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Juha Kallunki kallunki@kurp.hut.fi Metsähovi Radio Observatory

Juha Kallunki kallunki@kurp.hut.fi Metsähovi Radio Observatory. Technical improvements and possibilities to observe solar oscillations with the small Metsähovi radiotelescope. Metsähovi small radiotelescope. Total intensity measurements Facts: Diameter: 1,8 m (beam size: 81,6 arc min)

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Juha Kallunki kallunki@kurp.hut.fi Metsähovi Radio Observatory

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  1. Juha Kallunki kallunki@kurp.hut.fi Metsähovi Radio Observatory Technical improvements and possibilities to observe solar oscillations with the small Metsähovi radiotelescope

  2. 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

  3. 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

  4. Observations (1/2) • About 100 observation days --> selection based on stability of intensity (weather, power outages, service…), between 2007-2008 (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

  5. Observations (2/2)

  6. Antenna inner oscillations • 10-15 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

  7. 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.

  8. Solar oscillations (1/2)

  9. Solar oscillation (2/2)

  10. 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

  11. Big antenna Small antenna Bigger antenna vs. small antenna (2/2)

  12. 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

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

  14. The EndQuestions?

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