Sample globular cluster photometry fits

The plot below gives the first page of output for one of the runs of my fitting code. The black dots show the V magnitude vs. aperture points. The purple line is the best fit. Red points were excluded from the second round of fitting because they deviated too much from the original best fit. The dashed line at the top represents my derived total magnitude based on the profile fit. Note that most of the globulars are extremely well-behaved, even though the photometry usually comes from multiple sources. However, you can see that NGC 1841 (row 2, column 3) does not have a lot of data, so the fit doesn't have an appropriate shape; that's okay for apertures of 0.5 and 1.0 arcminutes, but not for an extrapolation to 2.0 arcmin. There is a serious problem with the photometry for NGC 2298 (row 3, column 3); note the very deviant points below the main curve. Because there are so many deviant points, the original fit would have ran through the white space above those points, and thus the fit excluded all points near 1 arcminute. The resulting fit actually isn't horrible, but I marked it in red in the main table. This is a fairly rare occurrence, and at some point I could go to the original literature and verify that the faint points are incorrect and do a good fit for this one.


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File last modified: 17 December 2004

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