Bias Time Dependence

I will give the bias for every session a go. However, how will that affect my darks since it has a different bias? With enough darks, would the difference show or would the dark current noise swamp it out and essentially treat the bias as a relatively constant offset? The important part of the bias is the amp glow, or what appears to be amp glow. That shows in my uncalibrated stacks very clearly and luckily are reliably corrected across the datasets.

Also, to an earlier question: is the longer download time in MaxIm DL vs CCDOPS normal? CCDOPS states a rate of 7.8MP/s, close to the stated 10MP/s, but MaxIm DL takes about twice as long. That makes me believe it is a handshake between driver and MaxIm that is longer than CCDOPS or the default digitization in CCDOPS is faster than the MaxIm "Normal Exposure" digitization rate. That is why I wonder if the bias frames from CCDOPS are comparable to the MaxIm DL ones because the bias would have more read noise with higher digitization rate, but I measured no difference in read noises.

I will upload a night of OIII data and the corresponding calibration frames since OIII shows the banding most clearly in my IC443 image. That way you have as much data as you see fit and can just download what you want.

Is that Johnson noise in the FETs and Amps and the type of CDS used? Detectors are among my favorite things to study so I am curious. Metrology is what I am considering doing after my degree, so I am more obsessed about characterizing my camera than maybe I should be.

 

I am not meaning to claim it is the bias frame. It was just my first idea since with a stack of 200 it was so apparent. I am just wondering if there is something on the camera or software level causing it or if it is somehow an optical issue.

Thank you for clarifying that. I forgot about the frame buffer. I think this is the first camera I have owned that has one. I am used to 10s+ downloads. Is the longer download speed in MaxIm DL normal vs CCDOPS?

I misinterpreted "bias shift" thinking you meant higher noise. But now I remember we were discussing the shift Colin mentioned. The STT and above cameras have impressive readout electronics. I was unsure how I felt about 11e- readout noise until I realized how high the digitization rate was, especially compared to. In the past, I dealt with an STL 1301E that had readout issues and a Yankee Robotics 6303 that had a water cooling issue from the previous owner that showed its hand by cracking through epoxy in the sensor chamber. So, I am always paranoid about thoroughly inspecting calibration frames for the slightest sign that something is off.

The images are in the shared folder. These images were taken while adjusting the collimation of my scope after adding a reducer, so the stars are off. I am switching to a Spike-a Flat panel to try to eliminate any flat issues. My OIII flat looks very odd and I want to make sure it isn't my EL flat panel which was not specifically made for astro.



Sidenote: Are the supplies you sell now 13.8V? I thought I saw you mention it somewhere and I would like to be safe, but the Cincon regulator used should be fine even with the voltage drop. But, better safe than sorry.

 

I usually have flat darks and fully calibrate every frame with appropriate darks and flats. However, OIII is the one flat exposure time I don't have darks for my SII flats and Ha flats both have their own matching darks and the pattern is slightly visible in Ha frames but I haven't seen it on SII. But, I haven't used my SII filter much. I will be getting a better flat panel that will allow me to avoid having 10-40 second flat darks. My OIII flats are 4 seconds while SII and Ha are 40 and 10 seconds and my LRGB filters are uncomfortably around .5-1s and I want to boost up to around 1-2 seconds for every filter.

I will do flat darks as you suggest. Hopefully I will get some clear nights around new moon.