Cassiopeia Observatory

Thin Crescent Venus, IC348 Nebula

Posted: 24 December 2013

After my previous ISS-Moon transit imaging session, with thin clouds over the moon, overcast skies were the norm. Even had some rain (0.36") on Friday, 20 December 2013. The sky cleared on Sunday, 22 December, but I wasn't able to do any observing that night. Monday, 23 December, was still clear.

I have decided to add the number of the session in the observatory to my reports and reformat the session opening and closing data. There have been 629 previous sessions in the observatory since "First Light" on 18 August 2009.

Session: 630
Opened: Monday, 23 December 2013, 1806 MST
Temperature: 52°F
Conditions: Clear, breezy

At 1812 MST, viewed Venus, 83X, low in the southwest sky. A thin crescent was visible but seeing was very bad. There was a lot of atmospheric distortion occurring. I decided to try imaging anyway. I mounted the D7000 DSLR on the 8" LX200-ACF using eyepiece projection (9mm eyepiece, 222X). I did some HD video recordings at various exposure settings. Seeing continued to be very bad. I located one frame on a video made at 1/1000sec, ISO 5000, that was fairly good:

I ended Venus imaging, removed the camera from the telescope, and slewed to IC348 (diffuse nebula). Seeing continued to be bad but I decided to try imaging anyway. I had previously imaged IC348 on 5 December. That night I did not locate a guide star and so the image posted was a stack (using Lynkeos) of six unguided 1 minute, ISO 6400, exposures. This night I mounted the D7000 DSLR at prime focus using the off-axis guider, but placed it at a slightly different orientation in the hopes of locating a guide star. I did a focus test on the star Capella using the Bahtinov Mask. Slewed back to IC348 and tried to locate a guide star in the illuminated reticle eyepiece. Unfortunately, no star was seen. I decided I would do unguided 1 minute, ISO 6400, exposures. I first did a framing test exposure, 1 minute, ISO 6400. Framing was good so I did 19 more 1 minute, ISO 6400, exposures. During post-processing, I edited the single exposures in Aperture software and then stacked the 20 images using Lynkeos. This is the resulting image, slightly cropped from the full-frame images:

The longer effective exposure this night vs. my 5 December image (20 minutes vs 6 minutes) brings out more nebulosity in this faint diffuse nebula.

At 1922 MST, just as I completed my final exposure of IC348, the neighbor to the north turned on his two bright, horizontally aimed, unshielded floodlights. I still don't understand the logic of the floodlights being horizontal and lighting up the surrounding area outside his property line. Why would someone want to pay to light up other property? Fotunately, by the time I had removed the camera from the telescope and stored the astrophotography accessories at 1931 MST, the lights were off. Thanks neighbor.

At 1934 MST, viewed IC348, 83X. I then went to Jupiter and viewed it at 83X. Seeing was lousy due to the poor seeing conditions and Jupiter's low altitude. Three moons were visible.

Due to the poor seeing conditions and the still blowing breezes, I decided to end the session. But it had been nice to be back under the stars again.

I received an alert from CalSky about an HST-Sun transit on Tuesday morning, 24 December 2013. Unfortunately, the sun would not rise above the hill to the east of the observatory until after the transit occurred.

A nice article comparing ISS-Moon transits from three locations was posted on 23 December at Paranoias Nocturnas. My 17 December transit image was included in the article. Check it out.