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Infrared-Array Measurements of Carbon Monoxide...(1Dec93)
Near 4.7 um
(from NSO, NOAO Newsletter No. 36, 1 December 1993)

In the June issue of the Newsletter, Bill Livingston and Keith Pierce
announced the availability of a large infrared-optimized grating in the
McMath-Pierce vertical spectrograph and illustrated the new capability
with spectral scans of carbon monoxide lines near 4.67 um. Recently,
the first bi-dimensional CO spectra were obtained using this grating,
NSO's Amber 256 x 256 InSb array, and the image-scanning hardware
developed for the Near Infrared Magnetograph (NIM). The array captures
a spectral range of about 3 cm-1 near 2140 cm-1, enough to record
several vibration-rotation lines with different excitation energies. CO
is a sensitive thermometer of the solar temperature-minimum region.
Ayres has hypothesized that the temperature-minimum region is thermally
bifurcated, with magnetic heating and CO cooling playing key roles. CO
lines also show prominent five-minute oscillations, as demonstrated at
the McMath two decades ago by Noyes and Hall. Ayres (CASA), Noyes,
Uitenbroek, and Avrett (CfA), Solanki (ETH), and Livingston and Rabin
(NSO) will be analyzing various aspects of spatially-resolved CO data.

Owing to thermal background, the region of the CO fundamental bands
should be observed using cold, narrowband (dl < 1000 A) filters.
Observers interested in a particular spectral region are encouraged to
contact us so that we can determine whether a suitable filter is
available or can be obtained at reasonable cost.

Doug Rabin, Bill Livingston, Dave Jaksha

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