[Loops] EM loci

[Harry Warren]

Markus,

I thought that your papers on the early STEREO data indicated that
background subtraction was reasonably well understood. You obtained similar
intensities from the two different vantage points.

Also, you've stressed the importance of computing the cross-correlation of
the emission at different temperatures. Considering only highly correlated
data removes many spurious broad DEM results.

I think that the most significant problem is our bias toward bright loops
that we can measure easily. They might not be representative.

Finally, a quick comment on the paper. I was expecting to see some Monte
Carlo simulations and least-square fits to the resulting data. Isn't the
real question how many lines and what level of uncertainty do we need to
determine the emission measure.

Best wishes,

Harry

On 9/23/10 10:20 AM, "Markus J. Aschwanden" <aschwanden at lmsal.com> wrote:

> Friends,
> 
> I'm glad to see that the EM loci method is put on a more quantitative basis,
> especially in relationship to Gaussian DEM functions with variable temperature
> spread. While the two methods can now being used interchangably thanks to
> this recent nice study of Landi and Klimchuk, the biggest diagnostic problem
> for 
> coronal loops is (in my view) still the proper background subtraction.
> Every contaminations from background fluxes introduces always a bias
> towards broader multi-thermal DEMs. This problem is even worse for AIA
> data, because more filters involve more confusion.
> 
> Looking forward to a patented background subtraction technique.
> 
> Cheers,
> Markus
> 
>

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