The Ring Nebual (M57) is a planetary nebula in the constellation Lyra. The image below is a composite stack of nine photos taken the night of October 24, 2009. Each individual photo was captured at f/10, ISO1600. Total exposure time is 9×30sec, or 4 min 30 sec.
M57 - Ring Nebula
Tonight I tried my hand at photographing a few Deep Sky Objects. The Hartman mask was extremely useful for focusing, but after tonight it’s clear that I’m going to need to control the D50 by tethering it to the laptop to get best results. Manipulating the zoom controls for the LCD is awkward at best. I may need to spend some time just practicing focusing on a few different stars.
Saturn was actually the first target before the DSOs. I captured a couple of images at ISO 800 and 4 sec exposure that included the moons Titan, Tethys, Dione, and Iapetus (Rhea was transiting and lost in Saturn’s glare). I reduced the exposure time several steps, but it was hard to see much detail in the LCD (another argument for tethered control), so I moved on.
Next I tried M13, the globular cluster in Hercules. This actually turned out to be the best subject of the night. One of the photos had some jitter from the wind shaking the telescope (did I mention it was occasionally quite breezy?). Most were fairly good, however, with nearly round stars — limited by the sharpness of the focus, most likely. Click the image to see a very large full-sized photograph. If you look closely you can see stars of several different colors in the cluster. M13: FL 2032mm, ISO 800, 30sec exposure, f/10.
M13
Next came M57, the Ring Nebula in Lyra. I captured several images, but they all showed noticeable wind jitter. I’m certain this is telescope vibration and not tracking error because the motion vector varies from one photograph to the next. I merged the four best frames in Registax, stretched to compensate for the motion vector, applied a gamma correction to increase the brightness, then reduced the image size to improve the apparent sharpness of the focus. M57: FL 2032mm, ISO 800, 30 sec exposure, f/10.
M57 - The Ring Nebula
The next target I tried was M27, the Dumbbell nebula. However, even with a 30 sec exposure at ISO 800 there was almost no trace of any nebulosity in the photo, so I moved on.
I decided to re-balance the telescope forward to compensate for the extra weight of the camera on the back. This, of course completed wrecked the scopes alignment so I had to restart. After alignment I focused the camera on Mizar (ζ UMa). It’s a nice blue double, but it’s included here for more than aesthetic reasons. According to SNP, the separation between Mizar A and B is 14 arc-seconds. In the unprocessed photo, the distance between the centers of the stars is approximately 19.3 pixels (along a diagonal). This puts the resolution for the camera at about 0.725 arc-seconds per pixel. By comparing similar measurements of other doubles I should be able to calculate the actual resolution more accurately. Mizar: FL 2032mm, ISO 800, 1/2 sec exposure, f/10.
Mizar A and B
After rebalancing I Attempted several images of the Whirlpool galaxy M51. The cores of M51 and its companion galaxy both appeared tiny and featureless over several photographic attempts.
Location: at home in Tomball, TX
Cloud cover: none
Transparency: excellent (5/5)
Seeing: average (3/5)
Darkness: bright quarter moon
Wind: none
Humidity: 25%-30%
Temperature: 50’s
Start Time: 7:45 pm CST
End Time: 9:15pm CST
OTA: 8″ SC
Venus half-illuminated, very bright even with ND filter. Lots of atmospheric turbulence.
Luna brilliant, just over half illuminated. Mons Piton and Mons Pico cast long black triangles toward the dark side. Occasional turbulence visible. Subtle “fractal” texture visible on the surface of Mare Imbrium. Pulled ep and diagonal then projected image onto white paper to see entire moon in FOV. Did not try to locate Pleiades nearby.
M42 nice with 12.5mm, less detail visible than two weeks ago due to moonlight. Noticed Trapezium E for the first time, a very faint mag 10.3 star between A and B, just outside the trapezoid. Observed a pair of mag 7 or 8 stars near the mouth, and another mag 8 or 9 that formed a nearly equilateral triangle with the two stars near theta2 orionis.
Beta Mon very cool, primary slightly brighter than two companions. Close triple, clean separation in the new 12.5mm ep. Open angle about 140°-150°.
M50 appeared to consist of an isoceles triangle, pinched at the narrow vertex, with stars dotting the edges. A smaller triangle inscribed the larger, fainter stars everywhere.
NGC2264 appeared like the outline of a large arrow pointing “this way up”.
Location: my backyard
Time: 8pm – 11pm
cloud cover: none
temperature: low 60s
humidity: maybe 60% climbing to 80%
seeing: good (4/5)
transparency: excellent (5/5)
darkness: no moon, suburban light pollution
instrument: 8″ SCT
Don and Carol came, brought binoculars. We started by observing Jupiter. Polar cloud caps visible, almost convinced myself I could see the GRS. Four moons visible, Don and I remembered all names but Callisto.
Pointed out summer triangle Vega-Deneb-Altair and constellation Cygnus. Observed familiar double stars Albireo and epsilon lyrae.
Clusters next. Started with M39 OC in Cygnus: clear blue pinpoints. Then looked at M15 GC in Pegasus: fuzzy ball with several distinct stars.
Next came planetary nebulae M27 in Vulpecula and M57 in Lyra. Outline of M27 was distinct but dumbell shape difficult to discern. Carol’s eyes seemed more sensitive than Don’s or mine. Ring of M57 clear, Carol could see dim star at center. First time I remember seeing planetaries so clearly.
Moved to Andromeda M31. Again Carol could see some swirling where Don and I only saw fuzzy core.
Ice giants came last. Uranus was a nice cyan disk with a white spec, remarkable color. Neptune was small, hard to make out as a disk or any color.
Finally used binoculars to view rising Pleiades. Very nice view in 12×50. Air was still enough for me to see three or four stars with naked eye, in the past it seems like I mostly saw a collective glow.
Dew became a problem later, corrector began fogging lightly around 10:45 even with dew shield. Humidity had coated the binocular
Location: Tomball, TX
Cloud cover: none
Transparency: clear
Seeing: moderate (3/5) or maybe poor (2/5)
Darkness: city sky glow, no moon
Limiting Magnitude: n/a
Wind: mild/none
Humidity: 65%-75%
Temperature: mid-40’s
Start Time: 8:00 pm CST
End Time: 10:00 pm CST
OTA: 8″ SC
EP: 25mm mostly, also 32mm for M44 and 10mm for Saturn
Need to learn names of stars in Cassiopeia if for no other reason than for picking alignment stars.
Mars – observed briefly, noticed that disc is no longer completely circular. Other details lost in atmospheric turbulence.
Ceres – used SNP to get visual geometry and RA/Dec. Asteroid visible at the intersection of two lines of stars slightly wider than a right angle. Did not realize until looking in SNP later that Ceres would move so “far” within just an hour. Might observe twice tomorrow night an hour or more apart. SNP reference shows that observation time must have been about 8:20 or 8:30 pm, but actual time was 9pm and later. SNP location was Houston instead of Tomball — could that make such a big difference?
M42 – Trapezium clear, nebula surrounding like wings of a heraldic eagle
M44 Beehive – small almost equilateral triangle near center with dim star on one edge
Saturn – rings distinct though nearly edge-on. Visible moons: Tethys, Titan, Dione, and Iapetus, plus three stars in the field of view. Dione and Tethys uncertain at first, stronger with continued observation. Did not see Enceladus (too dim or bad seeing?) or Rhea (maybe lost in Saturn’s glare?), both of which SNP shows very close to Saturn.
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