231 replies to this topic

[starblue]

If T CrB went into outburst while behind the sun, then fell back to its standard behavior after a week or so, how would we know the outburst happened once it became visible again?

[Redbetter]

Fortunately for most northern hemisphere observers, T CrB is relatively far north and the Sun is rather far south at solar conjunction.  So although T CrB will be low in the sky in early evening and shortly before dawn, there is still some opportunity to observe it.  Those at 50+ N are even better positioned for that.

[goodricke1]

If T CrB went into outburst while behind the sun, then fell back to its standard behavior after a week or so, how would we know the outburst happened once it became visible again?

 

Both in 1866 and 1946, there was a re-increase in brightness some 3 months after the outburst, which lasted for months, so that certainly won't be missed. 

[yuzameh]

Both in 1866 and 1946, there was a re-increase in brightness some 3 months after the outburst, which lasted for months, so that certainly won't be missed. 

what g1 said

 

If you have Burnham's Celestial Handbook both outburst lightcurves on the write up on T CrB are shown superposed on a nice graphlike graph.

[jcj380]

Fortunately for most northern hemisphere observers, T CrB is relatively far north and the Sun is rather far south at solar conjunction.  So although T CrB will be low in the sky in early evening and shortly before dawn, there is still some opportunity to observe it.  Those at 50+ N are even better positioned for that.

I was just noticing that it is rising in the morning now,  It's too low and obstructed for me, but I'm hoping it gets higher before it blows.  Assuming it blows anytime soon that is.

[gfamily]

An alert from the Astronomers' Telegram in the last couple of hours announces the detection of a rapid intensification of He II and H Alpha spectral features.

 

The He II 4686 line has undergone a strong increase relative to the end of 2024 Oct. with fluctuations in the intensity. Halpha increased in flux by nearly 1.5x and the profile has changed from a central absorption at vrad ~ -31 km/s on Oct. 13.8 UT to a weak emission peak on Nov. 11.8 UT.

https://www.astronom...org/?read=16912

[RLK1]

From the LAAS membership-messaging email received today(11-23-24):

 

Hi LAAS friends,

Would like to forward this message from the Executive Director
of the AAVSO.  In case others were also
in a semi-panic state – if they saw the ‘Spaceweather’ update this morning.


Begin forwarded message:

From: Brian Kloppenborg <bkloppenborg@aavso.org>
Subject: T Crb false alarm
Date: November 22, 2024 at 12:58:54 PM MST
To: "Dr. Brian Skiff" <bas@lowell.edu>

Brian,

I noticed your post over at:
https://groups.io/g/...o/message/27002

Based upon the spaceweather.com link.

This is a false alarm. The visual user forgot to put "<" in their submission. Can you please post that to the group?

When the system erupts, we have a plan in place to announce it to the world!

Thanks!

Dr. Brian Kloppenborg
Executive Director
American Association of Variable Star Observers
Phone: 617-354-0484 x107
Email: bkloppenborg@aavso.org

[gfamily]

What old news? I posted within 3 hours of the update

 

What false alarm? I simply reported an update.

Edited by gfamily, 23 November 2024 - 03:43 PM.

[gfamily]

18 Nov 2024; 14:45 UT is the date of the telegram, 5 days ago.  I read it on the 19th.  

 

So where is the new information?  I don't see any.

| posted within 3 2 hours of the post 

 

I can't be responsible for you not keeping up to date. There was a report of an increase - I'm not sure what point you're trying to make   

Edited by gfamily, 23 November 2024 - 06:30 PM.

[Domdron]

 

 

that is old news from 11/18 

Redbetter, gfamily posted the update here on 18 November 2024 - 07:37 PM (taken from his post time stamp), as he says few hours after it was published on astronomerstelegram.org. If you think a few hours are too much, ok fine, then just say so (but I don't agree). 

 

 And the latest data within the link was actually from 11/16.  So even the data was a week old at the time.  

It was 2 days old, not a week. But except that source data is readily publicly available, I don't think it's fair to take that as a reference as opposed to the publication date of the article on astronomerstelegram.org.

[Redbetter]

My apologies, this thread refreshed later in "my content" for some reason, so it appeared to be another of the frequent T CrB "happening soon" updates.  So my mistake, and my apology.

[truckasaurus]

Are we there yet...... I gotta pee......

 

but seriously, below is the link to the original announcement and a screenshot from aavso site that I took showing the same bands but with an additional year of observations.   maybe they called the start of the "dip" too soon.  you gotta figure those 1945 observations were not as thorough as what is happening now.....just saying....maybe the clock for the 1.3 year lag to the eruption didn't start ticking until May or June of 2024.....to put it a different way, maybe the pre-eruption dip was longer back in 1945 and they missed the actual start of it.   so sometime next fall?  

 

https://www.aavso.or...re-eruption-dip

 

Edited by truckasaurus, 25 November 2024 - 04:08 PM.

[jcj380]

Still in the trees to the east of me, but Arcturus was well up this morning, so it shouldn't be long before it's easy to see in the early morning.

Edited by jcj380, 01 December 2024 - 11:19 AM.

[Serack]

I enjoyed this writeup on the subject

https://www.space.co...n-the-night-sky

[Redbetter]

While Hays says, "We just can't pin it down to the month", the reality is that we can't even pin down the year.  First the prediction was 2023, then 2024, but more than likely it will be 2025 or beyond.

 

There was a better update posted in another thread last month in the Research Notes of the AAS:  "When will the Next T CrB Eruption Occur?" by Jean Schneider.  The idea is that the known eruptions fall at a given time period within the pair's orbit which has a period of 227.6 days.  So the next cycle would be late March 2025, and if not, then November 2025 and so on.   It will be very interesting if the eruption happens on the beat. 

 

The suggestion may or may not prove prescient, but at least it gets back to a more rational basis than marching forward as we did most of the past year--after a prediction on a dip that didn't actually happen as would have been required for the basis to be applicable.

[jgraham]

I have switched from evening to morning observations. I grab a brief set of photometric images with my Seestar (typically 20x10sec) about 20 minutes before nautical dawn. This places T CrB about 21 degrees above my horizon. Now all I have to deal with is Ohio weather.

 

Ugh. T CrB is like any other cataclysmic variable... we just don't know exactly when it's going to erupt. Unlike all of the others that I keep an eye on it's a bit more than +/- a few days or weeks. This has become a marathon. Still, lots of fun to watch!

[truckasaurus]

While Hays says, "We just can't pin it down to the month", the reality is that we can't even pin down the year.  First the prediction was 2023, then 2024, but more than likely it will be 2025 or beyond.

 

There was a better update posted in another thread last month in the Research Notes of the AAS:  "When will the Next T CrB Eruption Occur?" by Jean Schneider.  The idea is that the known eruptions fall at a given time period within the pair's orbit which has a period of 227.6 days.  So the next cycle would be late March 2025, and if not, then November 2025 and so on.   It will be very interesting if the eruption happens on the beat. 

 

The suggestion may or may not prove prescient, but at least it gets back to a more rational basis than marching forward as we did most of the past year--after a prediction on a dip that didn't actually happen as would have been required for the basis to be applicable.

How come you don’t think the identified dip was meaningful?

[Redbetter]

How come you don’t think the identified dip was meaningful?

Because it was a misidentified/misclassified dip (others noted this long before I did, I am just in agreement with them.)  It wasn't nearly as deep as the prior one that Schaefer's predictions were based upon.  Instead it was simply a return to the normal magnitude and periodic variability that had been present in the system prior to its active phase.  To have agreed with the prior dip it would have needed to dim to around 12 V mag, which did not happen.  Instead it just settled into its old channel reaching about 10.5 V mag at the faint end each time.

 

As Schaefer wrote:  "The fading (from immediately before the Dip to the depths of the Dip) was roughly 1.5 mag in the B and 2.5 mag in the V.  The V Dip faded fainter than the faintest ever observed, and the V light is almost entirely from the red giant companion."  [Note:  I have to give some credit here for putting faded, fainter and faintest all into the same sentence and still making sense.]    Schaefer also said that "this fading ended abruptly with the nova eruption."  None of that has proven true this time around.

 

It could still undergo the deep dip Schaefer was anticipating, but the fact is that it hasn't done that yet, and we don't know if it even will.  So there remains the possibility that both of the proposals could still prove true, a deep dip could happen, then a delay followed by an eruption on the beat suggested recently.  Or both could prove to be wrong, or it might erupt on the beat without the big dip happening.  Whatever it does, it should provide a better understanding of what is happening.

[truckasaurus]

Because it was a misidentified/misclassified dip (others noted this long before I did, I am just in agreement with them.)  It wasn't nearly as deep as the prior one that Schaefer's predictions were based upon.  Instead it was simply a return to the normal magnitude and periodic variability that had been present in the system prior to its active phase.  To have agreed with the prior dip it would have needed to dim to around 12 V mag, which did not happen.  Instead it just settled into its old channel reaching about 10.5 V mag at the faint end each time.

 

As Schaefer wrote:  "The fading (from immediately before the Dip to the depths of the Dip) was roughly 1.5 mag in the B and 2.5 mag in the V.  The V Dip faded fainter than the faintest ever observed, and the V light is almost entirely from the red giant companion."  [Note:  I have to give some credit here for putting faded, fainter and faintest all into the same sentence and still making sense.]    Schaefer also said that "this fading ended abruptly with the nova eruption."  None of that has proven true this time around.

 

It could still undergo the deep dip Schaefer was anticipating, but the fact is that it hasn't done that yet, and we don't know if it even will.  So there remains the possibility that both of the proposals could still prove true, a deep dip could happen, then a delay followed by an eruption on the beat suggested recently.  Or both could prove to be wrong, or it might erupt on the beat without the big dip happening.  Whatever it does, it should provide a better understanding of what is happening.

I see what your saying.  The V band never did reach mag 12.   Yeah, a little premature on that call.   

[jcj380]

I have switched from evening to morning observations. I grab a brief set of photometric images with my Seestar (typically 20x10sec) about 20 minutes before nautical dawn. This places T CrB about 21 degrees above my horizon. Now all I have to deal with is Ohio weather.

 

Ugh. T CrB is like any other cataclysmic variable... we just don't know exactly when it's going to erupt. Unlike all of the others that I keep an eye on it's a bit more than +/- a few days or weeks. This has become a marathon. Still, lots of fun to watch!

Substitute Illinois for Ohio...

 

I haven't felt like taking out a scope in the frigid mornings lately, so I slide open the back door and take a look with binos.  No blow as of ~0530 CST today.  

[jgraham]

Heh, heh, that's what I like about my Seestar. I can step outside in my jammers, set it down, turn it on, step back inside, and observe from inside my house. I luvs my eyepiece time, but not when it's bitterly cold.

Love it!

[truckasaurus]

Heh, heh, that's what I like about my Seestar. I can step outside in my jammers, set it down, turn it on, step back inside, and observe from inside my house. I luvs my eyepiece time, but not when it's bitterly cold.

Love it!

definitely one of the more intriguing aspects of the whole smart telescope category.  

[jcj380]

I got rather excited at 0515 LT this morning when I saw in my binos that T CrB had blown and was up to about mag +4.  Then I saw it was moving to the ESE.  

Edited by jcj380, 13 December 2024 - 03:31 PM.

[truckasaurus]

another way to check without going outside.  pretty good views.  Corona Borealis is just above the dome to the left of the Laser.    and if you are asleep at this time just slide the time back to about 5:20am.  enjoy.  all the shooting stars are fun to watch as well. 

 

 

 

https://www.youtube....h?v=6g4Fh8K-MhY

 

 

same feed with stars and some satellites identified (in Japanese though) 

https://www.youtube....h?v=QBEDMEyXKNE

 

 

I got rather excited at 0515 LT this morning when I saw in my binos that T CrB had blown and was up to about mag +4.  Then I saw it was moving to the ESE.  

Edited by truckasaurus, 13 December 2024 - 08:04 PM.

[Serack]

another way to check without going outside.  pretty good views.  Corona Borealis is just above the dome to the left of the Laser.    

 

 

TCrB.jpg

 

https://www.youtube....h?v=6g4Fh8K-MhY

 

 

same feed with stars and some satellites identified (in Japanese though) 

https://www.youtube....h?v=QBEDMEyXKNE

Thanks for sharing!  I've got clouds in the forecast until next Friday night.