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Low Temperature Statistics for the GBT

Since we now have restricted azimuth slew speed when the temperature goes to or below 16.5 F ( -8.6 C), it seems worthwhile to compile some statistics about when and how often these low temperatures happen.

Note weather restrictions, described here.

• The archived log data, samplers "TEMP_1" and "TEMP_2, from weather station 2 have been used.
• The minimum temperature in each FITS log file (about one file per hour usually) is noted.
• These file minima are what is plotted versus day number for each year, below.
• The percentage of readings in which the temperature goes below -8.5 C is tabulated in the table.
• (there is usually a reading per second)

Table: Percentage of time the temperature was below -8.5 C

Month / year:	_ 2003 _	_ 2004 _	_ 2005 _	_ 2006 _	_ 2007 _	_ 2008 _
JAN	35	34	19	--	12	22
FEB	7	12	8	7	37
MAR	2	2.3	8	1	2.5
APR	0	0	0	0	0.5
OCT	1	0	0.3	0	0
NOV	1	0.4	6.3	1.3	1.4
DEC	19	18	15	8.5	4.3

-- FrankGhigo - 26 Feb 2008

Plots of minimum temperatures per hour; x-axis is day number for the year The horizontal line is at Temp = -8.5 C. Sometimes the temperature monitors produce bogus values of -40 to -50 C. Ignore these !

Attachment:	Action:	Size:	Date:	Who:	Comment:
yplot_2008.gif	action	39925	27 Feb 2008 - 21:12	FrankGhigo	January 2008 minimum temperatures
yplot_2007.gif	action	90575	27 Feb 2008 - 21:13	FrankGhigo	Temperatures for 2007
yplot_2006.gif	action	75139	27 Feb 2008 - 21:14	FrankGhigo	Temperatures for 2006
yplot_2005.gif	action	72735	27 Feb 2008 - 21:14	FrankGhigo	Temperatures for 2005
mplot2004.gif	action	91303	27 Feb 2008 - 21:34	FrankGhigo	Temperatures for 2004
yplot_2003.gif	action	79919	27 Feb 2008 - 21:34	FrankGhigo	Temperatures for 2003