Lunar Occultations: 4-December-2005

Three of the stars involved are very close doubles. Unfortunately only the last of the three will be easy enough to view in a small scope. This star is bright enough and will disappear on the dark edge of the Moon. The other two tight double events occur on the sunlit side.

The Moon's altitude at the start of the series is 19°. It will descend to 13° when the close double 60 Sagittarii (separation = 0.05" (5 hundreths of an arcsecond)), is occulted on the dark limb.

I've never attempted to view tight doubles during a lunar occultation. Given clear skies this should be an interesting evening.

DEFINITION OF TERMS: Vertex Angle - the angle of the event around the limb of the moon measured anticlockwise from the vertex of the lunar limb - i.e. the point on the limb highest from the horizon. To help with above term I've converted it to an "o'clock" time (i.e 01:15 "o'clock") which will shows where the star will be seen on the limb of the Moon as if the Moon were a clock's dial as viewed naked eye or through a pair of binoculars. Cusp Angle - the angle of the event around the limb of the moon, measured from the nearest cusp. Negative (-) values indicate a bright limb event. The cusps are usually N (north) or S (south), but near full moon can be E (East) or W (west). (d/r D/R) If the letter in parentheses next to "Disappearance" and "Reappearance" are lowercase this means the star may not be visible in a small telescope. These events are useful to test the algorithm built into WinOccult 3.1.0 to see how it applies to various telescopes/binoculars.

Event: Total Lunar Occultations
Location: Central Park, New York City
Day/date: Sun., 04 December 2005

[Click on (d/r) or (D/R) for location on limb.]

Star: ZC 2910 (omega Sgr) / Mag.: 4.7
Duration (h:mm:ss): 0:09:34
Sun's altitude at disappearance: -3°

• ome Sgr is a double: mv 5.6 & 5.6, sep. 0.001" (PA 51.3)

¶ Disappearance (d): EVENT #1
Local time: 04 Dec 2005 04:42:17 PM
Vertex angle: 325° / 01:15 "o'clock"
Moon's alt/ill.: 19°SSW/14%
Cusp angle: -9°N

¶ Reappearance (r): EVENT #2
Local time: 04 Dec 2005 04:51:51 PM
Vertex angle: 307° / 01:45 "o'clock"
Moon's alt/ill.: 18°SSW/14%
Cusp angle: -25°N

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Star: SAO 188749 / Mag.: 8.1
Duration: [disappearance only]
Sun's altitude at disappearance: -8°

¶ Disappearance (d): EVENT #3
Local time: 04 Dec 2005 05:09:19 PM
Vertex angle: 347° / 12:30 "o'clock"
Moon's alt/ill.: 17°SSW/14%
Cusp angle: +18°N

EVENT #8: Check for reappearance starting at 5:48 PM around 3 "o'clock" on the dial.

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Star: SAO 188724 / Mag.: 7.7
Duration: [reappearance only]
Sun's altitude at reappearance: -8°

¶ Reappearance (r): EVENT #4
Local time: 04 Dec 2005 05:10:43 PM
Vertex angle: 229° / 04:15 "o'clock"
Moon's alt/ill.: 16°SSW/14%
Cusp angle: -80°S

Note: 188724 is double: mv 8.4 & 8.4, sep. 0.100" (PA45.0)

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Star: SAO 188764 / Mag.: 8.9
Duration: [disappearance only]
Sun's altitude at disappearance: -8°

¶ Disappearance (d): EVENT #5
Local time: 04 Dec 2005 05:11:09 PM
Vertex angle: 31° / 11:00 "o'clock"
Moon's alt/ill.: 16°SSW/14%
Cusp angle: +62°N

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Star: SAO 188779 / Mag.: 8.7
Duration: [disappearance only]
Sun's altitude at disappearance: < -12°

¶ Disappearance (d): EVENT #6
Local time: 04 Dec 2005 05:36:41 PM
Vertex angle: 38° / 10:45 "o'clock"
Moon's alt/ill.: 14°SW/14%
Cusp angle: +73°N

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Star: ZC 2914 (60 Sgr) / Mag.: 4.8
Duration (h:mm:ss): 1:01:47
Sun's altitude at disappearance: < -12°

ZC 2914 is double: mv 5.8 & 5.8, sep. 0.050" (0.0PA)

¶ Disappearance (D): EVENT #7
Local time: 04 Dec 2005 05:42:40 PM
Vertex angle: 16° / 11:30 "o'clock"
Moon's alt/ill.: 13°SW/14%
Cusp angle: +53°N

¶ Reappearance (r): EVENT #10
Local time: 04 Dec 2005 06:44:27 PM
Vertex angle: 227° / 04:30 "o'clock"
Moon's alt/ill.: 5°SW/14%
Cusp angle: -88°N

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Star: SAO 188817 / Mag.: 8.0
Duration: [disappearance only]
Sun's altitude at disappearance: < -12°

¶ Disappearance (d): EVENT #9
Local time: 04 Dec 2005 06:31:26 PM
Vertex angle: 53° / 10:15 "o'clock"
Moon's alt/ill.: 7°SW/14%
Cusp angle: +84°S

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