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uvedit

Section: User Commands (1)
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NAME

uvedit - Editing of the baseline of a UV data set.  

PERSON RESPONSIBLE

pjt  

CATEGORIES

calibration, uv-data  

DESCRIPTION

UVEDIT is a MIRIAD task which allows baseline editing of a UV data set. As a result of the editing, certain header variables of the data set are changed. The headers `corr' and `wcorr' are always changed since they are the data themselves. The headers `coord(2)' are the baseline coordinates and, as a result, are also always changed (except with the option nouv). The UV variable headers `lst', `ut', and `time' are updated whenever a time offset is entered. The headers `ra', `dec', `obsra', and `obsdec' are changed whenever a positional correction is entered with the ra or dec input. Finally, antenna coordinate corrections will cause the header `antpos' to be corrected.

NOTE: There can be NO select keyword for this routine! If one includes the select option, then data that is not selected will not be copied!  

PARAMETERS

vis
The name of the input UV data set. At least one file name must be supplied. Up to 50 visibility files are currently allowed.
source
The name of the source to apply corrections to if more than one source is present in a UV data set. All UV data that does not correspond to the input source name is copied without being edited. If this keyword is not set (the default), then all sources are edited. Only one source name may be input. Note: it probably doesn't make sense to use this keyword with any other options except the ra and dec keywords. If any other editing (except ra/dec) is requested along with this keyword, a warning message will be issued but the editing will proceed.
apfile
The name of a file that contains the absolute antenna positions entered in increasing antenna order. Only one antenna position file is permitted. The first line of the file is ALWAYS skipped and the remaining lines MUST contain three entries corresponding to the X, Y, and Z equatorial coordinates, respectively, in units of nanoseconds. The function of this keyword is identical to the ``antpos'' keyword except that there is no way to specify a subset of antennae; every antenna up to and including the largest antenna number must be present in the file. NOTE: You may only specify at most one of the ``apfile'',
      ``antpos'', or ``dantpos'' keywords.

In the case of options=sma, the apfile is the original antenna file which can be copied over from the original MIR-formated data, e.g. 050604_03:44:03/antennas which contains four entries corresponding to the antenna number, the X, Y, Z geocentric cooridnates in unit of meter. the reference antenna's X,Y,Z coordinates are specified to be zeros. Any corrections for the antenna positions must be given in the keyword smaoffset below. If no entries are input from the keyword smaoffset, positions in the ``apfile'' are considered as the updated values and will be used to correct for the vis data.

smaoffset
Inputs are the antenna coordinate offsets for SMA entered in the following order (NO checking is done for consistency):
     smaoffset = A1,X1,Y1,Z1,A2,X2,Y2,Z2,A3,X3,Y3,Z3,....
The input values are the antenna number and the three geocentric coordinate offsets (entered in units of millimeter). These input values are added to the original absolute coordinates read from the antenna file given in keywork apfile.

Note that A1 does not necesarily have to correspond to Antenna 1; it is used to represent the variable containing the antenna number. Antennas present in the data but not included in the input value list are treated as having a zero coordinate offset.

antpos
Inputs are the absolute equatorial coordinates entered in the following order (NO checking is done for consistency):
     antpos = A1,X1,Y1,Z1,A2,X2,Y2,Z2,A3,X3,Y3,Z3,....
The input values are the antenna number and the three equatorial coordinates (entered in units of nanoseconds). Note that A1 does not necesarily have to correspond to Antenna 1; it is used to represent the variable containing the antenna number. Antenna (and the corresponding coordinates) not included in the input listing do not have their coordinates changed. NOTE: An antenna position value of zero is not possible. If an antenna value is set to zero, the current value from the data is used. To force an antenna position value to be zero, use the keyword ``dantpos''. NOTE: You may only specify at most one of the ``apfile'',
      ``antpos'', or ``dantpos'' keywords.
dantpos
Inputs are the equatorial coordinate offsets entered in the following order (NO checking is done for consistency):
     dantpos = A1,X1,Y1,Z1,A2,X2,Y2,Z2,A3,X3,Y3,Z3,....
The input values are the antenna number and the three equatorial coordinate offsets (entered in units of nanoseconds). These input values are added to the absolute coordinates read from the data. Note that A1 does not necesarily have to correspond to Antenna 1; it is used to represent the variable containing the antenna number. Antenna present in the data but not included in the input value list are treated as having a zero coordinate offset. NOTE: You may only specify at most one of the ``apfile'',
      ``antpos'', or ``dantpos'' keywords.
NOTE: The dantpos keyword is the usually used when correcting antenna position errors in a VLA observation. The coordinate system used by Miriad and the VLA are the same, and the baseline changes provided by the VLAIS system need only be changed from units of meters to nanosec when using uvedit (1 nanosec = 0.2997 meters).
ra
Input is either an absolute or delta right ascension of the phase tracking center. If one value is present, it is considered as a offset position and is to be entered as time seconds. Otherwise, three values are expected and are to be entered in the following order:
     ra = HH,MM,SS.S
The right ascension (offset) is relative to the epoch coordinates. The default value is 0 seconds offset (no change).
dec
Input is either an absolute or delta declination of the phase tracking center. If only one value is present, it is considered as a offset position and is to be entered in arcseconds. Otherwise, three values are expected and are to be entered in the following order:
     dec = DD,MM,SS.S
The declination (offset) is relative to the epoch coordinates. The default value is 0 arcseconds offset (no change). If the absolute declination is negative but the DD value is 0, then make the MM value negative. If MM is also 0, then make SS.S negative.
time
Input is a time offset (in seconds) to be added to the clock time. The default value is 0 seconds offset (no change).
delay
Inputs are the delay error corrections for each antenna. The inputs are the delay values for each antenna entered in the following order (in units of nanoseconds):
     delay = D1,D2,D3,....
If no value for delay is specified, the array of antenna values are set to 0 nanoseconds offset. Also, a resulting difference (D[i]-D[j]) of less than 0.05 nanoseconds is ignored (no change). If a difference exists, the digital wide band data will be reconstructed. All previously flagged narrow band data will be ignored in the reconstruction. Also, the two (2) end channels of each window will be ignored in the reconstruction.
out
The name of the output visibility file. This parameter is ignored when more than one visibility file is given. If no value for ``out'' is given or more than one visibility file is input, then the output file name(s) will be the same as the input file name(s) but with an "_c" appended to the file name (ie. "Vis = saturn,jupiter" will result in output files "saturn_c" and "jupiter_c").
options
Task enrichment options. Minimum match is active.
  nouv     Do not recompute the uvw (coord(1..3)
           This option should, in principle, only be used with 
           the delay correction; 
           all other corrections should recompute u,v and w
  dra
           Multiply the dra values by a cos(obsdec) correction.
           This is used to correct the dra value in the uv
           dataset for MINT data taken at Hat Creek before
           11dec93.  Before that date, the 1/cos(obsdec)
           correction was not applied to the dra in the grid
           file, so that the pointing was incorrect (instead
           of dra arcseconds offsets, the offsets were
           dra*cos(obsdec) arcseconds).
           NOTE:  The obsdec used is the "old" obsdec.  If there
           is a correction in declination, this is NOT applied
           in computing the cos(obsdec).
  sma
           Allows to use the SMA corrdinates system, i.e.
           The geocentric coodinates in unit of meter
  uvrotate Rotate uv-coordinates from current to standard epoch.
           This is needed for BIMA data, or any data that keeps
           their UV(W) in current epoch instead of the more common
           standard epoch.
  time     adjust the time to the start of an integration time, 
           instead of the middle. Hence an offset of -inttime/2 will be 
           applied. Unlike the TIME keyword described above, this will have
           no other side effect. After this change 'ut' and 'time' should
           agree again as they did erroneously in BIMA data and CARMA
           data before Feb 2006.
           Normally 'ut' and 'time' are the mid point of each integration.
           Do not use this option unless you know what you are doing.


 

Index

NAME
PERSON RESPONSIBLE
CATEGORIES
DESCRIPTION
PARAMETERS

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Time: 18:35:38 GMT, July 05, 2011