Updating model for 3C48
Submitting this issue on behalf of Leah Morabito (where issues with her account are preventing her submitting it)
High resolution models have been constructed from images made with international stations for 3C48 and 3C147. The models were scaled such that the sum of all components are on the Scaife and Heald flux scale. To validate this, Pre-Facet-Calibrator was run twice, once with the old model and once with the new model, applying the solutions (clock and TEC were not applied as is default in the full_apply step, but rather the final phase calibration was used). WSclean was run to create three images:
1 - with the full array 2 - with the international stations only 3 - with the Dutch stations only
PyBDSF was then used to extract source information, with the fits visually checked.
For validation, ratios between old and new models were used as the snapshot imaging doesn't provide great uv coverage, and the beams are therefore not very well defined. The old models have been validated via LoTSS data processing, so as long as the new model reproduces what the old model does, it should be valid. Four comparisons were made:
A - the ratio of peak intensities from the old and new model images, using the Dutch station only images. Peak intensity was used rather than total flux density because the sources will be unresolved for the Dutch array, and the uv coverage means the beam isn't fantastic and this can impact the PyBDSF estimation of the total flux density. The ratio should be 1. B - The ratio of: total flux density of the new model, using the international only image to the old model peak intensity using the Dutch station image. Essentially, this is asking whether the total flux density in the new model is still on the Scaife & Heald flux scale. The ratio should be 1. C - The ratio of: total flux density of both the new and old models, using the international station only image. The ratio should be 1. D - The ratio of: the peak intensity in the new to old model. This should be less than 1, since we are dividing a single component into multiple components and therefore the peak intensity should decrease.
Results for 3C48: A ... LoTSS flux ratio (new/old): 0.99 B ... International to LoTSS ratio: 1.01 (new intl total / old lotss peak) C ... International stations flux ratio: 1.00 (new intl total / old intl total) D ... International stations peak flux ratio: 0.86 (new intl peak / old intl peak)
The ratios turn out exactly as we expect. Can you please replace the 3C48 model with this new one.
3C147 is still in progress.