Two-wavelength photospheric image sequences

A 70 min time series of co-spatial and co-temporal G-band 430.5 nm and wideband 468.6 nm filtergrams, obtained with the 50 cm Swedish Vacuum Solar Telescope on the island of La Palma, Spain.

The 29''×70'' field-of-view (FOV) near disk center contains both an enhanced network region and an (apparently) non-magnetic "quiet" region of granulation.

The mean time between frames is 23.5 s. Each frame is a Partitioned Phase-Diverse Speckle (PPDS; see Löfdahl & Scharmer 1994; Paxman et al. 1996) restoration of three realizations of the atmospheric turbulence acquired rapidly in sequence. The result is high-resolution movies of the solar photosphere, good enough to allow detection, tracking and analysis of ~0''.2 bright points. The process of wavefront sensing and restoration of the data is described by Löfdahl et al. (1998).



Analysis of the data has been performed by Berger et al (1998a,b) and Ballegooijen et al. (1998). For the analysis, two subfields have been identified, one with mainly quiet granulation and one with an active network and many "bright points".

Data files in ANA format for analysis:

Quiet G-band, 17 MBytes.
Quiet wideband, 17 MBytes.
Network G-band, 23 MBytes.
Network wideband, 20 MBytes.

ANA files can be read into IDL.

As with all data collected with the SVST, any paper that is based on these data should include the following sentence in the Acknowledgements section:

The Swedish Vacuum Solar Telescope is operated on the island of La Palma by the Royal Swedish Academy of Sciences in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.


Papers describing the methods used

M. G. Löfdahl & G. B. Scharmer (1994), Wave Front Sensing and Image Restoration from Focused and Defocused Solar Images, Astronomy & Astrophysics Supplements Series, 107, pp. 243-264

R. G. Paxman, J. H. Seldin, M. G. Löfdahl, G. B. Scharmer & C. U. Keller (1996), Evaluation of Phase-Diversity Techniques for Solar-Image Restoration, Astrophysical Journal, 466, pp. 1087-1099

M.G. Löfdahl, T.E. Berger, R.A. Shine & A.M. Title (1998), Preparation of a Dual Wavelength Sequence of High Resolution Solar Photospheric Images using Phase Diversity, Astrophysical Journal, 495, pp. 965


Papers on the analysis of these data

T.E. Berger, M.G. Löfdahl, R.A. Shine & A.M. Title (1998a), Measurements of Solar Magnetic Element Motion from High Resolution Filtergrams,
Astrophysical Journal, 495, pp. 973

T.E. Berger, M.G. Löfdahl, R.A. Shine & A.M Title (1998b), Measurements of Solar Magnetic Element Dispersal, Astrophysical Journal, 506, pp. 439

A.A. van Ballegooijen, P. Nisenson, Noyes, M.G. Löfdahl, Stein, Aa. Nordlund & V. Krishnakumar (1998), Dynamics of Magnetic Flux Elements in the Solar Photosphere, Astrophysical Journal, 509, pp. 435

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