The Pix Insight documentation specifies that most people would consider a star to be round when the Star Eccentricity is less than 0.42. The equation for Star Eccentricity is a bit convoluted but a star eccentricity 0f 0.42 is also equivalent to a Star Aspect Ratio of 0.91 or a Star Flatness of 0.10. I have chosen to have CaLIGHTs calculate what I call Star Roundness(%) which equals the Star Aspect Ratio multiplied by 100. So a CaLIGHTs Roundness value of 91% equals a Pix Insight Star Eccentricity of 0.42.…
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Declination Backlash…my story
I use a Celestron CGEM for my mount. It suffers from roughly 50 arc-seconds of declination backlash…which is big. This causes big headaches when trying to autoguide. I have invented a program I call “Backlash Assistant” which dramatically reduces the effect of declination backlash while autoguiding. The program is synchronized with PHD2 Guiding and operates in parallel with PHD2 to quickly move my declination axis thru its backlash such that my autoguiding barely notices what is happening. So… What is declination backlash? Most mounts use motors coupled to multiple sets…
Differential Flexure…my story
For years now I have been taking long exposure LIGHT frames. 500 second exposures at ISO200 was my goto setting for my Nikon D5300. With my QHY294C I have been using 600 seconds at GAIN=1600 for narrowband LIGHT frames and 200-300 seconds for broadband (LPR filter) LIGHT frames. I have been resisting buying an off-axis guider while focusing my attention on better guiding and a software based differential flexure compensation scheme. I hope to create a post detailing my work on improving my guiding. This post is going to focus…
Narrowband Color Shift in my Astrophotos
Revised Feb 5th, 2022 Recently I noticed that, in my narrowband astrophotos, the red color of the stars in my calibrated LIGHT frames seems shifted a few pixels. The blue pixels are also shifted but by a much smaller amount. I decided to invent a visualization tool for CaLIGHTs that makes it easy to study this color shift. In CaLIGHTs V3.1.6 I introduced a feature called SatGuard. This feature requires CaLIGHTs to be able to identify bright stars and determine what pixels need to be modified. I had already created…
QHY294C Cooler Performance
I log lots of information about my astrophotography system for every photo taken. I do this so I can go back at some later date and study what happened and learn what works and what doesn’t work. I have been using my QHY294C camera for 2 years now. In 2020 I used a cooler setpoint of 0 Celsius. I had no idea what to expect from the cooler and I certainly didn’t want to wreck it by driving it too hard. The QHYCCD folks talk about the possibility of a…