HOP 0182

abstract of observational proposal

The main goal of the proposal is to compare the horizontal velocity fields computed with "The Coherent structure tracking" (CST) method that we developped. This method consists to follow solar granules as tracer of the solar plasma.

From the preceding HINODE and SDO observations (August 30, 2010), we found a very good correlation (amplitude and direction) between horizontal flow fields computed from both time sequence (HINODE and SDO) figures 1 and 2.

Figure 1

Figure 2

The good correlation between flow fields at the disc center (HINODE and SDO) encouraged us to apply our method (CST) to the full Sun observation of SDO. As first step, we have chosen a temporal window 180s and spatial step of 2.5Mm. Figure 3 and 4 show the map of the velocity amplitudes for vx and vy respectively. These velocities are the projected velocities on the sky.

Figure 3 a and b : FULL SUN a) Vx (on the left) amplitude (positive and bright to the west), b) Vy (on the right) amplitude (positive and bright to the north).

Our final goal, if the quality of the measurement is good, is to produce horizontal velocity map in collaboration with SDO team for the solar community. We are in contact with Laurent Gizon.

In order to calibrate precisely these velocities over the Sun surface, we would like image time series at different latitudes along the central meridian and different longitudes along the equator, during at least 3h (or more if possible) for each position. The observations of the different locations can be done on different days.

request to SOT

SOT/BFI:　images in the Blue continuum: ideal time step: 45s , pixel = 0.1 arcsec

However, if telemetry needs it or if longer time sequence are thus do able, the time step may be increased up to 60s.

Different latitudes are required along the central meridian (south direction), namely 15°, 30°, 45°, 60°, 75° at fixed pointing (no solar rotation compensation).

Different longitudes are required along the equator (west direction), namely 15°, 30°, 45°, 60°, 75°at fixed pointing (no solar rotation compensation).