Posted in Technique on January 18th, 2009 by Northwest Astro
M42 Capture
I have been having trouble getting guiding to cooperate during the last couple nights out when the skies have been clear, and have been trying to reduce various sources of vibration and other error (that I have control over, anyways).
This weekend was actually pretty clear, and so the scope came out. I finally decided to try training the PEC on my mount for the first time. I used PHD Guiding through the LX200 to train the PEC on one of the stars in Orion. After training, I turned the scope to M42, imaging through the LX200 at f/6.3, and guiding using the Orion 80ED refractor at f/7.5. Guiding has definitely improved, and I am seeing a lot fewer ‘jumps’ in the guide star. Haven’t even bothered to try to measure the periodic error yet.
Above is a single 5-minute exposure at ISO 800 taken through the LX200R, showing the full DSLR frame. Stars still aren’t quite round, but they are worlds better than the last time I tried to take 5-minute exposures (they were previously long streaks, even when guiding with the SCT, and imaging with the refractor). Getting the periodic error down a bit has made it easier on the guiding, and I don’t see large adjustment spikes anymore.
For anyone else who is just starting out and having problems getting their exposures to last a bit longer: make sure you have trained your PEC, if your mount supports it. Even though training with an autoguider isn’t perfect, it is hands-free, and does help in a big way versus an untrained mount.
