Hi Chris,
thanks for reading the draft and for your questions!
There is still a lot to do to iron out the details of the analysis, but
below are my answers
On Thu, Jul 2, 2015 at 6:04 PM, Chris Carilli <[email protected]> wrote:
> Hi Gianni,
>
> was just getting around to reading your imaging draft. nice work. just a
> couple questions on first glance:
>
> 1. did you include all the visibilities down to the shortest spacings?
yes
> and did you use any uv limits in the self cal process?
>
> not sure what you mean here... do you mean any effect of the short
spacings on the solutions? If so I did not find any particular evidence for
that. But keep in mind I'm only solving for phases (I hope I spelled it out
clearly in the draft)
> 2. how much flagging did you do?
>
> need to double check, but I did not do any additional flagging on top of
what was done before compression
> 3. in mfs, what order did you use, and how much bandwidth was included?
>
> I used 1 order and the bandwidth between 120 and 170 MHz
> 4. in self cal, what is typical magnitude of corrections being made to
> antenna-based phases? and do you make a single correction across the full
> band, or channel-dependent corrections?
>
> I make a per channel correction every 10 minutes, so I assume you're
asking what the variation of the phase solutions is across the band (if I
misunderstood correct me). If so, for most of the dipoles it's small, a few
degrees across the band. For several of them is large as it is a slope
correction across the band (even 50 or more degrees). I believe that those
dipoles may have a wrong cable length correction. I can make a plot and
send it to you.
> 5. I am not sure how to interpret the 'RM slice' images?
>
> I should have probably put more context in the explanation. Each RM slice
shows the polarized intensity at that RM value. The polarized intensity was
not corrected for bias so it goes from 0 to Pmax. In other words, if a
source has a polarized flux density of 1 Jy and an RM = 10 rad/m^2 you
should see it appearing at the RM = 10 rad/m^2 with a 1 Jy peak flux. But
essentially all the polarized intensity I showed is not real, either coming
from leakage from bright sources like Fornax A, or from their frequency
dependent sidelobes.
Happy to discuss more if you like,
cheers!
Gianni
> thanks
> Chris
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