HerschelHIFI results suggest that hydrogen fluoride abundance is comparable to that of para-water over much of the interstellar medium, but not in the galactic center region where an enhancement of water abundance is observed. As part of the HEXOS GT KP, a strip scan of HF of a region of size 2" north and south towards the massive star-forming region of Sagittarius B2 (M) has been observed. We propose observations of a strip map of the para-H _2 O fundamental line towards the same region. The H _2 O strip would be extremely valuable to compare the spatial variations between HF and H _2 O and will allow us to study the nature of the water abundance enhancement towards the galactic center.
Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.