Telescopes Galore!

Northeast Astronomy Forum

I had a wonderful time April 18th at the Northeast Astronomy Forum (NEAF) in Suffern, NY. Similar astronomical meetings are usually on the west coast, and the majority of equipment manufacturers seem to be from western states far from my eastern Virginia home. This relatively nearby event was a great opportunity to inspect equipment first hand, speak to several experts in person, and do side by side comparisons of solar observing equipment.

More than 107 exhibitors came to the field house of Rockland Community College as shown in the imperfect panorama below.

I spent hours walking from booth to booth ogling the beautiful expensive equipment on display. I'd love to have a small dome like this in my back yard.

What to put in the dome? An excellent telescope, of course! Although I gazed on the instruments below with visceral desire, I can only dream of owning all these beautiful refractors.

If I could afford all these beauties, I might need a mount like this next one designed for telescope hoarders.

Sometimes, binoculars give the best views. For only about $3,000 I could own these magnificent 100X27.5 Lunt binoculars.

Some telescopes, like the one below, were custom made works of art.

Telescopes were not the only items on display. One exhibitor crafted beautiful equipment from wood, including this shielded laptop desk.

In another exhibit experts illustrated mirror grinding techniques.

A few vendors sold meteorites and fossils.

I bought one pretty slice of a rare pallasite meteorite from Steve Arnold, one of TV's Meteorite Men. My small extraterrestrial fragment has a beautiful green transparent oval of olivine (peridot) embedded within silvery criss-crossed iron-nickle crystals.

The sky cleared just in time for April 18th, so I had an opportunity to view the Sun through a number of instruments set up in a courtyard outside the exhibition hall.

One fascinating piece of equipment was the Shelyak spectroscope which produced a view of the solar absorption spectrum in glorious, clear, high resolution. I had seen many pictures of this spectrum, but never viewed it live through an eyepiece with my own eyes. It was an astounding sight to see dark absorption lines so brilliantly displayed against a bright rainbow background! By turning the micrometer dial, as the gentleman is doing below, I could slowly move through the entire spectrum from red to violet.

I was particularly interested in views of the Sun through the monster 152mm double stacked Lunt solar telescope pictured below.

I'm glad I had the chance to compare the 152mm with other scopes nearby. I strongly considered buying this giant scope until I saw the view it produced and listened to words of caution from expert observers. I expected the 152mm view to knock my socks off, but it wasn't better than views I get through my much less expensive 100mm scope. Instead of spending big bucks to get the 152mm, I decided to buy equipment to upgrade my 100mm. When my second Lunt etalon filter arrives, I will have a double stacked solar telescope like this one.

The best views available, in my opinion, came from the following pair of scopes.

The larger Astrophysics 6-inch refractor, on the left, equipped with a Daystar solar filter, showed a beautifully magnified prominence and spicules on the solar limb. The smaller companion double stacked Lunt 80mm scope on the right provided an astounding 3-dimensional view of the entire Sun through a binocular viewer. The binocular view was so beautiful I had to buy a binoviewer for myself later that afternoon. I'm anxious to see the image my upgraded 100mm scope will give with the binocular eyepiece. My equipment should produce equally astounding views.

I also purchased a new camera and solar guider at the show. I'll write about them in future posts.

Beautiful Day

Finally! Some Sunspots!

High thin clouds marred a perfect sky on April12th. The Sun had been mostly blank for two previous weeks, and clouds were forecast for many days in the future. So April 12th was an observing opportunity I couldn't afford to pass up. It was a beautiful day with comfortable 65 degree temperature and good seeing.

Significant sunspot group 2321 had just rotated into view around the Sun's eastern limb. The following picture is a 2-image mosaic made with a 2X Barlow lens. Sunspot group 2321 is on the left closest to the limb, and a small sunspot pair, named 2322, is near the right edge.

Small sunspots approaching the Sun's western limb were accompanied by a number of filaments. These spots would soon rotate out of view. The following 5-image mosaic shows 2323 on the left, and 2320 on the right.

These images seem a bit washed out to me. I expected sharper detail because the seeing was good. Perhaps intermittent high thin clouds caused some degradation.

Limb Fireworks

Cool Day, Hot Sun

Breezy conditions and chilly 40 degree temperature on March 29th made observing conditions almost uncomfortable. Seeing was poor, but absolutely clear skies were hard to resist.

Although most of the Sun was blank, one good-sized sunspot and a spiky eruption on the western limb made my efforts worthwhile. The first picture below is an 8-image mosaic made with a 2X Barlow lens. It shows the solitary major sunspot, 2305, below center and a dramatic jet associated with departing sunspots shooting out from the western limb on the right.

Thirty minutes later the erupting spikes had changed as shown in the following image.

It would have been nice to make a time lapse movie of these erupting features, but I decided against this for two reasons. First, no sunspot umbra was nearby. I use a relatively stationary umbra to align video frames and correct inevitable image drift over the duration of a time lapse movie. Second, seeing was really terrible! At times the solar surface was completely blurred.

During one short period of slightly improved seeing I recorded the following solo image of sunspot 2305.

This is far from the most detailed image I've ever made, but it's not bad considering the generally poor seeing conditions during today's observing session.

Stacking

Comet Lovejoy in Cassiopeia

Since my last post I've learned how to increase the effective exposure times of my sky photos by stacking individual images. The individual photos used below were taken on March 15th when comet Lovejoy was still visible in the constellation Cassiopeia. By this time the comet was getting dimmer, its tail was diminishing, and it was getting lower in the sky. I missed a great opportunity for nice photos two months earlier. I didn't have equipment for sky tracking in January and February when the comet was bright with a long prominent tail high in the sky. Equipment was finally in hand on March 15th, so I finally had a chance to capture the fading comet.

I practiced stacking with three increasing magnifications. The first picture below is a stack of three individual 3-minute exposures with a 55mm lens. The stacking, or addition, of the images was done with a program called Deep Sky Stacker. Comet Lovejoy is the small, fuzzy, green object left of center very close to the white star Delta-Cassiopeiae (Ruchbah). No tail is visible. The "W" shape of Cassiopeia's bright stars is entirely visible. The tight grouping of stars near the lower left corner is the double cluster in the constellation Perseus. The small pink object to the lower right of the comet is star cluster NGC 457.

The next more magnified image is a stack of three individual 2-minute exposures with a 110mm lens. The green comet and white star are more clearly separated, and the comet's tail is on the threshold of visibility.

The last picture, magnified a bit more, is a stack of three individual 2-minute exposures with a 150mm lens.

I was able to achieve a uniform dark sky background in the pictures above because one of my image processing programs, Star Tools, removed brightness gradients and vignetting. The next image illustrates what the previous picture would be like without gradient removal.

Colors seem nicer in this last picture even though the center is too bright. The comet's green color looks particularly nice. I really don't know what I'm doing with color management during image processing. In the future I'd like to try stacking 9 or 10 images to better capture faint details like the comet's tail not seen in the pictures above.

Learning Curve

DSLR Sky Photography

On a clear windy March 15th evening I fled glaring neighborhood lights for a serious first attempt at wide angle DSLR sky photography. I carried my tripod-mounted sky tracker with Nikon D40 camera to a darker nearby field, about a quarter mile from home, where I could actually see Polaris in the polar alignment scope instead of reflected lights. Once the mount was polar aligned I patiently took systematic exposures to gain practical experience with the camera and mount. Eventually, after two hours, I quit when the temperature dropped near 40 degrees, wind gusted stronger, and my fingers got too numb to operate the equipment.

I learned some valuable lessons during my time in the field. First, exposures longer than two minutes captured too much sky brightness from light pollution. In the future I'll use shorter exposures. Second, the camera mount and tripod were shaky. Every time I adjusted or moved the camera the mount was nudged and polar alignment was destroyed. I need to check and adjust polar alignment after every camera adjustment. Third, I should try setting ISO to 800 instead of 1600. Maybe that will reduce noise a bit. Fourth, I need to take more than three images for stacking in order to increase effective exposure time. Maybe I'll try for 9 images in the future.

Capturing images is only the first step towards producing a good picture. The camera's raw images need to be processed to remove flaws and bring out all the details. I downloaded three new image processing programs and spent hours learning to use them, mostly by trial and error. One of these programs, Star Tools, does a great job removing brightness gradients and vignetting which plague all my sky photos.

The first decent image obtained with my new equipment is the following picture of Jupiter and nearby star cluster M44, the Beehive Cluster, in the constellation Cancer. This is a single 120-second exposure through a 55-200 mm telephoto lens set at about 150 mm. I subtracted a dark frame, but did not apply a flat field. Stars are nice and round indicating good tracking, but colors are not vivid, and bright Jupiter at lower left is very overexposed. Color management is still a mystery to me.

The following picture of the Pleiades star cluster in the constellation Taurus reveals stars down to magnitude 11.8 as well as hints of blue reflection nebulosity present in the cluster. But the bright stars are overexposed, and the blue color seems too light. This is also a single 120 second exposure through a 150m lens with dark subtraction but no flat field.

I'll try stacking some images in my next post.

Solitary Sunspot

Sunspot Action

A long period of bitter cold, clouds, and snow followed my last solar observing session in February. Hardly any sunspots formed during this time, so I didn't miss much. Lousy weather finally ended on March 7th. Snow had melted and temperature was in the low 50's. One modest sunspot had rotated into view on the Sun's east side with some nice filaments nearby. Unfortunately, seeing was not good.

The following 6-image mosaic shows solitary sunspot 2297 near the eastern limb on the left with two distinctive filaments near the frame's bottom.

I noticed a faint thin stream of gas connected to a bright spot below the sunspot. The gas seemed to be arching up into space as you can see in the next image.

The sunspot had been erupting recently, so, I thought, with luck, I might record some action in a time lapse movie. I began recording movie frames at 1:54 pm EST, recording one image every 60 seconds. When seeing deteriorated drastically, I stopped recording at 2:26 pm EST after accumulating 32 frames. So the following movie captures 32 minutes of solar action. Hot gas seems to rain down from a magnetic arch into a thin stream hitting the bright spot below the sunspot.

There were also some nice prominences on the Sun's western limb shown in this 5-image mosaic.

I quit when bad seeing smeared detail into a blurry mess.

Sky Tracker

New Camera Mount

Over the years I've used my Nikon D40 DSLR camera to take pictures of constellations, conjunctions, and comets. Time exposures were limited to a maximum of 30 seconds for two reasons. First, 30 seconds is the longest available automatically timed exposure that can be done without unavoidable vibration caused by a finger physically depressing the shutter button. Second, 30 seconds is the maximum time before star images elongate due to Earth's rotation. I'm happy to say the 30 second barrier has been removed!

My new Ioptron Sky Tracker can follow Earth's rotation, so star images will remain round in long exposures. I also purchased a remote shutter control so I can manually control exposure time on the "bulb" setting without physically touching the shutter button. Check out my new sky photography setup below. The small cylindrical telescope tube to the right of the camera is the polar alignment scope. While gazing up through the polar alignment scope I adjust the black rectangular box in altitude and azimuth to bring the North Star, Polaris, to the proper position on an illuminated reticle. Once the mount is polar aligned, a battery powered motor inside the black rectangular box turns the camera at just the right speed to keep up with Earth's rotation.

The ball head camera attachment seen below allows variable camera pointing.

The whole camera mount is attached to a tripod.

I waited several weeks to try the new equipment. Weather was miserable - either too cold, too cloudy, or snowing. Finally, on March 7th the sky was clear and temperature was in the 40's. I carried the tripod into my back yard where I immediately cursed the many neighboring spotlights glaring at me from every direction. These lights made it hard to see Polaris through the alignment scope. I also learned alignment could easily be lost by the slightest nudge to the tripod. Camera position had to be changed very slowly and gently in order to maintain alignment.

With my lens set at 18mm I took 60- second and 120-second exposures of Orion, Taurus, and the Pleiades. The 120-second exposure is shown below. Tracking was excellent! Star images are round, though not in perfect focus. The winter Milky Way is visible to the left of Orion. The Hyades and Pleiades are to the upper right of Orion. Hints of pink hydrogen gas are present. This is a single image recorded in JPEG format with no fancy processing. I'm really pleased with the result and anxious to try again with better focus, image stacking, and dark subtraction.

Achieving exact focus continues to be a problem. All my attempts at magnified images were out of focus even though I thought they were in focus when I activated the shutter. It's so hard to judge focus on the camera's display screen. I make test exposures, magnify the results on the camera's image display, make small adjustments to the focus ring, and repeat until star images look sharp. But it's hard to see the display with so any blasted glaring lights all around, and it's hard to remain patient when my hands are freezing. I need to pay more attention to this in the future. I also need to get away from neighborhood lights.

The next image shows the effect of light pollution. This is a 120-second exposure of the constellation Cancer. The brightest object near center is Jupiter. Just above and to the right of Jupiter is the Beehive star cluster. I tried a more magnified image of Jupiter and the star cluster, but the result was out of focus. Notice how the sky is brighter in the lower left than in the upper right. The lower left was closer to the horizon and lit by neighborhood lights.

The zenith sky from my back yard was reasonably dark in 120-second exposures. When I tried 180-second exposures the background sky became light gray instead of black.

These first attempts are promising. I hope to try again soon.