Solar-granulation power spectra from speckle interferometry

Technical Report · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6952944

Von Der Luehe, O; Dunn, R B

Granulation was observed with a CCD array at the SPO tower telescope in a quiet region near the solar center. The authors took time series of short-exposure (4 ms) pictures of a 14 sec by 14 sec region. Consecutive frames were separated by 0.55s in time. They applied Labeyrie's (1970) speckle-interferometry technique in order to recover power spectra of the intensity fluctuations at high spatial frequencies. The spectral-ratio technique was applied to correct for seeing attenuation of the power spectra. Signal up to a spatial frequency of 2.5 line pair per arcsecond was recovered, corresponding to a wave number of 22 M/m or 40% of the diffraction limit of the telescope under 1.3 arcsec average seeing conditions. A corrected rms granulation contrast of 0.127 + or - 0.01 was estimated, and an exponential falloff was observed of power density towards higher spatial frequencies.

• Research Organization: Air Force Geophysics Lab., Hanscom AFB, MA (USA)
• OSTI ID: 6952944
• Report Number(s): AD-A-193883/6/XAB; AFGL-TR-88-0082
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
COHERENT SCATTERING
DIFFRACTION
DISTRIBUTION
IMAGE PROCESSING
INTERFEROMETRY
PROCESSING
SCATTERING
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR GRANULATION
SPATIAL DISTRIBUTION
SPECTRA
TELESCOPES
VARIATIONS
VISIBLE SPECTRA