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 (ΞΆ 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: 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
Caught Arcturus low in the west, twinkling across a wide spectrum, beautiful.
Also viewed Vega and Lyra-epsilon (double). Spotted M57 dim but distinct. Saw M29, but there are so many stars in Cygnus it’s hard to know which are part of that cluster.
Also wanted to try M2 and M15, but the mosquitos were terrible. Need more candles.
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