[daip] estimate the coherence time in AIPS (coher)

[Leonia Kogan]

 Hi Zhiqiang,

The coherence time may not depend on the ratio of scalar and vector 
averaging aparm(3), if

1. The number of visibilities for the given baseline and for the selected 
   source is less than 6. In this case the coherence time will be equal the
   scan time.

2. You have big noise, and so when you select aparm(2)=5 you cut off too 
   many points, and the rest numper of point can be less than 6 or even 2.

   Try aparm(2) =100 taking all point into account and look if the coherence 
   time depends on aparm(3).

You can examine your data with UVPRT selecting only one baseline for 
simplicity.

Leonia


----- Begin Included Message -----

>From daip-admin at donar.cv.nrao.edu Wed Apr  3 01:25 MST 2002
Mime-Version: 1.0
X-Sender: zshen at perseus.vsop.isas.ac.jp
X-Mailer: Macintosh Eudora Pro Version 4.2.1-J
To: daip at cv3.cv.nrao.edu
From: "Z.-Q. Shen" <zshen at vsop.isas.ac.jp>
Subject: [daip] estimate the coherence time in AIPS (coher)
Sender: daip-admin at donar.cv.nrao.edu
X-BeenThere: daip at listmgr.cv.nrao.edu
X-Mailman-Version: 2.0.8
Precedence: bulk
List-Help: <mailto:daip-request at listmgr.cv.nrao.edu?subject=help>
List-Post: <mailto:daip at listmgr.cv.nrao.edu>
List-Subscribe: <http://listmgr.cv.nrao.edu/mailman/listinfo/daip>,
	<mailto:daip-request at listmgr.cv.nrao.edu?subject=subscribe>
List-Id: This is the designated AIP list for AIPS support. <daip.listmgr.cv.nrao.edu>
List-Unsubscribe: <http://listmgr.cv.nrao.edu/mailman/listinfo/daip>,
	<mailto:daip-request at listmgr.cv.nrao.edu?subject=unsubscribe>
List-Archive: <http://listmgr.cv.nrao.edu/pipermail/daip/>
Date: Wed, 3 Apr 2002 16:54:48 +0900
X-Lines: 28
Status: RO

To Whom it may concern,

I tried to estimate the coherence time using AIPS task COHER.
I set the parameters as follows:

aparm(1)=3 (calibrator scan length)
aparm(2)=5 ------(I'm quite confused with this cutoff)
aparm(3)=0.9
aparm(4)=0 (for a detailed debug)
aparm(5)=0 (only use one 3 min scan)
aparm(6)=1 (FRING done earlier)
aparm(7)=0
aparm(8)=1 (for 43 GHz).

But I found the results are only affected by the selection of
aparm(8) and could be very different when aparm(8) are
picked up differently.  No matter what value I chose for
aparm(3), it always gave the same results (if aparm(8) is
not changed). This seems wrong to me.

I'd like to have your suggestions.

Regards,
Zhiqiang Shen
_______________________________________________
Daip mailing list
Daip at listmgr.cv.nrao.edu
http://listmgr.cv.nrao.edu/mailman/listinfo/daip


----- End Included Message -----