The Hiltner Telescope Manual claims that 0".7 FWHM can be obtained on the telescope. While there is no systematic, comprehensive study of seeing on the 2.4-meter, John Tonry and John Blakeslee took a long series of 1550 comparable seeing measurements during a sequence of six observing runs during 1992-1994. Since then the primary has been refrigerated, which seems to have made a significant improvement in seeing. Nonetheless, the median seeing from these earlier statistics is 0".97, with first quartile at 0".85, and 10th percentile at 0".76.

Histogram of Seeing FWHM values:



Tabulated Number of Seeing Values from Six Runs (1992-1994):

Seeing (FWHM)	Apr92	Aug92	Apr93	May93	Oct93	Feb94
0.60 arcsec	0	0	5	3	0	0
0.65	0	14	7	1	0	1
0.70	7	27	12	6	0	2
0.75	14	41	18	13	5	3
0.80	30	26	21	21	18	3
0.85	49	19	42	15	14	16
0.90	42	22	31	28	17	28
0.95	32	11	25	19	13	33
1.00	44	11	16	21	12	9
1.05	40	13	10	15	9	16
1.10	68	11	16	14	9	11
1.15	37	5	9	11	6	7
1.20	38	7	7	24	10	11
1.25	15	1	6	5	5	11
1.30	16	5	5	4	5	9
1.35	11	0	2	11	2	8
1.40	13	1	2	6	1	1
1.45	3	2	5	5	1	2
1.50	7	0	4	2	0	4
1.55	1	0	2	5	1	6
1.60	5	0	1	5	0	13
1.65	0	0	1	0	0	3
1.70	4	0	0	0	0	1
1.75	2	2	0	2	0	0
1.80	1	0	0	3	0	3
1.85	1	0	0	1	0	1
1.90	2	0	1	0	0	0
1.95	0	0	0	1	0	0
2.00	1	0	0	0	0	0
2.05	0	0	0	0	0	2
2.10	0	0	0	0	0	0
2.15	0	0	0	0	0	2
2.20	0	0	0	1	0	5
2.25	0	0	0	0	0	3
2.30	0	0	0	0	0	5
2.35	0	0	0	0	0	5
2.40	0	0	0	0	0	4
2.45	0	0	0	0	0	2
2.50	0	0	0	0	0	1