[daip] [!6528]: aips - OMFIT (31DEC15)

[Michael Bietenholz]

Michael Bietenholz updated #6528
--------------------------------

OMFIT (31DEC15)
---------------

           Ticket ID: 6528
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/6528



Its the "Error" (I think more accuratte would be "Uncertainty") on the fitted parameter values which I think is off - in the output below the 1.49861  mJy on the flux of 9.85672 mJy.  I haven't tracked down why your version gets a different number than mine, but like I said, in the simple case below, the uncertainty on the fitted flux density can be calculated a priori which is just the uncertainty on the visibilities of 100 mJy divided by sqrt(Nvis=9145), and comes up sqrt(2) lower than 1.49861, ie. 1.06, .  UVFIT and my version of OMFIT agree with the 1.06 mJy, so I think the AIPS:OMFIT values are in fact too high by sqrt(2).


OMFIT2:        9145 Vis. ,      18289 Deg. of Freedom
OMFIT2:  Fitted for          1 model parameters
OMFIT2: -------------------------------------------------
OMFIT2: ------- The MODEL after   5 iterations -------
OMFIT2: -------------------------------------------------
OMFIT2: Component #  1 ModelType <DOT     > Ident. #  1
OMFIT2: Parameter(units)         Value         Error
OMFIT2:  flux     (mJy     )       9.85672       1.49861
OMFIT2:  E-offset (mas     )       0.00000         fixed
OMFIT2:  N-offset (mas     )       0.00000         fixed
OMFIT2: -------------------------------------------------


------------------------------------------------------
Staff CP:  https://help.nrao.edu/staff