Down Time

The down time statistics are based on individual fault reports. In Table 1 I give the general down time statistics for period 37. A total of 95 fault reports were submitted, with an average time lost of 19 min per fault, for a total down time of 1.8% (0.1% on scheduled observing nights). Of these, 63 reported no time lost, 28 reported $<$ 2 hrs lost, and 4 reported 2 or more hrs lost.

Table 1: Technical down time statistic period 37: 2008-04-01 to 2008-10-01

Night included	Time lost	Nights	Percentage$^a$	Last semester	Last summer
All nights	1785 min	183	1.8%	0.8%	1.4%
Scheduled observing nights$^b$	610 min	146	0.1%	1.1%	1.8%
Technical nights	60 min	21	0.1%	0.4%	1.1%
Service nights$^c$	60 min	16	0.1%	1.1%	2.6%
Visitor instruments	1115 min	31	6.8%	0.0%	0.1%
$^a$ 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

This compares to a down time of 0.8% over all nights (1.1% on scheduled observing nights) in period 36, and 1.4% over all nights (1.8% on scheduled observing nights) in period 36. Of the 74 fault report in period 36, 47 reported no time lost, 24 reported $<$ 2 hrs lost, and 3 reported 2 or more hrs lost. Of the 118 fault report in period 35, 80 reported no time lost, 34 reported $<$ 2 hr lost, and 4 reported 2 or more hrs lost.

Although the total down time is slightly higher than in previous semesters, being completely dominated by a single fault, the overall numbers are rather normal.