header image 2

University of Southern California

Whats New
Ongoing projects
Low Cost Asses to Space-CAL-SO Program and Continuation and Improvement of the SOHO CELIAS/SEM Data Base

The SOHO CAL-SO program funded by the Low Cost Access to Space NASA grant NNG05WC09G is in the year of no-cost-extension. Thus far under this grant we have had two successful rocket underflights that return high quality EUV data and three successful calibrations of the SEM instrument at NIST. Analysis of the data from all underflights was completed in Dec 2008. The results will be presented at the Fall AGU Meeting (San Francisco, Dec 2008): Darrell Judge, Leonid Didkovsky, Seth Wieman, and Pradip Gangopadhyay. "13 Years of SOHO/CELIAS/SEM Calibrated Solar Extreme Ultraviolet Irradiance Data". The SEM calibrated data website at USC (http://www.usc.edu/dept/space_science) will be updated in Dec 2008 - Jan 2009 to publish the new version of the SEM data (Ver 3.1 of Dec 11, 2008). This work was partially supported by NASA grant NNG05WC09G; USC# 53-4882-3600 and NASA grant NASA-NNX08AM94G; USC# 53-4882-2820


The ESP flight and rocket instruments have been successfully calibrated at NIST and delivered to LASP and later to Goddard SFC. The flight instrument was assembled to the EVE and is a part of SDO. SDO was launched on Feb 12, 2010.

New Projects
A New Advanced Extreme Ultraviolet Optics Free Spectrometer

The Space Sciences Center is currently working (year two of two) on the Project to design and build a new OFS (NASA grant NASA-NNX07AN37G; USC# 53-4882-4640). The laboratory design is about to be fabricated at the USC mechanical shop. After assembling the focusing system, laboratory tests with EUV monochromator will begin in Jan 2009.

Degradation-Free Spectrometers (DFS) for Solar Physics (NASA-NNX08BA12G; USC# 53-4882-5920)

A Sounding Rocket flight NASA 36.263 with four USC EUV instruments onboard 36.263_payload was successfully launched from WSMR on 24 July 2012. The instruments for measuring solar absolute EUV irradiance included the Solar Extreme_ultraviolet Monitor (SEM) - a clone of the SOHO/CELIAS/SEM flight instrument, the Rare Gas Ionization Cell (RGIC) - an extremely stable Ne-gas ionization instrument which served for a long time as a secondary standard of EUV irradiance at NIST, the Optics-Free Spectromeer (OFS) , and the Dual-Grating Spectrometer (DGS). This was the first flight of the two latter instruments, both novel degradation-free spectrometers, while the SEM and RGIC data are used for calibration of existing EUV flight measurements, such as the SOHO/CELIAS/SEM and the SDO/EVE/ESP. The flight 36.263 met this observational challenge and the success criteria. The data from the flight 36.263 will be analyzed soon [Didkovsky et al., AGU Fall Meeting, San Francisco, 2012]. An important outcome of the flight is the confirmation of the robustness of the DGS filter-free design for observing solar EUV spectral lines of interest without degradation, e.g. the He II 30.4 nm line which has been widely used by the solar and Earth's atmosphere communities since 30.4 nm data became available from the SOHO/CELIAS/SEM. The OFS, which measures EUV wavlength spectra based on energy analysis of photoelectrons from Ne target gas, was calibrated at the NIST/SURF synchrotron prior to flight. OFS spectra of monochromatic EUV radiation from the NIST synchrotron at several different wavelengths show its ability to resolve spectral lines in the EUV. Once the OFS response to solar EUV is known, spectral resolution of the instrument can be further optimized.


    website last updated 9/1/2012