T72 Analysis

[theskyhound]

Hello,

I have been doing some analysis on T72, and thought people might be interested in what I have discovered.

1. The telescope description page lists the gain as 6.0 e-/ADU, which appears to be a typo. I measured the gain from calibration images and obtained a gain of 0.69 e-/ADU, which is consistent with the number from the manufacturer as a typical gain setting.

2. I also measured the read noise, which is not listed on the web page. It was quite large: 13.5 e. This camera has two readout modes, and the read noise depends on which mode you have it set to. According to the FITS header the camera is in the 12 Mhz faster readout mode, which typically has a read noise of 11.5 e. The slower readout 3 Mhz mode has much lower read noise associated with it, often as low as 7 e. Switching to the 3 Mhz mode would greatly improve the SNR of the images from this camera, for both science and pretty pictures, but at the expense of longer readout times. I found this camera to be so noisy as to be avoided in the future.

I have passed this information in to iTelescope in the hope that they will switch to the slower read mode. I will have an update to this telescope soon, which will include the accurate gain and read noise values, and also includes a better estimate of the Sky brightness at the telescope location.

[theskyhound]

Good news. iTelescope is changing the readout niose on T72, which will reduce the read noise. I'll release a new version of this iTelescope once I figure out what the new read noise is.