2021年5月1日 · The output ADU level of your Master Dark frames is the (Offset * Stride) + DarkCurrent. The Dark Current itself is proportional to the exposure but to see that you must first subtract off the Offset.

暗电流（Dark Current）效应 不仅仅是光子会刺激CCD/CMOS里的半导体产生自由电子，热量也具有同样的效应——被称为暗电流效应。 即使没有任何光子入射，半导体里的电子也会吸收热量而成为自由电子，然后被读出。

2022年5月19日 · In PixInsight, the ADU stats for the bias frame are avg = 1916.0 ADUs, std = 7.2 ADUs, and for the dark frame are avg = 1920.0, std = 10.3 ADU (normalized at 16-bit)

2024年9月14日 · Dark Flats are as you say are exposure matched to your Flats while Darks are exposure matched to your Lights. Dark Flats can be used to replace Bias. Here's what I do when using the ASiAir - Lights (exposure set manually), Darks (lens cap on exposure and matched to Lights), Flats (use ASi auto exposure and a flat panel) and Bias (lens cap on ...

2023年10月29日 · You will need to use a dark current value of 0.076 e-/pixel/sec (the value for my camera at an exposure of 480 sec, gain of about 1.5 e-/ADU and offset of 50) and a mean value for the master bias of 3154.632 (again, from my camera).

2017年6月4日 · Generally speaking, flats with a histogram peak between 1/3 and 1/2 the maximum ADU range of the camera are ideal. Note that this is the ADU range of the camera...not every camera supports 65535 ADU (i.e. the QSI6120 caps out at ~50000 ADU in it's high gain mode, and only ~32000 ADU in low gain mode!

The read noise of the CCD causes the ADU recorded for each pixel to differ from the ADU value that should be produced given the charge deposited in the pixel. Using the bias frames, we can measure the read noise by calculating the mean and standard deviation of the pixel values (after removing hot and dead pixels).

The number stored in a raw astronomical image straight off a telescope is called an Analog Digital Unit (ADU) or count, because internally the camera converts the analog voltage in each pixel to a numerical count.

2023年3月10日 · In one of Adam Block’s videos, he explains that Flats shorter than 30s can be calibrated with a Bias frame and Flats longer than 30s should be calibrated with a Dark frame (a Flat-Dark). But he also mentions that this is assuming well-behaving camera sensors.

Here we will need to scale the dark from the 90 sec exposure time of the dark frame to the exposure time of each flat image. The ccdproc function subtract_dark provides keywords for doing this scaling automatically.