[daip] [!5480]: aips - CVEL AIPS 2

[Eric Greisen]

Eric Greisen updated #5480
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       Staff (Owner): Eric Greisen (was: -- Unassigned --)
              Status: Closed (was: Open)
                 Due: - Cleared - (was: 15 September 2014 10:45 PM)

CVEL AIPS 2
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           Ticket ID: 5480
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/5480
           Full Name: Carolina Rodriguez
               Email: ca.rodriguez at crya.unam.mx
             Creator: User
          Department: AIPS Data Processing
       Staff (Owner): Eric Greisen
                Type: Issue
              Status: Closed
            Priority: Default
      Template Group: Default
             Created: 11 September 2014 10:45 PM
             Updated: 12 September 2014 02:47 PM



Note - you do not need to open a new ticket each
time you respond.  Just click on the existing ticket
and you can enter a new message.

CVEL adjusts the observed spectra so that one selected
channel is at a specific velocity with respect to some
"standard of rest" typical the "local" one which does:

Define a point in space that is moving on a perfectly circular
orbit around the center of the galaxy at the Sun's
galactocentric distance. We measure all velocities of stars
relative to this point, which is known as the Local Standard
of Rest. Now we define the velocity of stars relative to the LSR.

To quote a Google discovered reference.

Thus the Earth rotation, Earth motion around the Sun and
the Sun's peculiar motion around the Galaxy are removed.
Thus the date no longer matters.  You tell CVEL what velocity
you want in that rest frame and it gives it to you.  The shifts of
about 1.3 channels tells us that the observations were made at a
fixed frequency (on the Earth) chosen not quite correctly for
the actual date of observation, but close. 

The slight discrepancies you noticed in the display of the rest 
frequency has to do with the fact that all adverbs are only single
precision in the POPS language and alos with the choice of 
print formats in some verbs.  The result is close enough.

I am actually more worried about something in the SPLIT
print out.  You asked for CL table 2 but it used table 1.  That
suggests that you did not in fact apply any calibration beyond
the default one.  Did you run GETJY and then CLCAL after
CALIB?

Eric Greisen
 



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