# jointcal constrained photometry model is not better than processCcd photometry on DC2 run1.2

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## Details

• Type: Bug
• Status: To Do
• Resolution: Unresolved
• Fix Version/s: None
• Component/s:
• Labels:
None
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## Description

From a set of 7 visits from DESC DC2 Run1.2p I am taking 1 visit as an arbitrary reference and for each matched sources in the other visits I compute the difference of magnitude using 1- the processCcd calibration and 2- the jointcal calibration from the default constrained model.

The dispersion (19.9 mmag) is identical in both cases which looks very surprising. The size of the dispersion also looks very large.

In order to reproduce the problem the data are available on lsst-dev:/home/boutigny/2018-10-11 and the notebook to reproduce the plot is on: https://github.com/boutigny/LSST_notebooks/blob/master/DC2/multi_visit_Joincal.ipynb

I am not excluding an error on my side or a misusage of jointcal

## People

• Assignee:
Unassigned
Reporter:
Dominique Boutigny
Watchers:
Dominique Boutigny, Eli Rykoff, James Chiang, Jim Bosch, John Parejko, John Swinbank, Robert Lupton