Date: Tue, 2 Oct 2012 17:48:49 -0400 (EDT)
From: Jun-Hui Zhao 
To: Alice Argon 
Cc: thunter@nrao.edu
Subject: Re: SMA frequency scale as interpreted by CASA

Hi Alice,
    The SMA frequency-velocity system was a bit confusing.
    Quite a few problems were reported in the past (in SMA log and
email communications); some of them were listed in Todd Hunter (ALMA)'s
wiki page.
    Miriad-path made special routines of correcting those errors.
Todd Hunter was involved in the early development of SMA Miriad.
Unlike NRAO dopset and fixed sky-frequency at transit, Miriad uses
the true sky frequency and doppler-velocity in handling
velocity-frequency conversion. We have correctly converted
SMA online frequency-velocity to Miriad-system.
    Jun-Hui

On Tue, 2 Oct 2012, Alice Argon wrote:

> Hi Jun-Hui,
>
> There appears to be a problem with the frequency scale when reading
> calibrated SMA data into CASA.  See NRAO public wiki:
>  https://safe.nrao.edu/wiki/bin/view/Main/SMAVelocityScale
>
> The wiki then talks about "query[ing] the SMA database for the velocity
> being tracked at source transit" and correcting using NRAO's dopset.
> Is there a MIRIAD fix that would accomplish the same thing?
>
> Thanks,
>  Alice
>