Abstract:
The rst and preiminary results of the photometry of Large Yield
Radiometer (LYRA) and Sun Watcher using Active Pixel system detector
and Image Processing (SWAP) onboard PROBA2 are presented in this
paper. To study the day-to-day variations of LYRA irradiance, we have
compared the LYRA irradiance values (observed Sun as a Star) measured
in Aluminum lter channel (171 A - 500 A) with spatially resolved full
disk integrated intensity values measured with SWAP (174 A) and Ca ii
K 1 A index values (ground based observations from NSO/Sac Peak) for
the period from 01 April 2010 to 15 Mar 2011. We found that there is a
good correlation between these parameters. This indicates that the spatial
resolution of SWAP complements the high temporal resolution of LYRA.
Hence SWAP can be considered as an additional radiometric channel. Also
the K emission index is the integrated intensity (or
ux) over a 1 A band
centered on the K line and is proportional to the total emission from
the chromosphere, this comparison clearly explains the LYRA irradiance
variations are due to the various magnetic features, which are contributing
signi cantly. In addition to this we have made an attempt to segregate
coronal features from full-disk SWAP images. This will help to understand
and determine the actual contribution of the individual coronal feature to
LYRA irradiance variations.
Description:
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