First Light at L-Band for Mimir

12/15/2004 - Flagstaff, Arizona

Last night, Mimir was operated in the thermal infrared L-band (3.6 microns wavelength) for the first time on the Perkins telescope. The Mimir team used the high-resolution camera to test this new mode of the instrument, imaging a bright single star. As the background levels in the long thermal infrared wavlengths are much brighter than in the shorter, near-infrared bands, the detector array must be read out very quickly to prevent saturation. Additionally, most stars are fainter than the sky background at L-band. To be able to see these stars, two images are obtained, with the telescope offset slightly between the images, then the images are subtracted. This was done for these observations, and the star image below represents the difference of the two images.

Portion of the image obtained in L-band with the high-resolution camera mode of Mimir toward a bright star. Click on the picture to see a full-sized image.

The diagonal line across the image is from a portion of the detector crack. Its effects are minimized when images are flat-fielded and coadded from dithered frames.

The profile of this star shows a width of about 1.2 arcseconds, consistent with the seeing measured in K-band last night.