Cassiopeia Observatory

Long Imaging Session: Moon, M57, NGC6946/6939,
& Supernova 2012ec
Posted: 25 August 2012

Before I get into my report on last night's session, some catchups. During the day on Sunday, 19 August 2012, I completed connecting all the electrical items in the observatory that I had not done after my annual cleaning of the observatory on Saturday. Cloudy skies continued, with more monsoon storms in the area, as seen here in this panorama from Monday, 20 August:

The view above is from the southwest, west, northwest. The observatory is visible in the lower left corner.

This next panorama, south to southwest, was taken on Tuesday, 21 August, of some storms that were severe over Tucson:

After a brief monsoon storm Friday morning, 24 August, the skies began to clear during the afternoon hours. By sunset, the sky was mostly clear. So after two weeks of cloudy nights, Cassiopeia Observatory was finally opened again for night time observing and imaging. The observatory was opened at 1911 MST, 85°F. The only problem this night would be the humidity; the paper in my notebook became damp but fortunately my equipment did not dew up. However, seeing was not very good during the night.

At 1920 MST, viewed the First Quarter Moon, 77X. The terminator provided nice details on the moon. From 1930 to 1935 MST, using 364X, I watched a faint star almost graze along the moon's north pole region. It was fascinating to watch the star drift along just above the illuminated crater walls and mountain peaks. It was finally occulted at 1935 MST. I then switched from the star diagonal to the visual back and mounted the iPhone 4 using the MX-1 afocal adapter. This image was captured at 77X:

These next two iPhone images were captured at 154X, showing the north (left) and south (right) terminator regions:

Next, I captured this wide angle view of the Mars (left), Saturn (above), and Spica (below) triangle from inside the observatory using the D7000 DSLR, f/6.3, 1sec, ISO 1000, handheld:

I switched to the diagonal and redid the AutoStar alignment; it had been awhile since I had refreshed it. With the alignment completed at 2019 MST, I viewed Saturn, low in the sky, at 77X. Unfortunately, it was too low for good viewing.

At 2030 MST, I resumed lunar observing using 206X and 364X. I began monitoring some impressive shadows at Montes Alpes. There were six very elongated "spikes" and six very thin "spikes" visible. At 2106 MST, I took this handheld photo of Montes Alpes using the iPhone, afocal 364X, cropped:

At 2131 MST, I noticed that M31, the Great Andromeda Galaxy, was visible to the naked eye even with the still bright moonlit sky. I continued to observe the Montes Alpes shadows, but as the moon got lower in the sky I had to switch to 206X and then 133X. I also observed some very nice shadows on the floor of the Crater Archimedes.

I ended lunar observing at 2230 MST and slewed the 8" LX200-ACF to M57, the Ring Nebula. I then began preparing the D7000 DSLR for prime focus imaging as I waited for the moon to set. At 2303 MST, I took a quick look at M13, the Great Globular Cluster in Hercules, 77X. Then slewed to Vega, which would be the focus star for M57 imaging. At 2315 MST, I mounted the D7000 at prime focus using the Off-Axis Guider. I then did a focus test on Vega using the Bahtinov Mask. At 2324 MST, I was ready to begin imaging M57 as soon as the moon set. The temperature was now 70°F and the relative humidity was 60%.

Beginning at 2348 MST, I did 10 exposures of M57, each 2 minutes, guided, ISO 6400, for image stacking tests. Six of the images were accurately guided and stacked in Keith's Image Stacker (top) and in Lynkeos (bottom):

Next, I did 2, 3, 4, and 5 minute guided exposures at ISO 6400, ISO 3200, and ISO 1600. The best image was captured at 3 minutes, ISO 1600:

Lynkeos appears to have done a slightly better job of stacking, with more details visible than in the single exposure. All M57 images were cropped.

I completed M57 imaging at 0114 MST and removed the camera from the telescope. I added the focal reducer and slewed to NGC6946 (faint galaxy) and NGC6039 (open cluster). I was able to view both in the same field-of-view with the 26mm eyepiece + focal reducer. I mounted the D7000 DSLR at prime focus + focal reducer + Off-Axis Guider. Did a focus test on Deneb using the Mask. That was followed by several framing test images and guide star hunting. I was finally happy with the framing and guide star selection, and at 0212 MST, took this 5 minute, ISO 6400, guided exposure, showing the cluster in the upper left and the galaxy in the lower right:

Ended imaging at 0219 MST. Removed the camera and focal reducer. Next, I went to NGC1084, a faint galaxy, to see if I could see the recently discovered supernova 2012ec. I could not detect it at 77X. Decided to image it. Mounted the D7000 at prime focus + Off-Axis Guider, and did a focus test on Aldebaran using the Bahtinov Mask. Did some framing test exposures and searched for a good guide star. Finally located a good star and did a 5 minute, ISO 6400, guided exposure, cropped:

Ended imaging at 0307 MST. Viewed Jupiter, 77X, 206X, and 364X. All four Galilean Moons were visible. The North Equatorial Belt (NEB) was split into two halves by a long white horizontal cloud band. The South Equatorial Belt (SEB) also had a large white cloud embedded. These white clouds made for an unusual look on Jupiter. At 133X, the belts were very crisp.

At 0322 MST, viewed Venus, 133X, low in the eastern sky. The planet was half-illuminated.

I then decided to call it a night. The observatory was closed at 0334 MST, 71°F, 56% relative humidity. It was great being back in the observatory and doing a productive 8 hour 23 minute session.

Now that skies have cleared again, Cassiopeia Observatory has started its 4th year of astronomical observing and imaging. This chart shows my sessions in the observatory over the past three years:

Some sessions were very short and some were very long. That's one of the joys of having your own observatory! You can start observing quickly and can stay as long as needed or as long as the weather allows.

Comments are welcome; use the Comments section below, or you can Email Me. Thanks.