3-12-um images of HD44179 and M42: spectral differencing as a mid-infrared astronomical image enhancement technique

摘要

Abstract: NASA Ames Research Center and Lick Observatory have jointly developed two prototype infrared camera for astronomical imaging. The new cameras have been built using Amber Engineering Inc. 128 $MUL 128 SiGa and InSb focal plane arrays. We report observations of the BN-KL source complex in M42 and HD44179 which are used as a demonstration of the cameras' performance when used as narrow band spectral images. The images have a dynamic range in excess of 10$+3$/. The high signal to noise ratio and linearity of the images are used to demonstrate the power of spectral differencing as a tool for astronomical image enhancement at mid infrared wavelengths. The observations were made over a range of wavelengths 3.1 - 3.3 $mu@m and 8.4 - 11.5 microns in and out of the silicate absorption band, and in the PAH emission bands at 3.3 $mu@m and 11.3 $mu@m using approximately 2% spectral resolution. Bell and Crisp, 1991, have reported spatial resolution enhancement of images for the surface of Mars by division of multispectral images in and out of the H$-2$/O absorption feature at 3 $mu@m. We find that a similar image processing technique using normalized image differencing can be used in the 10 $mu@m silicate absorption feature and PAH emission bands to improve the contrast in mid-infrared astronomical images. This technique is expected to be applicable to imaging of galactic nuclei and other astronomical objects as well as embedded stellar infrared sources.!4