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-1278 DRP 2-D Pipeline <p>Check the basic properties of the objects in the catalog just to get us (=me) started.</p> PIPE2D-1278

Check the Gaia DR3 + PS1 DR2 matched data

Task Normal Done Done Masayuki Tanaka Masayuki Tanaka FLUXSTD Fri, 4 Aug 2023 02:15:59 +0000 Thu, 21 Dec 2023 01:45:11 +0000 Thu, 21 Dec 2023 01:45:11 +0000 0 2 <p>The matched catalog is stored in a local disk in Mitaka. It is missing some regions in the original catalog. Ishigaki-san checked the md5 checksum and confirmed OK. It seems it was simply an issue during the DB insertion. This has been fixed. But, it does mean that there was this problem in the previous version.</p> <p><span class="image-wrap" style=""><img src="https://pfspipe.ipmu.jp/jira/secure/attachment/16611/16611_distrib.png" height="407" width="548" style="border: 0px solid black" /></span></p> <p>The PS1-Gaia catalog has flags summarized at<br/> <a href="https://gea.esac.esa.int/archive/documentation/GDR3/Gaia_archive/chap_datamodel/sec_dm_cross-matches/ssec_dm_panstarrs1_best_neighbour.html" class="external-link" rel="nofollow">https://gea.esac.esa.int/archive/documentation/GDR3/Gaia_archive/chap_datamodel/sec_dm_cross-matches/ssec_dm_panstarrs1_best_neighbour.html</a><br/> We did not use any flag cuts before, but we exclude (1) Gaia objects matched to multiple PS1 objects, and (2) PS1 objects matched to multiple Gaia objects. Ishigaki-san told me that they account for 0.42% of the objects.</p> <p>The engineering data from July suggested that there is something going on at the very bright mags; they are often rejected by bad temperature estimates from the broad-band photometry. I suspected that this was due to saturation (recall we did not apply any quality cuts). </p> <p><span class="image-wrap" style=""><img src="https://pfspipe.ipmu.jp/jira/secure/attachment/16621/16621_image+%284%29.png" style="border: 0px solid black" /></span></p> <p>Ishigaki-san looked into this futher. These bright objects have low S/N. That is odd because they are bright objects. Although we have not fully understood the problem, bright objects do have varying S/N as shown in this plot. There are also a bunch of fainter objects with low S/N for their magnitudes. They are extended sources in PS1. Because we matched with Gaia, we must be looking at point sources, but these sources are likely blended with nearby sources. We'd better remove them as well. These objects indeed are often off from the stellar sequence. <span class="image-wrap" style=""><img src="https://pfspipe.ipmu.jp/jira/secure/attachment/16623/16623_PS1_gr_ri_gFlags.png" style="border: 0px solid black" /></span></p> <p><span class="image-wrap" style=""><img src="https://pfspipe.ipmu.jp/jira/secure/attachment/16622/16622_PS1_mag_sn_flags.png" style="border: 0px solid black" /></span></p> <p>We choose to apply <span class="error">&#91;grizy&#93;</span>FlagExtended==False. But, there remains a significant S/N scatter at the bright end. Ignore the colored points and lines in the figure. Photometry is PSF photometry. The figure is by Ishigaki-san.<br/> <span class="image-wrap" style=""><img src="https://pfspipe.ipmu.jp/jira/secure/attachment/16974/16974_SN_allbands.png" style="border: 0px solid black" /></span></p> <p>The log(S/N) version of the figure is here (the previous one was linear in S/N). Again, Ishigaki-san made this figure. S/N is nearly constant at the bright magnitude. We do not know exactly how the PS1 photometry is made, but we do not dig into this further. There are objects with very high S/N for their brightness and we may add a noise floor to the photometric error when we run brutus. This is the subject of a separate ticket (<a href="https://pfspipe.ipmu.jp/jira/browse/PIPE2D-1340" class="external-link" rel="nofollow">PIPE2D-1340</a>).</p> <p><span class="image-wrap" style=""><img src="https://pfspipe.ipmu.jp/jira/secure/attachment/16975/16975_SN_allbands_log.png" style="border: 0px solid black" /></span></p> <p>I think the catalog is now reasonably clean. <a href="https://pfspipe.ipmu.jp/jira/secure/ViewProfile.jspa?name=ishigaki" class="user-hover" rel="ishigaki">ishigaki</a> could you look at the comments above? If you think these are a reasonable summary of your work, please close this ticket.</p> <p>We will apply the bright magnitude cut of g/r/i/z/y = 14mag to exclude low-S/N objects at the bright end. </p> Development Epic Link PIPE2D-1277 Rank 0|zzsz5j: Reviewers ishigaki