Thursday, 10 January 2019

Lunar X and V Times for 2019


Lunar X and V Times - 2019
The Lunar X and V are optical effects which are visible on the lunar surface for about 3 - 4 hours, once a month. They are caused by sunlight illuminating the edge of craters. The X is caused by light illuminating the rims of craters Blanchinus, La Caille and Purback. The V is caused by light illuminating crater Ukert along with several smaller craters. 
  


The X and V are usually visible a few hours before First Quarter phase, however, due to libration, the exact time of the X and V being visible is different from month to month. As I did in previous years, I have used the NASA Scientific Visualisation Studio Moon Phase and Libration tool for 2019 to check the start time of the X and V. I did this by scrolling through each month close to First Quarter Phase, hour by hour, until I could record the times of the X and V being visible.  The times I recorded are listed below.  These times are approximate because I just scrolled through hour by hour.  If you want very precise information about the X and V start times and libration angles, please check out this very useful post on Cloudy Nights: 

https://www.cloudynights.com/topic/630098-lunar-x-start-times-2019/

Although the X and V are visible every month, they may occur before the Moon has risen or after it has set from your location, so you will not see them every month. Please also note that the times given are in 24 clock and are in UT (the same as GMT) so you will need to correct for time zones and daylight time savings changes. I have included the approximate moonrise and moonset times from Oxfordshire, UK and a note about when the X and V are visible from the UK.




Date
Start Time of X & V
Moonrise
Moonset
Visible From UK?
Sun 13th January
12:00 UT
11:30
00:10
Y
Tue 12th February
02:00 UT
10:40
01:30
N
Wed 13th March
15:00 UT
09:40
01:40
Y
Fri 12th April
04:00 UT /
05:00 BST
11:00
03:35
N
Sat 11th May
16:30 UT /
17:30 BST
11:10
02:55
Y
Mon 10th June
04:00 UT /
05:00 BST
12:55
02:20
N
Tue 9th July
16:00 UT /
17:00 BST
13:20
01:10
Y
Thur 8th August
04:00 UT / 
05:00 BST
15:02
00:26
N
Fri 6th September
16:00 UT /
17:00 BST
15:15
23:35
N
Sun 6th October
04:00 UT /
05:00 BST
15:55
00:00
N
Mon 4th November
17:00 UT
14:05
22:55
Y
Wed 4th December
07:00 UT
13:20
00:00
N
 
 
Please feel free to share this information with your local astronomy society, or anybody who may find it helpful.

Mary McIntyre


 
 

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