Hi Andy, Thanks for your quick reply. Yes, hovering over spectrum plot in tab 5 seems OK – very noisy, 4 images done in hurry with poor guiding, but think OK. Too excited with ALPY. Will attach plot. Used HD27819 – Miles – A7v – had aimed to try to follow Robin’s earlier set that he posted, but ran out of weather. Used “Predefined Mode” ALPY 600 (Balmer Lines) in Spectral Box of General tab. This is what appears in log file.
Wavelength fit deviation
point #1 x = 303.320 lambda = 3834.846 dlambda = 0.544
point #2 x = 318.889 lambda = 3889.410 dlambda = -0.360
point #3 x = 342.002 lambda = 3970.510 dlambda = -0.430
point #4 x = 379.334 lambda = 4101.764 dlambda = -0.014
point #5 x = 446.859 lambda = 4340.099 dlambda = 0.381
point #6 x = 593.448 lambda = 4861.471 dlambda = -0.131
point #7 x = 1081.158 lambda = 6562.787 dlambda = 0.023
point #8 x = 1179.852 lambda = 6872.013 dlambda = -0.013
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Coefficient a4 : -4.314777E-10
Coefficient a3 : 7.466854E-07
Coefficient a2 : -3.481507E-04
Coefficient a1 : 3.55629
Coefficient a0 : 2767.495
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RMS : 0.507955
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Don’t have ALPY Calibration Module – need coffers to refill for that. Have fashioned external fixed neon bulb in line with slit as per picture on Robin’s website, but didn’t use that – took some sky plus neon today though to play with later.
Am going to do it all over again next clear spell here, but will keep looking at it – still puzzled.