Sunday, October 23, 2011

Near and Far

I just returned home from a quick two night trip to Portal, Arizona where I had two excellent nights with my good friends Jerry Farrar and Bill Gates.  If you appreciate dark skies and stars, you owe it to yourself to make a visit to this little back country area on the southeast flank of the Chricauhua Mountains.  The weather was extremely cooperative and we had two nights of very low humidity and transparent skies.  While Friday night was excellent by most standards, Saturday night was very nearly perfect.  (For the astronomers among you, Bill commented that his impression was that we were experiencing sub-arcsecond seeing).  In terms of naked eye limiting magnitude at the zenith, I could see stars around magnitude 7.2...while Bill could see fainter.  At left is a picture of the purple light that was filling the western sky shortly after sunset.

HST image of NGC 6751
I observed many targets over two nights, near and far, more than I can recount here without putting you quickly to sleep.  For example, using my 12 inch LX 200 SCT, I observed the central star in the ring nebula at 610 power.  In addition to this easy planetary nebula, I decided to make a tour of some of the planetaries within the constellation of Aquila.  I made a few notes on about a half dozen of them with the most interesting (in other words, something more than a diffuse stellar blip, or an ethereal glow) being NGC 6751 and NGC 6804.  NGC 6751 revealed an easy central star at 381x, and increasing the magnification to 610x brought out the delicate structure, central hollow, and slightly brighter arcs on the perimeter.  NGC 6804 is a large oval shaped nebula with an easy central star and two additional stars superimposed on the nebula.

For some time I had been wanting to make a sketch of the Pleiades star cluster and nebula.  Considering the honored place that this object has in my life (it is after all, the Lost Pleiad Observatory), I was waiting for a trip to Portal where using my TEC 140 APO and a low power eyepiece I could fit the entire cluster into the field of view and see the nebula.  At left is my sketch completed at 0730 UT on October 23rd.  The bright stars of the cluster are very young in stellar terms, only about 100 million years old.  They are approximately 400 light years distant appearing in the constellation of Taurus the Bull.  While I was drawing, I enjoyed memories of camping with my late sister-in-law very near to Portal and looking up at these same stars.

Relatively near to us, almost two astronomical units away (about twice the earth-sun distance), Comet Garradd continues its slow trek through the solar system.  The comet has brightened considerably, and I would estimate it very close to magnitude 7.  Under the dark and steady skies of Portal, the tail was extensive with three main streamers visible, although not nearly as bright as my sketch at right would imply.  My drawing was completed at 0255 UT on October 22nd, at 147x with the 12 inch SCT telescope.  Comet Garradd is currently in Hercules and is an easy target even in a pair of 7 x 50 binoculars.

Finally, something far away...well, extra-galactic anyway.  Guided to the location by Jerry Farrar, I made an observation of Globular Cluster G1 (Mayall II) in the Andromeda Galaxy.  At 2.52 million light years away, this is the brightest cluster in the Andromeda galaxy, and quite possibly the remnant core of a dwarf galaxy that has merged with Andromeda.  What confirms this observation is separating the small 15th magnitude stars that closely attend the cluster.  While not much to look at, it is incredible to consider that using a small telescope we are able to see this object as clearly non-stellar, in another galaxy! Obviously, it is very massive, probably twice the size of Omega Centauri, the largest known globular cluster in the milky way.  It is theorized that there may be a black hole at the center of G1.  I made the sketch below with my 12 inch SCT at a magnification of 381x.  At right is an HST image of the cluster.  This cluster resides approximately 130,000 light years from the core of the Andromeda galaxy.  (If you are interested in hunting it down, it is at RA 00:32:46.8 ~ DEC +39:34:42)

HST image
Click to enlarge

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