An experiment will be performed at the Roseland Community Observatory, Roseland Community School, Tregony, Nr Truro, Cornwall, to survey the mid infrared (IR) spectrum of the corona. Astronomics 2000, who run the observatory with support from Plymouth University, are in charge of the experiment. Allan Ridgeley of Rutherford Appleton Laboratory (RAL) is providing the scientific input into this experiment. Nicolet Instruments are providing a Fourier Transform Infrared Spectrometer (FTIR) as is the Material Science Laboratory (MSL) of Daresbury Laboratory. Francisco Diego of University College London has been giving optical support.
A 22" siderealstat (borrowed from RAL) will direct radiation from the corona into two of the observatory's telescopes, a 12" F/7 Newtonian and a 12" F/4.5 Newtonian. The output from the 12" telescope is linked to the Nicolet FTIR which will cover the atmospheric windows between 1 and 5 microns wavelength. The MSL spectrometer will cover spectral region between 2.5 microns and 13 microns.
The coronal mid IR spectrum has been incompletely surveyed above 1.4 microns. Theory predicts that there are several observable "forbidden" spectral lines in this region. Observations during the 1998 solar eclipse by Kuhn and his co-workers would appear to indicate that one line in particular, the Si IX line at 4.9 microns, may be the strongest infrared coronal line.
The discovery of a strong coronal line in the mid IR has important implications for coronal magnetic field measurements. So far no direct measurement of coronal magnetic field lines has been made because of the weakness of these fields and the large Doppler widths associated with the million degree corona. The Zeeman splitting of spectral lines is relatively more pronounced in the IR. The presence of a strong infrared coronal line will make more viable a technique developed by Kuhn to measure Zeeman splitting of coronal lines.
Previous observations of the corona in the IR have produced evidence that cool (in coronal terms) material may exist in the corona. (Neutral hydrogen and helium lines have been observed). The MSL spectrometer will survey a spectral region rich in hydrogen and helium transitions between highly excited states, producing further experimental evidence whether or not such cool material exists in the corona.
The ICS experiment has been prepared on a very low cost budget. It has been put together with existing hardware. Staff involved with the experiment have given their own time to the experiment.