Post by Centaur on Aug 28, 2005 14:00:10 GMT -6
EDIT: This post is for observers in Chicagoland. See the post further down the thread for the graze path from Texas through Canada.
A grazing occultation is the most interesting variety. It occurs whenever a polar region of the Moon appears to just barely sweep by a star or planet. Observers at the right locations on Earth will see a star winking on and off as it moves behind lunar hills and valleys.
I've calculated that a grazing occultation of the 9th brightest star of the Pleiades cluster will occur across western and northern Chicagoland during the evening of 2005 OCT 19. Its path will include the towns of Crystal Lake and Round Lake. The graze will enter Chicagoland from farmland to the west. It will sweep diagonally from the southwest to the northeast entering Lake Michigan at Kenosha.
The Mag 5.4 star HD 23753 at RA 03:48.7 and Dec N 23°26' will be grazed by the northern limb of the Moon. Relative to the star, the Moon will be moving to the lower left. I've created a graphical preview of the event. To see it, click: www.curtrenz.com/astronomical.html
Those located south or east of the graze line will witness a brief occultation of the star. Those north or west of the graze line will see a close passage. Those on the graze line will be the lucky ones. Or perhaps they'll be the industrious ones who make an effort to bring their telescopes to the graze line.
As viewed from Chicago's Adler Planetarium there will be a brief occultation. Immersion will occur at 20:54:58 CDT at Zenith Angle 39.1° when the star will be at an Altitude of 17.3° above the horizon. Emersion will occur at 21:06:08 at Zenith Angle 16.3° and Altitude 19.3°. The Zenith Angle is measured counter-clockwise around the lunar limb with 0° pointing straight up toward zenith.
Mars will be shining brightly at Mag -2.3, 10° to the right of the Waning Gibbous (92%) Moon. The red planet will make its closest approach to Earth for the current apparition about 10 days later.
Below I've plotted the graze path through western and northern Chicagoland at 10' intervals of geographic longitude. That should allow easy interpolation. Nevertheless, if you wish to submit a more precise longitude, just reply within this thread and I'll calculate the rest of the data for you.
W 89°00' -- N 41°38'52" (41.64775) -- Paw Paw
Alt 17.2° -- ZA 27.8°
21:00:19 CDT
W 88°50' -- N 41°46'33" (41.77583) -- Shabbona
Alt 17.4° -- ZA 27.7°
21:00:30 CDT
W 88°40' -- N 41°54'16" (41.90451) -- DeKalb
Alt 17.6° -- ZA 27.6°
21:00:40 CDT
W 88°30' -- N 42°02'02" (42.03379) -- North Plato
Alt 17.8° -- ZA 27.5°
21:00:51 CDT
W 88°20' -- N 42°09'49" (42.16367) -- Lake in the Hills
Alt 17.9° -- ZA 27.4°
21:01:03 CDT
W 88°10' -- N 42°17'39" (42.29414) -- NW of Wauconda
Alt 18.1° -- ZA 27.3°
21:01:14 CDT
W 88°00' -- N 42°25'31" (42.42520) -- Milburn
Alt 18.3° -- ZA 27.2°
21:01:25 CDT
W 87°50' -- N 42°33'25" (42.55686) -- Kenosha
Alt 18.5° -- ZA 27.1°
21:01:37 CDT
W 87°40' -- N 42°41'21" (42.68910) -- Lake Michigan
Alt 18.7° -- ZA 27.0°
21:01:48 CDT
A grazing occultation is the most interesting variety. It occurs whenever a polar region of the Moon appears to just barely sweep by a star or planet. Observers at the right locations on Earth will see a star winking on and off as it moves behind lunar hills and valleys.
I've calculated that a grazing occultation of the 9th brightest star of the Pleiades cluster will occur across western and northern Chicagoland during the evening of 2005 OCT 19. Its path will include the towns of Crystal Lake and Round Lake. The graze will enter Chicagoland from farmland to the west. It will sweep diagonally from the southwest to the northeast entering Lake Michigan at Kenosha.
The Mag 5.4 star HD 23753 at RA 03:48.7 and Dec N 23°26' will be grazed by the northern limb of the Moon. Relative to the star, the Moon will be moving to the lower left. I've created a graphical preview of the event. To see it, click: www.curtrenz.com/astronomical.html
Those located south or east of the graze line will witness a brief occultation of the star. Those north or west of the graze line will see a close passage. Those on the graze line will be the lucky ones. Or perhaps they'll be the industrious ones who make an effort to bring their telescopes to the graze line.
As viewed from Chicago's Adler Planetarium there will be a brief occultation. Immersion will occur at 20:54:58 CDT at Zenith Angle 39.1° when the star will be at an Altitude of 17.3° above the horizon. Emersion will occur at 21:06:08 at Zenith Angle 16.3° and Altitude 19.3°. The Zenith Angle is measured counter-clockwise around the lunar limb with 0° pointing straight up toward zenith.
Mars will be shining brightly at Mag -2.3, 10° to the right of the Waning Gibbous (92%) Moon. The red planet will make its closest approach to Earth for the current apparition about 10 days later.
Below I've plotted the graze path through western and northern Chicagoland at 10' intervals of geographic longitude. That should allow easy interpolation. Nevertheless, if you wish to submit a more precise longitude, just reply within this thread and I'll calculate the rest of the data for you.
W 89°00' -- N 41°38'52" (41.64775) -- Paw Paw
Alt 17.2° -- ZA 27.8°
21:00:19 CDT
W 88°50' -- N 41°46'33" (41.77583) -- Shabbona
Alt 17.4° -- ZA 27.7°
21:00:30 CDT
W 88°40' -- N 41°54'16" (41.90451) -- DeKalb
Alt 17.6° -- ZA 27.6°
21:00:40 CDT
W 88°30' -- N 42°02'02" (42.03379) -- North Plato
Alt 17.8° -- ZA 27.5°
21:00:51 CDT
W 88°20' -- N 42°09'49" (42.16367) -- Lake in the Hills
Alt 17.9° -- ZA 27.4°
21:01:03 CDT
W 88°10' -- N 42°17'39" (42.29414) -- NW of Wauconda
Alt 18.1° -- ZA 27.3°
21:01:14 CDT
W 88°00' -- N 42°25'31" (42.42520) -- Milburn
Alt 18.3° -- ZA 27.2°
21:01:25 CDT
W 87°50' -- N 42°33'25" (42.55686) -- Kenosha
Alt 18.5° -- ZA 27.1°
21:01:37 CDT
W 87°40' -- N 42°41'21" (42.68910) -- Lake Michigan
Alt 18.7° -- ZA 27.0°
21:01:48 CDT
