How to get LMN coordinates?

[neetasha]

Step 2: Describe your environment

• irfu-matlab branch (e.g. master, devel): devel
• Matlab version used (e.g. Matlab R2020b): R2022a
• Operating system (e.g. Windows 10, Mac OS X 10.15.6, Linux Ubuntu 20.04): Windows 10 A 64-bit installation of Matlab was used.

Step 3: Describe the problem

Dear Sir, I was trying to get L, M, N coordinates using," [out,l,v]=irf_minvar(Bxyz,'mvar')", as given in the paper "Lower hybrid waves in the ion diffusion and magnetospheric inflow regions, Graham et.al., 2016". The output of v is a 3X3 matrix. I considered L=v(1,:); M=v(2,:); N=v(3,:), i.e. is L=[0.2250 -0.3921 0.8920] M=[-0.3476 -0.8875 -0.3025] N=[ 0.9103 -0.2420 -0.3360] However, the above mentioned LMN coordinates does not matched with the one given in Graham et al, 2016. What could be issue? Am using wrong function? If yes, What should I use for evaluating LMN coordinates from the B_GSE ?

Thanks in advance Regards, Neetasha.

[danbgraham]

Dear Neetasha,

There is a typo in the Graham et al., 2017 paper for the M vector direction. The LMN coordinates I used in the paper were computed using irf_minvar_gui or equivalently.

The LMN coordinates used in the paper are: L = [0.25 -0.40 0.88]; M = [-0.35 -0.89 -0.30]; N = [0.90 -0.23 -0.36];

Best regards, Daniel

[neetasha]

Thank you for getting back to me. The LMN coordinates you got using irf_minvar_gui are similar to the one I mentioned above, using the irf_minvar function of the irf_devel package. So, can we use the 'irf_minvar' function for LMN transformation from the GSE or GSM coordinate system?

Thanks in advance! Regards, Neetasha.