Friday, October 28, 2011

ISS Solar Transit

We had a very unique opportunity today in Tucson to see the International Space Station transit across the face of the Sun.  I have seen the ISS many times naked eye, and have even observed it through a small refractor as it tracked across the sky one in truth, while I thought it would be neat I was not that excited for the event.  Fortunately I had thrown my white light solar observation equipment into my truck before work this morning, so as the time approached I was able to drive straight to our observing location, the Babad Do'ag vista on the Mount Lemmon Highway.  There I met up with Dennis Nendza and Jerry Farrar who were already setting up for the event.  Dennis was going to take both video of the event, as well as digital still images through his C8 telescope.  Jerry was planning to observe the transit in hydrogen alpha and I was going to make a sketch.

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The transit was scheduled for 1:39 PM local time, and we knew that we had to be looking in advance and not paying too much attention to the exact time or we could miss it.  The ISS after all moves rather quickly and in fact only takes approximately 1 second to transit the Sun!  There was a pretty good breeze while I worked to sketch the Sun in advance of the transit, making it difficult to see fine detail.  At Approximately 1:30 I had the spots sketched and was now ready for the event.  At 1:38 I began to observe the Sun continuously and at approximately 1:39:12 the ISS flew on across!  I have to say that it was actually quite exciting and I am glad that Jerry kept reminding me throughout the week that this event was upcoming.  At left is my sketch which shows the approximate path of the ISS (hey, it flew by in a second!) as it moved northward.  It was very easy to see the central module, as well as all the solar panels arrayed out to either side.  In terms of size, the ISS appeared about the same size as the large sunspot AR11330 (although my sketch shows it slightly larger).

At the time of the transit, the Sun was at an altitude of 39.4 degrees and an azimuth of 210 degrees.  I hope to see the images and video that Dennis captured soon, and see how closely I was able to note the transit path during the one second I had to observe it.  The exact coordinates of the Babad Do'ag vista that we observed from are: 110:43:14.4 West, 32:18:32.9 North.  At right is a picture of our happy group, after our successful observation.

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
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Friday, October 14, 2011

SkyNights update

Momentum....Inertia...Whatever it is, I need to ride it.  I have managed to make several blog posts over the past month and do not want to slip back into infrequent posting mode.  The fact that you are loyally reading this right now is the very reason that I am taking a few quick minutes to post.  As you know (or should), I have been working at the Mount Lemmon SkyCenter leading public SkyNights programs and conducting occasional other outreach events.  Last weekend I conducted a program and one of the guests was a professional photographer named Howard Paley.  As it turns out, not only is Howard an accomplished photographer, he has known my family from as far back as the late 1980's.  That is one of the neat things about Tucson - no matter how it grows, it still feels like a one-horse town.  Howard sent me some images that he took during the program and provided me permission to post them below.  I'd strongly encourage you to visit his website and see some of his incredible photos from around the southwest.  All of the images in this blog post are copyrighted and should not be used without Howard's explicit permission.

One of the atmospheric phenomenon that visitors to our programs can experience, is to see and understand that shadows on earth are actually blue...not black or grey as commonly thought.  The short explanation for why our shadows are blue is that our atmosphere scatters blue light and this is what colors our shadows.  For the long explanation you need to come to a program.

Sunset is incredible from the summit.  At right, is a very pretty image of the Sun heading toward the horizon, approximately 3-4 minutes before the start of sunset.  At sunset, guests often see a unique phenomenon called the green rim.  How do I know that this photo is 3-4 minutes before sunset?  Come to the program, learn the answer, and see the green rim for yourself.

At left is an image of the nearly full moon that Howard captured during the program.  What is incredible is that this image was not taken through a telescope.  It was taken with a tripod mounted camera.  No doubt what makes it special is the photographer.

Finally, a beautiful image of the inside of the dome just after sunset.  While the red light was coming from dim lights within the observatory, the white light shining into the dome from the left is light from the moon.  Know what constellation appears through the dome slit?  If so, send me an email and if you are right I'll make it worth your while!

Saturday, October 8, 2011

Solar sketch October 8th

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A tremendous amount of activity on the Sun this morning, in terms of active regions and prominences.  We are having a cold spell with temperatures in Tucson lower than those in Minneapolis due to the jet stream residing overhead.  This is very unusual weather down here for early October and it has resulted in some poor atmospheric stability.  I completed the sketch at left at 1547 UT (8:47 AM local time) with my Lunt Solar Systems 60mm dedicated hydrogen alpha pressure tuned telescope.  Most unusual is the faint, expansive prominence off the east limb that appears to he lifting away from the Sun.  There were two distinct brighter knots in this arc of plasma.  Hopefully, some of the accomplished solar imagers around the world will post photos of this event soon.

Active regions 11309 and 11312 in the northern hemisphere both contain dark spots, and it appears that there is another active region rounding the northeast limb.  The southern hemisphere is awash with activity, although much of the plage regions are faint and the poor seeing conditions made visual observation challenging.  Region 11311 in the southwest contains a spot, as does region 11308 (or maybe it is 11310, I am having trouble figuring out which regions are which this morning...).  In the southeast, active region 11313 is the most dynamic of the regions with bright plage and what appears to be some bi-polar activity.  There are spots in the east and west ends of the region, along with some dark fibrils arcing between them.  There is an additional region of plage in the southern hemisphere, on the meridian, which is as of yet unnumbered.  Below are comparison images from Big Bear Solar Observatory at left (taken at 1556 UT) and from the Solar Dynamics Observatory at right (taken at 1539 UT).  Note that the image from SDO captures the massive prominence on the east limb beautifully.  Look closely at the Big Bear image and you can see that the prominence is ghostly just on the extreme edge of the field of view.

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Sunday, October 2, 2011

Twice the fun

Yesterday afternoon I visited one of the local astronomy vendors, Stellar Vision, to see if proprietor Frank Lopez had some hardware that would allow me to piggyback my Lunt 60mm Hydrogen Alpha Telescope onto my recently acquired Astro-Telescopes 102mm f/11 achromat.  I have been using the achromat for white light observations of the Sun and had been thinking about how great it would be if I could have both telescopes mounted simultaneously.  The great thing about Frank is that he is like the Wizard of Oz- he goes behind his curtain (literally) you hear some wheels turning, metal parts clanging around, steam venting, and soon enough out he comes with some hardware that achieves exactly what you are looking for.  Frank has spent years in the telescope business and deals in so much used equipment that I am not sure even he knows how many parts and he has behind the curtain.  At left you can see my current set-up...Thanks to Frank for the mini, ring-top saddle that allows me to piggyback the Lunt!  (Certainly I could have gone online and ordered this part from Losmandy, but I always believe in suporting the local vendor).  While mostly convenient for me, this piggyback arrangement will be very useful for outreach activities.

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As luck would have it, we are in the middle of about a half-day of clear skies and I was able to get everything together this morning and make my first two sketches of the Sun without changing scopes.  Right away I discovered how fun it is to notice a feature in either white light or hydrogen alpha and then to see if there is any associated feature visible in the other scope.  The skies were not great, with passing cirrus and haze but I was still able to tease out quite a bit of detail, particularly in hydrogen alpha, as seen at right.  This sketch was completed at 1535 UT (8:35 AM local).  Active regions 11302 and 11305 continue to show significant activity as they rotate toward the Western limb.  The spots in 11302 seem to have diminished a bit in size, although the plage and filaments in the region remain complex.  Regions 11306 and 11307 seem to be decaying as the plage areas in these regions are markedly fainter than previous days.  There is a new region that has rounded the NE limb that appears to have a spot (confirmed in white light...yeah!), and the region noted in the SE over the past two days has now been officially numbered 11308.  There is a very large and beautiful prominence associated with this region.

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At left, is my white light sketch completed about 20 minutes later at 1557 UT (8:57 AM local).  In addition to the numerous spots in the numbered regions, the new region in the northeast contains two very large spots, as well as a smaller spot.  These spots appear elongated when near the solar limb, due to what is called the "Wilson Effect."  This apparent elongation is the result of perspective- Keep in mind that the sun is a sphere.  When looking near the center of the disc we are looking straight into the Solar atmosphere, yet when looking near the limb, we are actually looking across its atmosphere.  Add to this the fact that sunspots are akin to depressions in the solar atmosphere and you get an obvious elongation.  This same effect can be seen looking at craters along the extreme limb of the moon.  

Saturday, October 1, 2011

Welcome October!

Today is the start of October and right on schedule the weather here in the Old Pueblo is changing.  While the Sun is shining steadily in clear blue skies this morning, later today will see heavy cloud cover, and increasing moisture for a few days.  By weeks end, temps in the upper 80's!!

Quick report today, the Sun appears much as it has for the past two days.  5 active regions are making their way westward across the northern hemisphere of the sun.  AR 11305 displays the strongest plage, and 11302 covers the largest area and contains the most spots.  There is potentially an emerging region that has come around in the southeast, as well as a small ephemeral region of plage that has persisted since yesterday in the south.  My sketch was completed at 1623 UT (9:23 AM local time) under very steady skies.

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Below are images in Hydrogen Alpha from the Big Bear Solar Observatory (taken at 1634 UT), and the Solar Dynamics Observatory (taken at 1514 UT).  I particularly enjoy the Big Bear image at left, as it is monochrome and more closely resembles the eyepiece view.

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