Liquid Nitrogen is no longer required to run Tbird. The new dewar is now permanently mounted on the telescope. Two gas lines for the cooler now run out the bottom of the dewar, around the pier of the telescope, and through the observing floor to a compressor which sits on the first floor level near the stairway. Changes in the pumping fixtures to the new dewar have required a new foreline to be installed on the pumping cart . The foreline now utilizes KF vacuum fittings.
Some work still remains to be done on the new dewar.
There are currently three problems with the current setup. This is sufficient to rid us of most of our dark noise, but not all. This coupling scheme will be improved by internal changes in the dewar at the end of this observing season. Second, the gas lines cause considerable drag on the telescope and are even dangerous in some orientations. This will also be fixed by the addition of some right angle fittings at the end of this observing season.