casacore
ParAngleMachine.h
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1//# ParAngleMachine.h: Converts a direction into parallactic angle
2//# Copyright (C) 2001,2002
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#ifndef MEASURES_PARANGLEMACHINE_H
28#define MEASURES_PARANGLEMACHINE_H
29
30//# Includes
31#include <casacore/casa/aips.h>
32#include <casacore/measures/Measures.h>
33#include <casacore/measures/Measures/MCDirection.h>
34#include <casacore/measures/Measures/MDirection.h>
35#include <casacore/measures/Measures/MCEpoch.h>
36#include <casacore/measures/Measures/MEpoch.h>
37#include <casacore/casa/Quanta/Quantum.h>
38#include <casacore/casa/Quanta/MVDirection.h>
39#include <casacore/casa/Quanta/MVEpoch.h>
40#include <casacore/casa/Arrays/Vector.h>
41
42namespace casacore { //# NAMESPACE CASACORE - BEGIN
43
44//# Forward Declarations
45class MeasFrame;
46
47// <summary> Converts a direction into parallactic angle
48// </summary>
49
50// <use visibility=export>
51
52// <reviewed reviewer="Mark Wieringa" date="2001/10/06" tests="tParAngleMachine.cc" demos="">
53// </reviewed>
54
55// <prerequisite>
56// <li> <linkto class=MDirection>MDirection</linkto> class
57// </prerequisite>
58//
59// <etymology>
60// From Parallactic Angle and machinery
61// </etymology>
62//
63// <synopsis>
64// The construction of a ParAngleMachine class object creates a machine that
65// can create parallactic angles from a series of time epochs given.
66//
67// The machinery needs an input
68// <linkto class=MDirection>MDirection</linkto> to specify the input
69// coordinates reference direction and coordinate system.
70// The parallactic (<em>vertical</em>)
71// angle will be calculated as the angle between the vertical in the
72// local coordinate system (<em>Az, El</em>) through the given direction and
73// the pole of the <em>J2000</em> coordinate system.
74// <note role=tip> To calculate the parallactic angle for another
75// coordinate system pole, add the <src>positionAngle</src> between the
76// <em>J2000</em> system and the pole in the other coordinate system. </note>
77//
78// The machinery also needs a <linkto class=MeasFrame>MeasFrame</linkto>,
79// with a position on Earth and
80// a reference epoch. The reference time is necessary to have an epoch type.
81//
82// The actual calculation of the parallactic angles is done by the
83// <src>operator()</src> accepting a time or a list of times in various
84// formats.
85//
86// The machine calculates the paralaactic angle for the first time given to
87// the machine. For subsequent times that are within a check interval,
88// the angle is calculated assuming that only the hour angle changes within
89// that interval. For moving objects the test interval is always forced
90// to zero. Tests show that the machine with a zero interval is about
91// 8 times faster than using brute force. Having an interval of an
92// hour improves that by another factor of 4.
93// <note role=tip> If the parallactic angles for a series of directions have
94// to be calculated, it is best to have separate machines for each such
95// <em>field</em>. </note>
96// </synopsis>
97//
98// <example>
99// <srcblock>
100// </srcblock>
101// </example>
102//
103// <motivation>
104// To speed up parallactic angle calculations
105// </motivation>
106//
107// <todo asof="2001/09/15">
108// <li>
109// </todo>
110
112 public:
113 //# Constructors
114 // Create an empty machine. It can only be used after appropriate 'set'
115 // methods
117 // Construct for the specified direction
119 // Copy constructor (deep copy)
121 // Copy assignments (deep copy)
123
124 //# Destructor
126
127 //# Operators
128 // Return parallactic angles (epoch in days if given as Double)
129 // <thrown>
130 // <li> AipsError if no frame or a frame without an Epoch (for type) or
131 // Position.
132 // </thrown>
133 // <group>
141 Double operator()(const Double &ep) const;
143 // </group>
144
145 //# Member functions
146 // Will have a group of set methods (in direction; reference time; a frame;
147 // a reference time valid period
148 // <group>
149 void set(const MDirection &in);
150 void set(const MeasFrame &frame);
151 // </group>
152 // Set the test interval (in days) over which to use simple formula
153 void setInterval(const Double ttime);
154
155private:
156
157 //# Data
158 // Input direction
160 // Conversion engine
162 // Measure frame
164 // Converted zenith
166 // Intermediate conversion result
168 // Time of last full solution (in days)
170 // Default time interval over which to do simple solution (days)
172 // Time interval over which to do simple solution (days)
174 // Calculation cache
175 // <group>
183 // </group>
184
185 //# Constructors
186
187 //# Private Member Functions
188 // Get position angle (Epoch is supposed to be in days if Double)
189 // <thrown>
190 // <li> AipsError if no frame or a frame without an Epoch (for type) or
191 // Position.
192 // </thrown>
193 // <group>
196 Double posAngle(const Double &ep) const;
198 // </group>
199 // Initialise machinery
200 void init();
201 // Initialise conversion
202 void initConv() const;
203 // Calculate position angle
204 Double calcAngle(const Double ep) const;
205};
206
207
208} //# NAMESPACE CASACORE - END
209
210#endif
Double posAngle(const Double &ep) const
MVDirection zenith_p
Converted zenith.
Double calcAngle(const Double ep) const
Calculate position angle.
Vector< Double > operator()(const Vector< Double > &ep) const
Double posAngle(const Quantum< Double > &ep) const
Get position angle (Epoch is supposed to be in days if Double)
ParAngleMachine(const ParAngleMachine &other)
Copy constructor (deep copy)
Double operator()(const Double &ep) const
ParAngleMachine & operator=(const ParAngleMachine &other)
Copy assignments (deep copy)
Double intvl_p
Time interval over which to do simple solution (days)
MeasFrame * frame_p
Measure frame.
void initConv() const
Initialise conversion.
Double lastep_p
Time of last full solution (in days)
Double defintvl_p
Default time interval over which to do simple solution (days)
Double UTfactor_p
Calculation cache.
Quantum< Vector< Double > > operator()(const Quantum< Vector< Double > > &ep) const
Return parallactic angles (epoch in days if given as Double)
ParAngleMachine(const MDirection &in)
Construct for the specified direction.
Quantum< Vector< Double > > operator()(const Vector< MEpoch > &ep) const
void setInterval(const Double ttime)
Set the test interval (in days) over which to use simple formula.
ParAngleMachine()
Create an empty machine.
Quantum< Double > operator()(const MEpoch &ep) const
void set(const MDirection &in)
Will have a group of set methods (in direction; reference time; a frame; a reference time valid perio...
MDirection::Convert * convdir_p
Conversion engine.
Vector< Double > posAngle(const Quantum< Vector< Double > > &ep) const
Quantum< Double > operator()(const Quantum< Double > &ep) const
MVDirection mvdir_p
Intermediate conversion result.
Vector< Double > posAngle(const Vector< Double > &ep) const
Quantum< Double > operator()(const MVEpoch &ep) const
void set(const MeasFrame &frame)
void init()
Initialise machinery.
MDirection * indir_p
Input direction.
Quantum< Vector< Double > > operator()(const Vector< MVEpoch > &ep) const
this file contains all the compiler specific defines
Definition: mainpage.dox:28
double Double
Definition: aipstype.h:55