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RT Cru brightening - Spectra requested

PostPosted: Wed Jul 08, 2020 3:52 pm
by Francois Teyssier
Juan Luna - CONICET-Universidad de Buenos Aires, Instituto de Astronom´ıa y Fısica del Espacio (IAFE) - draws out attention on a brightening of the symbiotic star RT Cru:

I would like to call the ARAS observers attention and encourage them to follow spectroscopically RT Cru, given that it is recovering from the low state and we suspect that Halpha and other emission lines should appear now or soon.

Send spectra to francoismathieu.teyssier at for inclusion in the database:

AAVSO lightcurve:
RTCru.PNG (8.68 KiB) Viewed 899 times


Re: RT Cru brightening - Spectra requested

PostPosted: Sun Sep 06, 2020 8:28 am
by Francois Teyssier
Juan Luna is recalling his request of spectra of RT Cru.
RT Cru is now observable in the morning sky for southern observers.
It remains at high luminosity (~ 12.3) according to recent observations in AAVSO data:

RTCru.PNG (9.2 KiB) Viewed 607 times

Comments from Juan:

During the last month or so, the Swift BAT flux has been steadily increasing and is coming out of the minimum that started about 1-2 years ago. Spectra now and for the next 6 months will be really useful as this is an opportunity that might happen again in ~10 years (if this is indeed periodic as we suspect).
We expect that the optical spectra should have strong Halpha and may be other emission lines.

Thanks for your help and best regards

Thanks in advance for the spectra.

Re: RT Cru brightening - Spectra requested

PostPosted: Tue Sep 08, 2020 4:41 am
by Peter Velez
This was a challenging task - I started imaging last night when the target was at around 33 degrees altitude and it dropped away from there. I was surprised that it didn't slip below the walls of the observatory. I shot 2 separate sets of images and have processed them separately.

Here are the results. Very ordinary spectral calibration and low SNR. But it does show Ha emission and a few other interesting emissions.

I will give it another go tonight - weather permitting.


Re: RT Cru brightening - Spectra requested

PostPosted: Wed Sep 09, 2020 6:56 pm
by Francois Teyssier
That's excellent, Peter
I think you have also He I 5876 and probably [OIII]

Comments from Juan Luna:

Thanks a lot for taking this!, it is exactly what I was expecting!, Halpha emerged. Ideally we would love a weekly cadence, but I know it is difficult, so anything between once a week and once a month would be greatly appreciated.

All the best,