Friday, August 13, 2010

SkyNights volunteering and observing report

In an earlier post I mentioned that I have recently been volunteering at the Mount Lemmon SkyCenter, assisting with the SkyNights public observing program on the 24 inch RC Optical Systems Ritchey-Chrétien telescope seen at right  (Photo credit to Adam Block/Mount Lemmon SkyCenter/University of Arizona (Board of Regents)).  Last night the sky center hosted an extended version of the SkyNights program where in addition to the standard educational and viewing program, guests brought lawn chairs and loungers to relax and stretch out under the stars to observe the annual Perseid Meteor shower.  We were very fortunate in that the weather pattern has been holding steady this week, and we were treated to a sky devoid of clouds, with better than average seeing conditions.  The shower certainly displayed several long and colorful meteors for the guests, however, in my opinion the shower was better on Wednesday night and early Thursday morning.  Regardless, all the visitors had a good time.

Another benefit of this extended program was that there was less of a rush to see objects at the telescope for the visitors.  We had more time, and folks were occupied looking for Perseids when not at the eyepiece.  The summer milky way dominates the view right now and guests were treated to most of the showpiece objects of the summer sky. They observed the Lagoon Nebula, the Swan Nebula, globular clusters M22 and M13 (the great Hercules Cluster), the Dumbbell, Veil and Ring nebula, as well as open clusters such as the Wild Duck and the Butterfly.  Of course, everyone was awed by the king of planets, Jupiter.  As the night wore on, most of the guests departed and a few very interested folks remained.  These folks were interested in seeing some of what the 24 inch RCOS could do, so we took a look at some advanced observing targets.

We aimed the scope at the ring nebula and using a 17mm Nagler eyepiece (297x) we attempted see the magnitude 15.7 central star.  Sure enough, with careful observation, 3 of the 4 of us spotted the star with averted vision!  This was quite exciting as I had never seen this star before.  Given the patience and ultimate success demonstrated by these guests, I then slewed the scope to M33, the Triangulum galaxy (image at left).  This galaxy is a very large  face on spiral galaxy, but has a very low surface brightness.  Using a 31mm Nagler eyepiece (153x) the galaxy filled the field of view.  Looking through the eyepiece I was able to detect the spiral structure of the galaxy as well as 5 of the brighter star forming regions in the arms.  If I had been alone and had time to study the galaxy I am sure I could have seen much more, but I was mostly looking for features quickly so that I could assist the visitors in observing the galaxy.  All 3 guests were able to enjoy the detailed view.  Since they were appreciating this more advanced look through the telescope we spent some time looking at other deep space targets.  I can not remember all of them, but we were treated to fantastically detailed views of NGC 6888, the Crescent nebula;  a picturesque view of NGC 7331 and the 4 accompanying galaxies that comprise the "deerlick" group; dust lanes in the Andromeda galaxy, and amazingly, structure in NGC 7662 the "Blue Snowball" nebula!

When the last guests departed I went back to NGC 7662 to make a sketch of what I was seeing.  This is a fine example of a planetary nebula and at 297x displayed a striking aquamarine color.  It is very large, about the same apparent size as Jupiter.  Most shocking to me was that there was a bright arc within the nebula itself as well as a bright knot in the southern portion of the outer halo.  This nebula is about 5000 light years away in the constellation Andromeda.  Here is my sketch as well as an image of the nebula:

My colleague Mike Terenzoni who was leading the program suggested we look at NGC 891, an edge on galaxy in Andromeda.  I had observed this galaxy before in my 9.25 inch SCT and it was always an attractive but faint target.  We slewed the scope over, inserted the 31mm Nagler, and the view about knocked my socks off.  What was always a faint smudge to me, was a bright and beautiful edge-on galaxy with a dust lane that bisected its entire length.  Most often when observing dust lanes one sees subtle differences in contrast that take experience, patience and averted vision to see.  Not so tonight!  This dust lane was dark and readily visible with direct vision.  The galaxy is brighter toward the core, and below is my sketch as well as an image.

We had a few minutes left and decided to take a look at Jupiter one last time.  Mike had a new Tiffen FL-D filter that we attached to the 31mm Nagler to improve contrast- and it worked splendidly.  While the seeing conditions had dropped to about average, we were still treated to a pleasing view of Jupiter that now featured the great red spot traversing across the disc.  There was no way that I could capture the details that we observed in a sketch, but I decided to give it a try.  Typically, Jupiter sports two dark cloud belts, named the north and south equatorial bands.  For the last couple months, the south equatorial band has vanished (this is very uncommon, happening most recently almost 20 years ago), although there are some indications that it may be reforming.  There is a dark band of material immediately south of the great red spot, and the spot itself is clearly sitting in a hollow.  The north equatorial band remains quite dark yet does show some disturbance toward the preceding limb of the planet.  Below are my sketch (completed at 0723 UT 8/13/2010), as well as an image posted on the internet from a little while after my sketch.  You can see that I need some practice in terms of getting the features into a more accurate latitude, but I am pleased with this attempt.

 All in all, it was a very fun evening, and if you have read this far I hope that you will sign up for one of the SkyNights programs...

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