Dark level, Readout-noise and their time-variations
of ORCA-AG


(measured by T.Matsumoto on 21th Mar. 2007)


* A/D: 12 bit, BIN: 2x2, Exposure time: 80 ms, Frame Rate: 12 Hz, Gain: 0
* Continuous 16 frames were grabbed in 13 times at every 10 min.
* Total duration is 120 min.
* So, the number of all frames is 16x13 = 208 frames.
* Error bars stand for RMS of all pixels of the CCD-chip,
  that we consider the typical level of the readout-noise.





[results]
 * After about 10 min, dark-level becomes stable
   whose value is 192.4 DN (= 4.7 % of 12 bit FullWell).
 * The size of typical readout-noise is about 1.6 DN (= 0.04 % of 12 bit FullWell).
 ( FullWell = 18,000 e- )




[Comparison between ORCA-AG and GE1650 ]

Estimated sizes of noises of both cameras
that are calculated from actually measured readout noises and dark levels.







Actual Ca K Line Profile obtained with GE1650 (on 2007/03/09) and ORCA-AG (on 2007/03/26),
on the only one line of the each CCD-chip.