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We report the detection of interstellar hydrogen deuteride (HD) toward thesupernova remnant IC443, and the tentative detection of HD toward the HerbigHaro objects HH54 and HH7 and the star forming region GGD37 (Cepheus A West).Our detections are based upon spectral line mapping observations of the R(3)and R(4) rotational lines of HD, at rest wavelengths of 28.502 and 23.034micron respectively, obtained using the Infrared Spectrograph onboard theSpitzer Space Telescope. The HD R(4)/R(3) line intensity ratio promises to be avaluable probe of the gas pressure in regions where it can be observed. Thederived HD/H2 abundance ratios are 1.19(+0.35/-0.24)E-5, 1.80(+0.54/-0.32)E-5,and 1.41(+0.46/-0.33)E-5 respectively (68.3% confidence limits, based uponstatistical errors alone) for IC443 (clump C), HH54, and HH7. If HD is the onlysignificant reservoir of gas-phase deuterium in these sources, the inferredHD/H2 ratios are all consistent with a gas-phase elemental abundance[n(D)/n(H)](gas) ~ 7.5E-6, a factor 2 - 3 below the values obtained previouslyfrom observations of atomic deuterium in the local bubble and the Galactichalo. However, similarly low gas-phase deuterium abundances have been inferredpreviously for molecular gas clouds in the Orion region, and in atomic cloudsalong sight-lines within the Galactic disk to stars more distant than 500 pcfrom the Sun.Comment: 12 pages, including 5 figures. Accepted for publication in ApJ  Letter

S p i t zer Observations of Hydrogen Deuteride