Solar Cycle 24 Main Discussion X

[kp5]

Feb 24, 2011 1:37:07 GMT af4ex said:

We're already picking up some "preglow" in x-ray, and even in microwaves, from the farside. So I'll raise my expectations and say that the hidden region is very active!

:-|

I too have a certain level of expectation during the middle to latter part of next week for a bit of minor geo-storming. That large c.h sure is stubborn! k5 in Jan, k6 in Feb (boosted slightly by cme effects) and now it's soon to swing into view for round three. The AR to it's east really does look alive. We could see some interesting times ahead.

[kp5]

M3.5 flare coming from the active region emerging on the eastern limb.

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[af4ex]

Looks like a keeper*!
;D

* keeper - a term used by fishermen to denote a caught fish that meets legal length limits and is worthy of keeping.

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[af4ex]

The M3.5 flare, caught by SDO's Atmospheric Imager in UV 1600A and EUV 131A light (a minute apart)


SDO/AIA 1600 2011-02-24 07:47:30 UT
SDO/AIA 131 2011-02-24 07:48:47 UT

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[Kevin VE3EN]

Feb 24, 2011 11:08:32 GMT af4ex said:

The M3.5 flare, caught by SDO's Atmospheric Imager in UV 1600A and EUV 131A light (a minute apart)


SDO/AIA 1600 2011-02-24 07:47:30 UT
SDO/AIA 131 2011-02-24 07:48:47 UT

Neat image, posted on main page.

Cheers

[af4ex]

Another snapshot (unfortunately at a low sample rate) of the flare. Note that the old filament cavity, south of the equator seems to be still active. In fact, it was shooting off long filaments for hours last night.

[w7psk]

Wonder if that would have made X class if it had been more Earth Facing.

Will we have 1 spotless day or will it rotate enough into view before the departing to count?

Time will tell.

[af4ex]

w7psk
> Wonder if that would have made X class if it had been
> more Earth Facing.

Flares are explosions in the corona, high above the photosphere, where absorption is minimal. That's why we can often "see" them when they happen on the far side. And the radiation pattern is fairly isotropic. So I think the M-rating is appropriate.

[af4ex]

There were two C-class flares in the 1163 region early this morning which I think were actually coming from a larger, more active region which has not quite rotated into view yet. You can see it's big from the coronal loops in EUV 171A.

Below is a snapshot of the C1.4 flare at 0520Z. There was also a C1.6 flare at 0540Z, which I think was mostly on the far side, and had some coronal mass ejection.

I think Planet X saw the second flare better than we did, and the ham radio operators on Planet X are probably sad that this region is rotating out of their view. It's our turn now. ;D

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[af4ex]

I said:
> ... Planet X saw the second flare better than we did ...

w7psk,
I think this is a case where the flare class might have been higher if facing the Earth, because the flare was far enough back that it was obscured by the limb itself (I couldn't see the flash of this 2nd flare clearly in microwaves, which is pretty high up in the corona).

Again, not the case for the M3.5 flare, because it was mostly Earthside when it popped.

:-|

[af4ex]

I'm still curious about those two C-Flares this morning, which NOAA rated at C1.4 and C1.6, peaking at 0518Z and 0544Z respectively.

Looking at the 17GHz imagery from Nobeyama one can clearly see the sharp 0518Z event (#263 post above), but the 0544Z event looks a little "mushy" (below), smeared over time (but representing a lot of integrated energy under the curve).

So the peak reading of the second event looks smaller in micro-waves. But the NOAA rating is based on the measured GOES 1-8A XRAY radiance. (Must have been a very brief pulse, because the 3-minute sampled value shows it maxing at Class B)

In fact, it looks like a much larger event (maybe even M) happened around 0600Z, way on the far side, producing a big CME plume (below), but barely a ripple on the Earthside sensors.

Dr. Svalgaard, are there any other sensors (maybe using helioseismic techniques) that can tell us if a big flare happened on the far side?


(Note: I mislabeled the "C1.6" event. It happened earlier, around 0545Z. The second arrow points to the "missed" event around 0600Z)

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[lsvalgaard]

Feb 25, 2011 15:32:01 GMT af4ex said:

I'm still curious about those two C-Flares this morning, which NOAA rated at C1.4 and C1.6, peaking at 0518Z and 0544Z respectively.


Dr. Svalgaard, are there any other sensors (maybe using helioseismic techniques) that can tell us if a big flare happened on the far side?

The SWAN data: sohowww.nascom.nasa.gov/data/summary/swan/
But its time resolution may be too crude to catch the flare in the act.

[arjan]

A sun diving comet got a little surprise before reaching the sun, a headon collision with the CME comming from 1163. The poor thing never made it to the sun It's a bit hard to see but it looks like it flares up a bit, but that could be the noise in the movie.

lasco-www.nrl.navy.mil/daily_mpg/110224_c3.mpg
Link to the LASCO C3 movie.

[af4ex]

> It's a bit hard to see but it looks like it flares up ...

Great movie, arjan! I think you're right, the comet seems to explode in Frame #63 (below). But difficult to track before and after that frame because of the explosion glare and noise.

I wonder if the CME had enough matter in it to exchange a significant amount of momentum during the collision? Maybe after the explosion, (vaporized ice?) the CME was able to blow away the remains (steam?).

:-|

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[arjan]

Thanks Af4ex also for you're daily contributions

I had the same questions. If the sparkle comes from the comet it seems to me, it must have slowed down alot, even reversed direction.
So close to the blast site the cme is much denser then what we ever measure on earth but if it's dense enough to significantly slow a object with such speed, i have no clue.