[CCD-astrometry-photometry] [Aavso-photometry] SXV-H9 linearity

[Arne Henden]

+/- 0.25percent is 1 part in 400.
   This is probably near Richard's measurement limit; the CCD
may be more linear than this.
   2x2 binning will almost always be more linear than 1x1, since
the binning sums all 4 pixels together, meaning that any one pixel
is exposed to 1/4 the total capacity it was for the same output
signal in 1x1 mode.  Nonlinearity in ABG systems occurs towards
full well.
   The reason the SXV-H9 appears linear is because the gain is
set such that you never reach full well on the detector - you run
out of ADC range before this.
   Nice camera, BTW.  I've been having fun with my loaner system.
Not much field on a 1.0m telescope, though!
Arne

Lawrence D. Lopez -- formerly unemployed softwae engineer. wrote:
> Richard:
> 
> +/- .25 % is 1 part in 200 !!!
> 
> that seems is poor, isn't it ?
> 
> Larry
> 
> Richard Miles wrote:
> 
> 
>>Domenico,
>>
>>Used at 2x2-binned mode the camera is linear to +/- 0.25% across the entire range (up to 65535 adu).
>>At higher binning, the camera is even more linear across the entire range.
>>
>>Used unbinned, it is linear +/-0.35% up to 43000 adu.  Above this there is an increasingly rapid 'roll-off' in response as well as an increase in noise above about 50000 adu (over that you expect from photon statistics).
>>
>>I have never seen any report about the increase in noise relative to photon noise at high signal levels in ABG cameras such as the SXV-H9.  The effect is very marked with a several-fold increase in noise kicking in as saturation takes over.
>>
>>Cheers,
>>Richard Miles
>> ----- Original Message ----- 
>> From: Domenico Licchelli 
>> To: aavso-photometry at aavso.org 
>> Sent: Thursday, December 02, 2004 10:38 PM
>> Subject: [CCD-astrometry-photometry] [Aavso-photometry] SXV-H9 linearity
>>
>>
>> hello 
>> someone knows how much ADU it's possible to reach in photometric work with an SXV-H9 ccd camera in binning mode? 
>> thank you so much for the answer
>> Domenico 
>>
>>
>> [Non-text portions of this message have been removed]
>>
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