Calibration of Magnetically Induced Solar Velocity Signals for the GOLF Investigation using Mt. Wilson 150-foot Tower

摘要

The effort during 1995 was directed toward the implementation of the 24-channel system which is now nearly installed. This system will permit us to make simultaneous line profile maps of the solar surface in the MDI lambda 6768 line and the Na D lines. The intercomparison of the GOLF and MDI data requires that we have a knowledge and understanding of the systematic differences between these two lines which are formed at different altitudes in the solar atmosphere. This system will have 5 major parts: 1) a new grating providing 7th, 8th and 9th order access to lambda 6768, lambda 5896 and lambda 5250 respectively. This grating is now in regular use and gives us a cleaner spectral sampling than the previous grating which produced an asymmetric profile with a HeNe laser and the Na cell absorption. 2) Three new fiber-optic reformatters to sample the solar spectrum at up to 20-points each (only 10 of which will be used for each reformatters during typical observations). Two will be used for the Na and Ni lines while the third is required for the synoptic alpha 5250 line due to the geometry change from the new grating. These fiber-optic assemblies are on order from Schott Fiber-Optics and are scheduled for delivery by the end of February 1996. 3) two new 12-channel exit slit stages with PMT's and amplifier electronics (two channels for each stage will be dedicated to the lambda 5250 synoptic program). These are now finished and undergoing final checkout. 4) A new digitizing/computer interface system to connect to the exist PDP-11 based data acquisition system. This is in regular operation and has functioned without problem for the past 18 months. 5) New acquisition and reduction software to permit the analysis of the 24-channels of data. This is in debugging.