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Widefield Astrophotography

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Summer 2007

July, 2007

There were two task on my list this evening. The first was to locate Comet C/2006 LINEAR VZ13 as it approached the globular cluster Messier 3. The second was to take several widefield images of the summer Milky Way for a presentation I was preparing. I expected to find the comet near in the constellation of Bootes near the star Seginus (see Sky Chart). First I had to focus the camera. This is accomplished using the brightest star I can find. The focus screen on a Canon Rebel camera is designed for bright daytime objects not stars. Correctly focusing is a combination of looking through the view finding and taking a few photos to examine the results. The other preparation step is to verify the alignment of the piggy-backed camera with the barrel of the telescope. Once aligned I can trust that the camera is pointing where the main telescope is pointing. After many tweaks of the alignment and focus it was time to hunt down LINEAR. I slewed the telescope to an area of the sky near Seginus and opened the zoom lens to the widest possible field of view. My first 1 minuute exposure was intended to locate the comet. If all goes well, I can then zoom in for a closer look. When the exposure is complete I examine the results on the small LED panel on the back of the camera. I can pan and zoom across the photo using several available buttons. Well LINEAR did not reveal itself on the first photo. I then increased the exposure to 2 minutes and raised the ISO setting from 400 to 800. This time the greenish hued comet appeared in the upperleft portion of the photo. I adjusted the telescope to center the comet and then zoom in for a longer 5 minute exposure. Many dim comets look like a green snowball. Others, such as Comet SWAN (see "Astronomy home"), will match your expectations. Click on the slide titled "C/2006 LINEAR VZ13" to view the results. I used a 300mm focal length zoom lens at F/5.6.

On to the Milky Way: I started my widefield shots by aiming towards the constellation of Scorpius in the south. As the night progressed, the Earth's rotation would would carry Scorpius behind a large white barn. I therefore decided to take images from Scropius to the east-northeast along the Milky Way band. Hover your mouse over each slide for a popup title. The first image of the night is titled "Messier 4-Jupiter" and was taken with my 300mm zoom lens piggy-back mounted on the main telescope tube assembly. Click on the slide for an enlargement of the field. The brightest object in the frame is actually the planet Jupiter. Immediately below Jupiter is the beautiful globular cluster known as Messier 4. See my page "Within the Milky Way" for a closer look at M4.

For the remaining photos I switched to a 55mm stock lens to gather light from as wide an area of the sky as possible. I aimed the camera to the south centering on an area between the constellations of Scorpius and Sagittarius. See the 5 minute exposure titled "Milky Way in Sagittarius-Scorpio". You'll also note the large barn I mentioned. It is a 2.5 story building which should give you some perspective on the Milky Way bands behind it. This photo is looking at the center of the Milky Way Galaxy in the direction of Sagittarius. A super massive black hole lurks to the upper left of the barn's peak and just north of the teapot's spout.

Two more photos cover the constellation of Aquila and area known as the "Summer Triangle" formed by the stars Deneb in Cygnus, Vega in Lyra and Altair in Aquila. The Summer Triangle spans the constellations of Cygnus, Lyra, Sagitta, Vulpecula, and Delphinus.

I couldn't resist a closer look at a couple Messier objects near the constellation boundaries of Sagittarius and Serpens. Messier 16, the Eagle Nebula and a grouping of two Messier 8 and 20. Messier 8 is known as the Lagoon Nebula. Messier 20 is called the Trifid Nebula. See my page titled "Within Milky Way" for closer looks at the Eagle and Trifid nebulae. A closer look at the Lagoon Nebula is still on my to do list!

Spring 2007

April 12, 2007

After a late season storm on April 11th and a long cloudy day on the 12th the skies finally cleared for a few hours. The atmosphere was hazy but improved as the frost dried the air. The conditions were decent for widefield astrophotography. The photos here were taken with my Canon Rebel XT using a 300mm focal length zoom lens at F/5.6. All exposures are approximately 5 minutes in duration at ISO 800.

Messier 65-66 : Located in the constellation Leo. M65 (center) is estimated to be 24 million light years distant and M66 (lower left) at 21.5 million light years. M66 is known as a "barred spiral". It's appearance reminds me of a tumbleweed or a comma punctuation mark. Both of Messier objects are spiral galaxies. Try holding a plate at arms length. Turn the plate face-on so you can see its entire circular surface. Now slowly twist the plate edge-on so you see only the thin line of its thickness. As you twist note how the plate appears as an oval or elliptical shape. Take another look at M65 and M66. M65's cigar shape results from its near edge-on orientation to our line of sight. M66 is more face-on revealing its central "bar". Click this link to see another example of a barred spiral M109 in the constellation of Usra Major. Also visible at upperleft is NGC 3628 which appears edge-on. Note the distinct dark dust lane through the nucleus of NGC 3628.

In past years I've attempted longer exposures of M65 and M66. They are challenging objects as no convenient guide stars are near by. My CCD camera has two imaging chips. The main chip is responsible for the astrophotos. The second chip is vertically offset from the main chip. It is much smaller in size and its role is precision guidance correction. By positioning a bright star in the center of the guide chip my CCD control software will work to keep it in the cross hairs. The control software gathers an image from the guide chip, determines any changes to the position of the target star and issues corrections to the mount. This process repeats 15-20 times per minute. The result, when all things function as planned, is high precision tracking which yields very nice images from the main chip. As long as I can find a bright star to place on the guide chip I can usually take long exposures. Bright stars are often tough to find when aiming into the depths of the cosmos. The deep sky objects in Leo lack convenient guide stars and I am often spending valuable time manually turning the camera trying to locate guide stars. Altering the setup forces refocusing, etc. so I rarely do it. I'm waiting for a new imaging component called a Pyxis CCD Rotator that will mechanically rotate the camera about the field of view without affecting focus. Stay tuned in for my future attempts at the Leo galaxies.

Messier 95, 96 and 105: This photo is a much wider field of view from the the M65-M66 photo. Below center you will note three fuzzy patches of light grouped close together. With a little imagination they appear as a right triangle. The largest and brightest patch is the elliptical galaxy known as Messier 105 at 26 million light years. Directly below and to the left is another elliptical galaxy known as NGC 3371. The third member of the trio is a spiral galaxy known as NGC 3389. From this trio, look to the upper right for the next bright patch. This the bright spiral galaxy Messier 96. Continuing to the upper right our next stop is the bright barred spiral galaxy Messier 95. The photo almost resolved the central bar of M95. If you concentrate you can see what appears to be ear lobes of either side of a bright central line. Both M95 and M96 are 26.5 million light years distant.

The Virgo Cluster: Have you ever looked at at dark patch of night sky and wondered what you might be hidden there? The dim constellation of Virgo is host to perhaps thousands of galaxies. I used digital image processing adjustments to help reveal the large number of galaxies captured in this photo. At upper right you will note an interesting group of galaxies. The brightest patch in the center of this group is the giant elliptical galaxy Messier 86. Immediately above is another bright elliptical Messier 84. At 2:00 is the spiral galaxy NGC 4388; at 6:30 is the spiral NGC 4438; at 7:00 the spiral galaxy NGC 4435; and at 9:00 the spiral galaxy NGC 4402. NGC 4388 and NGC 4435 are oriented edge-on to our line of sight. This grouping leaves me with the impression of looking through a fish-eye lens. Spend some time browsing the rest of the image and try counting the number of faint fuzzy patches. Each are distant galaxies of the rich Virgo Cluster.

Messier 51: Well I had a nifty photo started and must have bumped the telescope before it finished. Even so Messier 51, known as the Whirlpool Galaxy, still looks stunning in this short 5 minute photo. You can see closer views of M51, including its 2005 supernova(!), taken through my 10" telescope at the 2 Million Years To Here page.

Messier 97 and 108: Before closing up for the evening I aimed at Ursa Major (Big Dipper) for one last photo or two Messier objects. The ghostly green Owl Nebula, Messier 97 and the spiral galaxy Messier 108. The light from M108 is reaching us for 46 million light years distance. M97 is a relatively near by planetary nebula within the Milky Way. M97 is 1630 light years away. How's that for a perspective on the cosmos!

Spring 2006

April 16, 2006

Messier 81-82 Messier 81-82 Messier 84 Neighborhood

The evening of April 16th, I piggy-backed my Canon XT on my big scope along with a 300mm zoom lens. I targeted Messier 81-82 in Ursa Major and exposed a series of 3-5 minute images. The big scope did all the tracking. I just stodd by and waited for the exposures to complete. The digital speed was set to ISA800. Hover over the image before clicking to view the popup label. One is a wide angle view showing the M81 Spiral arms. M82 is known as a irregular galaxy. We're seeing it "edge-on" from the Milkway. M81 is slightly tilted but for the most part a stunning example of a face-on spiral. Scroll down the page a bit to see an image of M81 taken with the main 10" telescope. Also shown here is widefield image with the same digital camera centered on the Messier 84 elliptical galaxy. I took the image to test the camera's sensitivity to dim light. This area of Virgo is packed with distant galaxies. Unfortunately the image is a bit out of focus due to intense winds that drove me indoors soon after. Two Cedar astronomers reported a count of 22-24 galaxies in this image. How many can you distinguish? Some rainy day, I will add a labeled image to the site.

Winter 2006

February 20, 2006

A friend loaned me his Meade ETX90 to see how well tracking would perform for piggy-back digital astrophotography. The photos here are 2-3 minute exposures at 800 ASA using my Canon XT digital camera. The Orion-Monoceros image is just stunning (though the light gradient at right resulted from aiming too close to a near-by white metal building). The Canis Major-Monoceros photo appears a little uninteresting but look closely and you might spot the Messier catalog open star cluster objects M41, M46, M47, M50 and M93 (I'll label them eventually).

20060220 Orion-Monoceros 20060220 Canis Major-Monoceros 20060220 SaturnBuzzingBehive 20060220 SevenSistersAndMars

Also noteworthy is the faint band of the Milkyway. Another photo shows the planet Saturn hovering close to another Messier open star cluster (M44) known as the Behive Cluster. The last image of the evening shows the planet Mars visiting yet another Messier open star cluster (M45) known as The Pleiades or Seven Sisters. How's that for a quick tour of the February southern skies!

Widefield Gallery

Updated February 20, 2006