T CrB observing campaign

American Association of Variable Star Observers (AAVSO)
Tue, 08/03/2021 - 16:54

AAVSO Alert Notice 750 announces an observing campaign on the recurrent nova T CrB. Please see the notice for details and observing instructions.

There are threads for this campaign under the following forums:

- Campaigns and Observation Reports: https://www.aavso.org/t-crb-campaign-2021-2022
- Novae: https//www.aavso.org/t-crb-campaign-2021-2022-01
- Spectroscopy: https//www.aavso.org/t-crb-campaign-2021-2022-02

Please subscribe to these threads if you are participating in the campaign so you can be updated by the astronomer and by HQ. Join in the discussion or ask questions there!

Many thanks, and Good observing,

Elizabeth O. Waagen, AAVSO HQ

American Association of Variable Star Observers (AAVSO)
XMM and HST observations coming up soon


Thank you for continuing to observe T CrB, despite the excitement over RS Oph!

The XMM and HST observations of T CrB are scheduled within the next week: XMM observation is scheduled Aug 23 at 09:20 UT through Aug 24 at 03:07 UT, then HST observation follows on Aug 26.  The AAVSO data have been essential in reassuring the people at Space Telescope Science Institute that T CrB has not gone into an outburst and therefore it is safe for HST to observe it.

Please keep observations coming!

Thanks - Koji

American Association of Variable Star Observers (AAVSO)
Update: HST observation will be re-done


The XMM observation of T CrB was successful, but there was a technical issue with the HST observation, and we ended up with no usable data. Since it was a technical issue and not our fault, they are going to re-do the observations. We don't know the schedule yet - however, please keep observing T CrB at a high cadence for the foreseeable future.

Thanks - Koji Mukai

American Association of Variable Star Observers (AAVSO)
HST observation update

The HST folks have decided that it was not possible to schedule a replacement observation this fall. So here is the updated status/schedule of our XMM-Newton/HST observations of T CrB:

(1) X-ray observation no. 1 - August 2021 with XMM-Newton (done); no (successful) contemporaneous UV observation.

(2) X-ray observation no. 2/UV observation no. 1 - January/Feburary 2022. Detailed schedule TBD.

(3) UV observation no. 3 - later in 2022 with HST. No more XMM-Newton observation, but we will try to get some X-ray coverage with Swift.

Observers - thank you for your corperation. With the postponement of HST observation, there is less urgency from our side, although T CrB remains a high-value target . More importantly, we're approaching the least favorable season to observe T CrB.

I'll be back later in the year or very early next year, to give you an update on the scheduling of XMM-Newton  observation no.2/HST observation no. 1.

Thanks - Koji (for Paul, Jeno and Juan)

American Association of Variable Star Observers (AAVSO)
HST and XMM-Newton observations scheduled

T CrB observers - the coordinated (but unlikely to be strictly simultaneous - that's ok) observations with HST and XMM-Newton are currently scheduled for February 1 and 2, respectively. Please monitor its brightness (particularly in the B band), first to assure HST people that it's safe to observe T CrB (i.e., it's not too bright), second to put the current activity level in the context of the long-term AAVSO light curve, and finally to limit any changes in T CrB between the HST and XMM observations.

Any spectroscopy would also be welcome.

Thanks - Koji, Paul, Juan, and Jeno

American Association of Variable Star Observers (AAVSO)
Scheduling update

Unfortunately, another technical issue with the HST observation of T CrB  has forced them to postpone it, hopefully by just a couple of weeks but not sure when the new date will be. XMM is also following suit.  WIll keep you updated as I learn more.

Thanks - Koji

American Association of Variable Star Observers (AAVSO)
March XMM-Newton and HST observations of T CrB

After many a false start, the coordinated X-ray and UV observations of T CrB are currently scheduled as follows.

X-rays with XMM-Newton: 2002-03-08 01 UT to 19 UT.

UV with HST: March 10 or 11.

I hope that, this time, things will go well, and thanks again for all your observations that will help us put thise data in the proper context.

Koji, Paul, Juan, and Jeno

American Association of Variable Star Observers (AAVSO)
Another set of HST+XMM observations of T CrB coming up

T CrB observers,

Thank you all for your continued monitoring of this fascinating object.

We're going to have another set of coordinated HST/XMM-Newton observations coming up at the end of the month.

The HST observation is scheduled just after midnight on July 30th UTC. The XMM-Newton observation is scheduled between July 29 17:47 UT and July 30 09:35 UT.

Please continue to monitor T CrB - AAVSO data have been very important in reassuring the HST people in particular that the object can be safely observed with HST (which won't be the case should it go into its next recurrent nova eruption).

Clear skies,

Koji, Paul, Juan & Jeno

American Association of Variable Star Observers (AAVSO)
T CrB needs V and B coverage

Hi Everyone,

I know there are several targets competing for your attention as they are being observed with satellites this week and this month - and definitely continue your crucial coverage of them - but please don't forget about T CrB. Coverage in V and B in its current observing season is extremely important. We need to keep a close eye on it to be able to see if/when its anticipated outburst might be getting ready to happen. Visual observations are important, too. We need a good record of its behavior! (I know the skies have been cloudy in many places a lot of the time, but please do your best to catch T CrB when you can.)

Many thanks, and good observing,


American Association of Variable Star Observers (AAVSO)
Why is coveryage in V and B so particularly important?

Hello Elizabeth:

I am a newbie, and I am just about to start observing T CrB. I was just about to ask my mentor about which of my filters to use, when I stumbled upon your note about V and B,

I was planning on V, but I am curious aboout the rationale behind V and B coverage?

Thanks for your advice.

Patrick Kavanagh

Copernicus Club

Huiixquilucan, Mexico


American Association of Variable Star Observers (AAVSO)
Hi, Patrick,


Hi, Patrick,

Parallel measurements in B and V give valuable information about the change in color of the system (the B-V index) - whether it is becoming redder or bluer. This information is critical for cataclysmic variable stars. They are usually most active in U, but this spectrum is inaccessible to hobbyists using standard CMOS cameras for astrophotography. The difficulty in imaging in B comes from the fact that the signal is usually weaker. My astronomy mentor, who specializes in cataclysmic variables, always requires a little B in the time-series I do. For example, on 5 V frames, I do a B as well, and for the B I increase the exposure to gather more signal.