Saturday 06/25/11 BSC star party
By: Steve Short
June 22, 2011 2:47AM PDT
Views: 3358

BSC Star Party Notice - Saturday June 25th, 2011


Hello Fellow OCA club members!


This Saturday, I plan to open the gate at 7:30 pm, which is about a half hour before the sun sets. The weather report for this Saturday indicates that Orange County will be clear, sunny and warm, with humidity at 60%. 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.


We will have a 3rd quarter moon that doesn’t rise until well after midnight so we will have fairly dark skies. 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 one Mag -.5 visible pass Saturday evening starting at 11:04:15 10 degrees high NNW rising to 16 degrees at 11:05:21 N where it will fade from view.. The HST (Hubble Space Telescope) will not make any visible passes Saturday evening.  There will be three visible Iridium flares Saturday evening with the first at 9:44:24 pm from Iridium (satellite) 68 up at 47 degrees high ENE (72 degrees) going from Mag -3 to -8.  The second flare will be at 10:22:45 pm from Iridium (satellite) 40 at 11 degrees high W (265 degrees) going from Mag -3 to -6.  The third flare will be at 10:59:12 pm from Iridium (satellite) 25 at 42 degrees high NE (42 degrees) going from Mag -5 to -6.  I am sure we will also see a few dim satellites pass over as we are looking up in the sky.


~Mercury, (Mag -1.1) sets at 9 pm just after the sun sets so might be seen low on the horizon this Saturday evening. It is about 118 million miles from Earth in constellation Gemini.

~Venus, (Mag -3.8) will not be seen Saturday evening as it sets about 7 pm but can be seen in the morning as it rises about 4:45 am in constellation Taurus. It can be seen just before dawn, very low on the horizon. Venus is now about 154 million miles from Earth.

 ~Mars, (Mag 1.4) is now also in Constellation Taurus setting about 5:45 pm so cannot be seen this Saturday evening. It rises at 3:45 am so can be seen a few hours before sunrise. It is about 209 million miles away, just a 4” disk so still too far away to see any detail on the planet.

~Jupiter, (Mag -2.1) will set about 3:30 pm in constellation Aries before the sun sets so will not be seen Saturday evening. It now is about 505 million miles from Earth getting a little closer every day. It can be seen about 30 degrees high just before dawn outshining any other star in the sky.

~Saturn, (Mag 0.9) rises about 1:30 pm Saturday in constellation Virgo so will be visible high in the sky at the BSC star party not setting until 1:30 am. Saturn is about 875 million miles away slowly moving further from Earth. The rings are tipped about 7 degrees from edge on and the planet disk is about 18” across. The bright star near the planet, just 1 degree away, is 3rd magnitude Gamma Virginis (Porrima), a famous double star. Moon Rhea will be just East of Saturn and above the rings while Enceladus will be about a ringed planet width East in line with the rings.  Moon Tethys will be farther East and Moon Dione will be farthest East. Giant moon Titan will be far west of the planet.

~ Uranus, (Mag 5.9) will not rise until 1 am this week in constellation Pisces so will not be seen Saturday evening. When seen, it shows up as a small blue-green disc in a telescope. Since Uranus will rise at 1 am, it can be seen in the morning up to dawn. It is about 1.872 billion miles away, moving closer to Earth.

~ Neptune, (Mag 7.9) is in constellation Aquarius, about 2.743 billion miles away this week slowly moving closer to Earth. It is seen as a bluish gray 2.3” disc in a telescope but we will not be able to see it at BSC this Saturday evening, as it doesn’t rise until 11:30 pm. However, it could be spotted high in the sky well after midnight. Neptune was discovered 164 years ago, and its orbit is about 164 years so it is now completing its first orbit since German astronomer Johann Galle first spotted it.

~ Pluto, (Mag 14.0) rises at 8 pm and will reach opposition and peak visibility a few days after this Saturday. It is 2.9 billion miles from Earth in constellation Sagittarius. Since it is so dim, you will need a 10” or larger telescope to see it visually. It lies about 1 degree west of the 5th magnitude star cluster M25.



The June Bootid meteor shower peaks June 27th when one might see up to 50 meteors per hour from the radiant 30 degrees west of Arcturus. We normally see a few stray meteors at every BSC star party even when no meteor shower is expected.



The brightest comet visible right now is dim magnitude 10.4 C/2009 P1 Garradd in constellation Pisces. But it will not become visible until around 11 pm so we will not get much of a chance to see it Saturday evening. This comet is heading north and if it brightens as expected, it will become visible to the naked eye in early 2012. It is now 222 million miles from Earth and can be found 9 degrees below the southern leg (starting with Beta star Scheat) of the Great Square Pegasus.


Then there is magnitude 11.6 Comet P/2007 R5 Soho 15 degrees between the Scorpion’s head and Corvus the Crow in constellation Libra. It is 95 million miles away with a period of 3.99 years.


Brightest visible asteroids:

Minor Planet 4 Vesta (Mag 7.0), the 2nd most massive object in the asteroid belt, can be found 16 degrees above the middle of constellation Capricornus along the ecliptic. Vesta has a diameter of about 330 miles and was discovered in 1807. It is about 131 million miles from Earth at this time and has an orbit period of 3.63 years. It will become visible about 9:30 pm so might be seen at the BSC star party.


Minor Planet 1 Ceres (Mag 8.8) is the biggest object in the asteroid belt with a diameter of about 590 miles. It is in constellation Aquarius below the Ecliptic. Ceres is about 256 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 not be visible Saturday evening until about 11:30 pm so will probably not be seen at the BSC star party.


Minor Planet 10 Hygiea (Mag 9.8) is the 4th largest object in the asteroid belt with an oblong diameter of about 220 -310 miles. It is in constellation Libra and can be found about 20 degrees directly in front and above the Scorpion’s 3 head stars.  This asteroid can be seen Saturday evening. Hygiea is about 182 million miles from Earth and has a period of 5.56 years. It was Annibale Gasparis’s first asteroid discovery made on April 12th, 1849. He lived in Naples, Italy and went on to discover 8 more asteroids.



Deep Sky:

This month let’s consider hunting down some star clusters in the Scorpion.


M4 (Mag 5.9), the Cat’s Eye globular cluster is just 1 degree west of bright star Antares. It is 14,000 light years away and has a diameter of 107 light years. This cluster is estimated to be 10 billion years old and was first observed by Messier in 1764.


M6 (Mag 4.2), the Butterfly Cluster is another open cluster found just a few degrees north of the Scorpion’s stinger. It is about 1,500 light years away and spans about 6.6 light years. This cluster is estimated to be 51 million years old and was first observed by Messier in 1764.


M7 (Mag 3.3) is an open cluster found just a few degrees east of the Scorpion’s stinger. It is about 800 light years away and spans 20 light years. This cluster is estimated to be 220 million years old and was first observed by Messier in 1764.



Don't forget to bring your gloves, coats & sweaters because it can get 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 darken. 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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