Bandpass: Difference between revisions
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Created page with '== Help for bandpass: == <pre> Calculates a bandpass calibration solution Determines the amplitude and phase as a function of frequency for each spectral window c…' |
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Revision as of 20:43, 16 March 2012
Help for bandpass:
Calculates a bandpass calibration solution Determines the amplitude and phase as a function of frequency for each spectral window containing more than one channel. Strong sources (or many observations of moderately strong sources) are needed to obtain accurate bandpass functions. The two solution choices are: Individual antenna/based channel solutions 'B'; and a polynomial fit over the channels 'BPOLY'. The 'B' solutions can determined at any specified time interval, and is recommended if each channel has good signal-to-noise. Other, 'BPOLY' is recommended. Keyword arguments: vis -- Name of input visibility file default: none; example: vis='ngc5921.ms' caltable -- Name of output bandpass calibration table default: none; example: caltable='ngc5921.bcal' --- Data Selection (see help par.selectdata for more detailed information) field -- Select field using field id(s) or field name(s). [run listobs to obtain the list id's or names] default: ''=all fields If field string is a non-negative integer, it is assumed a field index otherwise, it is assumed a field name field='0~2'; field ids 0,1,2 field='0,4,5~7'; field ids 0,4,5,6,7 field='3C286,3C295'; field named 3C286 adn 3C295 field = '3,4C*'; field id 3, all names starting with 4C spw -- Select spectral window/channels default: ''=all spectral windows and channels spw='0~2,4'; spectral windows 0,1,2,4 (all channels) spw='<2'; spectral windows less than 2 (i.e. 0,1) spw='0:5~61'; spw 0, channels 5 to 61 spw='0,10,3:3~45'; spw 0,10 all channels, spw 3, channels 3 to 45. spw='0~2:2:6'; spw 0,1,2 with channels 2 through 6 in each. spw='0:0~10;15~60'; spectral window 0 with channels 0-10,15-60 NOTE: ';' to separate channel selections spw='0:0~10,1:20~30,2:1;2;3'; spw 0, channels 0-10, spw 1, channels 20-30, and spw 2, channels, 1,2 and 3 selectdata -- Other data selection parameters default: True timerange -- Select data based on time range: default = '' (all); examples, timerange = 'YYYY/MM/DD/hh:mm:ss~YYYY/MM/DD/hh:mm:ss' Note: if YYYY/MM/DD is missing dat defaults to first day in data set timerange='09:14:0~09:54:0' picks 40 min on first day timerange= '25:00:00~27:30:00' picks 1 hr to 3 hr 30min on next day timerange='09:44:00' data within one integration of time timerange='>10:24:00' data after this time uvrange -- Select data within uvrange (default meters) default: '' (all); example: uvrange='0~1000kl'; uvrange from 0-1000 kilo-lamgda uvrange='>4kl';uvranges greater than 4 kilo-lambda antenna -- Select data based on antenna/baseline default: '' (all) If antenna string is a non-negative integer, it is assumed an antenna index otherwise, it is assumed as an antenna name antenna='5&6'; baseline between antenna index 5 and index 6. antenna='VA05&VA06'; baseline between VLA antenna 5 and 6. antenna='5&6;7&8'; baseline 5-6 and 7-8 antenna='5'; all baselines with antenna 5 antenna='5,6,10'; all baselines with antennas 5, 6 and 10 scan -- Select data based on scan number - New, under developement default: '' (all); example: scan='>3' msselect -- Optional complex data selection (ignore for now) --- Solution parameters solint -- Solution interval (units optional) default: 'inf' (~infinite, up to boundaries controlled by combine); Options: 'inf' (~infinite), 'int' (per integration), any float or integer value with or without units examples: solint='1m'; solint='60s', solint=60 --> 1 minute solint='0s'; solint=0; solint='int' --> per integration solint-'-1s'; solint='inf' --> ~infinite, up to boundaries enforced by combine combine -- Data axes to combine for solving default: 'scan' --> solutions will break at field and spw boundaries, but may extend over multiple scans (per field and spw) up to solint. Options: '','scan','spw',field', or any comma-separated combination example: combine='scan,spw' --> extend solutions over scan boundaries (up to the solint), and combine spws for solving refant -- Reference antenna name (string) default: '' (no reference antenna) example: refant='13' (antenna with index 13) refant='VA04' (VLA antenna #4) Use 'go listobs' for antenna listing minblperant -- Minimum number of baselines required per antenna for each solve Antennas with fewer baaselines are excluded from solutions. Amplitude solutions with fewer than 4 baselines, and phase solutions with fewer than 3 baselines are only trivially constrained, and are no better than baseline-based solutions. default: 4 example: minblperant=10 => Antennas participating on 10 or more baselines are included in the solve solnorm -- Normalize bandpass amplitudes and phase for each spw, pol, ant, and timestamp default: False (no normalization) bandtype -- Type of bandpass solution (B or BPOLY) default: 'B'; example: bandtype='BPOLY' 'B' does a channel by channel solution for each specified spw. 'BPOLY' is somewhat experimental. It will fit an nth order polynomial for the amplitude and phase as a function of frequency. Only one fit is made for all specified spw, and edge channels should be omitted. Use taskname=plotcal in order to compare the results from B and BPOLY. fillgaps -- Fill flagged solution channels by interpolation default: 0 (don't interpolate) example: fillgaps=3 (interpolate gaps 3 channels wide and narrower) degamp -- Polynomial degree for BPOLY amplitude solution default: 3; example: degamp=2 degphase -- Polynomial degree for BPOLY phase solution default: 3; example: degphase=2 visnorm -- Normalize data prior to BPOLY solution default: False; example: visnorm=True maskcenter -- Number of channels to avoid in center of each band default: 0; example: maskcenter=5 (BPOLY only) maskedge -- Fraction of channels to avoid at each band edge (in %) default: 5; example: maskedge=3 (BPOLY only) append -- Append solutions to the (existing) table default: False; example: append=True --- Other calibrations to apply on the fly before determining bandpass solution gaintable -- Gain calibration table(s) to apply default: '' (none); examples: gaintable='ngc5921.gcal' gaintable=['ngc5921.ampcal','ngc5921.phcal'] gainfield -- Select a subset of calibrators from gaintable(s) default:'' ==> all sources in table; same syntax as field example: gainfield='0~3' gainfield=['0~3','4~6'] interp -- Interpolation mode (in time) to use for each gaintable default: '' --> 'linear' for all gaintable(s) example: interp='nearest' interp=['nearest','linear'] Options: 'nearest', 'linear', 'aipslin' spwmap -- Spectral windows combinations to form for gaintable(s) default: [] (apply solutions from each spw to that spw only) Example: spwmap=[0,0,1,1] means apply the caltable solutions from spw = 0 to the spw 0,1 and spw 1 to spw 2,3. spwmap=[[0,0,1,1],[0,1,0,1]] append -- Append solutions to the (existing) table default: False; example: append=True --- Other calibrations to apply on the fly before determining bandpass solution gaintable -- Gain calibration table(s) to apply default: '' (none); examples: gaintable='ngc5921.gcal' gaintable=['ngc5921.ampcal','ngc5921.phcal'] gainfield -- Select a subset of calibrators from gaintable(s) default:'' ==> all sources in table; same syntax as field example: gainfield='0~3' gainfield=['0~3','4~6'] interp -- Interpolation mode (in time) to use for each gaintable default: '' --> 'linear' for all gaintable(s) example: interp='nearest' interp=['nearest','linear'] Options: 'nearest', 'linear', 'aipslin' spwmap -- Spectral windows combinations to form for gaintable(s) default: [] (apply solutions from each spw to that spw only) Example: spwmap=[0,0,1,1] means apply the caltable solutions from spw = 0 to the spw 0,1 and spw 1 to spw 2,3. spwmap=[[0,0,1,1],[0,1,0,1]] gaincurve -- Apply internal VLA antenna gain curve correction (True/False) default: False; Use gaincurve=True ONLY for VLA data opacity -- Opacity correction to apply (nepers) default: 0.0 (no opacity correction) example: opacity=0.051 Typical VLA values are: 5 GHz - 0.013, 8 GHz - 0.013 15 GHz - 0.016, 23 GHz - 0.051, 43 GHz - 0.07 parang -- If True, apply the parallactic angle correction (required for polarization calibration) default: False