NGC7023 - The Iris Nebula
Description: NGC7023 the Ring Nebula is in the constellation of Cepheus. This image was taken on August 28, 2008 from the Oregon Star Party. This was my first serious attempt at imaging with the Canon in several years. The first thing that I discovered is that Maxim/DL has problems guiding the CGE using telescope commands (I normally using the guiding relays with the SBIG camera, but the Meade does not support that.) After each guide exposure in Maxim/DL, the mounts tracking was turned off (yikes!) Fortunately, we had a satellite based ISP up at the Star Party and I was able to download a copy of Stark Labs PHD Guiding. I have to say that I am very impressed with PHD. It was very easy and effective to use. The other issue with this image is that there is some horizontal banding just above the center of the image. I don't know where this is coming from. I was running the camera off of a Canon A/C adapter powered by my motorhome's inverter. The problem may be related to noise in the A/C current produced by the inverter (although this problem does not appear in my SBIG cameras, which are known to be sensitive to power.) Next time, I'll run the camera off of a battery. Also, the dark frame calibration did not fully remove the amp glow in the lower right corner.
Equipment: The image was taken with an 8" Meade LX200ACF telescope on a Celestron CGE mount. The camera was a Canon 20D with an Astro-Physics .67 Telecompressor. The guide scope and camera were an AstroTech AT66ED refractor with a Meade DSI Pro using PHD Guiding. Focusing was done manually.
Exposures: 29x300 seconds at ISO400.
Processing: Bias, dark & flat calibration, image registration & color registration were done in Maxim/DL. Curves, levels, zone sharpening & noise reduction were done in Photoshop CS2. Gradient processing was done with GradientXTerminator.
Click on image for full resolution.