"unphysical rms" when attempting to extract spectral index from mutlichannel cube

[kendak333]

Can someone please help me understand why I am getting the following error:

"Thread raised exception A region with an unphysical rms value has been found. Please check the input image."

I am trying to extract a source catalogue inclusive of spectral index values, using a multi-channel cube. This error only pops up when I have spectralindex_do=True. I'm not sure what I'm meant to be looking for in the image, or how to circumvent this.

Abell_2751_aFix_pol_I_Farcsec_fcube_cor.fits.pybdsf.log

[mhardcastle]

Not saying this is your problem, but the frequency_sp in the log is a little bit odd!

Did you resolve the problem?

[sarrvesh]

I encountered this issue today. Not sure if you have resolved your problem, but here is how I worked around the "unphysical rms" error. While creating my cube, I inserted the MFS image as the first channel. Then, I ran process_image() with collapse_mode='single', collapse_ch0=0. If I understand the documentation and the log correctly, this makes pybdsf detect sources on the first channel (which is the MFS image), and then derive spectral indices using flux measurements from the individual channels.