Sunday, February 26, 2017

Mystery "Lights" At Kitt Peak

In an earlier post I wondered what the round, bright feature was that appeared to be hanging in the air to the left of the large Mayall telescope structure at the north end of the Kitt Peak observatory complex (above). I asked Carl Hergenrother what he thought and he sent back the image below with following comments:

I see four of these objects in the field. Two in the sky (the one you see and one in the upper right) and two on the mountain (all are circled in the attached image). I think all four are hot (or bad) pixels that become more and more common as webcams age. It is possible they are only visible when it is dark and the signal is low. It’ll be interesting to see if they reappear tonight. 

The other object that struck me as out-of-the-ordinary is the small white dot on the horizon (circled to the right of the Mayall. It could be a cloud or mountain top catching the morning Sun.

Carl and I both looked again when it was darker and found that these were indeed bad pixels as he thought. The image above is from a bit after 05:00 am MST this morning and that below is from a bit after 06:00 am. Carl's follow-on comment was:

I looked at a few night shots from the webcam and the field is full of red and blue bad pixels. Four of them correspond with the ones we saw yesterday. My guess is that as the camera autosets increases its gain setting for low light conditions, these bad pixels become visible. I wish bad pixels weren’t a problem with all low light detectors (from a $50 webcam to a $15M spacecraft CCD), but they are a part of our reality.

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