Flares, Longitudes, and Limbs (oh my!)

[Drax Spacex]

Espied - great word of the day!  Double plus good.  Halcyon too - esp. as the noun - a mythical bird said by ancient writers to breed in a nest floating at sea at the winter solstice, charming the wind and waves into calm.  I'm going to work that into casual conversation somehow.

Ahh STEREO B - the rebellious one, the evil twin, the goateed Spock.  Like HAL in 2010, perhaps STEREO B can yet be revived.  But keep that little red pocket calculator handy, just in case the Borg got to it.

[Drax Spacex]

Running this algorithm for the next ten 24-day periods, we might hypothesize that strong flares will occur (C5+, M, X class) near the projected Earth-view longitudes (+/-30°) corresponding to the Sun-fixed Active Longitude close to the indicated dates (+/-5 days).

Presume Active Longitude = 1° (Lo, Carrington longitude) based on the significant activity of AR2860.

The 24-day strong-flare start date could be presumed as 2021-08-28 given the M4.8 flare from AR2860.  The earth-view location of the flare was S29W01.  These will comprise the algorithm date and location initial settings (2021-08-28, W01).

Where will AR2860 be 24 days after the M4.8 flare?

Assume a typical rotation rate of an AR per day to be 360°/27.27days
= 13.2°/day.

The number of degrees of rotation in 24 days = 13.2°/day*24days
= 316.8°.

Every 24th day, a returning region in earth-view will appear to lag behind the location in its previous rotation in longitude by (360°-316.8°)
=43.2°.

Initial Settings:

Start date 2021-08-28
Start Earth-view longitude=W01

Run the algorithm:

+24 days=2021-09-21
((24*13.2)mod360)-360+1=-42.2=E42.2
=East Disk flare

+48 days=2021-10-15
((48*13.2)mod360)-360+1=-85.4=E85.4
=East Disk/Limb flare

+72 days=2021-11-08
((72*13.2)mod360)-360+1=-128.6=E128.6
=Far Side flare

+96 days=2021-12-02
((96*13.2)mod360)-360+1=-171.8=E171.8
=Far Side flare

+120 days=2021-12-26
((120*13.2)mod360)+1=W145.0
=Far Side flare

+144 days=2022-01-19
((144*13.2)mod360)+1=W101.8
=West Limb flare

+168 days=2022-02-12
((168*13.2)mod360)+1=W58.6
=West Disk flare

+192 days=2022-03-08
((192*13.2)mod360)+1=W15.4
=Center/West Disk flare

+216 days=2022-04-01
((216*13.2)mod360)-360+1=-27.8=E27.8
=Center/East Disk flare

+240 days=2022-04-25
((240*13.2)mod360)-360+1=-71.0=E71.0
=East/Limb Disk flare

2021-09-21 marks the 24th day after the M4.8 flare.  AR2860, if there's anything left of it, will be at or near S29E42.  Will lightning strike twice?

Looking much further out, the dates near 2022-03-08 and 2022-04-01 look particularly interesting for possible increased chance of strong flares located near the center of the solar disk with Earth-facing longitudes.

Edited September 5, 2021 by Drax Spacex
wordsmithery

[Archmonoth]

2 hours ago, Drax Spacex said:

Running this algorithm for the next ten 24-day periods, we might hypothesize that strong flares will occur (C5+, M, X class) near the projected Earth-view longitudes (+/-30°) corresponding to the Sun-fixed Active Longitude close to the indicated dates (+/-5 days).

Presume Active Longitude = 1° (Lo, Carrington longitude) based on the significant activity of AR2860.

The 24-day strong-flare start date could be presumed as 2021-08-28 given the M4.8 flare from AR2860.  The earth-view location of the flare was S29W01.  These will comprise the algorithm date and location initial settings (2021-08-28, W01).

Where will AR2860 be 24 days after the M4.8 flare?

Assume a typical rotation rate of an AR per day to be 360°/27.27days
= 13.2°/day.

The number of degrees of rotation in 24 days = 13.2°/day*24days
= 316.8°.

Every 24th day, a returning region in earth-view will appear to lag behind the location in its previous rotation in longitude by (360°-316.8°)
=43.2°.

Initial Settings:

Start date 2021-08-28
Start Earth-view longitude=W01

Run the algorithm:

+24 days=2021-09-21
((24*13.2)mod360)-360+1=-42.2=E42.2
=East Disk flare

+48 days=2021-10-15
((48*13.2)mod360)-360+1=-85.4=E85.4
=East Disk/Limb flare

+72 days=2021-11-08
((72*13.2)mod360)-360+1=-128.6=E128.6
=Far Side flare

+96 days=2021-12-02
((96*13.2)mod360)-360+1=-171.8=E171.8
=Far Side flare

+120 days=2021-12-26
((120*13.2)mod360)+1=W145.0
=Far Side flare

+144 days=2022-01-19
((144*13.2)mod360)+1=W101.8
=West Limb flare

+168 days=2022-02-12
((168*13.2)mod360)+1=W58.6
=West Disk flare

+192 days=2022-03-08
((192*13.2)mod360)+1=W15.4
=Center/West Disk flare

+216 days=2022-04-01
((216*13.2)mod360)-360+1=-27.8=E27.8
=Center/East Disk flare

+240 days=2022-04-25
((240*13.2)mod360)-360+1=-71.0=E71.0
=East/Limb Disk flare

2021-09-21 marks the 24th day after the M4.8 flare.  AR2860, if there's anything left of it, will be at or near S29E42.  Will lightning strike twice?

Looking much further out, the dates near 2022-03-08 and 2022-04-01 look particularly interesting for possible increased chance of strong flares located near the center of the solar disk with Earth-facing longitudes.

 

Your observations and detail are refreshing, thank you, and I will be watching. 

 

Edited September 5, 2021 by Archmonoth

[Drax Spacex]

On 9/5/2021 at 9:34 AM, Drax Spacex said:

+24 days=2021-09-21

((24*13.2)mod360)-360+1=-42.2=E42.2
=East Disk flare

2021-09-21 marks the 24th day after the M4.8 flare.  AR2860, if there's anything left of it, will be at or near S29E42.  Will lightning strike twice?

Well, like Han Solo said, "Our position's correct, except no Alderaan."

2021-09-21
Region 2871
Location S28E42
Number of sunspots 8
Size 280
Class Magn Beta-Delta
Class Spot DKO

Given a few more days, maybe it will fire off some C5+ or M flares as it passes the center longitudes of the solar disk. Maybe.

[Drax Spacex]

On 9/21/2021 at 12:18 PM, Drax Spacex said:

Given a few more days, maybe it will fire off some C5+ or M flares as it passes the center longitudes of the solar disk. Maybe.

Maybe becomes a yes:

2021-09-23
Region 2871
Location S28E16
Number of sunspots 9
Size 290
Class Magn Beta-Gamma-Delta
Class Spot DKO

M2.8 flare at 2021-09-23 04:42 UTC

M1.9 flare at 2021-09-23 15:28 UTC

Edited September 23, 2021 by Drax Spacex
Another M flare

[Archmonoth]

2 hours ago, Drax Spacex said:

Maybe becomes a yes:

2021-09-23
Region 2871
Location S28E16
Number of sunspots 9
Size 290
Class Magn Beta-Gamma-Delta
Class Spot DKO

M2.8 flare at 2021-09-23 04:42 UTC

M1.9 flare at 2021-09-23 15:28 UTC

Fantastic! Your 2022 predictions aren't that far away, very exciting. 

[Drax Spacex]

The literature describes two active longitudes on the sun, one for the northern solar hemisphere and one for the southern solar hemisphere.  These two active longitudes are typically somewhere in the neighborhood of 180° apart.

So far on this thread I've only been tracking the strong flares we've seen in the southern hemisphere.  With the recent M flare in the northern hemisphere, we could assume that corresponds to the northern hemisphere active longitude.  We could also start tracking that active longitude.

The Carrington longitude of the AR that spawned that northern hemisphere M flare was 156°.  From the SWPC forecast discussion on 2021 Oct 09 1230 UTC: "Region 2882 N17E06, Dho/beta-gamma, produced an M1/2b flare at 09/0653 UTC."

A good question would be whether the 24 day strong flare period applies independently to northern and southern hemispheres or if it is only for the entire sun.  I'll assume separate 24 day periods for the two hemispheres and run the numbers for the northern hemisphere:

Initial Settings (Northern Hemisphere):

Start date 2021-10-09
Start Earth-view longitude=E06

Run the algorithm:

+24 days=2021-11-02
((24*13.2)mod360)-360-6=-49.2=E49.2
=East Disk flare

+48 days=2021-11-26
((48*13.2)mod360)-360-6=E92.4
=East Disk/Limb flare

+72 days=2021-12-20
((72*13.2)mod360)-360-6=E135.6

+96 days=2022-01-13
((96*13.2)mod360)-360-6=E178.8

+120 days=2021-02-06
((120*13.2)mod360)-6=W138.0

+144 days=2021-03-02
((144*13.2)mod360)-6=W94.8
=West Disk/Limb flare

+168 days=2021-03-26
((168*13.2)mod360)-6=W51.6
=West Disk Flare

+192 days=2021-04-19
((192*13.2)mod360)-6=W8.4
=Center Disk Flare