Technical improvements and possibilities to observe solar oscillations with the small Mets

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Technical improvements and possibilities to
observe solar oscillations with the small
Metsähovi radiotelescope

• Juha Kallunki
• kallunki_at_kurp.hut.fi
• Metsähovi Radio Observatory

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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

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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

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Observations (1/2)

• About 100 observation days --gt 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

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Observations (2/2)
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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

0 5 min (1540) 5 10 min (2820) 10 15 min (4960)
Avg. 12,9 29,6 55
Min. 5 10 30
Max. 20 50 100
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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.

Interval Class
2 - 4 min 3 min
4 - 7,5 min 5 min
7,5 12,5 min 10 min
12,5 - 17,5 min min
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Solar oscillations (1/2)
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Solar oscillation (2/2)
3 min 5 min 10 min 15 min
Avg. 770 1540 2820 4960
Standard deviations 46 83 171 358
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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

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Bigger antenna vs. small antenna (2/2)

• Big antenna

• Small antenna

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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

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Future works

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

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The EndQuestions?