1. A large-scale darkening observed in EUV and radio emissions
V. Grechnev, A. Uralov,
I. Kuzmenko, I. Chertok et al.

2. SOHO/EIT 304 Å
Before, during, and after
2004 July 13

3. SOHO/EIT 195 Å & LASCO/C2
SOHO telescopes show an eruptive event:

4. TRACE 171 Å
00:07:52
00:13:37
00:16:50
00:19:42
00:21:36
00:48:08

5. Flare and eruptive filament
Big Bear H images
Flare and eruptive filament

6. Mauna Loa H images
Original image
Fixed-base difference

7. 2004 July 13 event: GOES M6.7 in AR 10646 (N15W49)
Very impulsive microwave burst
Flux GHz
Duration ~10 min
H flare not reported by patrol stations
but Big Bear images show it
Filament eruption and CME

8. Probable causes of large darkening in HeII 304 Å
Dimming due to density depletion? – Usually well observed in 195 Å
Occultation by absorbing material:
resonant absorption in cooler HeII (<50000 K)?
non-resonant absorption in H (<10000 K)?

9. Evolution of 195 Å dimming

10. Summary on 195 Å dimming
304 Å
Density-depletion 195 Å dimming lives
much longer
Configuration quite different
 Not a density-depletion dimming
Min{Images}
Images[0] Min{Images}/ Images[0]
195 Å

11. NoRH shows Ejected material: First bright on the disk
Then bright above the limb, and dark on the disk
Dark moving feature is not large
Ejecta is inhomogeneous

12. Multi-frequency radio fluxes
EIT 304 Å
observation
NoRP & Ussuriysk 2.8 GHz
Solid: observed
Dotted: thermal emission of flare subtracted
Normalized to the quiet sun’s level
Absorption 
TFil < TQS 3.75 = 23,000 K

13. Frequency dependence of radio absorption
, GHz
AreaEIT304=0.067
Symbols: observed
Solid: calculated considering the ejecta and corona above it
 Ejected mass 
(6–9)·1015 g with
depth = (20–200) Mm

14. Epilogue-I
The phenomenon was due to occultation of the quiet sun rather than an active region
This unique event was revealed from EIT 304 Å data and independently from Ussuriysk 10.7 cm records
It was possible to detect it from total flux radio records thanks to shortness of the main burst

15. …Which would be important…
Epilogue-II
Murphy’s Low works perfectly:
No SSRT 5.7 GHz data
No high-cadence CORONAS-F/SPIRIT 304 Å data
…Which would be important…
Nevertheless, non-imaging multi-frequency total flux records allowed us to study the event

16. We acknowledge
Shibasaki San and NSRO for the opportunity to work here under perfect conditions
Staff members of the NSRO for the hospitality