31 December 2005

Observing Location	New York City
Observational Period
Atmospheric Conditions	It has been raining andsnowing lightly today. It is completely overcast tonight. Clear Sky Clock graphic
Instruments	Short Wave Radio
Observing Party	Charlie Ridgway

Target	Leap Second
Constellation
Category
Time	31Dec05; 18h 59m 60s EST
Comments	A Leap Second needs to be added to the clocks today to keep the atomic clocks, which keep perfect time, in sync with our solar clock, which has a little bit of variability in it. This is the first time a Leap Second has been added (or subtracted) in seven years. It also may be the last one we ever see if the US government has its way. It appears that this is being driven by the communications industry but that needs more research as it has been a highly secretive process on the part of the government (sound familiar?). But that means that clock time will bear no relation to mean solar time (UT) and this will be an even bigger problem for astronomers. The international timekeeping community is generally opposed to the abolition of the Leap Second but recently agreed to postpone debate on the issue. This is something that will have to be watched to see what is ultimately decided and what the ramifications are for the astronomical community. But for the time being we still have the Leap Second and will indeed have one today. Here is a copy of the official notice of the event: I had been wondering which year the new second would belong to and what it would be called. In their notification about the event on 4Jul05, the International Earth Rotation and Reference Systems Service (IERS) or Service International de la Rotation Terrestre et des Systemes de Reference, located at the Observatory of Paris states: UTC TIME STEP on the 1st of January 2006 A positive leap second will be introduced at the end of December 2005. The sequence of dates of the UTC second markers will be: 2005 December 31, 23h 59m 59s 2005 December 31, 23h 59m 60s 2006 January 1, 0h 0m 0s So the extra second is clearly second 60 (the 61st second since seconds are numbered 0-59) of the 59th minute of the 23rd hour of 31Dec05. Since the Leap Second is being inserted into UT it will occur at 18:59:59 EST. Reading into the history of the Leap Second debate of 2005 in the file regerenced at the University of California Observatories seems to indicate that the move to abolish said second has been instigated by the communications industry. Any decision to abolish future Leap Seconds has been put off until 2007 to give everyone time to study the “problem” more fully and, in particular, document any problems that occur on the insertion of an extra second tonight. It is now nearly 2300 EST, five hours after the Leap second and, as far as I can tell anyway, the world is still here and spinning as before, although now with better synchrony between atomic time and solar time. Radio propagation was slightly better than usual in the apartment this evening, but not good enough that I could reliably hear the minute announcements and second ticks on WWV. I took the radio outside and stood in the light rain but reception really wasn’t any better out there. I completely missed the announcements for 2358 and 2359. I heard the announcement for 0000 but there were no second ticks to count after it. It seemed like there might have been a slightly longer pause between the announcement and the minute tone but that is a purely subjective assessment. The Leap Second story from StarDate CNN Leap Second story A Sky and Telescope story about the Leap Second and an editorial in Sky and Telescope about the Leap Second debate Information (mostly links to other sources) on abolishing the Leap Second from the University of California Observatories

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2005 Observing Statistics

	Night			Day			Total
	Hours	Days	Avg	Hours	Days	Avg	Hours	Days	Avg
Jan	9.80	4	2.44	3.80	4	0.94	13.50	6	2.25
Feb	14.00	9	1.56	1.30	2	0.63	15.30	9	1.69
Mar	15.30	9	1.69	2.50	2	1.25	17.80	10	1.78
Apr	40.50	11	3.86	6.80	4	1.69	49.30	12	4.10
May	18.30	6	3.04	4.80	8	0.59	23.00	9	2.56
Jun	22.80	9	2.53	16.30	16	1.02	44.80	16	2.80
Jul	26.00	12	2.17	3.70	15	0.25	29.70	16	1.86
Aug	19.00	9	2.11	8.00	6	1.33	27.00	13	2.08
Sep	61.30	15	4.08	3.80	14	0.27	65.00	19	3.42
Oct	16.50	5	3.30	7.50	7	1.07	24.00	8	3.00
Nov	24.00	9	2.67	4.50	5	0.90	28.50	11	2.59
Dec	12.50	5	2.50	3.30	3	1.08	15.8	8	1.97
Total	281.75	102	2.76	66.99	88	0.76	355.49	137	2.59

Clear Sky Clock Accuracy for the Month of December 2005

During the past month I have kept track of the Clear Sky Clock forecasts and the actual weather to try to assess the accuracy of the forecast. This assessment isn't scientific. It is only 31 days long and I missed collecting data on two of those days. And on some days I didn't make good notes about my feelings on the accuracy of the forecast so have had to back them out from what I did document about the actual conditions.

I made my assessment based on whether I felt that the prevailing conditions at my normal observing time were in agreement with , were better or worse, or were much better or much worse than the Clear Sky Clock forecast. As would be expected, the graph of the results of the assessment formed a bell curve. There was only two cases where I felt the forecast was much different than the subsequent conditions. Nearly 60% of the time the forecast was on target. The remaining forty percent of the time it was fairly evenly split between conditions being worse and better than forecast. Worse had a slight edge, but by only two occurrences and with a sample size only 29 events I am not sure there would be any statistical significance to the difference. One thing that was noted was that the forecasts seemed to be clustered. There would be a string of good forecasts followed by some that were worse than forecast or a cluster of better than forecast, but they didn't seem jump all over the place.