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SJaffa / Jplots

Astrophysical data analysis tool: quantifying the shape of pixelated structures using moments
GNU General Public License v3.0
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Question about the calculation of J moments #5

Open chen-ying-ying opened 7 hours ago

chen-ying-ying commented 7 hours ago

Hi, I have some questions for you. Does the J-plots algorithm have any special requirements on the format of the input real observation data? The data I need to analyse now is 2D PP data (3D PPV data obtained by integrating in the velocity direction). According to what is stated in J-plots: a new method for characterising structures in the interstellar medium, the molecular cloud core should belong to the centrally concentrated type of shapes, and then most of the calculated J-values should be in the first quadrant (i.e., J1 is greater than 0 and J2 is greater than 0). However, I have tried a lot of data and the value of J2 is less than 0, but I don't know what is wrong.

chen-ying-ying commented 3 hours ago

I see that you mentioned in the code notes that you can use the mask obtained after detection as an input to the J-plots, so how should I calculate the J moments?