NIRC warmups can be from LHe to LN2, from LN2 to ambient (dome) temperatures, or from LHe all the way to ambient. The latter is not necessarily a concatenation of the first two since we are dealing with a nonequilibrium process started at two distinct states.

LHe to LN2

Shown below is a warmup from LHe to LN2. At about 5 hours the LHe dewar runs out of cryogen. Note the inflection point at 20 hours. This may be due to the cold trap beginning to outgas, or the level sensors may have been turned on. (The level sensors dump significant amounts of heat into the LHe dewar.)

Also note that throughout this time the detector is being controlled at its operating temperature. You can tell this because the detector curve if constant just under 30 K until the LHe dewar reaches the same temperature. Then it stays nearly in lockstep with the dewar. Normally the detector tempertuare will lag the LHe dewar during an unforced warmup.

After 140 hours the LHe dewar and the detector have still not reached equilibrium.

LHe to ambient

A fuller warmup curve is shown below. At about 32 hours the LHe dewar runs out of liquid cryogen. Again, some 10-15 hours after this the LHe warmup accelerates (at tempreatures of 20 K, higher than the 10 K acceleration seen above). At around 86 hours the LN2 can runs out of cryogen.

A close-up of the LHe to LN2 transition from above shows the plateau, lasting more than 40 hours. This could be due to LO2 boiloff, or it could be due to LN2 remaining in the dewar, still boiling off slowly as the still cold LHe dewar keeps it relatively cold.

The following, patchy but long-term coverage shows a warmup which took roughly 90 hours, with some rather inexplicable behavior during that time period. For example, at ~65 hours the LN2 temperature drops, as if the LN2 dewar was refilled.

Below is a warmup whose coverage starts during the "plateau" phase. Once the plateau phase ends, at ~45 hours, ambient temperature is reached after another 100 hours, although the dewar is certainly cold enough to pump well before this.