Monthly Newsletter

April 2003

There have been three solar rotations during the SORCE mission, of which the last two solar rotations have been observed continuously by the SORCE instruments. This figure shows the time series of the bright solar Lyman-a emission at 121.6 nm from the SORCE XPS and also shows the 10.7 cm radio flux (F10.7) that is often used as a proxy for the solar UV radiation. The XPS values are preliminary results as validation is still in progress.

The Sun was especially active between days 2003/076 and 2003/079 (Mar. 17-20) when several large flares occurred on the Sun. This figure shows that the solar X-ray radiation (0.1-7 nm) changed by more than a factor of 10 for a couple of these flares. The changes are less, as expected, for the solar UV radiation, showing an increase of about 10% for the Lyman-a emission during the large flare on day 2003/076. Most of this flare energy is absorbed in the atmosphere below 100 km, so the photochemistry affected by these flares include NO and H2O, which in turn affect the O3 chemistry in the mesosphere.

Spacecraft Status –
All spacecraft systems are performing exceptionally well. The spacecraft is in its nominal Sun pointing mode.

Mission/Science Operations Center –
The Operations Center has two contacts per day with SORCE between 8 a.m. and 10 p.m. Two staff people (one professional and one student) are on hand to receive the data and to make sure the outgoing commands are sent. The SORCE spacecraft and instruments generate approximately 120 Megabytes (MB) of raw telemetry data per day. Since the launch, these data are routinely delivered to the Goddard Space Flight Center for permanent archival. Delivery activities continue to operate smoothly, with minor adjustments being made to associated science data processing software to improve performance and diagnostic capabilities.

Weekly Status Report –
SORCE team members are producing a weekly SORCE Status Report to document progress during the mission. It summarizes the spacecraft activity, ground contacts, the instrument measurements, spacecraft and instrument planning, and data processing. This report is available on the SORCE web site at

SORCE Team Member Retired –
It’s official! George Lawrence celebrated his retirement with family, friends, and co-workers at a dinner in his honor on March 31st. Pictures from the evening are available on the LASP website at Fortunately for LASP, George is very interested in SORCE data analysis and we plan to see him back at LASP part-time after a relaxing break.

page 2