A
astropixel
Guest
Hi.
I have a question about pixel rejection with temperature regulated DSLR bias frames - My question is, referring to the info below, do I need to bother with pixel rejection at all? What am I missing here?
The bias frames attached were acquired with a temperature regulated DSLR @ 0C. The camera is a cold finger Peltier mod regulated by Arduino PWM switching a MOSFET. Accuracy at best is +/- 0.2C at worse +/- 0.5C.
The frame on the right is a single bias frame straight out of the camera. The typical cross hatch can just be seen - if you look closely. k values range from 0.0035 - 0.0045 - mostly 0.0039
The frames on the left are from the same set (40 in total). The top frame was integrated with Windsorized Sigma Clipping. The bottom frame was integrated with No Rejection. k values are identical pixel by pixel. A broad sample across the frames found no variation - k values range from 0.0038 - 0.0042. There are no horizontal lines as in the single frame.
Noise analysis for the single frame σK = 5.183e-05, N = 8989064 (88.45%), J = 4
For the Windsorized stack - σK = 1.572e-05, N = 8668784 (85.29%), J = 4
For the No Pixel rejection stack - σK = 1.594e-05, N = 8542290 (84.05%), J = 4
I don't fully understand the data above. An explanation would be helpful.
Also I am not happy with the results that I am getting with integrated dark frames, but I will post separately.
Many thanks,
Rowland.
I have a question about pixel rejection with temperature regulated DSLR bias frames - My question is, referring to the info below, do I need to bother with pixel rejection at all? What am I missing here?
The bias frames attached were acquired with a temperature regulated DSLR @ 0C. The camera is a cold finger Peltier mod regulated by Arduino PWM switching a MOSFET. Accuracy at best is +/- 0.2C at worse +/- 0.5C.
The frame on the right is a single bias frame straight out of the camera. The typical cross hatch can just be seen - if you look closely. k values range from 0.0035 - 0.0045 - mostly 0.0039
The frames on the left are from the same set (40 in total). The top frame was integrated with Windsorized Sigma Clipping. The bottom frame was integrated with No Rejection. k values are identical pixel by pixel. A broad sample across the frames found no variation - k values range from 0.0038 - 0.0042. There are no horizontal lines as in the single frame.
Noise analysis for the single frame σK = 5.183e-05, N = 8989064 (88.45%), J = 4
For the Windsorized stack - σK = 1.572e-05, N = 8668784 (85.29%), J = 4
For the No Pixel rejection stack - σK = 1.594e-05, N = 8542290 (84.05%), J = 4
I don't fully understand the data above. An explanation would be helpful.
Also I am not happy with the results that I am getting with integrated dark frames, but I will post separately.
Many thanks,
Rowland.