Technical improvements and possibilities to observe solar oscillations with the small Metsähovi radiotelescope Juha Kallunki Metsähovi Radio Observatory

Metsähovi small radiotelescope Total intensity measurements Facts: –Diameter: 1,8 m (beam size: 81,6 arc min) –Center frequency: 11,2 GHz –Band: 1 GHz –two different sample record interval Since 2001 To detect solar flare  ”fishing float” Average level of total intensity

Recent technical upgrades and studies Solve technical problems –weather effects  mechanical improvements –calibration  some method to do calibration –pointing  renewing the pointing algorithm –”inner oscillations” To study possibility to observe solar oscillations

Observations (1/2) About 100 observation days --> selection based on stability of intensity (weather, power outages, service…), between (May-August)  period of low solar activity Each day, period of 8 hours (the highest elevation) 50 samples per second  one second average FFT analysis Cold and hot load measurements

Observations (2/2)

Antenna inner oscillations days with hot load (ideal attenuator)  ambient temperature Same measurement principle All values are in relative units Also with cold load (sky) measurements Amplitudes of inner oscillations are less than 5% for the typical level of solar oscillations Possible reasons: –EMC –Reflections –Mechanical vibrations –etc.  extremely difficult to say exact reason 0 – 5 min (1540) 5 – 10 min (2820) 10 – 15 min (4960) Avg.12,929,655 Min Max

Classification of solar oscillations Own classification Choosing the highest amplitude at certain interval We have been concentrated to study oscillations in interval of 3-15 minutes. IntervalClass min3 min 4 - 7,5 min5 min 7,5 – 12,5 min10 min 12,5 - 17,5 min15min

Solar oscillations (1/2)

Solar oscillation (2/2) 3 min5 min10 min15 min Avg Standard deviation σ

Bigger antenna vs. small antenna (1/2) big antenna (36,8 GHz; 2,5 arcmin) some comparison during solar flares big antenna: track of active area small antenna: whole disk

Bigger antenna vs. small antenna (2/2) Big antennaSmall antenna

Conclusions possible to observe solar oscillations with small antenna of cource it is not possible to say about coordinates of the flare, for that we need to use some other observation instruments, for example big antenna in case of solar flares can be seen similarities between small and big antenna

Future works more observations (”active periods”) simultaneous observations with big and small radiotelescopes possible technical improvements –radome –dicke radiometer –etc.

The End Questions?