Line data Source code
1 : //# MSUVWGenerator.h: Generate and insert the (u, v, w)s of a MS.
2 : //# Copyright (C) 2008
3 : //# Associated Universities, Inc. Washington DC, USA.
4 : //#
5 : //# This library is free software; you can redistribute it and/or modify it
6 : //# under the terms of the GNU Library General Public License as published by
7 : //# the Free Software Foundation; either version 2 of the License, or (at your
8 : //# option) any later version.
9 : //#
10 : //# This library is distributed in the hope that it will be useful, but WITHOUT
11 : //# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 : //# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
13 : //# License for more details.
14 : //#
15 : //# You should have received a copy of the GNU Library General Public License
16 : //# along with this library; if not, write to the Free Software Foundation,
17 : //# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
18 : //#
19 : //# Correspondence concerning AIPS++ should be addressed as follows:
20 : //# Internet email: aips2-request@nrao.edu.
21 : //# Postal address: AIPS++ Project Office
22 : //# National Radio Astronomy Observatory
23 : //# 520 Edgemont Road
24 : //# Charlottesville, VA 22903-2475 USA
25 : //#
26 : //# $Id$
27 : //#
28 : #ifndef MS_MSUVWGENERATOR_H
29 : #define MS_MSUVWGENERATOR_H
30 :
31 : #include <casacore/casa/aips.h>
32 : #include <casacore/casa/BasicSL/String.h>
33 : #include <casacore/ms/MeasurementSets/MeasurementSet.h>
34 : #include <casacore/ms/MeasurementSets/MSColumns.h>
35 : #include <casacore/measures/Measures/MBaseline.h>
36 :
37 : // FTMachine::rotateUVW(casacore::Matrix<casacore::Double>& uvw, casacore::Vector<casacore::Double>& dphase,
38 : // const VisBuffer& vb)
39 :
40 : namespace casacore{
41 :
42 : class MeasurementSet;
43 : class LogIO;
44 : }
45 :
46 : namespace casa { //# NAMESPACE CASA - BEGIN
47 :
48 :
49 : // <summary>Generates and inserts the (u, v, w)s of a casacore::MS that may or may not
50 : // already have them. Includes antenna offsets when known.</summary>
51 : // <use visibility=export>
52 : //
53 : // <reviewed reviewer="" date="yyyy/mm/dd" tests="" demos="">
54 : // </reviewed>
55 : //
56 : // <prerequisite>
57 : // <li> <linkto class=casacore::MeasurementSet>MeasurementSet</linkto>
58 : // <li> <linkto class=casacore::Measure>Measure</linkto>
59 : // </prerequisite>
60 : //
61 : // <etymology>
62 : // It generates a UVW column for the casacore::MS, whether or not it already has one.
63 : // It is an adaptation of alma/apps/asdm2MS/UvwCoords to work with MSes instead
64 : // of ASDMs.
65 : // </etymology>
66 : //
67 : // <synopsis>
68 : // (u, v, w)s are needed for imaging, but some data sets may not come with them
69 : // included, or the (u, v, w)s may need correction.
70 : // </synopsis>
71 : //
72 : // <motivation>
73 : // Currently (10/30/2008), ASDMs from either the ALMA Test Facility or the
74 : // EVLA do not come with (u, v, w)s, and need to be processed with the UVFIX
75 : // task in AIPS. It would be preferable to process them entirely inside CASA.
76 : // </motivation>
77 : //
78 : // <todo asof="11/20/2008">
79 : // It requires as input the casacore::MS timeCentroids item which is an output in the
80 : // ASDM DAMs.
81 : // - the use-case when the timeCentroid is baseline-based and or spectral
82 : // window based.
83 : // - correlationMode filter (hopefully handled by SDM -> casacore::MS import routines).
84 : // direction item in the field table.
85 : // @note The current limitations are set by the status of the ASDM
86 : // - OTF not supported due to a limitation in the model of the phase
87 : // </todo>
88 : class MSUVWGenerator
89 : {
90 : public:
91 : // Constructor
92 : // @param ms_ref Reference to the casacore::MS's columns.
93 : // @post - The relative positions for all the antennas in the Antenna
94 : // table are in bl_an_p.
95 : // - timeRes_p has been conservatively calculated using rough
96 : // estimates of the maximum baseline length and field of view.
97 : MSUVWGenerator(casacore::MSColumns& ms_ref, const casacore::MBaseline::Types bltype,
98 : const casacore::Muvw::Types uvwtype);
99 :
100 : // Destructor
101 : ~MSUVWGenerator();
102 :
103 : // Determine the uvw for a single phaseDir and timeCentroid, and pair of
104 : // feeds (which may be the same).
105 : //
106 : // @param ant1 Row number in the ANTENNA table of the 1st antenna.
107 : // @param feed1 Row number in the FEED table of the 1st feed.
108 : // @param ant1 Row number in the ANTENNA table of the 2nd antenna.
109 : // @param feed2 Row number in the FEED table of the 2nd feed.
110 : // @param uvw The returned UVW coordinates.
111 : void uvw_bl(const casacore::uInt ant1, const casacore::uInt feed1,
112 : const casacore::uInt ant2, const casacore::uInt feed2, casacore::Array<casacore::Double>& uvw);
113 :
114 : // Calculate the uvws for the field IDs in flds that are not -1, and set
115 : // those phase directions according to phaseDirs.
116 : // @param flds A map from row numbers in the FIELD table to
117 : // indices in phaseDirs. For example, if the casacore::MS has
118 : // 5 fields, and the user wants to (re)calculate the
119 : // UVWs of only 0, 2, and 4, phaseDirs will have 3
120 : // entries and flds will be [0, -1, 1, -1, 2].
121 : casacore::Bool make_uvws(const casacore::Vector<casacore::Int> flds);
122 : private:
123 : // Sets up the antenna positions as baselines (bl_an_p), the number of
124 : // antennas (nant_p), and timeRes_p.
125 : void fill_bl_an(casacore::Vector<casacore::MVBaseline>& bl_an_p);
126 :
127 : // Determine antUVW_p for every member of the sequence of antennas
128 : // defining a (sub)array.
129 : // @param timeCentroid An epoch, the 'when' characterization.
130 : // @param fldID The row number in the FIELD table which gives
131 : // the phase tracking center.
132 : // @param WSRTConvention If true (WSRT only?), the l in the ul + vm
133 : // phase calculation decreases toward increasing
134 : // RA. If false (VLA), it increases with
135 : // increasing RA. See the code for more info.
136 : // @note This function only calculates UVWs for a single time and a
137 : // single phase center. Fields can potentially have multiple phase
138 : // directions, so be prepared to call this function from within a loop
139 : // that also takes care of setting timeCentroid and phaseDir.
140 : // @warning timeCentroid can be initialized like
141 : // casacore::MEpoch timeCentroid(casacore::Quantity(<double>, "s"), casacore::MEpoch::TAI);
142 : // but the accuracy is limited since there is no extra precision
143 : // attribute (see Main table of casacore::MS v2).
144 : void uvw_an(const casacore::MEpoch& timeCentroid, const casacore::Int fldID,
145 : const casacore::Bool WSRTConvention=false);
146 :
147 : // (Sub-)array parameters constraining order and size of the output vector
148 : // of UVW coords triplets.
149 : // struct ArrayParam{
150 : // public:
151 : // casacore::Int subarrayId; // (sub)array identifier
152 : // vector<Tag> v_ant; //<! sequence of antennas
153 : // unsigned int nrepeat; //<! number of casacore::MS main table rows
154 : // // per antenna baseline
155 : // Enum<CorrelationMode> e_correlationMode; //<! correlation mode (original
156 : // // mode passed through the user
157 : // // filter) (FOLLOWUP: is this needed?)
158 : // string show(){
159 : // ostringstream os;
160 : // os << " nrepeat " << nrepeat;
161 : // return os.str();
162 : // }
163 : //};
164 :
165 : //****************** Member variables ********************************
166 :
167 : //**************** Initialized by ctor, ******************************
168 : //**************** so they should appear ******************************
169 : //**************** here in the same order ******************************
170 : //**************** as they do in the ctor. ******************************
171 :
172 : casacore::MSColumns& msc_p; // the columns of the measurement set.
173 :
174 : // casacore::Coordinate system selectors.
175 : casacore::MBaseline::Ref bl_csys_p;
176 :
177 : const casacore::MSAntennaColumns& antColumns_p;
178 :
179 : // The antenna positions of ms_p in ITRF. It cannot be const because of the
180 : // need to update satellite positions.
181 : // antPositions_p and antOffset_p are references and must therefore be
182 : // initialized in the initialization list.
183 : const casacore::ROScalarMeasColumn<casacore::MPosition>& antPositions_p;
184 :
185 : // The offsets between the phase reference point (see feed_offsets below for
186 : // clarification) of each antenna and the closest point which is fixed
187 : // relative to the antenna position (i.e. an axis). Since no one else has
188 : // defined it yet, I am defining it as the offset when the antenna is
189 : // pointing at zenith, oriented so that if it slewed down, it would move
190 : // toward the north. (x, y, z) = (east, north, up).
191 : //
192 : // This appears to be a required column of the ANTENNA table in version 2.0
193 : // of the casacore::MeasurementSet definition
194 : // (http://aips2.nrao.edu/docs/notes/229/229.html), so it is assumed to be
195 : // present. However, it is usually a set of zeroes, based on the common
196 : // belief that it is only needed for heterogeneous arrays, since the
197 : // receivers of homogeneous arrays move in concert. That is not true when
198 : // there are independent pointing errors.
199 : const casacore::ROScalarMeasColumn<casacore::MPosition>& antOffset_p;
200 :
201 : // The position of the first antenna.
202 : casacore::MPosition refpos_p;
203 :
204 : // Ditto for feed.
205 : //const casacore::MSFeedColumns *feedColumns_;
206 :
207 : // The offset between the feed and the phase reference point of each antenna
208 : // in the same frame as ant_offsets. Therefore the feed position is
209 : // ant_positions_p(ant) + [rotation matrix](pointing) (ant_offsets_p[ant] +
210 : // feed_offsets_p[ant])
211 : const casacore::ROScalarMeasColumn<casacore::MPosition>& feedOffset_p;
212 :
213 : casacore::MBaseline::Types refposref_p;
214 :
215 : // The antenna positions - refpos_p.getValue().
216 : casacore::Vector<casacore::MVBaseline> bl_an_p;
217 :
218 : casacore::uInt nant_p; // # of antennas
219 :
220 : // The minimum time difference for forcing an update of the UVWs. We're not
221 : // trying to do time averaging here, so it should be small, but not so small
222 : // that uvw_an() is called for every baseline, even when the times are
223 : // practically the same.
224 : casacore::Double timeRes_p;
225 :
226 : //************* Initialized later, if at all. ********************
227 :
228 : // Log functions and variables
229 : casacore::LogIO sink_p;
230 0 : casacore::LogIO& logSink() {return sink_p;}
231 :
232 : //map<Tag, ArrayParam> m_array_p; // FIX: Tag
233 :
234 : // The UVW "positions" of each antenna being used during a time bin,
235 : // i.e. the (u, v, w) of the baseline between antennas m and n is
236 : // antUVW_p[n] - antUVW_p[m].
237 : // <todo asof="02/18/2009">
238 : // Generalize to multifeed systems.
239 : // </todo>
240 : casacore::Vector<casacore::Vector<casacore::Double> > antUVW_p;
241 :
242 : // the 3 fundamental attributes of the state machine
243 : casacore::ArrayColumn<casacore::Double> phaseDir_p;
244 : //casacore::Int subarrayId_p;
245 :
246 : // The number of wavelengths by which a feed may move relative to the
247 : // corresponding feed in another antenna of the array without requiring the
248 : // offset to be included in uvw calculations. If < 0 the offset will always
249 : // be included.
250 : //
251 : // Offsets include:
252 : // ant_offset: OFFSET in the ANTENNA table of an MS.
253 : // The separation between an antenna's "phase reference
254 : // point" and its closest point (usu. an axis) fixed rel
255 : // to its position.
256 : //
257 : // feed_offset: POSITION in the FEED table of an MS.
258 : // The separation between a feed and ant_pos + ant_offset.
259 : // Just another offset to add to ant_offset, but unlike
260 : // ant_offset it is likely to change when the band is
261 : // changed.
262 : //
263 : // rec_offset: Not found in MSes, acc. to vers. 2 of of the MeasurementSet
264 : // definition (http://aips2.nrao.edu/docs/notes/229/229.html).
265 : // The separation between a receptor and its feed.
266 : // Only needed for feed arrays. The above URL defines a feed
267 : // (incl. feed arrays) as a set of receptors that should be
268 : // calibrated as a single entity. Predicting how observers
269 : // will decide to calibrate feed arrays is difficult,
270 : // especially since there are no interferometers with feed
271 : // arrays yet, but it can be argued that rec_offset can be
272 : // ignored in many cases. If a feed array's output is
273 : // combined before leaving the feed (i.e. a beamforming
274 : // array), it may as well be treated as a single feed. If the
275 : // receptor outputs are kept separate longer, they likely need
276 : // to be calibrated separately and get their own FEED tables.
277 : //
278 : // They affect how the baselines of heterogeneous arrays vary with phase
279 : // tracking direction, and make the baselines of any array depend on pointing
280 : // errors. The latter effect is often neglected, and the offsets are written
281 : // as sets of zeroes, even though they really are not.
282 : //
283 :
284 : //
285 : };
286 :
287 : } //# NAMESPACE CASA - END
288 :
289 : #endif
|
