Solar event 080426, a flare in a spotless region, followed by type II/IV emission
This was the Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 117 Issued at 2200Z on 26 Apr 2008:
Analysis of Solar Active Regions and Activity from 25/2100Z
to 26/2100Z: Solar activity was very low. The solar disk is void of
spots. Nonetheless there was a B3/Sf flare at 1408Z from an
unnumbered area of spotless plage near N08E09.
The flare was associated with a wave that was visible in EUV imagery on STEREO and
SOHO, type II and type IV radio sweeps, as well as a slow, faint, full
halo CME visible in coronagraph imagery. The estimated plane of sky
speed for the CME was around 430-480 km/s.
This is Jim Brown's observation of the event.
I believe it is the only one filed in Radio Jove's Archive :
Nancay Decameter Array http://www.obs-nancay.fr/a_index.htm
RHP and LHP enlargements
Flare movies:
http://www.lmsal.com/solarsoft/latest_events_summary/gev_20080426_1354/gev_20080426_1354_lm.html
http://www.lmsal.com/solarsoft/latest_events_summary/gev_20080426_1354/gev_20080426_1354_secchilm.html
links provided by Tom Ashcraft.
WIND spacecraft WAVES experiment spectra
http://lep694.gsfc.nasa.gov/waves/waves.html
All instruments summary
RAD1
This is the type II emission, observable well before the flare time 1408
This is type IV emission 4 hours after the flare, lasting for 3 hours
This another presentation of the RAD1 data where you can see an event
starting at 0400 that looks like a fainter Type II preceding the main
event
RAD2 1-10 Mhz band
-----------------------------------------------
Analysis by Tom Ashcraft posted in Radio Jove List :
Re: Nancay Sun UT0804261408 Flare and Radioemission
Just a quick comment about the solar emissions on the Nancay
spectrogram:
The straight up and down emission is Type III solar bursting.
Following that tall spiking emission is some bursting that curves
downward and to the right. This curving emission is the signature of
Type II bursting or what is called "slow drift bursting". It moves
slower and downward in time than the Type III bursts.
In this instance the Type II appears at around 45 MHz and ends at around
20 MHz a few minutes later on the spectrogram. Whenever you see that
kind of downward curve signature you know it is Type II emission.
Tom
------------------------------------------------
The WIND Spacecraft
http://pwg.gsfc.nasa.gov/istp/wind/
Just a few of the very interesting orbits it has navigated :
Victor Herrero
