\n10 x 3 second exposures through V and 10 x 8 second exposures through B were acquired in succession. Images were calibrated (bias, dark, flat) in the normal manner.<\/p>\n
Reference Information<\/h2>\n
A comparison chart of the NGC 3532 field was generated using the AAVSO\u2019s Variable Star Plotter, specifying the centre coordinates for NGC 3532 and choosing standard field<\/em>.<\/p>\n The NGC 3532 sequence, courtesy of the American Association of Variable Star Observers (AAVSO, 2017).<\/p><\/div>\n The associated photometry table (not shown) includes an AAVSO Unique Identifier (AUID) for the sequence. Tagged\u00a0stars must<\/span> be labelled with the AUID in order for Transform Generator<\/em> to work.<\/p>\n Aperture photometry was undertaken using MaxIM DL<\/em> \u2013 one of the applications directly supported by Transform Generator<\/em>. All B & V images were\u00a0processed simultaneously using the Photometry tool in MaxIM DL<\/em>. The first star was tagged as a \u2018reference star\u2019 prompting entry for published B and V band magnitudes. All other stars were\u00a0tagged as as \u2018new objects\u2019 for which no magnitudes are specified. Once complete, the CSV file produced by MaxIM DL<\/em>\u00a0was\u00a0configured to include instrumental magnitudes – required by Transform Generator<\/em>.<\/p>\n NGC 3532 imaged using SPO’s SBIG ST-10XEI. A 3 second V-band image with stars tagged in MaxIM DL.<\/p><\/div>\n Transform generator<\/em>\u00a0was installed and configured as per the instructions on the AAVSO web site. It uses Python<\/em> which requires additional installation. Once installed, the process is\u00a0self-explanatory:<\/p>\n The default Transform Generator dialogue.<\/p><\/div>\n Each of the computed transforms appears and can be reviewed graphically by selecting them in turn. Data outliers can be deactivated from the plot with the resulting transforms and errors immediately updated.<\/p>\n The resulting colour transform, exhibiting an excellent linear fit.<\/p><\/div>\n Deselecting the outlier (red data point at bottom left) re-computes the line of best fit and associated B magnitude transform coefficient in real time.<\/p><\/div>\n The software also provides the means to manage and average historical sets.<\/p>\n Transforms can be applied manually (spreadsheet means) using the standard methodology. Transform Applier<\/em> is another application available through AAVSO that facilitates the process of applying transforms to AAVSO formatted data.<\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" Changes in the optical train at Shenton Park Observatory together with a renewed 2017 AAVSO transform campaign have prompted revisiting photometric B and V band transformation coefficients. The addition of an AAVSO sequence for the southern hemisphere cluster NGC 3532, … Continue reading ![\"Screen](\"http:\/\/jazzistentialism.com\/blog\/wp-content\/uploads\/2017\/05\/Screen-Shot-2017-06-01-at-2.11.32-pm.png\")
<\/a>Deriving instrumental magnitudes<\/h2>\n
<\/a>Transform Generator<\/h2>\n
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<\/a><\/a><\/a>Applying transforms to photometric measures<\/h2>\n