Down Time

The down time statistics are based on individual fault reports. In Table 1 I give the general down time statistics for period 44.

A total of 130 fault reports were submitted, with an average time lost of 8 min per fault, for a total down time of 0.9% (1.1% on scheduled observing nights). Of these, 95 reported no time lost, 33 reported $<$ 2 hrs lost, and 2 reported 2 or more hrs lost.

This compares to a down time of 1.2% over all nights (1.3% on scheduled observing nights) in period 43, and 0.5% over all nights (0.6% on scheduled observing nights) in period 42. Of the 144 fault report in period 43, 96 reported no time lost, 47 reported $<$ 2 hrs lost, and one reported 2 or more hrs lost. Of the 85 fault reports reported in period 42, 59 reported no time lost, 26 reported $<$ 2 hrs lost, and none reported 2 or more hrs lost.

Table 1: Technical down time statistic period 44: 2011-10-01 to 2012-04-01

Night included	Time lost	Nights	Percentage$^a$	Last semester	Last Winter
All nights	1100 min	183	0.9%	1.2%	0.5%
Scheduled observing nights$^b$	1000 min	138	1.1%	1.3%	0.6%
Technical nights	50 min	22	0.3%	0.8%	0.0%
Service nights$^c$	445 min	39.5	1.7%	1.5%	1.1%
Visitor instruments	50 min	23	0.3%	0.0%	0.0%
$^a$ Taking the average length of time within nautical twilight. Exact numbers for each night
are used when looking at ``All nights''
$^b$ Excluding technical nights and visitor instruments
$^c$ Excluding service nights with SOFIN

The number of fault reports is still at a bit higher level than normal, mostly caused by things related to the introduction of the new detector controller for the ALFOSC CCD. Beyond that, the relatively high percentage of downtime is cause by a single large error (see below).