BCS Astronomy Class of 7 Feb 06

User avatar
Astro Day Coordinator
Posts: 3849
Joined: Fri Jun 13, 2003 9:03 pm

BCS Astronomy Class of 7 Feb 06

Unread post by Pete »

Although we’ve got the moon to contend with, it looked like a good night for class observing. I’d set the 14”, the 12” the 22X100s and the 15X70s out for cool down, along with a 4-1/2” Newtonian on a Polar mount.

During the 7pm to 9pm 2-hour class we observed in the following sequence from W to E:

Mars – The Red Planet is now 105 million miles from Earth, and as we observe it it’s only a tiny 7.8 arc-seconds in size. Last fall it approached within 40 million miles and was a relatively large 20” in size. See: http://seds.lpl.arizona.edu/nineplanets ... /mars.html

M31 – the Andromeda Galaxy is 2.2 million light years distant. The view through the 14” at 115X only showed the very center of the core as a dim fuzz ball. Viewed thru the 22X100 binoculars a much larger part of the core was visible, and the whole image seemed brighter. See: http://www.seds.org/messier/m/m031.html Sharper class members will note that SEDS claims M31 to be 2.9 million light years away. And I've got other data saying it's 2.5mil. Hmmm.

M42 – the Great Orion Nebula We viewed M42 successively through the 15 X 70 binoculars, thru the 12” at 179X, and then thru the 14” with a narrow band filter at 115X. See: http://seds.lpl.arizona.edu/messier/m/m042.html

M45 – the Pleiades – Viewed thru both binoculars See: http://www.seds.org/messier/m/m045.html

M44 Viewing thru the 14”, we didn’t have the field of view to do justice to this wonderful open cluster. http://www.seds.org/messier/m/m044.html The seds photo doesn’t do it justice.

Asteroid 4 Vesta At 7.0 magnitude, this is the brightest of the asteroids. It’s about 311 miles in diameter, and is presently 1.7 AU from Earth. http://seds.lpl.arizona.edu/nineplanets ... roids.html I had trouble verifying Vesta as my printed chart was for almost 3 hours prior to our viewing it, and it had moved since. But after class I checked on the computer and verified that the bright object that we’d viewed was indeed Vesta.

M81/M82 galaxies were viewed thru the 12”. Edge-on M82 was a bit easier to see, but both were reduced by light from the moon.

Saturn & Saturn’s moons With just a quick glance thru the 14” at 115X I picked out equatorial banding, the Cassini Division, the Crêpe Ring, Titan, Rhea, Enceladus and Dione. http://seds.lpl.arizona.edu/nineplanets ... aturn.html
http://seds.lpl.arizona.edu/nineplanets ... anets.html

Luna – the Terminator – Craters Plato & Copernicus The seeing is outstanding. We were able to tour the lunar surface at 296X, viewing huge detail. http://seds.lpl.arizona.edu/nineplanets ... /luna.html

21:00 hrs. It took about 20 minutes to put everything but the 14” away for the night. It’s in the high 20s and I’m pretty comfortable. Despite the moon, I’m going to hunt down a few asteroids. The temperature’s down to 28°F, but the breeze has pretty much died down.

7 Feb 06; 21:25 hrs. Asteroid 550 Senta is at 13.9 magnitude tonight. It lies 10’ to the NW of a distinctive triangle of 8th mag stars, so homing in on it is straightforward. I’ve got it thru the 14” at 209X using averted vision – although it’s in and out. Senta is 25 miles in size. It is presently 2.2 AU from Earth, and its heliocentric radius is 3.1 AU.

7 Feb 06; 22:07 hrs. 205 Martha is a minor planet 53 miles in size. It’s presently 1.9 AU from Earth, and supposedly shining at 13.3 magnitude. No way! Martha is 44° from the moon, but it’s a son-of-a-gun to view. I’m easily seeing stars to 13.9 mag, but had to crank the 14” up to 209X . Now with averted vision I’m seeing a couple of objects in the area not plotted on the chart. Ducking into the hours and using the internet I bring up the Deep Sky Survey and confirm these stars and finally confirm that I’ve sighted Martha. This is really weird – I’m seeing a star plotted by Guide 8 as 15.0 magnitude. And I don’t believe that either. I estimate Martha to be 14.2 magnitude tonight. This asteroid orbits 2.8 AU from the sun.

7 Feb 06; 22:42 hrs. 640 Brambilla is a 52-mile diameter asteroid that’s supposed to be shining at 13.9 magnitude tonight. It’s about 4’ N of a 9th mag star, and I have to take the 14” up to 296X before I’m viewing it in and out with averted vision. And even then I had to download an area image from the Deep Sky Survey to confirm the sighting. Brambilla orbits Sol at 3.3 AU, and is presently 2.4 AU from Earth.

Conclusions and observations:

Everyone in the class seemed to have enjoyed themselves, although the ladies were very chilled at the end of the session. I think that I forgot to tell folks to feel free to step into the kitchen and warm up. Sorry class.

Everyone tried using the 4-1/2” scope, and I think everyone viewed Saturn with it as a comparison. Views were what you’d expect of a department store telescope on a shaky mount, so I limited magnification to 42X. There was a lesson here.

Everyone got to use binoculars on M42, and I think that they were pleased to find something on their own.

Class Homework: Please go to each of the SEDS hyperlinks associated with the objects we viewed, and learn a little more about them. Then, using material from your Night Sky magazine, pick out one object that you’d like to view at our next observing class.

I only viewed 3 normally easy asteroids in almost 2 hours. Those moonbeams have a long reach, and I wouldn’t have even attempted viewing if the 14” wasn’t already out and running. The 77% phase moon severely limited viewing tonight. Next week it’ll be at 97% phase and waning, but it doesn’t rise until 6:40pm and it will be low in the sky and not as obtrusive as it was for our first observing session. We’ll have no moon at all for our last two class sessions.

Pete (posted 11 Feb 06)