What does a yellow porch light mean? Yellow porch lights are bug lights. By bug light I mean they are not supposed to attract bugs as bad as regular light bulbs.
GPS Week Number Rollover. The GPS Week Number count began at approximately midnight on the evening of 05 January 1980 / morning of 06 January 1980. Since that time, the count has been incremented by 1 each week, and broadcast as part of the GPS message. The GPS Week Number field is modulo 1024. This means that at the completion of week 1023, the GPS week number rolled over to 0 on midnight GPS Time of the evening of 21 August 1999 / morning of 22 August 1999. Note that this corresponded to 23:59:47 UTC on 21 August 1999.
ISO week number. With ISO week numbers, week 1 starts on the Monday of the first week in a year with a Thursday. This means that the first day of the year for ISO weeks is always a Monday in the period between Jan 29 and Jan 4. In Excel 2013, there is a new function called ISOWEEKNUM.