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T CrB observing campaign

weo
Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 08/03/2021 - 16:50

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

weo
Affiliation
American Association of Variable Star Observers (AAVSO)
Mon, 05/08/2023 - 14:46
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,

Elizabeth

MZK
Affiliation
American Association of Variable Star Observers (AAVSO)
Sun, 09/10/2023 - 16:05
Comps?

Elizabeth et al:

I'll start with a question/observation. During my ensemble photometric analysis, I noticed that the available VSP comps in the FOV seem to exhibit inconsistency in the estimated target magnitude. Comps seem to show target estimates that differ by several tenths mag, and show distinct groups/pairs based on magnitude? The 6 comps I used are not saturated but bright at 30s exposure. Has anyone noticed this?

Ken

PS: I hope the nova doesn't pop during conjunction!? ;-(

Sebastian Otero
Affiliation
American Association of Variable Star Observers (AAVSO)
Mon, 09/11/2023 - 15:51
Magnitudes inconsistencies

Hi Ken,

We found that this is one of the fields having wrong comparison star magnitudes coming from the WBVR catalogue. There were some problems with the catalogue columns and transformations that caused some miscalculations and we are working on fixing them all right now.
This is a high priority issue so we hope to be able to share some good news soon.

Cheers,
Sebastian

Sebastian Otero
Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 10/10/2023 - 05:28
Comparison star sequence correction

Hi Ken et al.,

we have uploaded corrected magnitudes for almost 3,000 stars in the comparison star database (VSD), including several stars in the T CrB field. Can you download a new chart and check if the inconsistencies are now gone?

The problem lied in an incorrect transformation of data coming from the WBVR catalog that we had used to populate VSD back in 2008.

We are going to write a blog post about this work soon.
It took almost 3 months to complete it.

A big kudos to George Silvis for his help with this project!

Cheers,
Sebastian

MZK
Affiliation
American Association of Variable Star Observers (AAVSO)
Wed, 10/11/2023 - 00:32
New Comp Mags

Sebastian:

Ran first set of images since update. I would say that the comp mags are more consistent in the sense that for my ensemble with new updated mags, the mean target mag yields a tighter/smaller STD for the target than with the old comp mags.

I noted a significant shift in B and I target mag with the new comp mags BUT I think most of that is due to moisture on my scope's corrector lens during the run. So, I hold my final assessment until another run.

Thanks to George and you for working on this issue.

Ken

DEY_VAR
Affiliation
American Association of Variable Star Observers (AAVSO)
Wed, 10/11/2023 - 21:49
Comp star changes

Greetings, Sebastian,

Will there be a list of all the fields with changed comp star magnitudes?  It would help observers so we may know to grab new VSP magnitudes for the stars we observe.  Not all of us use the AAVSO reduction tools.

Thanks for you efforts.

Jim (DEY)

Sebastian Otero
Affiliation
American Association of Variable Star Observers (AAVSO)
Thu, 10/12/2023 - 14:48
What has changed

Hello Jim,

unfortunately, those nearly 3,000 stars are spread over any sky area between -26º and +90º (at least you can rule out some southern fields). The way VSD saves the information, that is, not relating a comparison star with a specific variable star sequence, makes it impossible to provide a useful list.

Keep in mind that these are only bright stars, only 30 are fainter than Vmag. 8.0 and only 3 are fainter than 9.0, with the faintest one being a 9.5 star. So anything fainter than that hasn't been affected.

And for visual observations, it is important to note that the V magnitudes haven't been affected in most cases, since the problems were mostly related to the Rc and U transformations. All Rc values changes, most U values changed and some B values changed.
But regarding V, only 4 records changed significantly.
They are:

AUID           Label  Vmag.    Coordinates
000-BBC-963  92  8.878  01 30 29.14 +02 58 16.3
000-BBR-364  26  1.995  10 19 58.35 +19 50 29.4
000-BBX-304  59  5.992  16 19 00.42 -14 52 22.2
000-BBZ-475  60  6.134  17 50 48.38 +22 18 58.8

"Label" is the previous one, Vmag. is the new magnitude (in the first case, the new label is "89").

So this will affect mostly electronic observers doing multicolor photometry. Especially those taken Rc band data (all magnitudes changed).

Cheers,
Sebastian

DEY_VAR
Affiliation
American Association of Variable Star Observers (AAVSO)
Mon, 10/23/2023 - 14:06
T CrB sequence on D problems

Greetings again,

This morning I ran a D chart for T CrB to check for the sequence changes noted recently.

The 105 star to the south of T is no longer shown or listed.  The new sequence shows comps down to 143 tho.

Problem for me, maybe problem for all my old obs. in the db, maybe a problem for others, is that I used the 105 comp star as my primary reference since 2459106 at least..

Is this an error on my part?  Is the 105 comp really gone?  How should I proceed to fix this?  Reprocess and resubmit?  

I want my 105 comp back.

Jim (DEY)

 

DEY_VAR
Affiliation
American Association of Variable Star Observers (AAVSO)
Mon, 10/23/2023 - 20:16
The AUID for the 105 is 000…

The AUID for the 105 is 000-BJS-901 from the chart ID X25666AJM photometry table.

The B-V is +0.606 which I presume is why it is not in the current charts.  I have been doing B,V,Rc,Ic transformed and have never seen any issues in this comp. star.  The photometry using this star should be dominated by spectral variations in T CrB.

000-BJS-901 15:59:26.42 [239.8600769°] 26:08:47.1 [26.14641762°] 105 11.133 (0.080) 1 10.527 (0.047) 1 0.606 (0.093) 10.222 (0.060) 19.933 (0.065) 1

Jim (DEY)

Sebastian Otero
Affiliation
American Association of Variable Star Observers (AAVSO)
Wed, 10/25/2023 - 05:14
The 105 is a 106 but it is okay

We checked and we think that the 105 was deleted accidentally in 2021.
The current APASS values are:

B= 11.19 (0.172), V= 10.566 (0.089), Rc= 10.153 (0.158), Ic= 9.766 (0.199), g= 10.847 (0.205), r= 10.427 (0.071), i= 10.25 (0.097).

We have trouble updating it due to the accidental deletion but at least now you have the magnitudes, until we are able to re-upload the data.
I confirmed with Gaia DR3 and ASAS-3 that this V magnitude is better (and that the star is not variable).

Cheers,
Sebastian