First Light for Mimir's High Resolution (F/17) Camera Mode

12/15/2004 - Flagstaff, Arizona

The Mimir instrument achieved first light for its high-resolution, f/17 camera mode last night on the Perkins telescope. This camera provides a pixel plate scale of 0.18 arcseconds per pixel with a full field of view of about 3x3 arcminutes. Last night's test was the first time this camera mode has been used in the Mimir instrument while on the Perkins telescope.

Images of stars seen through the wide-field, f/5 camera on Mimir (which has 0.58 arcseconds per pixel and about a 10x10 arcmin full field of view) last night showed profile widths of just over 2 pixels, or about 1.2 arcsecond "seeing." The high-resolution camera was driven into the optical path by the cryogenic stepper motor and drive system within the Mimir cryostat and several images were obtained in the Ks band (2.2 microns wavelength). A range of telescope focus settings were tried and images obtained until the stellar profile width was minimized. This yielded a profile FWHM of 6.3 pixels or about 1.1 arcseconds. Short exposures revealed the clear presence of "speckles," the breaking up of the stellar image into a small number of diffraction-limited sub-images. The speckle sizes were as small as the 0.3 arcsecond diffraction limit of the Perkins telescope at K band.

Small portion of the high-resolution camera image showing a single star. The profile width of this star is 1.1 arcseconds. Click on the picture to see the full sized image.

The best focus setting for the f/17 camera at K-band is the same as the best focus setting for the f/5 camera. Tests for all the Mimir wavebands are planned for later in this engineering run.