Down Time

The down time statistics are based on individual fault reports. In Table 1 I give the general down time statistics for period 42.

A total of 85 fault reports were submitted, with an average time lost of 7 min per fault, for a total down time of 0.5% (0.6% on scheduled observing nights). Of these, 59 reported no time lost, 26 reported $<$ 2 hrs lost, and none reported 2 or more hrs lost.

This compares to a down time of 0.4% over all nights (0.4% on scheduled observing nights) in period 41, and 0.5% over all nights (0.5% on scheduled observing nights) in period 40. Of the 79 fault reports reported in period 41, 57 reported no time lost, 22 reported $<$ 2 hrs lost, and none reported 2 or more hrs lost. Of the 87 fault report in period 40, 58 reported no time lost, 29 reported $<$ 2 hrs lost, and none reported 2 or more hrs lost.

Table 1: Technical down time statistic period 42: 2010-10-01 to 2011-04-01

Night included	Time lost	Nights	Percentage$^a$	Last semester	Last winter
All nights	605 min	183	0.5%	0.4%	0.5%
Scheduled observing nights$^b$	600 min	152.5	0.6%	0.4%	0.5%
Technical nights	5 min	22	0.0%	0.7%	0.2%
Service nights$^c$	285 min	37	1.1%	0.1%	0.5%
Visitor instruments	0 min	7.5	0.0%	0.0%	0.4%
$^a$ 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

Also with reference to Table 2, the general conclusion is that the level of downtime is rather stable with similar amounts of fault reports and no major failures during the past 5 semesters.