{"id":1539,"date":"2013-05-30T09:00:48","date_gmt":"2013-05-30T17:00:48","guid":{"rendered":"http:\/\/jazzistentialism.com\/blog\/?p=1539"},"modified":"2015-09-17T22:18:41","modified_gmt":"2015-09-18T06:18:41","slug":"an-aperture-photometry-test-using-maxim-dl-and-ucac3","status":"publish","type":"post","link":"https:\/\/jazzistentialism.com\/blog\/?p=1539","title":{"rendered":"An aperture photometry test using MaxIM DL and UCAC3"},"content":{"rendered":"

\"Screen<\/a><\/p>\n

Non photometric catalogues are notoriously unreliable, but are increasingly used by novices amateur astronomers using commercial software such as\u00a0TheSky<\/em>\u00a0and\u00a0MaxIM DL.<\/em><\/p>\n

The following basic magnitude ‘measurement’ test shows\u00a0results using MaxIM DL’s photometry tool, unfiltered images of a random field of stars, and UCAC3.<\/p>\n

<\/p>\n

Image details<\/h2>\n

RA 10 23 30.0
\nDec -24 24 41.0
\nTelescope Alt: 78\u00b0
\nAir Mass: 1.019
\nExposure: 50 seconds
\nFilter: Luminance
\nDate: 2013-05-23 11:12 UTC
\nCCD Temp: -30\u00b0
\nSNR of faintest measured star: 10.968
\nSNR of brightest measured star: 1064.284<\/p>\n

Method<\/h2>\n

Using the\u00a0MaxIM DL<\/em>\u00a0photometry tool, two reference stars were defined from\u00a0UCAC3 magnitudes taken from\u00a0image field information displayed\u00a0in\u00a0TheSkyX<\/em>. One check star was defined.<\/p>\n

25 stars were measured. Stars were chosen in groups across the field, within magnitudes defined by SNR and saturation. This provided\u00a0a sample within a magnitude range of 10.8 to\u00a016.4 (UCAC3 values).<\/p>\n

\"Screen<\/a>

Figure 1: Distribution of measurements across image<\/p><\/div>\n

The plot was exported\u00a0to a CSV file. Magnitudes for each measured star were\u00a0compared to published\u00a0UCAC3 values from\u00a0TheSkyX<\/em>.<\/p>\n

\"Screen<\/a>

Figure 2: Table of measured vs published magnitudes<\/p><\/div>\n

The average difference\u00a0between \u00a0measured and UCAC3 values is 0.14 mag.<\/p>\n

A\u00a0maximum difference 0.875 mag was\u00a0noted \u00a0for object 19. \u00a0This was a significant \u2018outlier\u2019 compared to the other objects.<\/p>\n

\"Screen<\/a>

Figure 2: Measured vs published magnitudes<\/p><\/div>\n

Findings<\/h2>\n

Magnitudes seem to correlate well over the range, despite a relatively small sample and the fact that magnitudes in UCAC are unreliable (UCAC is not a photometric catalogue). The relatively large deviation in at least one outlier suggests a considerable likelihood for error in small samples when using this method.<\/p>\n

MaxIM DL<\/em>\u00a0appears to have a reliable function for ascertaining instrumental magnitudes based upon a defined reference.<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Non photometric catalogues are notoriously unreliable, but are increasingly used by novices amateur astronomers using commercial software such as\u00a0TheSky\u00a0and\u00a0MaxIM DL. The following basic magnitude ‘measurement’ test shows\u00a0results using MaxIM DL’s photometry tool, unfiltered images of a random field of stars, … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0},"categories":[20],"tags":[],"_links":{"self":[{"href":"https:\/\/jazzistentialism.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1539"}],"collection":[{"href":"https:\/\/jazzistentialism.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jazzistentialism.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jazzistentialism.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/jazzistentialism.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1539"}],"version-history":[{"count":2,"href":"https:\/\/jazzistentialism.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1539\/revisions"}],"predecessor-version":[{"id":1624,"href":"https:\/\/jazzistentialism.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1539\/revisions\/1624"}],"wp:attachment":[{"href":"https:\/\/jazzistentialism.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1539"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jazzistentialism.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1539"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jazzistentialism.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1539"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}