Wild Ducks and Jupiter (11 Jun 2020)

 DSO, Jupiter, Open Cluster, Planet, Solar System, Wide FOV  No Responses »
Jun 132020
 

While waiting for Jupiter and Saturn to clear my tree line, I did some more testing with my wider FOV scope that has a simple DSLR mounted on it. I am still manually focusing the system but it doesn’t take too long to accomplish. The recently installed flattener corrects the distortion apparent in the stars at the corners of each image.

The target for tonight’s testing was Messier 11 (The Wild Duck Cluster). Legend has it the cluster was given its name by British Admiral William Henry Smyth (1788-1865). When describing the cluster, the Admiral, a very accomplished astronomer and avid hunter, commented the V-shaped group of stars looked like a flock of wild ducks.

Classified as an open star cluster, the flock is located in the constellation Scutum (The Shield). The constellation is right in the middle of the plane of the Milky Way and towards the center of the galaxy. That is fairly apparent by the sheer number of stars in the image. North is to the right putting M 11 right on the northern edge of the Scutum star cloud. The dark area towards the bottom right side of the image is not a lack of stars. It is a large area of dust and gas dense enough to block the light of more distant stars. Several of these areas were individually cataloged as dark nebulae by American astronomer E. E. Barnard, hence the B numbers on the matching chart.

Wild Duck Cluster (M 11) [M:11x120s]

As can be seen on the constellation chart, Scutum is in the southern sky located between Aquila and Sagittarius. The image and matching chart are rotated 90° to the constellation chart.

Chart generated by Cartes du Ciel

Chart courtesy of the IAU and Sky&Telescope

Once Jupiter and Saturn cleared the trees I switched over to planetary equipment and was able to get a couple of series of both planets before wispy clouds moved in from the south. As usual, the best Jupiter image was uploaded to NASA’s JunoCam web page for mission planning.

Jupiter [(V)TR:2506×0.74ms;TG:2501×1.1ms;TB:2505×1.7ms]

 Posted by at 15:32

Beehive cluster (M 44)

 DSO, General Commentary, Open Cluster, Wide FOV  No Responses »
Apr 072020
 

I have been testing a new optical configuration to give the PTO the ability to record larger FOV images. Mounting my Nikon D90 to a 80mm f/6 apochromatic telescope gives a 2.9°x 1.9° FOV image. The resulting 5.26 sq° image is 97% larger than the standard science image used for asteroid/comet analysis. The size of the camera chip is large enough though that significant distortion is visible at the extreme corners of the image. As you can see the stars are ‘stretched out’ with each pointing towards the center of the image. This is known as pincushion distortion. A field flattener will need to be added to correct this problem.

The test target is a fairly large open cluster. It lies in the center of the constellation Cancer and is known as the Beehive cluster. The current population count is about 1,000 stars although only the brightest form the naked eye object. This is one of the first objects observed by Galileo when he first turned a telescope to the sky. He counted 40 stars.

Beehive Cluster (M 44)
[M:4x60s]

The compressed display makes the image background much brighter than it should be. Click on the image for a larger more accurate view. This will also make the corner distortion easier to see.

 Posted by at 14:24

The Great Orion Nebula (M 42)

 DSO, Nebulae  No Responses »
Jan 012020
 

With the PTO’s science camera still in the shop, I drug out my 15 year old Nikon D50. Although it doesn’t have the dynamic range or resolution of the science camera it sure is easier to create a full color image.

The Orion nebula is one of the nearest star forming regions to the Sun and based on recent analysis, is home to 700+ stars in various stages of formation. The mighty Hubble space telescope has also recorded more than 150 infant solar systems in the stellar nursery. Technically, the young systems are known as protoplanetary disks AKA proplyds.

Orion Nebula (M 42) [F:15x30s]

The nebula is just at the limit of naked eye visibility. It is the middle object in the ‘sword’ that hangs from the hunter’s three star belt.

 Posted by at 21:37

PTO vs. HST

 DSO, Galaxy  No Responses »
Jun 132019
 

If you have ever wondered what a bazillion dollars buys you in the Astronomy world, here is an example. Yesterday’s Astronomy Picture of the Day (APOD) is a shot of M 96 (AKA NGC 3368) taken by the HST (Hubble Space Telescope). Below is the same galaxy taken in 2013 by the PTO deep space camera through my 10″ scope.

M 96 [C:9x300s]

You can definitely see the prominent dust lanes visible in the HST image although in mine you cannot positively identify them as such. They could be gaps between spiral arms. In the HST shot you can also see what appear to be either background galaxies or satellite galaxies on the upper right and middle left of the main target as well as a bright young cluster of blue stars on the galaxy’s left. All three are visible in the PTO shot but they all appear as small blurry spots.

 Posted by at 10:50

Wide Field Experimentation

 DSO, Wide FOV  No Responses »
Oct 232018
 

I am doing some wide field experimenting with my ancient and honored Nikon D50 DSLR. The images below were taken through a 18-55mm zoom lens, set at a focal length of 55mm. This generates a FOV of 25.7°x17.0° with each pixel representing 30.5″ of arc. The camera is mounted on a GEM (Losmandy G-11) to prevent long exposures smearing the stars.

I haven’t come up with a way to flat field these images yet which is why there are some dark splotches visible. These are known as dust donuts and are the result of dust or other material somewhere in the light path. Additionally, the camera was manually focused resulting in a soft look to the stars.

The first image is centered between the open star clusters Pleiades and Hyades. Most of the image is in the constellation Taurus. The bright star at the bottom right is the star Aldebaran. The ‘V’ shaped Hyades, the lower cluster, forms the head of the Bull with Aldebaran representing the eye. The orientation of this image is north to the left and east down and is slightly cropped to remove the tree line along the southern edge.

Taurus [M:17x60s] (mouse over for labels.)

The second image contains most of the constellation Orion. Visible in the ‘sword’ is the Orion nebula (M 42;NGC 1976) and just at the limit of visibility is a hint of the Flame nebula (NGC 2024) next to Alnitak. Curiously, M 42 is not identified in the annotated image. The orientation of this image is north up and east to the left.

Orion [M:30x60s] (mouse over for labels)

My next steps will be to try some different techniques to eliminate what appears to be some external reflections in the images and to add in the color. I like the scale of the image when the lens is set to 55mm and the optical distortion at the edge of the FOV is not as extreme as when the lens is set to a faster focal length. I think I will add this configuration to my list. I will also look for an affordable 50-55mm non-zoom lens.

 Posted by at 16:39
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