Saturday December 17th Black Star Canyon star party
By: Steve & Bonnie Short
December 14, 2011 4:46AM PDT
Views: 4318

BSC Star Party Notice  - Saturday December 17th, 2011


Hello Fellow OCA club members!


This Saturday, I plan to open the gate around 4:15 pm, which is about a half hour before the sun sets. The weather report for this Saturday indicates that Orange County will be sunny. But keep an eye on the OCA website where I will post a notice on the home page should the star party be cancelled for any reason.


The 3rd quarter moon will not rise until midnight so we should have fairly dark skies Saturday. First time visitors might want to get to BSC while it is still light so they can find their way down the dirt road and into the parking area. Remember that you take the 2nd farm gate on the left after turning on Black Star Canyon Road (the 1st farm gate is the Xmas Tree farm). If you come in after dark, you should drive in with your headlights off!!! The dirt road will be marked with red flashers and you can hold a flashlight out the driver’s window to light up the road directly in front of your car.


Warning:  No Pets allowed!  (This is an Irvine Ranch Conservancy property rule)



  The ISS (International Space Station) will make two visible passes Saturday evening with the first -3.3 magnitude  pass starting at 5:12:30 pm 10 degrees high SW going to 89 degrees high SE at 5:15:45 and then dropping to 10 degrees NE at 5:19. The second ISS -0.3 magnitude pass will start at 6:51:17 pm 10 degrees high NW and rise to 11 degrees NW at 6:51:43 where it will slip out of sight.

  The HST (Hubble Space Telescope) will also make two passes Saturday evening with the first 2.0 magnitude pass starting at 4:59:11 pm 10 degrees high WSW rising to 41 degrees high S at 5:03:13 and then dropping down to 10 degrees ESE at 5:07:14.  The second HST 2.3 magnitude pass will start at 6:40:51 pm 10 degrees high WSW and then rise to 30 degrees SSW at 6:44:35 and drop down to 28 degrees high S at 6:45:14.

  We should also see one Iridium flare Saturday evening that will go from magnitude -0 at 4:59:41 pm 70 degrees high ENE (62 degrees) to a magnitude -9 from Iridium satellite 68.  I am sure we will also see a few dim satellites pass over as we are looking up in the sky.

Planets & Pluto:

~Mercury, (Mag 0.4) sets at 3:45 pm so won’t be seen this Saturday evening but can be seen in the morning sky 1.5 hours before dawn. It is about 76 million miles from Earth in constellation Scorpius, is 63% lit with a 6.6” diameter disk.

~Venus, (Mag -3.8) should be seen Saturday evening as it does not set until 7 pm, in constellation Sagittarius, and will be about 14 degrees above the horizon 45 minutes after sunset. Venus is now about 129 million miles from Earth, is 86% lit with a 12” disk.

 ~Mars, (Mag 0.5) is now in Constellation Leo setting about noon so cannot be seen this Saturday evening until it rises at 11 pm. It is about 112 million miles away, just an 8” disk so small scopes can now see some detail on the red planet like the white shrinking north polar cap

~Jupiter, (Mag -2.6) will rise about 1:45 pm in constellation Pisces so will be high in the sky when the sun sets Saturday evening. It now is about 400 million miles from Earth getting a little farther every day. It will outshine any other point of light in the sky with a diameter of 46”. We should see moon Callisto far East of the big planet while moon Europa will be much closer. Moon Io will be to the west of Jupiter while largest moon Ganymede will be farthest west.

~Saturn, (Mag 0.7) sets about 1:45 pm Saturday in constellation Virgo so it cannot be seen at the BSC star party as it won’t rise until 2:20 am.  Saturn is about 950 million miles away slowly moving closer to Earth. Saturn’s globe measures 16” and the rings span 36” and tilt 15 degrees to our line of sight. That is the maximum tilt for 2011 so will provide observers with a good look at the dark Cassini Division that separates the two brightest rings.

~ Uranus, (Mag 5.8) will be visible as the sun sets this week in constellation Pisces so can be seen Saturday evening at BSC. It will not set until just after midnight and shows up as a small 3.5” blue-green disc in a telescope. It is about 1.852 billion miles away, moving further from Earth. Uranus is easy to find using the two stars on the eastern edge of the Great Square of Pegasus and look along that line about 15 degrees south.

~ Neptune, (Mag 7.9) is in constellation Aquarius, about 2.826 billion miles away this week slowly moving farther from Earth. It is seen as a bluish gray 2.2” disc in a telescope and we should be able to see it at BSC this Saturday evening, as it doesn’t set until just before 11 pm. The 2011 September issue of Sky & Telescope Magazine shows the path Neptune is following on page 53. That page also shows the path of Uranus.

 ~ Pluto, (Mag 14.1) sets at 7:45 pm and reached opposition and peak visibility in late June. It is 3.078 billion miles from Earth in constellation Sagittarius slowly getting farther from Earth. Since it is so dim, you will probably need a 10” or larger telescope to see it visually at BSC until it sets about 6 pm.  The 2011 July issue of Sky & Telescope Magazine shows the path Pluto is following on page 64.



The Geminid meteor shower peaks December 14th but competes with the waning gibbous Moon which will drown out most meteors. The Ursid meteor shower starts on the 17th and peaks on the 22/23rd when one might see up to 10 meteors per hour. The radiant lies inside Ursa Minor near the top of the Little Dipper’s bowl and the meteors are probably from debris left by Comet Tuttle. We normally see a few stray meteors at every BSC star party even when no meteor shower is expected.



The magnitude 7.5 Comet C/2009 P1 Garradd is in the southern section of constellation Hercules so might be viewed this Saturday evening. The comet is now heading north and if it brightens as expected, it will become visible to the naked eye in early 2012. It is now 193 million miles from Earth and can be found west of the Summer Triangle Altair/Vega side and below the eastern edge of the Hercules keystone. The 2011 November issue of Sky & Telescope Magazine shows the path this comet is following through February 6th on page 52.


Brightest visible asteroids:

Minor Planet 4 Vesta (Mag 8.0), the 2nd most massive object in the asteroid belt, can be found along the eastern bottom of constellation Capricornus. Vesta has a diameter of about 330 miles and was discovered in 1807. It is about 242 million miles from Earth at this time and has an orbit period of 3.63 years. It should become visible shortly after sunset so might be seen at the BSC star party up to 11 pm. NASA’s Dawn spacecraft has just gone into orbit around this asteroid and will study it for a year getting as close as 110 miles from its surface.


Minor Planet 15 Eunomia (Mag 8.2) is a potato shaped 200 mile wide rock close enough to Earth this month that it is the 2nd brightest asteroid we can see. It is passing through Perseus, sliding along the Hero’s feet. It is about 120 million miles from Earth at this time and has an orbit period of 4.30 years. It should become visible shortly after sunset so might be seen at the BSC star party all the way up to midnight and later. It is found between Auriga and Triangulum.


Minor Planet 1 Ceres (Mag 8.2) is the biggest object in the asteroid belt with a diameter of about 590 miles. It is in constellation Aquarius and can be found between the Whale’s head and Aquarius. Ceres is about 260 million miles from Earth and has a period of 4.60 years. It was discovered in 1801 and for 50 years was classified as the 8th planet. It will be visible Saturday evening after the sun sets up to midnight so might be seen at the BSC star party. This asteroid will be the next stop for the Dawn spacecraft.


Deep Sky:

This month let’s consider looking at the bright Messier nebulas in Orion:


M42 (Mag 4) is the famous Great Orion Nebula discovered by Huyghens in 1656 and first reported by messier in 1769. It is an emission nebula 1,500 light years away, containing 4 young hot stars (called the Trapezium because they are in the shape of a trapezoid), each about a million years old that heat the gas so it gives off light. This gas cloud is a stellar nursery that is 29 light years by 26 light years in size. To locate this object, find the constellation Orion and look for the Hunter’s 3 sword stars below the bright 3 belt stars. The middle sword star is not a star. It is the glowing gas of the Orion Nebula.


M43 (Mag 9) is an emission nebula also 1,500 light years away, next to M42 with a single 6.9 magnitude star that stimulates the gas cloud to glow. It appears as a circular haze adjacent to M42 so most observers think it is part of M42. But Messier saw it as a separate nebulosity below M42 in his 1769 observations. The hardest part of identifying M43 is distinguishing it from M42.


M78 (Mag 8) is a refection nebula observed by messier in 1780. It is thought to be 1,600 light years away and spans 4 light years. There are two faint stars of magnitude 8 in the nebulosity and its shape is conical. This object forms a right angle with belt star Alnitak and is as far from Alnitak as the width of the three belt stars in the direction of Betelgeuse.


Don't forget to bring your gloves, coats & sweaters because it can get very cold after the sun sets and the night approaches midnight when we close. After you set up your telescope, there are three picnic tables where you can sit and eat food you might bring, while waiting for the sky to get dark. Please remember to cart off all your trash as there are no garbage cans at BSC. Hope to see you there.


Your OCA star party host,


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