Dear Joan,
Thanks for your reply. However, you evaded the crucial point about what background you subtracted. If you subtracted the background very close to the loop edges then you should be fine, but if you took the background away from the loop then your background-subtracted fluxes are heavily contaminated by the background corona. I wish your paper would quantify what you did. All the paper says is "... we choose 10 pixels from a CLEAN background area...". Since the loop fluxes typically make up only about 10% of the total flux, the background level is at 90%. If you choose a background in a dark part of the image away from the loop (perhaps this is what you mean with a CLEAN background area ?), say at a 50% level, your background-subracted loop flux is 50% instead of 10%, and then the DEM is dominated by the background corona rather than by the loop-associated flux. This is why I want to know what background you subtracted, so that I can judge whether the resulting DEM is pertinent to the loop or to the corona. It makes all the difference !
Looking forward for a clarification. Thanks !
Regards, Markus
On Nov 23, 2010, at 11:10 AM, Joan T Schmelz (jschmelz) wrote:
Dear Markus,
(2) What are the total fluxes F_tot and background fluxes F_bg that you used in your DEM modeling of the loop fluxes F_loop=F_tot - F_bg in the 6 coronal AIA filters? If the reader knows these 12 numbers, one could verify or reproduce your DEM modeling.
We’ve already used two quite different DEM methods on these data and gotten very similar results, and personally, I do not want a repeat of what happened after your re-analysis of our CDS loop data. (If anyone is reading this and does not know what I’m talking about, that’s probably a good thing.) I think what might be of greater interest is an entirely independent analysis of your own.
Also, you don’t just need 12 numbers; you need the uncertainties as well. These are extremely important, especially for loops that are not visible in all the filters. We always want high- and low-temperature constraints, but we also need to know how strong those constraints are.
(3) What are the cross-sectional flux profiles F_tot(x), F_bg(x), F_loop(x) you inferred at the analyzed loop segments. If you show these profiles to the reader, one could inquire or judge whether the same loop or multiple loops are seen at the analyzed location of the loop, and what the background contamination in the loop flux could be.
Same as (2) above.
Regards, Joan
____________________________________________ Dr. Markus J. Aschwanden Solar & Astrophysics Laboratory Lockheed Martin Advanced Techology Center Org. ADBS, Bldg. 252 3251 Hanover St., Palo Alto, CA 94304, USA Phone: 650-424-4001, FAX: 650-424-3994 URL: http://www.lmsal.com/~aschwand/ e-mail: aschwanden@lmsal.com _______________________________________ ____________________________________