-------- Forwarded Message --------
Subject: Re: HERA 19 configuration (Version 3)
Date: Wed, 1 Jul 2015 15:18:00 -0700
From: Jonathan Pober <[email protected]>
To: Chris Carilli <[email protected]>
Yeah, I think anything outside the HERA footprint is out. Attached is
a picture of the single channel, snapshot uv coverage of all the PAPER
dipoles (not just the imaging circle; rotated dipoles are excluded,
though). Left hand plot is linear, right is logarithmic; units on both
is number of samples. Throw in bandwidth synthesis, and it's filled out
pretty out to 100 lambda. Absolute max length is 150 lambda (at 150
MHz), since the cables are fixed at 150 m.
On Wed, Jul 1, 2015 at 3:12 PM, Chris Carilli <[email protected]
<mailto:[email protected]>> wrote:
might be nice to have imaging config have longer baselines, ie
larger radius, but that might not be possible given cable lengths?
cc
On 07/01/2015 03:38 PM, Jonathan Pober wrote:
Based on further discussion on Monday's data telecon, I have
another iteration of a HERA 19 configuration proposal. We need a
final decision by early next week, so tomorrow's telecon is a good
time to reach consensus. I will be late, unfortunately, but
that's no reason to postpone discussion.
A summary of changes from Version 2:
* The polarization dipole rotation experiment (red) now rotates
the same dipoles in each column (as opposed to a staggered
scheme).
* The PAPER 19 hex (purple) has been moved to the east side of
the future HERA core. This was due to concerns over shadowing
from the HERA 19 elements. The hex outriggers (orange) have
been shifted to match.
* Similarly, the 9 (formerly pink) dipoles that were positioned
near HERA 19 have been eliminated. Suspicion was that
shadowing would make these baselines too difficult to interpret.
* There are now 38 dipoles in the imaging configuration
(green). Other configurations besides a circle have been
suggested, but no pressing need seemed to necessitate it.
Currently, the single-frequency, snapshot uv coverage is
nearly filled to 50 lambda, with good coverage out to 75-100
lambda.
Concerns:
* The two eastern most orange hex outriggers likely cannot be
reached with 150 m cable. Do we still want the hex outriggers
if we can't place all of them?
* I still have not checked for any position conflicts with the
correlator container or receiverators, but by eye we seem OK.
Jonnie
