[obs-tap]:updates on the Proposed recommendation + new document

[Rob Seaman]

On Jul 8, 2011, at 6:36 AM, Arnold Rots wrote:

> Just two quick comments. Both highlight how this standard is still
> heavily slanted toward optical images.

Undoubtedly true and such biases should be minimized.

> Mireille Louys wrote:
> [ Charset ISO-8859-1 unsupported, converting... ]
>> Dear Arnold, Dear all,
>> 
>>> o_stat_error is an interesting case. Since our unit is counts, the
>>> proper value would be "POISSON"; I realize that that is not a double,
>>> but what else can we give as a value?
>> 
>> 
>> This was meant only for quantitative estimation of the error and does  
>> not cover the statistical properties of the signal.
> 
> I realize that, but the problem is that one can't give a single
> quantitative value in the case of Poisson noise. However, identifying
> it as Poisson does immediately provide the value for each point in the
> image.

Well, it provides a heuristic for making estimates of the error/noise/variance values.  That is certainly better than picking a scalar.  Even in the optical a purely scalar error is an artificial choose, see for example: http://arxiv.org/abs/0910.3733

Negative numbers are presumably non-physical and could be used to encode special values corresponding to "POISSON" or even "POISSON+GAUSSIAN" with the absolute value representing the scalar gaussian contribution (e.g., read noise + sky noise).

Might consider providing the error as a variance, too.

Rob