Results
This pages contains the results of various tests we have performed to determine the reliability and accuracy of the results output by the LSS. Most of these tests are based on the analysis of simulated images as they allow us to compare the outputs against known inputs.
One of the primary goals of GOTO is to accurately measure absolute and differential photometry. As such, a key test for the LSS is to assess how reliably and accurately it can measure source photometry. The LSS provides a number of methods to measure photometry. These include:
- Aperture photometry in a range of circular apertures;
- PSF photometry using the PSF characterised (by the LSS) from selected point sources distributed around the image;
- Kron photometry;
- Gaussian fit photometry, in which a 2D-Gaussian is fit to the source;
- CModel photometry, in which a linear combination of a deVaucouliers and exponential light profile is fit to the source;
While the first two (aperture and PSF) work well for point sources, they typically fail to give reliable results for extended objects. The latter three (Kron, Gaussian, and CModel) have been developed to overcome this problem.
The following plots show the input vs. output magnitudes obtain by running LSS on the simulated image: GOTO_01_20170525_0001_01.fits using v13.0 of the stack. These are the output photometry obtained by running singleFrameDriver.py with commit XXXX of obs_goto.
First, aperture photometry using a 12 pixel diameter (i.e., ~15 arcsec diameter) aperture:
There's clearly something