20:00 22:00 00:00 02:00 04:00 05:00 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 Time in zone EST5EDT on 2019-07-22 (local date at sunset) Airmass 100.0 -1.0 100.0 -1.0 20:00, 13.33 20:05, 13.33 20:10, 13.33 20:15, 13.33 20:20, 13.26 20:25, 12.66 20:30, 11.87 20:35, 11.05 20:40, 10.26 20:45, 9.53 20:50, 8.87 20:55, 8.27 21:00, 7.72 21:05, 7.24 21:10, 6.80 21:15, 6.40 21:20, 6.03 21:25, 5.70 21:30, 5.40 21:35, 5.13 21:40, 4.88 21:45, 4.65 21:50, 4.43 21:55, 4.24 22:00, 4.06 22:05, 3.89 22:10, 3.73 22:15, 3.58 22:20, 3.45 22:25, 3.32 22:30, 3.20 22:35, 3.09 22:40, 2.99 22:45, 2.89 22:50, 2.79 22:55, 2.71 23:00, 2.63 23:05, 2.55 23:10, 2.47 23:15, 2.40 23:20, 2.34 23:25, 2.28 23:30, 2.22 23:35, 2.16 23:40, 2.11 23:45, 2.06 23:50, 2.01 23:55, 1.96 0:00, 1.92 0:05, 1.88 0:10, 1.84 0:15, 1.80 0:20, 1.76 0:25, 1.73 0:30, 1.69 0:35, 1.66 0:40, 1.63 0:45, 1.60 0:50, 1.57 0:55, 1.55 1:00, 1.52 1:05, 1.50 1:10, 1.47 1:15, 1.45 1:20, 1.43 1:25, 1.41 1:30, 1.39 1:35, 1.37 1:40, 1.35 1:45, 1.33 1:50, 1.31 1:55, 1.30 2:00, 1.28 2:05, 1.26 2:10, 1.25 2:15, 1.24 2:20, 1.22 2:25, 1.21 2:30, 1.20 2:35, 1.19 2:40, 1.17 2:45, 1.16 2:50, 1.15 2:55, 1.14 3:00, 1.13 3:05, 1.12 3:10, 1.12 3:15, 1.11 3:20, 1.10 3:25, 1.09 3:30, 1.08 3:35, 1.08 3:40, 1.07 3:45, 1.06 3:50, 1.06 3:55, 1.05 4:00, 1.05 4:05, 1.04 4:10, 1.04 4:15, 1.03 4:20, 1.03 4:25, 1.03 4:30, 1.02 4:35, 1.02 4:40, 1.02 4:45, 1.01 4:50, 1.01 4:55, 1.01 5:00, 1.01 Airmass plot for M 31 RA = 00:42:44.32, Dec = +41:16:07.5; Middlebury College Observatory, VT. Lat, long = 44.0134, -73.1813 90 56 45 38 33 30 27 24 Elevation (degrees)