Declination Drift Can Cause High Rejection Rates

curtismacc

I just finished summarizing data I collected over the last months showing the impact of declination drift on the frame capture rates with my Seestar S50 and S30 Pro. I measured the frame capture rates for a series of deep sky objects at different declinations in the same nights, repeating this over multiple nights to get a good average of the data. I was amazed at how well correlated the capture rate was with the declination of the object being live stacked. I also measured the impact of different polar alignment offsets and different exposure times as well.

I suspect that a lot of folks who are having high rejection rates do not realize that declination drift is the root cause of their problem. While there are many other things that can cause high rejection rates, these have been well discussed but I have found very little input other than my own on declination drift.

I put the information in a new video on my YouTube channel but, obviously I cannot post the link here. You will have to search for it.

I highly recommend that some of the ZWO Seestar engineers take a look at it as well.

3AC9bx99

It is a good video to watch with good data to back it up. I also hope ZWO take note as well.

curtismacc

Thanks for your feedback. And yes, I hope ZWO does take a look at this. They should already be aware, but perhaps they haven't done such extensive testing themselves. I guess I just have too much time on my hands.

Nasa-HSIA

curtismacc Dear Curtis, I've watched your videos and they are great. Thank you for your hard works and huge experiments. I understand what you done. One question is coming, for relation of frame capture rate vs Dec. drift, assuming the object located in Dec. = -30 deg, is the frame capture rate with this angle (Dec. =-30) equal to the frame capture rate with Dec. = 30 deg? If not, how is the frame capture rate (Dec. = -30 deg) represented?

curtismacc

Nasa-HSIA Thanks for the feedback. It doesn't matter whether the object is 30 deg below or above the celestial equator, the dec drift will be the same. Ignore the plus or minus sign.