https://pfspipe.ipmu.jp/jira This file is an XML representation of an issue en-us 8.3.4 803005 13-09-2019 https://pfspipe.ipmu.jp/jira/browse/PIPE2D-1175 DRP 2-D Pipeline <p>Extractions near bright object are problematic right now, as <a href="https://pfspipe.ipmu.jp/jira/secure/ViewProfile.jspa?name=kiyoto.yabe" class="user-hover" rel="kiyoto.yabe">Kiyoto Yabe</a> shared here <span class="image-wrap" style=""><a id="15548_thumb" href="https://pfspipe.ipmu.jp/jira/secure/attachment/15548/15548_fiberProfiles%2C+1-every-fourth.png" title="fiberProfiles, 1-every-fourth.png" file-preview-type="image" file-preview-id="15548" file-preview-title="fiberProfiles, 1-every-fourth.png"><img src="https://pfspipe.ipmu.jp/jira/secure/thumbnail/15547/_thumb_15547.png" style="border: 0px solid black" /></a></span></p> <p>We can see on this plot that those fibers are contaminated by signal coming from the neighbouring fibers.</p> <p>Try to build to fiberProfiles with narrower swaths, or any other method that you think could improve the extraction in the context of the engineering data release.</p> <p>But, in longer terms, measuring good odd and even profiles and solve for them simultaneously should still be a better option, IMHO.</p> PIPE2D-1175

measure fiberProfiles from fewer swaths

Task Normal Done Done price arnaud.lefur Wed, 1 Mar 2023 14:51:18 +0000 Mon, 27 Mar 2023 17:24:33 +0000 Mon, 27 Mar 2023 17:24:33 +0000 0 2 <p>Neither a smaller radius nor fewer swaths nor both together is sufficient to prevent the steps in the extraction.</p> <p>Have you quantified by how much the neighbouring fibers are contaminated ? Yabe-san figure shows quite high level.<br/> I looked at the only <em>1-every-4th</em> fiber profiles we have from november : <span class="image-wrap" style=""><a id="15548_thumb" href="https://pfspipe.ipmu.jp/jira/secure/attachment/15548/15548_fiberProfiles%2C+1-every-fourth.png" title="fiberProfiles, 1-every-fourth.png" file-preview-type="image" file-preview-id="15548" file-preview-title="fiberProfiles, 1-every-fourth.png"><img src="https://pfspipe.ipmu.jp/jira/secure/thumbnail/15548/_thumb_15548.png" style="border: 0px solid black" /></a></span> <br/> The first neighbours show contamination less than 1%.</p> <p>I don't believe this is an issue with contamination: a profile with a radius of two pixels should have zero overlap with neighbouring fibers. Rather, I believe there's a problem with how the profile is used in the extraction.</p> <p>Well, I agree there is no overlap in the profiles themselves.<br/> But again, if my understanding is correct, so far, as a good approximation, we considered that each pixel is some flux measured from one object <b>only</b> right ?<br/> But because of the wings, each pixel is actually the sum of multiple objects with some weights.<br/> The problem is we don't know those weights, and until we do there is nothing much we can do.<br/> That's what I called contamination, the fact that if you have an bright object that peak at 20k in one fiber, then the pixels from neighbouring fibers will get an extra 200 counts on top of their own object.</p> <p>Sure, but that can't produce the strong steps in the extracted spectrum.</p> <p>The steps in the spectra are remedied if the profiles go to zero. Currently, they don't because they were measured on full-fiber-density images and therefore have small <tt>radius</tt>, so the outermost profile samples are signficantly above zero. If I force them to zero (by subtracting the average of the outermost samples), the steps disappear. The attached plot shows the same fibers as before, but from a pfsArm.</p> <p><span class="image-wrap" style=""><img src="https://pfspipe.ipmu.jp/jira/secure/attachment/15553/15553_pfsArm-83244-r3.jpg" width="1000" style="border: 0px solid black" /></span></p> <p>Updated the <tt>CALIB</tt> in <tt>/work/drp</tt> at Subaru and in <tt>/projects/HSC/PFS/Subaru</tt> on Tiger at Princeton.</p> <p>Paul did some experiments, but without actual improvement.<br/> Again, profiles are now generated differently (<a href="https://pfspipe.ipmu.jp/jira/browse/PIPE2D-907" title="Solve profiles for multiple fibers simultaneously" class="issue-link" data-issue-key="PIPE2D-907"><del>PIPE2D-907</del></a>), should be wider and less subject to that kind of issues. </p> Development Rank 0|zzswc7: Sprint 2DDRP-2023 A