Palomar Seeing and Photometric Data

May 21, 1997 to November 1, 2000

Total Nights	1261
Engineering Nights	38
Holidays	6
Potential Observing Nights	1217

(OPEN) = Opened All Night
(HALF) = Opened For Less Than Half Of The Night (weather, etc)
(CLOSE) = Closed All Night

Number Of Photometric Nights	371	31%
with Seeing < 1.0", (OPEN)	29	(2%)
with Seeing < 1.0", (HALF)	1	(0.1%)
with Seeing = 1.0", (OPEN)	54	(4%)
with Seeing = 1.0", (HALF)	4	(0.3%)
with 1.0 < Seeing <= 1.5", (OPEN)	159	(13%)
with 1.0 < Seeing <= 1.5", (HALF)	4	(0.3%)
with 1.5 < Seeing <= 2.0", (OPEN)	63	(5%)
with 1.5 < Seeing <= 2.0", (HALF)	14	(1%)
with Seeing > 2.0", (OPEN)	31	(3%)
with Seeing > 2.0", (HALF)	12	(1%)

Number Of Partial (1/2 or better) Photometric Nights	289	24%
with Seeing < 1.0", (OPEN)	37	(3%)
with Seeing < 1.0", (HALF)	0	(0%)
with Seeing = 1.0", (OPEN)	46	(4%)
with Seeing = 1.0", (HALF)	2	(0.2%)
with 1.0 < Seeing <= 1.5", (OPEN)	86	(7%)
with 1.0 < Seeing <= 1.5", (HALF)	19	(2%)
with 1.5 < Seeing <= 2.0", (OPEN)	53	(4%)
with 1.5 < Seeing <= 2.0", (HALF)	6	(0.5%)
with Seeing > 2.0", (OPEN)	30	(3%)
with Seeing > 2.0", (HALF)	10	(0.8%)

Number Of Non Photometric Nights	331	27%
with Seeing < 1.0", (OPEN)	16	(1%)
with Seeing < 1.0", (HALF)	0	(0%)
with Seeing = 1.0", (OPEN)	36	(3%)
with Seeing = 1.0", (HALF)	12	(1%)
with 1.0 < Seeing <= 1.5", (OPEN)	120	(10%)
with 1.0 < Seeing <= 1.5", (HALF)	34	(3%)
with 1.5 < Seeing <= 2.0", (OPEN)	45	(4%)
with 1.5 < Seeing <= 2.0", (HALF)	19	(2%)
with Seeing > 2.0", (OPEN)	25	(2%)
with Seeing > 2.0", (HALF)	24	(2%)

Number Of Nights Closed	226	(19%)
Fog / Humidity	80	(7%)
Snow	46	(4%)
Rain	45	(4%)
Clouds	35	(3%)
Smoke / Ash	12	(1%)
Snow On Dome (clear sky)	5	(0.4%)
Instrument Failure	3	(0.3%)

Number Of Nights Opened For Half Or Less Of The Night (Total HALF)	161	(13%)
Total Number Of Nights Closed (CLOSE + HALF)	387	(32%)

Nightly Average Seeing

Number Of Nights With Seeing < 1.0"	83	(7%)
Number Of Nights With Seeing = 1.0"	154	(13%)
Number Of Nights With 1.0 < Seeing <= 1.5"	422	(35%)
Number Of Nights With 1.5 < Seeing <= 2.0"	200	(16%)
Number Of Nights With Seeing > 2.0"	132	(11%)

Month	Total Nights	Nights Closed							Nights Open
Month	Total Nights	Fog	Snow	Rain	Clouds	Ash	Other	Total	Photometric	0.5 Photometric	Non Photometric	Average Seeing
January	93	7	5	10	5	-	1	28 (12%)	9	15	41	1.7
February	83	5	17	8	5	-	1	36 (16%)	4	4	39	1.8
March	89	12	9	3	2	-	-	26 (12%)	15	26	22	1.6
April	90	11	14	2	-	-	-	27 (12%)	26	25	12	1.5
May	99	14	-	2	-	-	-	16 (7%)	21	29	33	1.4
June	98	10	1	1	-	-	-	12 (5%)	59	16	11	1.4
July	123	-	-	2	3	3	-	8 (4%)	54	30	31	1.2
August	124	-	-	1	5	9	-	15 (7%)	40	41	28	1.2
September	120	6	-	5	2	-	-	13 (6%)	61	26	20	1.3
October	120	9	-	6	4	-	1	20 (9%)	47	28	25	1.6
November	91	4	1	2	8	-	-	15 (7%)	18	27	31	1.5
December	87	2	4	3	1	-	-	10 (4%)	17	22	38	2.1