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 it is called “central”). In addition, Earth will not be far from its aphelion while the Moon will be near its apogee. Such conditions add up to yield an unusually long period of totality: (103.4±0.2) minutes. The predicted value of Δt for this eclipse is 69.2s.  Figure 1 illustrates the geometry and global visibility of the eclipse.  Listed in Table 1, are circumstances for primary contacts visible from Brazil.

 

TABLE 1 – ECLIPSE CIRCUMSTANCES

Contact/Event

Time

UTC

Umbral

Magnitude

Penumbral Magnitude

Moon`s Visible Magnitude

Greatest Eclipse

20:21:44.3

1.611

2.669

-0.8

U3 (End of Total Eclipse)

21:13:24

1.00

2.071

-3.5

U4 (End of Umbral Eclipse)

22:19:14

0.00

1.070

-12.0

Last Perception of Penumbra

22:40

0.00

0.750

-12.4

P4 (End of Penumbral Eclipse)

23:28:52

0.00

0.000

-12.7

 

 

The eclipse will be very dark because the Moon will cross the central axis of Earth's shadow, where there is much less residual light. Our expectation is that in the middle of the eclipse the visible magnitude of the Moon should be roughly m=-(0.8±0.6), that is about 12 magnitudes (roughly 6x104 times) darker than the Full Moon. In addition, current records do not list any volcanic eruption that could further darken this eclipse, although that situation may still change. In that case, new predictions for the brightness of this eclipse will be posted here. 

 

Although the Moon will rise approximated at mid-eclipse for observers located on the Brazilian East coast, many minutes will pass until there is enough contrast for it to be found in the twilight sky, since it will be extremely pale, still initiating its recovery in brightness. This fact should delay the start of record keeping, largely reducing anyone`s chance of getting nice photos and making accurate brightness estimates for some 40 minutes after the predicted Moonrise time. Thus, observers should be aware that they should persist in the search for the Moon (preferably with binoculars) using as reference its predicted azimuth and altitude. However, in the half hour that will follow, those observations will have a much greater chance of succeeding. Be sure to record when the Moon becomes visible in the sky (possibly when its brightness rivals that of Jupiter or even Venus) in addition to the end of totality, times of limb and crater contacts. Based on such data, the contribution of Earth`s atmosphere to the umbra, which varies from eclipse to another, will be calculated. Estimates of the brightness of the Moon during totality or partiality will also be much welcomed as they inform us on the amount of volcanic aerosols present in the stratosphere.

 

By analyzing past eclipses, I have concluded that the contribution of our atmosphere to Earth`s shadow remains considerably lower than over the last 4 decades. Therefore, an atmospheric enlargement factor of 1.65% for the radius of Earth`s umbra, corresponding to an increase of 1.18% 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)

18:24:14

-1.2

Riccioli

18:26:10

2.9

Grimaldi

18:26:50

1.8

Billy

18:31:11

-1.8

Kepler

18:39:10

6.1

Campanus

18:40:23

-7.6

Aristarchus

18:40:55

12.1

Copernicus

18:47:52

5.9

Tycho

18:48:36

-13.0

Birt

18:49:35

-6.5

Pytheas

18:50:36

9.9

Timocharis

18:56:00

11.8

Abulfeda

19:02:12

-4.5

Pico                             

19:03:40

17.7

Nicolai                         

19:03:43

-14.0

Manilius                        

19:04:09

6.3

Plato                            

19:05:14

19.3

Bullialdus                       

19:05:28

-7.3

Dionysius                         

19:06:27

1.5

Menelaus                   

19:08:00      

6.7

Plinius                           

19:11:39

6.0

Eudoxus                    

19:12:36     

16.3

Censorinus                 

19:13:39     

-0.4

Aristoteles                

19:13:42     

18.0

Stevinus                   

19:15:42    

-12.1

Posidonius                 

19:16:26     

11.7

Goclenius                  

19:17:27     

-4.4

Taruntius                  

19:20:22      

1.4

Proclus                           

19:21:35

5.4

Langrenus                   

19:23:01     

-4.4

Mare Crisium               

19:25:34      

5.4

U2 (Totality Begins)

19:30:02

7.0

TABLE 2B - MID-CRATER UMBRAL CONTACT PREDICTIONS

 

EMERSIONS FROM THE UMBRA

 

Contact/Crater

TIME (UTC) (hh:mm:ss)

Umbral Angle

(°)

 

U3 (Totality Ends)

21:13:24

23.2

 

Riccioli

21:15:14

19.1

 

Grimaldi

21:16:36

18.0

 

Billy

21:22:46

14.4

 

Aristarchus

21:22:55

28.3

 

Kepler

21:26:43

22.2

 

Campanus

21:33:10

8.6

 

Pytheas

21:35:04

26.1

 

Copernicus

21:35:44

22.1

 

Plato

21:38:30

35.5

 

Timocharis

21:38:38

27.9

 

Pico

21:39:09

33.9

 

Tycho

21:40:37

3.2

 

Birt

21:42:28

9.7

 

Aristoteles

21:48:43     

34.2

 

Eudoxus

21:49:53

32.5

 

Manilius

21:51:45

22.5

 

Abulfeda

21:54:50

11.7

 

Menelaus

21:55:18     

22.8

 

Nicolai

21:55:20

2.2

 

Dionysius

21:57:02     

17.7

 

Bullialdus

21:58:18

8.9

 

Posidonius

21:59:00

27.9

 

Plinius

21:59:24

22.2

 

Censorinus

22:04:57

15.8

 

Stevinus

22:07:38      

4.1

 

Proclus

22:09:32

21.5

 

Goclenius

22:09:45     

11.8

 

Taruntius

22:10:42     

17.6

 

Mare Crisium                  

22:13:19

21.6

 

Langrenus

22:15:03

11.8

 

U4 (Partiality Ends)

22:19:14     

 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

***********************************************************************

TABLE 4 - CIRCUMSTANCES AS THE UMBRA LEAVES THE DISK

TIME (UTC)   MAG     OBSC      P.A.°      RU/RM   ALT°     AZIM°

***********************************************************************

                                                                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