[daip] POSSM question

Hanno Spreeuw spreeuw at astron.nl
Tue Nov 13 09:38:38 EST 2007


Hello, by accident I ran POSSM with sour ''.
The scalar averaged cross power spectrum seems to show a "comb" of very 
strong RFI that I cannot reproduce by specifying each of the sources in 
the multi-source file individually. Each of the individual sources show 
hardly any RFI.
This is P-band data, the "comb" is usually seen in 4-band.
I am not sure what POSSM shows when sour=''.
Do you know?
Thanks,
Hanno.
PS: this is AIPS07 with the MNJ.

 >inp
AIPS 6: POSSM     Task to plot total and cross-power spectra.
AIPS 6: Adverbs     Values                 Comments
AIPS 6: ----------------------------------------------------------------
AIPS 6: USERID        0                    User number
AIPS 6: INNAME     'STEPBYSTEP'            Input UV file name (name)
AIPS 6: INCLASS    'UVCOP'                 Input UV file name (class)
AIPS 6: INSEQ         6                    Input UV file name (seq. #)
AIPS 6: INDISK        1                    Input UV file disk unit #
AIPS 6: SOURCES    *all ' '                Source list
AIPS 6: QUAL         -1                    Source qualifier -1=>all
AIPS 6: CALCODE    ' '                     Calibrator code '    '=>all
AIPS 6: SELBAND      -1                    Bandwidth to select (kHz)
AIPS 6: SELFREQ      -1                    Frequency to select (MHz)
AIPS 6: FREQID       -1                    Freq. ID to select.
AIPS 6: UVRANG        0           0        UV range to be plotted
AIPS 6: TIMERANG   *all 0                  Time range to be plotted
AIPS 6: STOKES     ' '                     Stokes type(s) to select.
AIPS 6: BIF           0                    Lowest IF number 0=>all
AIPS 6: EIF           0                    Highest IF number 0=>all
AIPS 6: BCHAN         1                    Lowest channel number 0=>all
AIPS 6: ECHAN         0                    Highest channel number 0=>all
AIPS 6: SUBARRAY      0                    Subarray, 0=>1
AIPS 6: ANTENNAS   *all 0                  Antennas to select
AIPS 6: BASELINE   *all 0                  Baselines with ANTENNAS
AIPS 6: DOCALIB       2                    > 0 calibrate data & weights
AIPS 6:                                    > 99 do NOT calibrate weights
AIPS 6: GAINUSE       3                    CL (or SN) table to apply
AIPS 6: DOPOL        -1                    If >0 correct polarization.
AIPS 6: BLVER        -1                    BL table to apply.
AIPS 6: FLAGVER       1                    Flag table version
AIPS 6: DOBAND        1                    If >0 apply bandpass cal.
AIPS 6:                                    Method used depends on value
AIPS 6:                                    of DOBAND (see HELP file).
AIPS 6: BPVER         9                    Bandpass table version
AIPS 6: SMOOTH     *all 0                  Smoothing function. See
AIPS 6: ** press RETURN for more, enter Q or next line to quit print **
#
AIPS 6:                                    HELP SMOOTH for details.
AIPS 6: SHIFT         0           0        Position shift:
AIPS 6:                                    RA, Dec (arcsec)
AIPS 6:                                    0 => no shift
AIPS 6: APARM      *all 0                  Control information:
AIPS 6:                                    1: = 0 => scalar average
AIPS 6:                                       > 0 => vector average
AIPS 6:                                    2: = 0 => self-scale
AIPS 6:                                       > 0 => fixed scale
AIPS 6:                                        (use APARM(3-6))
AIPS 6:                                    3: min. amplitude
AIPS 6:                                    4: max. amplitude
AIPS 6:                                    5: min. phase (degrees)
AIPS 6:                                    6: max. phase
AIPS 6:                                    7: x-axis labelling
AIPS 6:                                       = 0 = > in channels.
AIPS 6:                                       = 1 = > in Hz (or secs
AIPS 6:                                           if corr. fn)
AIPS 6:                                       = 2 = > in m/s
AIPS 6:                                    8: = 0 => plot cross power
AIPS 6:                                       = 1 => plot total power
AIPS 6:                                       = 2 => plot BP table
AIPS 6:                                       = 3 => plot ACF
AIPS 6:                                       = 4 => plot XCF
AIPS 6:                                       = 5 => plot cross power of
AIPS 6:                                              individual antennas
AIPS 6:                                              for cross polaris.
AIPS 6:                                              (STOKES=RL, or LR)
AIPS 6:                                    9: > 0 => plot several IF's
AIPS 6:                                       and/or polarizations
AIPS 6:                                       together as though one
AIPS 6:                                       long spectrum (see HELP)
AIPS 6:                                    10: > 0 => reverse direction
AIPS 6:                                       of plotted spectrum, so
AIPS 6:                                       velocity increases to
AIPS 6: ** press RETURN for more, enter Q or next line to quit print **
#
AIPS 6:                                       right.
AIPS 6: CODETYPE   ' '                     'A&P ', 'AMP ', 'PHAS',
AIPS 6:                                    'R&I ', 'REAL', 'IMAG'
AIPS 6:                                    other => 'A&P '
AIPS 6: POLPLOT    ' '                     Option to display various
AIPS 6:                                    combinations of polzns to
AIPS 6:                                    plot: 'RL/RR', 'RL/LL',
AIPS 6:                                    'LR/RR', 'LR/LL', 'RR/LL'
AIPS 6:                                    'LL/RR'; other = don't use
AIPS 6:                                    this option.
AIPS 6: SOLINT        0                    If SOLINT > 0 then it enables
AIPS 6:                                    the user to make multiple
AIPS 6:                                    plots per pass of POSSM.
AIPS 6:                                    It defines the averaging time
AIPS 6:                                    for each individual plot.
AIPS 6:                                    Task will start at TIMERANG
AIPS 6:                                    and make a plot for every
AIPS 6:                                    SOLINT minutes. If SOLINT
AIPS 6:                                    = -1 will do the same but
AIPS 6:                                    will do scan averages if NX
AIPS 6:                                    table is present.
AIPS 6: NPLOTS        6                    Number of plots per page
AIPS 6: BPARM      *all 0                  More control information:
AIPS 6:                                    1: If = 1 divide by 'channel
AIPS 6:                                       0' before plotting data.
AIPS 6:                                       0 => do not divide.
AIPS 6:                                    2: Start chn. of 'channel 0'
AIPS 6:                                       (0 => determined by POSSM)
AIPS 6:                                    3: Stop chn. of 'channel 0'
AIPS 6:                                       (0 => determined by POSSM)
AIPS 6:                                    4: ignore spectrum when ampl.
AIPS 6:                                       channel 0 < BPARM(4) Jy
AIPS 6:                                    5-9: unused
AIPS 6:                                    10: =1 => don't write header
AIPS 6:                                    info when writing to outfile
AIPS 6: ** press RETURN for more, enter Q or next line to quit print **
#
AIPS 6:                                    useful for appending several
AIPS 6:                                    spectra into a single outfile
AIPS 6:                                    [see EXPLAIN POSSM]
AIPS 6: OUTFILE    ' '
AIPS 6:                                    Filename in which to write
AIPS 6:                                    spectrum. Default = ' ' =
AIPS 6:                                    do not write spectrum. The
AIPS 6:                                    file is written only if
AIPS 6:                                    NPLOTS = 0
AIPS 6: LTYPE         3                    Type of labeling: 1 border,
AIPS 6:                                    2 no ticks, 3 - 6 standard,
AIPS 6:                                    7 - 10 only tick labels
AIPS 6:                                    <0 -> no date/time
AIPS 6: FACTOR        0                    Scale plus signs by FACTOR
AIPS 6: XYRATIO       0                    XY plot ratio: 0 -> 1.636
AIPS 6: BADDISK    *all 0                  Disks to avoid for scratch
AIPS 6: DOTV          1                    > 0 Do plot on the TV, else
AIPS 6:                                    make a plot file
AIPS 6: GRCHAN        0                    Graphics channel 0 => 1.
 >tvini
 >go
AIPS 6: Resumes




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