Down Time

The down time statistics are based on individual fault reports. In Table 1 I give the general down time statistics for period 41.

A total of 79 fault reports were submitted, with an average time lost of 5 min per fault, for a total down time of 0.4% (0.4% on scheduled observing nights). Of these, 57 reported no time lost, 22 reported $<$ 2 hrs lost, and none reported 2 or more hrs lost.

This compares to a down time of 0.5% over all nights (0.5% on scheduled observing nights) in period 40, and 0.7% over all nights (0.8% on scheduled observing nights) in period 39. Of the 87 fault reports reported in period 40, 58 reported no time lost, 29 reported $<$ 2 hrs lost, and none reported 2 or more hrs lost. Of the 93 fault report in period 39, 63 reported no time lost, 30 reported $<$ 2 hrs lost, and none reported 2 or more hrs lost.

Table 1: Technical down time statistic period 41: 2010-04-01 to 2010-10-01

Night included	Time lost	Nights	Percentage$^a$	Last semester	Last summer
All nights	400 min	183	0.4%	0.5%	0.7%
Scheduled observing nights$^b$	305 min	137	0.4%	0.5%	0.8%
Technical nights	95 min	25	0.7%	0.2%	1.1%
Service nights$^c$	10 min	37	0.1%	0.5%	0.9%
Visitor instruments	0 min	21	0.0%	0.4%	0.2%
$^a$ 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 4 semesters.