-------------------------
Occultation of HIP 72373 by P2M00 Venus on 2018 Dec 21
                  Centre              Star  Star   Sun      Path Limits           Error Limits       Alt
  E. Longitude   Latitude      U.T.    Alt    Az   Alt    Limit 1    Limit 2    Limit 3    Limit 4   Crn
      o  '  "     o  '  "    h  m  s     o     o     o    o  '  "    o  '  "    o  '  "    o  '  "
                                                         Latitude   Latitude   Latitude   Latitude
   -124  0  0    46 14  3   12  0 30     0   109   -39  -14  6 59   .. .. ..  -14 19 37   .. .. ..   ....
   -123 30  0    46  6 54   12  0 30     0   109   -39  -14 16 11   .. .. ..  -14 28 49   .. .. ..  -0.11
   -123  0  0    45 59 42   12  0 30     1   110   -39  -14 25 26   .. .. ..  -14 38  4   .. .. ..  -0.35
   -122 30  0    45 52 25   12  0 30     1   110   -38  -14 34 44   .. .. ..  -14 47 23   .. .. ..  -0.44
   -122  0  0    45 45  5   12  0 30     2   110   -38  -14 44  6   .. .. ..  -14 56 46   .. .. ..  -0.49

   -121 30  0    45 37 40   12  0 30     2   111   -38  -14 53 31   .. .. ..  -15  6 11   .. .. ..  -0.52
   -121  0  0    45 30 12   12  0 31     2   111   -37  -15  3  0   .. .. ..  -15 15 40   .. .. ..  -0.54
   -120 30  0    45 22 40   12  0 31     3   111   -37  -15 12 31   .. .. ..  -15 25 12   .. .. ..  -0.55
   -120  0  0    45 15  4   12  0 31     3   112   -37  -15 22  6   .. .. ..  -15 34 47   .. .. ..  -0.56
   -119 30  0    45  7 24   12  0 31     3   112   -36  -15 31 44   .. .. ..  -15 44 26   .. .. ..  -0.57

   -119  0  0    44 59 41   12  0 31     4   112   -36  -15 41 25   .. .. ..  -15 54  7   .. .. ..  -0.58
   -118 30  0    44 51 54   12  0 32     4   113   -36  -15 51  9   .. .. ..  -16  3 51   .. .. ..  -0.59
   -118  0  0    44 44  2   12  0 32     5   113   -35  -16  0 55   .. .. ..  -16 13 39   .. .. ..  -0.59
   -117 30  0    44 36  8   12  0 32     5   113   -35  -16 10 45   .. .. ..  -16 23 29   .. .. ..  -0.60
   -117  0  0    44 28  9   12  0 32     5   114   -35  -16 20 38   .. .. ..  -16 33 22   .. .. ..  -0.60

   -116 30  0    44 20  7   12  0 33     6   114   -34  -16 30 33   .. .. ..  -16 43 17   .. .. ..  -0.60
   -116  0  0    44 12  0   12  0 33     6   115   -34  -16 40 31   .. .. ..  -16 53 16   .. .. ..  -0.60
   -115 30  0    44  3 51   12  0 33     6   115   -34  -16 50 32   .. .. ..  -17  3 17   .. .. ..  -0.61
   -115  0  0    43 55 37   12  0 34     7   115   -33  -17  0 35   .. .. ..  -17 13 20   .. .. ..  -0.61
   -114 30  0    43 47 20   12  0 34     7   116   -33  -17 10 40   .. .. ..  -17 23 27   .. .. ..  -0.61

   -114  0  0    43 38 59   12  0 35     8   116   -32  -17 20 49   .. .. ..  -17 33 35   .. .. ..  -0.61
   -113 30  0    43 30 35   12  0 35     8   116   -32  -17 30 59   .. .. ..  -17 43 46   .. .. ..  -0.61
   -113  0  0    43 22  7   12  0 36     8   117   -32  -17 41 12   .. .. ..  -17 54  0   .. .. ..  -0.62
   -112 30  0    43 13 35   12  0 36     9   117   -31  -17 51 28   .. .. ..  -18  4 15   .. .. ..  -0.62
   -112  0  0    43  5  0   12  0 37     9   117   -31  -18  1 45   .. .. ..  -18 14 33   .. .. ..  -0.62

   -111 30  0    42 56 22   12  0 37    10   118   -31  -18 12  5   .. .. ..  -18 24 53   .. .. ..  -0.62
   -111  0  0    42 47 39   12  0 38    10   118   -30  -18 22 26   .. .. ..  -18 35 15   .. .. ..  -0.62
   -110 30  0    42 38 54   12  0 39    10   118   -30  -18 32 50   .. .. ..  -18 45 39   .. .. ..  -0.62
   -110  0  0    42 30  5   12  0 39    11   119   -29  -18 43 16   .. .. ..  -18 56  5   .. .. ..  -0.62
   -109 30  0    42 21 12   12  0 40    11   119   -29  -18 53 43   .. .. ..  -19  6 33   .. .. ..  -0.62

   -109  0  0    42 12 16   12  0 41    12   119   -29  -19  4 13   .. .. ..  -19 17  3   .. .. ..  -0.62
   -108 30  0    42  3 17   12  0 41    12   120   -28  -19 14 44   .. .. ..  -19 27 34   .. .. ..  -0.62
   -108  0  0    41 54 14   12  0 42    12   120   -28  -19 25 17   .. .. ..  -19 38  8   .. .. ..  -0.62
   -107 30  0    41 45  8   12  0 43    13   120   -28  -19 35 51   .. .. ..  -19 48 42   .. .. ..  -0.63
   -107  0  0    41 35 59   12  0 44    13   121   -27  -19 46 27   .. .. ..  -19 59 19   .. .. ..  -0.63

   -106 30  0    41 26 46   12  0 45    14   121   -27  -19 57  5   .. .. ..  -20  9 57   .. .. ..  -0.63
   -106  0  0    41 17 30   12  0 46    14   122   -26  -20  7 44   .. .. ..  -20 20 36   .. .. ..  -0.63
   -105 30  0    41  8 12   12  0 46    14   122   -26  -20 18 24   .. .. ..  -20 31 17   .. .. ..  -0.63
   -105  0  0    40 58 49   12  0 47    15   122   -26  -20 29  6   .. .. ..  -20 41 58   .. .. ..  -0.63
   -104 30  0    40 49 24   12  0 48    15   123   -25  -20 39 49   .. .. ..  -20 52 42   .. .. ..  -0.63

   -104  0  0    40 39 56   12  0 49    16   123   -25  -20 50 33   .. .. ..  -21  3 26   .. .. ..  -0.63
   -103 30  0    40 30 25   12  0 50    16   123   -24  -21  1 18   .. .. ..  -21 14 11   .. .. ..  -0.63
   -103  0  0    40 20 50   12  0 51    16   124   -24  -21 12  4   .. .. ..  -21 24 58   .. .. ..  -0.63
   -102 30  0    40 11 13   12  0 53    17   124   -24  -21 22 51   .. .. ..  -21 35 45   .. .. ..  -0.63
   -102  0  0    40  1 33   12  0 54    17   124   -23  -21 33 39   .. .. ..  -21 46 33   .. .. ..  -0.63

   -101 30  0    39 51 49   12  0 55    18   125   -23  -21 44 28   .. .. ..  -21 57 22   .. .. ..  -0.63
   -101  0  0    39 42  3   12  0 56    18   125   -22  -21 55 17   .. .. ..  -22  8 12   .. .. ..  -0.63
   -100 30  0    39 32 14   12  0 57    18   125   -22  -22  6  7   .. .. ..  -22 19  2   .. .. ..  -0.63
   -100  0  0    39 22 23   12  0 58    19   126   -21  -22 16 58   .. .. ..  -22 29 53   .. .. ..  -0.63
   - 99 30  0    39 12 29   12  1  0    19   126   -21  -22 27 49   .. .. ..  -22 40 44   .. .. ..  -0.63

   - 99  0  0    39  2 31   12  1  1    20   126   -21  -22 38 41   .. .. ..  -22 51 36   .. .. ..  -0.63
   - 98 30  0    38 52 32   12  1  2    20   127   -20  -22 49 33   .. .. ..  -23  2 28   .. .. ..  -0.63
   - 98  0  0    38 42 30   12  1  4    21   127   -20  -23  0 25   .. .. ..  -23 13 21   .. .. ..  -0.63
   - 97 30  0    38 32 25   12  1  5    21   127   -19  -23 11 18   .. .. ..  -23 24 14   .. .. ..  -0.63
   - 97  0  0    38 22 18   12  1  6    21   128   -19  -23 22 11   .. .. ..  -23 35  6   .. .. ..  -0.63

   - 96 30  0    38 12  8   12  1  8    22   128   -18  -23 33  3   .. .. ..  -23 45 59   .. .. ..  -0.63
   - 96  0  0    38  1 56   12  1  9    22   129   -18  -23 43 56   .. .. ..  -23 56 52   .. .. ..  -0.63
   - 95 30  0    37 51 41   12  1 11    23   129   -18  -23 54 49   .. .. ..  -24  7 45   .. .. ..  -0.63
   - 95  0  0    37 41 24   12  1 12    23   129   -17  -24  5 42   .. .. ..  -24 18 38   .. .. ..  -0.63
   - 94 30  0    37 31  5   12  1 14    23   130   -17  -24 16 35   .. .. ..  -24 29 31   .. .. ..  -0.63

   - 94  0  0    37 20 44   12  1 15    24   130   -16  -24 27 27   .. .. ..  -24 40 23   .. .. ..  -0.64
   - 93 30  0    37 10 21   12  1 17    24   130   -16  -24 38 19   .. .. ..  -24 51 15   .. .. ..  -0.64
   - 93  0  0    36 59 55   12  1 19    25   131   -15  -24 49 11   .. .. ..  -25  2  7   .. .. ..  -0.64
   - 92 30  0    36 49 28   12  1 20    25   131   -15  -25  0  2   .. .. ..  -25 12 58   .. .. ..  -0.64
   - 92  0  0    36 38 59   12  1 22    26   131   -15  -25 10 52   .. .. ..  -25 23 49   .. .. ..  -0.64

   - 91 30  0    36 28 27   12  1 24    26   132   -14  -25 21 42   .. .. ..  -25 34 39   .. .. ..  -0.64
   - 91  0  0    36 17 54   12  1 26    26   132   -14  -25 32 32   .. .. ..  -25 45 28   .. .. ..  -0.64
   - 90 30  0    36  7 19   12  1 27    27   133   -13  -25 43 20   .. .. ..  -25 56 17   .. .. ..  -0.64
   - 90  0  0    35 56 42   12  1 29    27   133   -13  -25 54  8   .. .. ..  -26  7  5   .. .. ..  -0.64
   - 89 30  0    35 46  4   12  1 31    28   133   -12  -26  4 55   .. .. ..  -26 17 52   .. .. ..  -0.64

   - 89  0  0    35 35 24   12  1 33    28   134   -12  -26 15 41   .. .. ..  -26 28 37   .. .. ..  -0.64
   - 88 30  0    35 24 42   12  1 35    29   134   -11  -26 26 26   .. .. ..  -26 39 22   .. .. ..  -0.64
   - 88  0  0    35 13 59   12  1 37    29   134   -11  -26 37 10   .. .. ..  -26 50  6   .. .. ..  -0.64
   - 87 30  0    35  3 15   12  1 39    29   135   -11  -26 47 53   .. .. ..  -27  0 49   .. .. ..  -0.64
   - 87  0  0    34 52 29   12  1 41    30   135   -10  -26 58 34   .. .. ..  -27 11 30   .. .. ..  -0.64

   - 86 30  0    34 41 42   12  1 43    30   136   -10  -27  9 15   .. .. ..  -27 22 11   .. .. ..  -0.64
   - 86  0  0    34 30 53   12  1 45    31   136    -9  -27 19 54   .. .. ..  -27 32 50   .. .. ..  -0.64
   - 85 30  0    34 20  4   12  1 47    31   136    -9  -27 30 31   .. .. ..  -27 43 27   .. .. ..  -0.64
   - 85  0  0    34  9 13   12  1 49    31   137    -8  -27 41  7   .. .. ..  -27 54  3   .. .. ..  -0.64
   - 84 30  0    33 58 21   12  1 52    32   137    -8  -27 51 42   .. .. ..  -28  4 37   .. .. ..  -0.64

   - 84  0  0    33 47 29   12  1 54    32   138    -7  -28  2 15   .. .. ..  -28 15 10   .. .. ..  -0.64
   - 83 30  0    33 36 35   12  1 56    33   138    -7  -28 12 46   .. .. ..  -28 25 41   .. .. ..  -0.64
   - 83  0  0    33 25 41   12  1 58    33   138    -6  -28 23 16   .. .. ..  -28 36 11   .. .. ..  -0.64
   - 82 30  0    33 14 45   12  2  1    34   139    -6  -28 33 44   .. .. ..  -28 46 39   .. .. ..  -0.64
   - 82  0  0    33  3 50   12  2  3    34   139    -5  -28 44 10   .. .. ..  -28 57  4   .. .. ..  -0.64

   - 81 30  0    32 52 53   12  2  5    34   140    -5  -28 54 34   .. .. ..  -29  7 28   .. .. ..  -0.64
   - 81  0  0    32 41 56   12  2  8    35   140    -5  -29  4 56   .. .. ..  -29 17 50   .. .. ..  -0.64
   - 80 30  0    32 30 58   12  2 10    35   140    -4  -29 15 16   .. .. ..  -29 28 10   .. .. ..  -0.64
   - 80  0  0    32 20  0   12  2 13    36   141    -4  -29 25 34   .. .. ..  -29 38 28   .. .. ..  -0.64
   - 79 30  0    32  9  2   12  2 15    36   141    -3  -29 35 50   .. .. ..  -29 48 44   .. .. ..  -0.64

   - 79  0  0    31 58  4   12  2 18    36   142    -3  -29 46  4   .. .. ..  -29 58 58   .. .. ..  -0.64
   - 78 30  0    31 47  5   12  2 20    37   142    -2  -29 56 16   .. .. ..  -30  9  9   .. .. ..  -0.64
   - 78  0  0    31 36  6   12  2 23    37   143    -2  -30  6 25   .. .. ..  -30 19 18   .. .. ..  -0.64
   - 77 30  0    31 25  7   12  2 25    38   143    -1  -30 16 32   .. .. ..  -30 29 25   .. .. ..  -0.64
   - 77  0  0    31 14  8   12  2 28    38   144    -1  -30 26 36   .. .. ..  -30 39 29   .. .. ..  -0.64

   - 76 30  0    31  3  9   12  2 31    39   144     0  -30 36 39   .. .. ..  -30 49 31   .. .. ..  -0.64

Uncertainty in time = +/- 1 secs

[which results in a separate uncertainty of +/- 0.01 degrees in the path longitudes]

Prediction of 2018 Dec  5.0




Interactive GoogleMap
Path distances for multiple locations file can be viewed HERE

This gives the altitudes of the Sun and Venus at the central time of the occultation. Since the cities are ordered by distance from the central line, from south to north, itís best to copy the whole file into an editor such as Notepad or Word, and search for your city, or one nearby.
Planet contact times for multiple locations can be viewed HERE

(note that due to the Sunlit limb of Venus the disappearance will not be visible)
The predictions are ordered alphabetically by the country 2-letter code (such as, CA for Canada and US for the USA), and alphabetically by the city name; US cities have the State 2-letter abbreviation following the city name.
Occultation of 6th-mag. star by Venus in N. America Thurs. am Dec. 21
Animation of event from near centerline, times for near Atlanta, GA
(made using Guide 9.1)
You will likely need to "
save link as" to view
Animation speed ~75X
More files for this event
       Around 12h UT (7am EST, 4am PST) on Thursday morning, Dec. 21st, there will be a rare occultation of the 5.9-mag. star ZC 2110 = HIP 72373 = SAO 158808 by Venus visible from most of North America. Venus’ 30" disk will be 41% sunlit. Only the dark-side reappearance can be seen, but it can be observed well, with any telescope with high power, since the dazzling sunlit parts of Venus will be at least 15" away. A central occultation will last 833s or 13.9 min . You can see the geometric appearance of the occultation in the upper right of https://occultationpages.com/Venus_Occ.html (top of this page). But those with large telescopes will probably see the star faintly a few minutes before the predicted reappearance, due to refraction of the star’s light. In fact, due to Venus’ thick atmosphere, the star will never completely disappear, but will appear as a spot, at about 12th magnitude at its faintest, on the edge of Venus at the point on its disk closest to the star. It might provide an opportunity for those with large telescopes to image, or even video record, this phenomenon. The only recording of this phenomenon that I know about was made in 2001 with the 200-in. Palomar telescope during an occultation of a double star by Titan. You can see it at https://www.reddit.com/r/Astronomy/comments/5nxyy3/titan_lenses_a_passing_binary_star/
You can faintly see the first star move around the top of Titan’s disk between the D and R, and similarly with the second star around the bottom of Titan’s disk. This one’s a little better: https://www.syfy.com/syfywire/titanic-occultation but you need to go about 40% of the way down the page to find the video.

    Detailed predictions for the occultation are given at
https://occultationpages.com/Venus_Occ.html (lower on this page) . You should find your city, or the one closest to you, in the first (Planet contact times) list that gives contact times (times of disappearance and reappearance) for hundreds of large and medium-sized cities throughout the region of visibility. The predictions are ordered alphabetically by the country 2-letter code (such as, CA for Canada and US for the USA), and alphabetically by the city name; US cities have the State 2-letter abbreviation following the city name. The times are Universal time (U.T.); 12h U.T. is 7am EST, 6am CST, 5am MST, and 4am PST. You should also consult the second (Path distances for multiple locations) list; since itís ordered by distance from the central line, itís best to copy the list and edit it in word processing software line Notepad or Word, finding your city, or the one closest to you thatís in the list. The last columns give the altitudes of Venus and the Sun when the occultation occurs.

A Chance to Record a Resolved Central Flash;

    We are most interested in the central line for the occultation, which passes from Wyoming to South Carolina; within a few km of it, a strong central flash should occur as the spherical atmosphere of Venus focuses the star's light. This phenomenon has been observed several times by distant objects with atmospheres, but in all of those cases, only a total photometric recording of the event was made, as the planetís disk was not resolved. The most recent example is last August 15thís occultation by Pluto, where the Lucky Star project was able to predict the central line to an accuracy of 8 km. One of the best recordings of a central flash was made in October last year during an occultation by Neptuneís moon Triton where the star became about 2 Ĺ times its unocculted brightness during the central flash; see https://www.skyandtelescope.com/astronomy-news/surprising-results-from-octobers-triton-occultation/ . Venus, being almost perfectly spherical, may produce an even brighter central flash. But since Venusí disk will be resolved, the central flash will instead appear as a ring around the planetís disk, visible along the dark side. The sharpness of the central flash is limited perhaps most by the angular diameter of the spectral type K1III star, which subtends 0.0011
according to the Warner relation. This means that the maximum of the central flash would last 0.03 second and be visible from a strip 500m wide. But there should be at least a few seconds ramp-up to the maximum that would also give some central flash visibility over a range of 20 or more kilometers. The structure of the visible central flash ring will vary over time and distance, with different parts and layers of Venusí atmosphere. The prediction for the central line, where this can be seen, should be very accurate, as explained below. The Gaia DR2 position of the star should be very accurate, to less than 0.001" or the angular diameter of the star noted above. The next question is error in Venusí ephemeris that has been accurately determined from radiometric tracking of spacecraft that have orbited the planet. By design, and by observation of quasar radio sources, the Gaia DR2 frame is extremely close to the ICRF frame of the planetary ephemerides. Jon Giorgini at JPL writes: ďThe Venus solution in the planetary ephemeris is driven by the tracking data of Venus Express in orbit around Venus as seen from Earth (2006-2014).

One way to look at uncertainties:

#1) Solution DE423 (done in 2010) used VEX data from 2006-2009.
    Solution DE438 (done in 2018) more than doubles that data-arc, to 2006-2014.

Doubling the VEX spacecraft tracking data in the Venus solutions changes the predicted relative position of Earth-Venus by 90 meters
on 2018-Dec-21. So not much change in nominal geometry even given
five more years of spacecraft tracking data.

#2) As far as the solution covariance (formal uncertainties) ...
On December 21, the Earth-Venus relative velocity in plane-of-sky
is increasing, but still coming off a minimum in November.

This is helpful since slow relative motion in plane-of-sky means
the relative position uncertainties will be near their minimum.

From solution covariance for Dec 21,

3-sigma RA ~ +/- 0.3 km,
3-sigma DEC ~ +/- 0.3 km,
3-sigma range ~ +/- 0.015 m

(3 sigma is 99.7% confidence; divide by three to get 1-sigma values, 68.3% confidence).

    So two different ways of considering ephemeris error (consistency
and statistical) suggest somewhat less than 0.5 km uncertainty in
Earth-Venus relative position prediction for Dec 21.Ē

    So again, the errors are smaller than, or roughly comparable to, the stellar angular diameter. Jon also notes that the GAIA DR2 frame was intended to be within the uncertainties of the ICRF2 and the DE 43X a realization probably within about 0.0002 arcseconds of ICRF2. Jon also notes the similarity of the central line with that for the August 2017 total solar eclipse (but variations from it are up to 200 km).

Dave Herald discusses the JPL DE ephemeris used by the Occult program, on which our predictions are based:

    The path over the US is near the edge of the Earth (as seen from Venus), and the RA of 14.8hrs means that there will have been a noticeable frame rotation due to precession from 2000. Which means the [earlier] path differences arise from the changes I implemented a few months ago to ensure the prediction was rigorous.

    On the ephemeris used for the predictions. For any predictions generated with recent versions of Occult (those that generate an xml prediction file), the DE version will be given in the line at bottom left of the path plot. Prior to now, the latest version available in Occult is DE436 - but Jon referred to DE438. From the available documentation (not much) I get the impression that there are no Ďmajorí improvements. I have Ďprocessedí that DE version.and uploaded it, so it is now available for download. It makes almost no difference to the prediction. At the level of 1Ē in latitude [about 30m], there is a change in the last digit in about every 4th or 5th line of the path....

    On 1981 November 17, there was an occultation of sigma Sagittarii (Nunki) by Venus. Gordon Taylor travelled to Kenya to observe the event with a few others. They observed visually with a 20cm SCT. Gordon was ready with a stopwatch and time signals, but was frustrated in that the phenomenon produced no sharp event that he could time. The star just faded from its 2.1 unocculted brightness down to about 8th magnitude, with that point of light just creeping around the dark edge of Venus, like the view in the Titan occultation video, until it reached the sunlit side and became invisible. David and Joan Dunham tried to also use a 20cm SCT to video record the same occultation from the central line in northern Somalia, using a neutral density filter to cover half of the sensor of the video camera, which was quite insensitive relative to todayís cameras. They recorded part of the starís disappearance, but then the declination slow motion slipped and the tracking was too poor to recover. On 1959 July 7, several observers watched an occultation of Regulus by Venus from 31 locations, but the event was observed in daylight so no faint Venus atmospheric refraction phenomena were seen.

David Dunham, dunham@starpower.net