Mission
Update –
Heading towards six months since launch, SORCE continues to make
excellent daily solar observations, with nightly stellar observations
for calibration. Scientists and engineers continue to verify the
instrument calibrations and data processing software. As of the
end of May, measurements are being validated, and some preliminary
data are being distributed to the science community through the
Goddard Space Flight Center DAAC.
Spacecraft
and Instrument Status –
All spacecraft systems continue to perform exceptionally well.
The spacecraft is in its nominal Sun pointing mode, and is making
two scheduled contacts each day. There are no plans to change
spacecraft operations in the near future.
The calibration process continues on all of the SORCE instruments,
which are currently operating in normal mode. The preliminary
data products generated are meticulously reviewed, and compared
to earlier instrument expectations. The data are also compared
with observations of similar instruments on other spacecrafts
currently operating. After investigating the similarities and
anomalies, scientists work towards data validation by improving
data processing code.
The weekly SORCE Status Report is available on the SORCE website
at http://lasp.colorado.edu/sorce. It summarizes the spacecraft
activity, ground contacts, the instrument measurements, spacecraft
and instrument planning, and data processing.
A
Closer Look at the SOLSTICE
Instrument –
This newsletter explores the preliminary data results from the
SOLSTICE (Solar Stellar Irradiance Comparison Experiment) instruments.
There are two identical SOLSTICE instruments onboard SORCE. They
each measure ultraviolet solar and stellar radiation from 115
to 320 nm. SOLSTICE A and B are unique in that they also measure
the irradiances from a group of 18 bright blue stars for calibration
purposes. The intrinsic variability of these stars is insignificant
making this precise calibration possible. 
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The SOLSTICE
instruments are performing very well, collecting precise radiation
measurements. Scientists are comparing the SOLSTICE measurements
from SORCE to the measurements collected from the SOLSTICE instrument
on board the UARS experiment, launched in 1991. The results are
very similar, but the SORCE SOLSTICE has a better spectral resolution
at all the wavelengths. Following are two plots comparing SORCE
and UARS SOLSTICE measurements. 
Click on image for larger view
This plot shows that the wavelength measurements from the
SORCE SOLSTICE (black line) extend to the left much further than
the UARS SOLSTICE (red line). SORCE SOLSTICE wavelength range
in FUV extends down to 115 nm.
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