COMICS high-resolution N-band spectroscopy

The high-resolution N-band grating provides a resolution of ~10,000 (0.33'' slit) and a dispersion of 0.00058 um/pixel. Spectroscopy can only be performed where narrow-band filters are available and is, at present, limited to the regions around the 8.99-um [Ar III], 10.51-um [S IV], and 12.81-um [Ne II] lines. The spectrum is dispersed onto the 3rd of the COMICS spectrograph's 5 detectors. Note that the wavelength axis is tilted with respect to the array columns, so only 0.138 um (about 240 pixels) are covered along the entire 40'' length of the slit.

The point-source sensitivity of the NH grating has only been determined around 12.8-um, and is shown in the following figure (1 sigma for 1 second of on-source integration time). Except for the four regions where there is strong sky emission (indicated by arrows), much of the high-frequency variation is not real.

Estimates of the sensitivity with the other narrow-band filters can be made from the figures on the spectrograph index page and the following plots of sky transparency. In regions where the transparency drops below ~80%, successful observations may not be possible due to bright sky lines.

[Ar III] [S IV] [Ne II]

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