In February 1996, SUMER performed a 31-hour-raster of the Sun in the light of the Carbon IV emission line at 1548 Å (transition region, temperature 100 000 K).
The raster step size was 1.9 arcsec, the exposure time 15 seconds per raster step. The spectral window consisted of 50 pixels and was wide enough to contain not only the C IV line but also part of the neighbouring continuum.
Therefore it was possible to compose an image showing the Sun in the radiation of the continuum near 1549 Å (chromosphere, less than 6000 K). This is probably the "coldest" full disk picture ever made by SUMER.
The images above were binned by setting 3 arcsec x 3 arcsec to 1 pixel.
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IED, 29.Apr.97
