| | 1 | Using the 'BAD FLAGS', the PSF_QF and the XY_MOMENTS values we have made some progress regarding the removal of spurious sources from the differenced image cmf files. Note that PSF_QF, or psf quality fit, represents the fraction of good pixels found within the aperture used to measure the source - therefore if this value is low then we know that a lot of the pixels have been masked. Below you will find a plot of all of the differenced sources found within one June 2009 MD08 exposure; red points are sources where a bad flag has been set against it, green points are source where no bad flag has been set. Also plotted are 7 of the best SN candidates that we at QUB found in the June 2009 data release (all epochs). It is clear that the SNe generally have low XY Moments (i.e. point source like) and a high PSF QF. Combined with the removal of the 'BAD FLAG' sources, we can use these two parameters to remove some spurious sources that contaminate the true sources. |
