<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Sep 23, 2010, at 8:43 AM, Harry Warren wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div><br>Markus,<br><br>I thought that your papers on the early STEREO data indicated that<br>background subtraction was reasonably well understood. You obtained similar<br>intensities from the two different vantage points.<br><br></div></blockquote><span class="Apple-tab-span" style="white-space:pre"> </span>Dear Harry,</div><div> Good point, with STEREO we have a double-check of the background,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>which gives us more confidence on background definition methods.</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>However I find a high sensitivity of the DEM width on the background definition</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>using 6 coronal AIA filters. With 3 filters from STEREO it is easier in a</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>more restricted temperature range.</div><div><br><blockquote type="cite"><div>Also, you've stressed the importance of computing the cross-correlation of<br>the emission at different temperatures. Considering only highly correlated<br>data removes many spurious broad DEM results.<br></div></blockquote><div><br></div><span class="Apple-tab-span" style="white-space:pre"> </span>In principle, yes, but I there are more near-cospatial loops in 6 AIA filters</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>than in 3 filter data from TRACE or STEREO.<br><blockquote type="cite"><div><br>I think that the most significant problem is our bias toward bright loops<br>that we can measure easily. They might not be representative.<br></div></blockquote><div><br></div><span class="Apple-tab-span" style="white-space:pre"> </span>I fully agree with this bias. On the other side, bright loops have a higher</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>probability of multi-strand structuring, so finding near-isothermal bright</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>loops is even a stronger argument than near-isothermal week strands.</div><div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"></span> Cheers,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Markus<br><blockquote type="cite"><div><br>Finally, a quick comment on the paper. I was expecting to see some Monte<br>Carlo simulations and least-square fits to the resulting data. Isn't the<br>real question how many lines and what level of uncertainty do we need to<br>determine the emission measure.<br><br>Best wishes,<br><br>Harry<br><br>On 9/23/10 10:20 AM, "Markus J. Aschwanden" <<a href="mailto:aschwanden@lmsal.com">aschwanden@lmsal.com</a>> wrote:<br><br><blockquote type="cite">Friends,<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">I'm glad to see that the EM loci method is put on a more quantitative basis,<br></blockquote><blockquote type="cite">especially in relationship to Gaussian DEM functions with variable temperature<br></blockquote><blockquote type="cite">spread. While the two methods can now being used interchangably thanks to<br></blockquote><blockquote type="cite">this recent nice study of Landi and Klimchuk, the biggest diagnostic problem<br></blockquote><blockquote type="cite">for <br></blockquote><blockquote type="cite">coronal loops is (in my view) still the proper background subtraction.<br></blockquote><blockquote type="cite">Every contaminations from background fluxes introduces always a bias<br></blockquote><blockquote type="cite">towards broader multi-thermal DEMs. This problem is even worse for AIA<br></blockquote><blockquote type="cite">data, because more filters involve more confusion.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Looking forward to a patented background subtraction technique.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Cheers,<br></blockquote><blockquote type="cite">Markus<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><br>-- <br>// ---------------------------------------------------------------------<br>// Harry P. Warren phone : 202-404-1453<br>// Naval Research Laboratory fax : 202-404-7997<br>// Code 7673HW email : <a href="mailto:hwarren@nrl.navy.mil">hwarren@nrl.navy.mil</a><br>// Washington, DC 20375 www : <a href="http://tcrb.nrl.navy.mil/~hwarren">http://tcrb.nrl.navy.mil/~hwarren</a><br>// ---------------------------------------------------------------------<br><br><br><br>_______________________________________________<br>Loops mailing list<br><a href="mailto:Loops@solar.physics.montana.edu">Loops@solar.physics.montana.edu</a><br>https://mithra.physics.montana.edu/mailman/listinfo/loops<br></div></blockquote></div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div>____________________________________________</div><div>Dr. Markus J. Aschwanden</div><div>Solar & Astrophysics Laboratory</div><div>Lockheed Martin Advanced Techology Center</div><div>Org. ADBS, Bldg. 252</div><div>3251 Hanover St., Palo Alto, CA 94304, USA</div><div>Phone: 650-424-4001, FAX: 650-424-3994</div><div>URL: <a href="http://www.lmsal.com/~aschwand/">http://www.lmsal.com/~aschwand/</a></div><div>e-mail: <a href="mailto:aschwanden@lmsal.com">aschwanden@lmsal.com</a></div><div>_______________________________________</div><div>____________________________________</div><br class="Apple-interchange-newline"></span></span></span></span><br class="Apple-interchange-newline">
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