[daip] Question about AIPS task RM {External}

[ailingZeng]

Dear friend,
	I am using a task called RM in AIPS to do a Faraday rotation measure map. I use VLBA data at 5GHz and 8.4GH. When I run RM , MSGSRV window shows : ' TOO FEW POINTS ON f AXIS FOR RM FIT,  Purports to die of UNNATURAL causes. ‘ 

	first, I use COMB to combine Q and U image at 5 GHz. And do the same again for 8.4GHz data.
	then, use FQUBE to combine these two cubes derived by COMB.
	next, use TRANS to put frequency at first dimension.
	finally, use RM, and failed.

	I want to ask that if RM can deal with a cube image with only 2 frequencies, I mean, it need more than 2 frequencies so it failed and said too few points on frequency axis. Or maybe I carried on something wrong so it failed. Hope to get some suggestions from you.

	Thank you very much for your kind consideration and I am looking forward to your early reply. 

Sincerly, yours
Ailing Zeng


________________________________
Best regards

Ailing Zeng
Division of Radio Astronomy Science and Technology
Shanghai Astronomical Observatory
80 Nandan Road, Shanghai 200030, P.R.China