Some example images:
This is a section of a first light image from the MMTF, a 15 minute exposure of the local starburst galaxy NGC 4945 in H-alpha emission, with the MMTF at about 20 A filter width. This image has been processed (bias subtraction, flat fielding) and assembled into a mosaic - the dark lines are the inter-chip gaps of the IMACS 8-chip mosaic.
A larger view of the central region of NGC 4945. (Even this view is binned 2x2 to make the GIF image.) At the center of the galaxy, the ionization cone from the active nucleus is visible, pointing down and to the left.
A section of a 15 minute MMTF H-alpha image of the local peculiar elliptical NGC 5128 (Centaurus A). The light from the elliptical essentially fills the field; the dark dust lanes and H-alpha emission are from a gas disk resulting from a galaxy collision or merger.
Here are the full mosaic images:
Comments on these images: These have been reduced with a set of IRAF scripts that handles bias subtraction and flatfielding for the 8-chip mosaic data. The flat field looks pretty good, in the sense that chip-to-chip offsets are small and there hasn't been a major variation out to the edges of the field. Looking at the full-mosaic images, there are ring-like structures in the sky, which are expected due to night sky lines and the variation of the tunable filter's passband with radius (field angle). These can be taken out by averaging in annuli, unless your object is round and fills the center of the field as for NGC 5128; objects like that are better observed off-center. The light/dark patches at the edge of the full mosaic images are due to a guider probe that changed position between image and flatfield.
These objects were observed at full moon, and applying our preliminary flux calibration, the sky brightness was about R=18.5 mag/sq arcsec. In dark sky conditions the sky should be significantly fainter, R~20.8 mag/sq arcsec.
For questions and comments on the MMTF, the primary contact is the PI, Prof. Sylvain Veilleux, veilleux at astro.umd.edu. For specific questions about these webpages, contact Benjamin Weiner, bjw at astro.umd.edu.
Benjamin Weiner
bjw at astro.umd.edu, updated August 2006.