Waiting for T CrB aka the Blaze star

[MalcolmP]

The News:

today there is no news,
again !
It remains stubbornly at about m10.5 +/- , see in pic below two comparison magnitudes taken from the   BAA chart. 

But there is a little anecdote - After much rain and cloud during yesterday evening the forecast for midnight and later was promising.
Lo! just before midnight I could see, through patchy cloud and thin haze, Vega high above and Arcturus in the west just about to descend into some trees. Not much else could be seen but ever hopeful I began setting up tripod and camera. When I next glanced up, a few more stars could be seen and about where CrB should be, to the left of Arcturus I could see two stars.
Wot ! Heart nearly stops, cloud tries to ruin things, and a moment later a star moves out of the cloud and continues to climb slowly towards the zenith !

 edit later : DSLR static (not tracked)  on a tripod,
Canon 60d +135mm lens @f2.8
400x2sec subs stacked in DSS + pp in Gimp
(10x 2sec is ok to show TCrB in the noise but, 400 makes it nicer !)
 

 

Edited July 13 by MalcolmP

[Ratlet]

I feel silly asking this, but is it literally just a case of compare the brightness of it to the brightness of a star with static brightness to determine it's magnitude?

Also, that's an interesting double just to the left.  Wonder if it is visible visually.

[JeremyS]

47 minutes ago, Ratlet said:

I feel silly asking this, but is it literally just a case of compare the brightness of it to the brightness of a star with static brightness to determine it's magnitude?

Also, that's an interesting double just to the left.  Wonder if it is visible visually.

For visual observing, Yes that’s pretty much it. One technique is to find a comparison star slightly brighter and another slightly fainter, then estimate how far T is between.

For images, you need photometry software to extract the photometry.

Edited July 13 by JeremyS

[MalcolmP]

Forgot to include details of the pic. :-
DSLR static (not tracked)  on a tripod,
Canon 60d +135mm lens @f2.8
400x2sec subs stacked in DSS + pp in Gimp
(10x 2sec is ok to show TCrB in the noise but, 400 makes it nicer !)
 

[MalcolmP]

50 minutes ago, Ratlet said:

 that's an interesting double just to the left.  Wonder if it is visible visually.

Using angle measure in Stellarium they are 40.5" apart, un-named m10.55 & m10.85
Using ASTAP to interrogate Simbad gives BD cat numbers for them @ m10.6 & m10.9 :-->

 

 

[MalcolmP]

and we have another clear sky, , , with no news !

Hot off the camera just now, a single 2sec sub @ 11pmBST, fetched out of the noise by the clever ASTAP , shows it still at m10 or less

 

 

Edited July 13 by MalcolmP

[Geoff Lister]

Hot off the Dwarf 2 - again no news

Geoff

[Mr Spock]

I got it around 10.2 last night with the 6"CC. Looks clear again tonight so I'll try and get an image.

[MalcolmP]

10pm BST :-  in the twilight I could only see Vega but my Canon60d could see the main stars of CrB
and the clever ASTAP platesolved and assured me that there was no 'guest star' brighter than about mag9.

Trying again in darker sky now but I dont expect any great news !
 

[Paul M]

I've been keeping an eye in this during rare breaks in the cloud cover, with my remote Cumbrian Allsky camera. 

I've already requested for the burst to happen during the next New Moon period, coming up soon. That is a good window as the sky gets darker, but CrB is now past its best, at least for my cameras position, and heading into the western sky and some tree obscuration. It will become ever more compromised!

Here it is 2 nights ago, the last clear period, drawing a blank but a meteor did put on a show.

[MalcolmP]

6 hours ago, Paul M said:

  but a meteor did put on a show.

Nice meteor, shame about T CrB no-show !
I have the same problem of trees in the w,est, so the window is only 10 until midnight and rapidly narrowing  

 

[Mr Spock]

You know it's going to flare when CrB is out of sight. That would be typical.

[Paul M]

8 hours ago, Mr Spock said:

You know it's going to flare when CrB is out of sight. That would be typical.

No! We must stay positive!

Hmmm, your probably right though.... ☹️

I had (have!) delusions of T CrB starting to flare just after dusk one night over the next new Moon, while I'm running off 20 sec exposures and I'll have enough data to generate a nice light curve of the main brightening phase.

Stay positive!

[Geoff Lister]

The FOV of my Dwarf II (night of 27th to 28th) shows T CrB and magnitude 4-ish epsilon CrB. When T is brighter than epsilon - bingo!

The 3 bright stars in a horizontal line below T CrB are, from left to right, roughly magnitude 7, 8, & 9. The 5 stars, forming a "U" to the right of T CrB, are in the Mag. 9.5 to 11 range.

NOTE: Stellarium has T CrB roughly 2700 light-years away, so there may be more nova events in the pipeline😊

Geoff

Edited July 30 by Geoff Lister
NOTE added

[Paul M]

4 minutes ago, Geoff Lister said:

The 3 bright stars in a horizontal line below T CrB are, from left to right, roughly magnitude 7, 8, & 9. The 5 stars, forming a "U" to the right of T CrB, are in the Mag. 9.5 to 11 range.

Herein lies my main issue with the allsky camera. It currently makes 20 sec exposures and with housekeeping downtime, the RasPi manages 2 frames per minute. Optimal for pretty all-sky timelapes, but gives a limiting magnitude of maybe 6 at the zenith, much worse over in the murk of the western sky. 

I need to get my imaging scope on it!

 

[JeremyS]

1 hour ago, Paul M said:

Herein lies my main issue with the allsky camera. It currently makes 20 sec exposures and with housekeeping downtime, the RasPi manages 2 frames per minute. Optimal for pretty all-sky timelapes, but gives a limiting magnitude of maybe 6 at the zenith, much worse over in the murk of the western sky. 

I need to get my imaging scope on it!

 

Mag 6 is good enough to detect the eruption. It will rise from mag 10 to 2 in a matter of hours.

[Geoff Lister]

6 minutes ago, JeremyS said:

It will rise from mag 10 to 2 in a matter of hours.

Let's hope these are not during UK daylight.

[JeremyS]

2 hours ago, Geoff Lister said:

Let's hope these are not during UK daylight.

In 1946, the first 4 sightings were by visual observers - the first 3 were amateur astronomers. It was February so only those looking near local Dawn would have had the target high enough.

The order was: USSR (Siberia), UK (Newport, S Wales), UK (Surrey), USA (Yerkes Obsy).

In many places it was daylight, of course.

[JeremyS]

I’ve updated my article on T CrB here: https://britastro.org/section_news_item/get-set-for-the-next-eruption-of-the-recurrent-nova-t-coronae-borealis

[saac]

31 minutes ago, JeremyS said:

I’ve updated my article on T CrB here: https://britastro.org/section_news_item/get-set-for-the-next-eruption-of-the-recurrent-nova-t-coronae-borealis

"On average, someone in the world observes T CrB every 6 mins."

Wow that is something to really reflect on.  Surely the moment itself then would be unlikely to evade our watch. 

Jim

[JeremyS]

1 minute ago, saac said:

"On average, someone in the world observes T CrB every 6 mins."

Wow that is something to really reflect on.  Surely the moment itself then would be unlikely to evade our watch. 

Jim

The key word is “average”. There will still be gaps due to weather or few observers. The latter particularly in the sparsely populated pacific region. There may consequently be an advantage for sky watchers on the western side of the Pacific, e.g. the Philippines has lots of observers. Or China. 
Then depending on the time of year it erupts, eg winter, there might be an advantage for northern observers.

So it’s always worth checking as soon as it gets dark at the moment.

[Paul M]

The window of opportunity is rapidly closing on T CrB. There have been precious few breaks in the cloud over my remote allsky camera. It's been truly awful. I tweaked a setting 10 days ago and still can't see the result   

The very brief glimpse I had of the constellation [removed word] asterism a few days ago drew a negative on T CrB but did remind me that it's disappearing into the western tree clutter and sky glow. 

My operational mode is now shifting to hoping that the flare waits until the spring reappearance.

Edit:  the removed word would have been ok with use of hyphens as in "constellation-[removed word]-asterism"  Yikes, star porn... 🤣#

Second edit, ok the removed word is "charlie uniform mike." 😁

Edited August 24 by Paul M

[Nik271]

I am lucky with my western horizon and can follow TCrB from my back garden all until January, of course if weather permits. Then it will be binoculars only early in the morning. 

I just looked at it with my Skymax 127. Still mag 10, and easy to see even in twilight at 9pm, by now I know it's position very well. 

The wait goes on ...😴

[chrisecurtis]

I measured it last night (about 20:20UTC) with a median of 9.96 (highest 9.73 and lowest 10.1 - lots of twinkling going on: seeing not great). That's just a little brighter than my typical measurement over recent weeks of 10.1 but within "normal" variability. It looked reddish in the phone app of my Vespera 2 Smart Scope and more so than I seem to remember, but I don't have a spectroscope and it might just be imagination!

[Nik271]

I also see it slightly red visually, more so when it is on the bright side of its cycle. The primary is a red giant and the cyclic variabilty is from the change of its profile as it rotatates with the white dwarf every 200 days or so. It's fascinating how much we know about these objects thousands of light years away just from their light curve.