– images in the Blue and Red continua (1 image in each wavelength)
– G-band images (1 image)
– magnetograms (1 magnetogram)
– 20 positions equally separated from the N to the S limb, along the central meridian
– 10 positions equally separated from the E to the W limb, close to the equator
– repeat the N-S and E-W scans four times, consecutively, on four consecutive days (this means that 16 images in each wavelength and 16 magnetograms should be taken in each position on the central meridian and on the equator)
– repeat it twice a year, early January and early July, close to the 5th of each month, when the solar and terrestrial polar axis are alined, during the entire Hinode life.
Observations should be made at 10 positions between the equator and each pole; the Sun along central meridian will thus observed without any gap. East-West scans close the the equator are required , in order to compare N-S variations to E-W variations along the equator, supposed to be homogeneus, and see possible latitude departures. 10 positions between the E and W limbs are sufficient because of the 220 '' long field of view. Our recent investigation of Pid du Midi data has shown that the statistical noise due to granule evolution is 4% pic to pic for a field of view 218'' x 109''. In order to reduce this noise to the 1% level required to detect a granulation size variation related to the solar cycle ( the variation of the contrast is larger than the 4% level), N-S and E-W scans should be repeated 4 times, if possible on four consecutive days, in order to get 16 time and space independent images at each latitude and each position on the equator. This will also allow us to avoid active regions, with a high probability. Blue continuum and G-band images, as well as magnetograms are needed for this program, in order to see whether the local magnetic flux, visible in the G-band images and measured in the magnetograms, is responsible of the granulation variations. The observations should be repeated twice a year, early January and early July, near the 5th of each month, when the solar and terrestrial axis are closely alined. This will simplify the foreshortening effects and make image analysis much easier. We are aware of possible thermal problems in July, during the eclipse season.
It will be interesting to include red continuum images, in order to derive center-to-lim variations of the solar granulation in two wavelengths, i.e. at two heights in the photosphere.
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