GBT Ophiuchus HI Datacube

Description: 21 cm HI maps obtained at the 100 m NRAO Green Bank Telescope. The line profiles of HI in Ophiuchus reveal a strong and extensive HI Narrow SelfAbsorption (HINSA; Li & Goldsmith 2003) component, which is well correlated with molecular emission. Telescope: GBT Status: Complete. Areal Coverage: 5 square degrees Noise Properties: 1 -sigma rms/channel: 0.15 K Sampling: On-the-fly mapping and frequency switching with a 1 MHz throw were used together with a data dumping rate of twice the Nyquist sampling rate, i.e. 4 dumps as the telescope moves over a whole beam. The 12.5 MHz total bandwidth mode of the GBT Spectrometer was used with two spectral windows, one at 1420.4 MHz for HI, the other centered at 1666.4 MHz for the two OH lambda-doubling lines (not available here). The spectral resolution is 0.32 k m s-1. Comments on Reduction: During reduction, frequency-switched data at both frequencies (+/- frequency throw) were treated independently because of instrument baseline stability.