[daip] issues with RM task?

[Sayali Avachat]

Hello,

I am a PhD student of Florida Institute of Technology. I am working on data
analysis of galaxy M87.
I have obtained RM maps for one of the time epochs in my data. But I am not
sure if the RM is giving me the right thing. I tried to plot position angle
Versus wavelength squared to see the lambda^2 signature of Faraday rotation
in my data, making a least squares fit. The slopes of position angle Vs
lambda^2 are way higher than the maximum value of rotation measure in my RM
map. Also I do not see any negative RM values in my map (which it should
give me since there is negative rotation measure in M87 jet, as per earlier
work on it). Its range is 0-1300 rad/m^2, while slope of PA Vs lambda^2 is
around 2000-4000 rad/m^2.
I am not sure if I am entering the inputs in RM properly. First I tried
setting to default APARM values and then tried successively to increase the
APARM(4) 5000, 10000, 15000 etc.
The RM maps looks different each time (obviously) but the range still stays
same, 0-1300 rad/m^2.  Even setting the initial guess for RM value by
APARM(3) does not help getting the reasonable  result.
What is that I am missing when plotting RM map? Is there any other
parameter that I need to set to get what I want? Or is there any other task
to obtain RM map?

Thank you,
-- 
Sayali S Avachat
PhD Candidate
Department of Physics and Space Sciences
Florida Institute of Technology
savachat2008 at my.fit.edu
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