PREDICTIONS FOR THE TOTAL LUNAR ECLIPSE OF 2018 JULY 27 INCLUDING CONTACT TIMES FOR CRATERS

Helio C. Vital

A very deep umbral eclipse will be seen on July 27 2018 from South America, Africa, Antarctica and much of Europe and Asia. Most of the second half of the phenomenon will be observed from Eastern Brazil. The path of the Moon will make it cross the axis of Earth`s shadow (for that reason the eclipse is called “central”). In addition, Earth will not be far from its aphelion and the Moon will be near its apogee. Such conditions add up to yield an unusually long period of totality: 103 minutes and 37 seconds (±8 s). The predicted value of Δt for this eclipse is 69.1s. Figure 1 illustrates the geometry and global visibility of the eclipse. Listed in Table 1, are circumstances for some events visible from Brazil.

TABLE 1 – ECLIPSE CIRCUMSTANCES
Contact/Event	Time UTC	Umbral Magnitude	Penumbral Magnitude	Moon`s Visible Magnitude
Greatest Eclipse	20:21:43.3	1.613	2.670	-0.8
U3 (End of Total Eclipse)	21:13:32	1.00	2.071	-3.5
U4 (End of Umbral Eclipse)	22:19:22	0.00	1.070	-12.0
Last Perception of Penumbra	≈22:40	0.00	0.750	-12.4
P4 (End of Penumbral Eclipse)	23:28:53	0.00	0.000	-12.7

The eclipse will be relatively dark since the Moon will cross the central axis of Earth's shadow, where there is much less residual light. The visible magnitude of the Moon should be roughly m=-(0.8±0.6) at mid-eclipse. Such figure is about 12 magnitudes (roughly 6x10⁴ times) dimmer than the Full Moon. In addition, current records do not include any large volcanic eruption that could have impacted the stratosphere and might further darken the eclipse significantly.

By analyzing past eclipses, I have concluded that the contribution of our atmosphere to Earth`s shadow remains lower than its mean value over the last 4 decades. Therefore, an atmospheric enlargement factor of 1.816% for the radius of Earth`s umbra, corresponding to an increase of 1.286% in the equatorial horizontal parallax of the Moon, has been used in the calculations. Thus the predictions listed in Table 2A (Immersions) and Table 2B (emersions) are as rigorously as they can be and they can serve as an accurate guide for planning your observations. The use of telescopic magnifications between 40x and 80x is recommended for observers who are willing to time crater contacts. Although the theoretical edge of the penumbra is in practice undetectable and fuzzy, similar predictions for penumbral contacts have also been included, as Table 3A (immersions) and Table 3B (emersions). They are aimed at assisting those who are also interested in monitoring the advance of the penumbra across the disk of the Moon with photometers, CCD cameras or other sensitive devices for scientific purposes. Finally, Table 4 provides tens of instantaneous eclipse circumstances as the umbra gradually leaves the lunar disk. Figures for the horizontal coordinates of the Moon have been calculated for Rio de Janeiro. All predictions on this page have been calculated by the author.

Your crater timings should be expressed to the nearest second (hh:mm:ss). If contrast is poor, try using lower magnifications or stick to the brightest craters. Observers are encouraged to send crater timings and magnitude estimates of this eclipse to [email protected]

PREDICTED LIMB AND CRATER CONTACTS WITH THE UMBRA

TABLE 2A - MID-CRATER UMBRAL CONTACT PREDICTIONS
IMMERSIONS INTO THE UMBRA
Contact/Crater		TIME (UTC) (hh:mm:ss)		Umbral Angle (°)
U1 (Partiality Begins)		18:24:07		-1.2
Riccioli		18:26:03		2.9
Grimaldi		18:26:43		1.8
Billy		18:31:03		-1.8
Kepler		18:39:02		6.1
Campanus		18:40:15		-7.6
Aristarchus		18:40:47		12.1
Copernicus		18:47:44		5.9
Tycho		18:48:28		-13.0
Birt		18:49:28		-6.5
Pytheas		18:50:28		9.9
Timocharis		18:55:52		11.7
Abulfeda		19:02:05		-4.5
Pico		19:03:31		17.7
Nicolai		19:03:36		-14.0
Manilius		19:04:01		6.3
Plato		19:05:06		19.2
Bullialdus		19:05:21		-7.3
Dionysius		19:06:19		1.5
Menelaus		19:07:52		6.6
Plinius		19:11:31		6.0
Eudoxus		19:12:28		16.3
Censorinus		19:13:32		-0.4
Aristoteles		19:13:33		18.0
Stevinus		19:15:35		-12.1
Posidonius		19:16:18		11.7
Goclenius		19:17:19		-4.4
Taruntius		19:20:14		1.4
Proclus		19:21:28		5.4
Langrenus		19:22:53		-4.4
Mare Crisium		19:25:26		5.4
U2 (Totality Begins)		19:29:55		6.9
TABLE 2B - MID-CRATER UMBRAL CONTACT PREDICTIONS
EMERSIONS FROM THE UMBRA
Contact/Crater	TIME (UTC) (hh:mm:ss)		Umbral Angle (°)
U3 (Totality Ends)	21:13:32		23.2
Riccioli	21:15:22		19.0
Grimaldi	21:16:44		18.0
Billy	21:22:54		14.4
Aristarchus	21:23:03		28.2
Kepler	21:26:51		22.2
Campanus	21:33:18		8.6
Pytheas	21:35:12		26.1
Copernicus	21:35:52		22.1
Plato	21:38:39		35.4
Timocharis	21:38:47		27.9
Pico	21:39:18		33.8
Tycho	21:40:45		3.2
Birt	21:42:35		9.7
Aristoteles	21:48:51		34.2
Eudoxus	21:50:01		32.5
Manilius	21:51:53		22.5
Abulfeda	21:54:58		11.7
Menelaus	21:55:26		22.8
Nicolai	21:55:28		2.2
Dionysius	21:57:10		17.7
Bullialdus	21:58:26		8.9
Posidonius	21:59:08		27.9
Plinius	21:59:32		22.1
Censorinus	22:05:05		15.8
Stevinus	22:07:45		4.1
Proclus	22:09:40		21.5
Goclenius	22:09:53		11.8
Taruntius	22:10:50		17.6
Mare Crisium	22:13:27		21.5
Langrenus	22:15:11		11.8
U4 (Partiality Ends)	22:19:22		15.0

PREDICTED LIMB AND CRATER CONTACTS WITH THE PENUMBRA

TABLE 3A - MID-CRATER PENUMBRAL CONTACT PREDICTIONS
IMMERSIONS INTO THE PENUMBRA
Contact/Crater		TIME (UTC) (hh:mm:ss)	Umbral Angle (°)
P1		17:14:35	-3.6
Riccioli		17:16:07	-1.9
Grimaldi		17:16:55	-2.4
Billy		17:21:35	-4.4
Kepler		17:28:37	-0.1
Aristarchus		17:29:08	3.1
Campanus		17:30:59	-7.7
Copernicus		17:37:21	-0.2
Tycho		17:39:03	-10.7
Pytheas		17:39:19	2.0
Birt		17:40:11	-7.0
Timocharis		17:44:17	2.9
Pico		17:50:18	6.0
Plato		17:51:21	6.8
Abulfeda		17:52:45	-5.9
Manilius		17:53:33	0.0
Nicolai		17:54:08	-11.2
Bullialdus		17:56:05	-7.5
Dionysius		17:56:32	-2.6
Menelaus		17:57:20	0.2
Eudoxus		17:59:40	5.3
Aristoteles		18:00:13	6.2
Plinius		18:01:06	-0.2
Censorinus		18:03:56	-3.6
Posidonius		18:04:43	2.9
Stevinus		18:06:15	-10.2
Goclenius		18:08:00	-5.9
Taruntius		18:10:28	-2.7
Proclus		18:11:09	-0.5
Langrenus		18:13:35	-5.9
Mare Crisium		18:15:08	-0.5
P2		18:19:38	-1.5
TABLE 3B - MID-CRATER PENUMBRAL CONTACT PREDICTIONS
EMERSIONS FROM THE PENUMBRA
Contact/Crater	TIME (UTC) (hh:mm:ss)			Umbral Angle (°)
P3	22:23:49			14.8
Riccioli	22:25:18			14.3
Grimaldi	22:26:32			13.7
Billy	22:32:22			11.7
Aristarchus	22:34:42			19.2
Kepler	22:37:17			16.0
Campanus	22:42:33			8.5
Copernicus	22:46:15			15.9
Pytheas	22:46:22			18.1
Tycho	22:50:08			5.5
Timocharis	22:50:22			19.1
Birt	22:51:51			9.1
Plato	22:52:25			23.0
Pico	22:52:33			22.2
Aristoteles	23:02:13			22.3
Manilius	23:02:21			16.1
Eudoxus	23:02:51			21.4
Abulfeda	23:04:16			10.2
Nicolai	23:04:54			4.9
Menelaus	23:05:58			16.3
Dionysius	23:06:57			13.5
Bullialdus	23:07:40			8.7
Plinius	23:09:57			16.0
Posidonius	23:10:43			19.1
Censorinus	23:14:40			12.5
Stevinus	23:17:04			6.0
Goclenius	23:19:11			10.3
Proclus	23:19:59			15.7
Taruntius	23:20:35			13.5
Mare Crisium	23:23:45			15.7
Langrenus	23:24:29			10.3
P4	23:28:53			12.6

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TABLE 4 - CIRCUMSTANCES AS THE UMBRA LEAVES THE DISK

TIME (UTC) MAG OBSC P.A.° R_U/R_M ALT° AZIM°

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MOONRISE 20:26:52.5 1.5972 1.000 192.1 2.6524 -0.25 110.6

20:28:25.3 1.5879 1.000 197.5 2.6524 0.08 110.5

20:29:12.4 1.5824 1.000 200.1 2.6524 0.24 110.4

20:29:59.6 1.5764 1.000 202.5 2.6524 0.40 110.3

20:30:46.7 1.5700 1.000 204.9 2.6524 0.57 110.3

20:31:33.9 1.5632 1.000 207.1 2.6524 0.70 110.2

20:32:21.0 1.5561 1.000 209.2 2.6524 0.83 110.1

20:33: 8.2 1.5485 1.000 211.2 2.6524 0.97 110.0

20:33:55.4 1.5407 1.000 213.1 2.6524 1.10 110.0

20:34:42.5 1.5326 1.000 214.8 2.6524 1.24 109.9

20:35:29.7 1.5242 1.000 216.5 2.6524 1.39 109.8

20:36:16.8 1.5155 1.000 218.1 2.6524 1.53 109.7

20:37: 4.0 1.5066 1.000 219.6 2.6524 1.68 109.7

20:37:51.1 1.4976 1.000 221.0 2.6524 1.82 109.6

20:38:38.3 1.4883 1.000 222.4 2.6524 1.97 109.5

20:39:25.4 1.4788 1.000 223.7 2.6524 2.12 109.4

20:40:12.6 1.4692 1.000 224.9 2.6524 2.28 109.4

20:40:59.8 1.4595 1.000 226.0 2.6524 2.43 109.3

20:41:46.9 1.4496 1.000 227.1 2.6524 2.58 109.2

20:42:34.1 1.4395 1.000 228.1 2.6524 2.74 109.2

20:43:21.2 1.4294 1.000 229.1 2.6524 2.89 109.1

20:44: 8.4 1.4191 1.000 230.0 2.6524 3.05 109.0

20:44:55.5 1.4088 1.000 230.9 2.6524 3.20 108.9

20:45:42.7 1.3984 1.000 231.7 2.6524 3.36 108.9

20:46:29.8 1.3878 1.000 232.5 2.6524 3.52 108.8

20:47:17.0 1.3772 1.000 233.3 2.6524 3.68 108.7

20:48: 4.2 1.3665 1.000 234.0 2.6524 3.83 108.7

20:48:51.3 1.3558 1.000 234.7 2.6524 3.99 108.6

20:49:38.5 1.3449 1.000 235.3 2.6524 4.15 108.5

20:50:25.6 1.3341 1.000 236.0 2.6524 4.31 108.5

20:51:12.8 1.3231 1.000 236.6 2.6524 4.47 108.4

20:51:59.9 1.3121 1.000 237.1 2.6524 4.63 108.3

20:52:47.1 1.3011 1.000 237.7 2.6524 4.80 108.2

20:53:34.2 1.2900 1.000 238.2 2.6524 4.96 108.2

20:54:21.4 1.2788 1.000 238.7 2.6524 5.12 108.1

20:55: 8.6 1.2677 1.000 239.2 2.6524 5.28 108.0

20:55:55.7 1.2564 1.000 239.7 2.6524 5.44 108.0

20:56:42.9 1.2452 1.000 240.1 2.6524 5.61 107.9

20:57:30.0 1.2339 1.000 240.6 2.6524 5.77 107.8

20:58:17.2 1.2226 1.000 241.0 2.6524 5.93 107.8

20:59: 4.3 1.2112 1.000 241.4 2.6524 6.10 107.7

20:59:51.5 1.1999 1.000 241.8 2.6524 6.26 107.6

21: 0:38.7 1.1884 1.000 242.1 2.6524 6.42 107.6

21: 1:25.8 1.1770 1.000 242.5 2.6524 6.59 107.5

21: 2:13.0 1.1656 1.000 242.8 2.6524 6.75 107.4

21: 3: 0.1 1.1541 1.000 243.2 2.6525 6.92 107.3

21: 3:47.3 1.1426 1.000 243.5 2.6525 7.08 107.3

21: 4:34.4 1.1310 1.000 243.8 2.6525 7.25 107.2

21: 5:21.6 1.1195 1.000 244.1 2.6525 7.41 107.1

21: 6: 8.7 1.1079 1.000 244.4 2.6525 7.58 107.1

21: 6:55.9 1.0963 1.000 244.7 2.6525 7.74 107.0

21: 7:43.1 1.0847 1.000 245.0 2.6525 7.91 106.9

21: 8:30.2 1.0731 1.000 245.2 2.6525 8.07 106.9

21: 9:17.4 1.0615 1.000 245.5 2.6525 8.24 106.8

21:10: 4.5 1.0498 1.000 245.7 2.6525 8.40 106.7

21:10:51.7 1.0382 1.000 246.0 2.6525 8.57 106.7

21:11:38.8 1.0265 1.000 246.2 2.6525 8.73 106.6

21:12:26.0 1.0148 1.000 246.5 2.6525 8.90 106.5

21:13:13.1 1.0031 1.000 246.7 2.6525 9.07 106.5

21:14: 0.3 0.9914 0.998 246.9 2.6525 9.23 106.4

21:14:47.5 0.9797 0.994 247.1 2.6525 9.40 106.3

21:15:34.6 0.9679 0.988 247.3 2.6525 9.57 106.3

21:16:21.8 0.9562 0.981 247.5 2.6525 9.73 106.2

21:17: 8.9 0.9444 0.973 247.7 2.6525 9.90 106.1

21:17:56.1 0.9326 0.964 247.9 2.6525 10.07 106.1

21:18:43.2 0.9209 0.955 248.1 2.6525 10.24 106.0

21:19:30.4 0.9091 0.945 248.2 2.6525 10.40 105.9

21:20:17.5 0.8973 0.934 248.4 2.6525 10.57 105.9

21:21: 4.7 0.8855 0.923 248.6 2.6525 10.74 105.8

21:21:51.9 0.8737 0.912 248.8 2.6525 10.90 105.8

21:22:39.0 0.8618 0.900 248.9 2.6525 11.07 105.7

21:23:26.2 0.8500 0.888 249.1 2.6525 11.24 105.6

21:24:13.3 0.8382 0.875 249.2 2.6525 11.41 105.6

21:25: 0.5 0.8263 0.862 249.4 2.6525 11.58 105.5

21:25:47.6 0.8145 0.849 249.5 2.6525 11.74 105.4

21:26:34.8 0.8026 0.836 249.7 2.6525 11.91 105.4

21:27:21.9 0.7908 0.822 249.8 2.6525 12.08 105.3

21:28: 9.1 0.7789 0.808 249.9 2.6525 12.25 105.2

21:28:56.3 0.7670 0.794 250.1 2.6525 12.42 105.2

21:29:43.4 0.7551 0.780 250.2 2.6525 12.59 105.1

21:30:30.6 0.7432 0.766 250.3 2.6525 12.75 105.0

21:31:17.7 0.7314 0.751 250.5 2.6525 12.92 105.0

21:32: 4.9 0.7195 0.737 250.6 2.6525 13.09 104.9

21:32:52.0 0.7076 0.722 250.7 2.6525 13.26 104.8

21:33:39.2 0.6956 0.707 250.8 2.6525 13.43 104.8

21:34:26.3 0.6837 0.692 250.9 2.6525 13.60 104.7

21:35:13.5 0.6718 0.678 251.0 2.6525 13.77 104.7

21:36: 0.7 0.6599 0.662 251.2 2.6525 13.94 104.6

21:36:47.8 0.6480 0.647 251.3 2.6525 14.11 104.5

21:37:35.0 0.6360 0.632 251.4 2.6525 14.27 104.5

21:38:22.1 0.6241 0.617 251.5 2.6525 14.44 104.4

21:39: 9.3 0.6122 0.602 251.6 2.6525 14.61 104.3

21:39:56.4 0.6002 0.587 251.7 2.6525 14.78 104.3

21:40:43.6 0.5883 0.572 251.8 2.6525 14.95 104.2

21:41:30.7 0.5763 0.556 251.9 2.6525 15.12 104.2

21:42:17.9 0.5644 0.541 252.0 2.6525 15.29 104.1

21:43: 5.1 0.5524 0.526 252.1 2.6525 15.46 104.0

21:43:52.2 0.5405 0.511 252.1 2.6525 15.63 104.0

21:44:39.4 0.5285 0.496 252.2 2.6525 15.80 103.9

21:45:26.5 0.5165 0.481 252.3 2.6525 15.97 103.8

21:46:13.7 0.5046 0.466 252.4 2.6525 16.14 103.8

21:47: 0.8 0.4926 0.451 252.5 2.6525 16.31 103.7

21:47:48.0 0.4806 0.436 252.6 2.6525 16.48 103.7

21:48:35.1 0.4687 0.421 252.6 2.6525 16.65 103.6

21:49:22.3 0.4567 0.406 252.7 2.6525 16.82 103.5

21:50: 9.5 0.4447 0.392 252.8 2.6525 16.99 103.5

21:50:56.6 0.4327 0.377 252.9 2.6525 17.16 103.4

21:51:43.8 0.4207 0.363 253.0 2.6525 17.33 103.3

21:52:30.9 0.4087 0.348 253.0 2.6525 17.50 103.3

21:53:18.1 0.3967 0.334 253.1 2.6525 17.67 103.2

21:54: 5.2 0.3848 0.320 253.2 2.6525 17.84 103.2

21:54:52.4 0.3728 0.306 253.2 2.6525 18.01 103.1

21:55:39.5 0.3608 0.292 253.3 2.6525 18.19 103.0

21:56:26.7 0.3488 0.278 253.4 2.6525 18.36 103.0

21:57:13.9 0.3368 0.265 253.4 2.6525 18.53 102.9

21:58: 1.0 0.3248 0.252 253.5 2.6525 18.70 102.8

21:58:48.2 0.3127 0.238 253.6 2.6525 18.87 102.8

21:59:35.3 0.3007 0.225 253.6 2.6525 19.04 102.7

22: 0:22.5 0.2887 0.213 253.7 2.6525 19.21 102.7

22: 1: 9.6 0.2767 0.200 253.8 2.6525 19.38 102.6

22: 1:56.8 0.2647 0.188 253.8 2.6525 19.55 102.5

22: 2:43.9 0.2527 0.175 253.9 2.6525 19.72 102.5

22: 3:31.1 0.2407 0.163 253.9 2.6525 19.90 102.4

22: 4:18.3 0.2286 0.152 254.0 2.6525 20.07 102.4

22: 5: 5.4 0.2166 0.140 254.1 2.6525 20.24 102.3

22: 5:52.6 0.2046 0.129 254.1 2.6525 20.41 102.2

22: 6:39.7 0.1926 0.118 254.2 2.6525 20.58 102.2

22: 7:26.9 0.1806 0.107 254.2 2.6525 20.75 102.1

22: 8:14.0 0.1685 0.097 254.3 2.6525 20.92 102.1

22: 9: 1.2 0.1565 0.087 254.3 2.6525 21.10 102.0

22: 9:48.3 0.1445 0.077 254.4 2.6525 21.27 101.9

22:10:35.5 0.1324 0.068 254.4 2.6525 21.44 101.9

22:11:22.7 0.1204 0.059 254.5 2.6525 21.61 101.8

22:12: 9.8 0.1084 0.051 254.5 2.6525 21.78 101.8

22:12:57.0 0.0963 0.043 254.6 2.6525 21.96 101.7

22:13:44.1 0.0843 0.035 254.6 2.6525 22.13 101.6

22:14:31.3 0.0723 0.028 254.7 2.6525 22.30 101.6

22:15:18.4 0.0602 0.021 254.7 2.6525 22.47 101.5

22:16: 5.6 0.0482 0.015 254.8 2.6525 22.64 101.5

22:16:52.7 0.0361 0.010 254.8 2.6525 22.82 101.4

22:17:39.9 0.0241 0.005 254.9 2.6525 22.99 101.3

22:18:27.1 0.0120 0.002 254.9 2.6525 23.16 101.3

U4 22:19:14.2 0.0000 0.000 255.0 2.6525 23.33 101.2