When calculating the error on the FWHM of a 2D Moffat fit (mpdaf/obj/image.py line 2291), the script divides the second error component by the error in eccentricity rather than the eccentricity itself. In most cases, this leads to strange-looking reported FWHM results such as: [INFO] fwhm = (4.60711,4.32469) (error:(0.802868,87.6039)). A more reasonable value seems to appear if the code is changed to divide the second component by eccentricity only, obtaining [INFO] fwhm = (4.60711,4.32469) (error:(0.802868,0.753652)) in the same case.
Image.py line 2291 reads: err_fwhm = np.array([err_fwhm, err_fwhm / err_e])
Changed to: err_fwhm = np.array([err_fwhm, err_fwhm / e])
Is the choice to divide by the error in eccentricity by design, or would it be best to use just the eccentricity?
Python 3.7.6 numpy 1.18.2 astropy 4.0 MPDAF 3.4
When calculating the error on the FWHM of a 2D Moffat fit (mpdaf/obj/image.py line 2291), the script divides the second error component by the error in eccentricity rather than the eccentricity itself. In most cases, this leads to strange-looking reported FWHM results such as:
[INFO] fwhm = (4.60711,4.32469) (error:(0.802868,87.6039)). A more reasonable value seems to appear if the code is changed to divide the second component by eccentricity only, obtaining[INFO] fwhm = (4.60711,4.32469) (error:(0.802868,0.753652))in the same case.Image.py line 2291 reads:
err_fwhm = np.array([err_fwhm, err_fwhm / err_e])Changed to:err_fwhm = np.array([err_fwhm, err_fwhm / e])Is the choice to divide by the error in eccentricity by design, or would it be best to use just the eccentricity?