Date: Thu, 26 Jul 2012 16:50:43 -0400 (EDT)
From: Jun-Hui Zhao 
To: Claudia J. Cyganowski 
Subject: Re: miriad questions


Hi Claudia,

On Thu, 26 Jul 2012, Claudia J. Cyganowski wrote:

> Hi Jun-Hui,
>
> Thanks.
>
> To clarify re the antenna positions: how recent is "recent" data?  (e.g.
> since what month/year?)  Do I understand correctly that no refant needs to
> be specified for recent data (even if antenna 6 is not on pad 1)?

    I cannot recall the exact date when SMA put antennas file under
the data file directory. It is for sure after 2006 we have this
file in. You can double check to see if 'antennas' is present.
If not present, then one might have to copy over from other data files
observed in the same array configuration or from system.
>
> What about the case when antenna positions need to be updated (question
> (2) below)?

     In the case, if better baseline solutions are obtained, then
one has to recalculate the uvw coordinates using uvedit. There are two
ways to do so:

1) with the original antennas file and position offsets derived
from baseline fitting program.

2) copy over the updated antennas file replacing the old one.
The detailed usage for uvedit has been given in the users' guide:
http://www.cfa.harvard.edu/sma/miriad/manuals/SMAuguide/smauserhtml/node49.html

     Jun-Hui



>
> Thanks,
> Claudia
>
>
> On Thu, 26 Jul 2012, Jun-Hui Zhao wrote:
>
> > Hi Claudia,
> >     For recent data, the antenna positions read directly from
> > the file 120711_03:23:40/antennas. The reference antenna position
> > should be zero. In early data, the antenna position is decoded
> > from the baselines, so the calculation requires reference antenna.
> >     I have tried all the tested observing modes for your 2012 MAR 16 data
> > but not successful. Looks like that observation used a peculiar
> > observing mode. I will take a close look next week after
> > submit a NRAO proposal.
> >     Jun-Hui
> >
> >
> > On Thu, 26 Jul 2012, Claudia J. Cyganowski wrote:
> >
> > > Hi Jun-Hui,
> > >
> > >
> > > I also have a few other questions, mostly related to antenna positions.
> > >
> > > (1) Recently, antenna 6 has not been on pad 1 (or even in the array).
> > > The smalod mirhelp documentation (copied below) implies that the default
> > > assumes antenna 6 is on pad 1.  Does this mean that if antenna 2 is on pad
> > > 1, I need to specify the refant, e.g.
> > > smalod in='120711_03:23:40' out=g14_x rxif=0 sideband=2 refant=2
> > > ?
> > >
> > > Keyword: refant
> > >          The reference antenna. Default is 6. The reference antenna needs
> > >          to be present while the antenna positions are being decoded
> > >          from baseline vectors stored in SMA MIR data. The geocentrical
> > >          coordinates for the antennas can be retrieved from SMA sybase.
> > >          For double checking the antenna positions, one can login to
> > >          d2o.sma.hawaii.edu (IP:128.171.116.111) and use the following
> > >          command:
> > >          dBValue -d hal9000-newdds -v dsm_dds_hal_x_v11_d -t "2004-11-16
> > > 00:00:0
> > >          dBValue -d hal9000-newdds -v dsm_dds_hal_y_v11_d -t "2004-11-16
> > > 00:00:0
> > >          dBValue -d hal9000-newdds -v dsm_dds_hal_z_v11_d -t "2004-11-16
> > > 00:00:0
....