[daip] aips

[Amy Mioduszewski]

Hi Wu,

 > Sorry to bother you ,I 've just finished reducing an EVN data,and 
have > got the image of one source,but I searched ADS,based on the same 
data > ,some professor have published one paper about this data,I 
compared my > image with his image,and find that the beam size of my 
image is a
 > little larger than his,nearly the same ,the peak flux of my image is
 > lower than his (the peak of my image is about 73mJy,and the peak of
 > his image is about 92mjy),do you know the possible reason of the
 > difference between our images,is there a problem ,he did not published
 > the location of the component,do you think the difference of the peak
 > flux will affact the difference of the component's location( the same
 > data).thank you very much.

It could be any number of things.  Here are a few things I would check:
Does the a priori amplitude calibration seem reasonable?  Compare the 
amplitudes for baselines that cross in the U-V plane, they should be the 
same.  Have you done amplitude self-calibration, that can change the 
amplitude?  Are the peaks you are reporting in mJy or mJy/beam?  If the 
later the beam size difference could make a difference.  If it will 
affect the component's position depends on the reason for the 
difference.  If it just a scaling difference, in other words, all the 
antenna amplitudes are for some reason low then it will not effect the 
position.  But if is caused by bad models used in self-calibration, that 
could affect the position.

Cheers,

Amy