An Evaluation of the Performance of the 4K×4K CCD on the YNAO Full-Disk Hα Telescope for Solar Observations

The performance of a CCD device is very important for astronomical observations using the CCD.Usually, a CCD device is tested in a laboratory before being mounted on a telescope.However, in our case, the 4K×4K CCD device used for the YNAO (Yunnan Observatory) full-disk Hα telescope for solar observations has to be evaluated during routine observations.Therefore, we have developed a special test program and we show the test results in this paper.The best active area of the CCD is between (140,128) and (4035, 4023);its bias level is around 670 ADU and its read-noise is about 13.5e^-.The dark current of the CCD is about 0.5e^-/second at -10℃.The dark-current level is higher than the specification of the manufacturer (KADAK), but it is low enough for observations.From the evaluation results we confirm the feasibility and reliability of our test approach.This approach can also be used to monitor changes of CCD parameters during routine observations, which can incorporate such tests.