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Summary of Lunar Occultations for 2009

More about occultations.

Introduction

During 2009, there are approximately 700 lunar occultations potentially observable from East Anglia, although many involve faint stars. During the year, the Moon occults the Pleiades twice, providing evenings with multiple occultations of bright stars, and the tracks of two grazing occultations cross the region. There are no good planetary occultations visible from the region during the year.

There is a partial lunar eclipse on the early evening of 31 December 2009, during which several faint stars are occulted.

This article summarises the circumstances of the best occultations during the year. It provides details for the location of Orwell Park Observatory; differences will in general be negligible for locations throughout East Anglia.

Occultations of Bright Stars

Table 1 lists occultation events during the year, of stars down to magnitude 5.0, where the circumstances are favourable. These events should be readily visible in small telescopes or binoculars.

The first two columns of the table list the date and time (UT) of the occultation. Column three specifies the phenomenon: "D" denotes a disappearance and "R" a reappearance. The table lists circumstances of D and/or R as dictated by the visibility of each phenomenon (determined by altitude, lunar phase, etc). Column four details the lunar phase (positive waxing and negative waning). Columns five and six give the altitude of the Sun and the star, both in degrees. (A negative solar altitude means that the Sun is below the horizon.) Columns seven and eight provide the star's magnitude and catalogue number.
 

Date
2009
Time
(UT)
D
R
Lunar
Phase
Sun
Alt (°)
Star
Alt (°)
Mag Star
07 Jan16:52:46
17:52:54
D
R
0.83+-8
-16
40
49
3.920 Tau, Maia
07 Jan16:53:15D0.83+-8414.319 Tau, Taygeta, q Tau
07 Jan17:19:46R0.84+-11443.717 Tau, Electra
06 Feb04:05:38D0.83+-3194.8139 Tau
06 Feb19:30:43
20:38:26
D
R
0.89+-25
-35
55
61
3.127 Gem, ε Gem, Mebsuta
16 Jun00:44:29
01:47:29
D
R
0.49--14
-11
8
18
4.518 Psc, λ Psc
30 Jun20:57:02
21:51:15
D
R
0.64+-5
-10
16
11
4.869 Vir
03 Jul21:49:24D0.89+-10125.0ZC 2298
18 Jul01:21:40
02:01:44
D
R
0.22--15
-12
13
19
4.123 Tau, Merope, V971 Tau
18 Jul02:01:04
02:20:40
D
R
0.22--12
-11
19
22
2.825 Tau, η Tau, Alcyone
18 Jul02:20:49
03:13:26
D
R
0.22--11
-6
22
30
3.627 Tau, Atlas
04 Dec20:56:41
21:53:07
D
R
0.91--46
-53
23
31
3.555 Gem, δ Gem, Wasat
07 Dec04:30:43D0.70--29495.05 Leo, ξ Leo

Table 1. Occultations of stars of magnitude 5.0 or brighter.
 

Occultation Seasons

The Moon’s orbit is defined by a range of periodicities, both short and long term. The short term periodicities mean that the Moon’s path through the sky follows a pattern whereby it almost repeats itself every month. The longer term periodicities gradually shift the orbit so that no particular pattern of approximate repetition can last more than a few years. This results in so called "occultation seasons", lasting for months or years, during which particular stars are repeatedly occulted, or repeatedly not occulted. During 2009, there are repeated occultation of the stars of Taurus.

Nights With Many Occultation Events

During the year, the Moon traverses some rich star fields. When this happens, a large number of occultations can occur during a single evening. Table 2 lists all evenings throughout the year when the Moon occults more than 10 stars. The large numbers of occultations at the end of April are associated with the passage of the Moon through rich fields of Taurus and Gemini.
 

Date, No occs Date, No occs Date, No occs Date, No occs
01 Jan, 16 07 Jan, 18 30 Jan, 17 31 Jan, 18
01 Feb, 11 02 Feb, 13 01 Mar, 14 02 Mar, 13
29 Mar, 14 30 Mar, 26 01 Apr, 24 02 Apr, 12
28 Apr, 57 29 Apr, 60 27 May, 16 28 May, 13
21 Nov, 21 21 Dec, 14 31 Dec, 14 -

Table 2. Nights with more than 10 occultations.
 

Grazing Occultations

The tracks of two grazing occultations cross East Anglia during the year. Table 3 summarises the circumstances. Columns one and two give the date and time of the graze and column three specifies the lunar limb involved. Column four indicates the distance between Orwell Park Observatory and point X on the track, on land, where the distance between the two is least; column five links to a plot of the lunar limb profile visible from X. Column six specifies a north or south displacement of the observer's position, relative to the track, based upon inspection of the limb profile, to maximise the chances of witnessing multiple disappearance and reappearance events. Column seven links to an on-line Google Earth plot of the track and column eight links to an off-line image of it. (The plot and image illustrate the nominal track, with no displacement applied.) Column nine details the lunar phase (positive for waxing, negative for waning) and column 10 the altitude of the Sun (a negative solar altitude means that the Sun is below the horizon). Columns 11 and 12 provide the horizontal co-ordinates of the star (azimuth in the order N→E→S→W). Columns 13 and 14 specify the star and its magnitude.
 

Date
2009
Time
(UT)
Limb Dist
OPO
(km)
Limb
Profile
Track
Shift
(km)
Google
Earth
Track
Google
Earth
Image
Lunar
Phase
Sun
Alt
(°)
Star
Alt
(°)
Star
Azi
(°)
Mag Star
07 Jan 17:55 S 15 Profile 0.5 N Track Track 0.84+ -16 49 117 2.8 25 Tau, η Tau, Alcyone
18 Jul 02:08 N 11 Profile 0 Track Track 0.22- -12 20 76 6.3 24 Tau

Table 3. Grazing lunar occultations.
 


James Appleton