where I gathered these four photometric observations,  you can see a change in magnitude tendency that is difficult to notice to see them separately.

From my point of view, monitoring this star, or other ones, with spectroscopy and photometry could be useful to their study, it could be very good complementary AAVSO information.

Photometry is easy to obtain at the same time one is taking spectroscopy and could give surprising outcomes, due to, in my case, I need to give between two to three hours to take a spectrographic observation of T CrB and other similar weak stars with my equipment, it permitted take sufficiently long photometric sequences too.

Regards, J.Guarro.

[Joan Guarro Flo]

Hello,

T CrB seems to be a relaxed season despite little variations in its Hydrogen lines.

Photometry is moving too, the empty is due to bad weather.

Cheers, J. Guarro.