001 /**
002 *
003 */
004 package edu.nrao.sss.astronomy;
005
006 import java.util.Arrays;
007
008 import edu.nrao.sss.util.EnumerationUtility;
009 import edu.nrao.sss.util.StringUtil;
010
011 /**
012 * A frame of rest against which a velocity is measured.
013 * <p>
014 * This list was based on the list found at
015 * <a href="http://www.gb.nrao.edu/~fghigo/gbtdoc/doppler.html">
016 * http://www.gb.nrao.edu/~fghigo/gbtdoc/doppler.html</a>.
017 * <p>
018 * <b>CVS Info:</b>
019 * <table style="margin-left:2em">
020 * <tr><td>$Revision: 161 $</td></tr>
021 * <tr><td>$Date: 2006-12-15 11:48:34 -0700 (Fri, 15 Dec 2006) $</td></tr>
022 * <tr><td>$Author: btruitt $</td></tr>
023 * </table></p>
024 *
025 * @author David M. Harland
026 * @since 2006-03-31
027 */
028 public enum VelocityFrame
029 {
030 /**
031 * Rest frame based on the observer's position.
032 */
033 TOPOCENTRIC,
034
035 /**
036 * Rest frame based on the earth's center of mass.
037 */
038 GEOCENTRIC,
039
040 /**
041 * Rest frame based on our solar system's center of mass.
042 */
043 BARYCENTRIC,
044
045 /**
046 * Rest frame based on our sun's center of mass.
047 */
048 HELIOCENTRIC,
049
050 /**
051 * Conventional Local Standard of Rest.
052 * <p>
053 * From the source in the class comments, this is:
054 * <blockquote>
055 * based on average velocity of stars in the Solar neighborhood.
056 * </blockquote>
057 */
058 LSR_KINEMATIC("LSR-K"),
059
060 /**
061 * Dynamic Local Standard of Rest.
062 * <p>
063 * From the source in the class comments, this is:
064 * <blockquote>
065 * [The] solar peculiar velocity with respect to a frame in circular
066 * motions about the galactic center.
067 * </blockquote>
068 */
069 LSR_DYNAMIC("LSR-D"),
070
071 /**
072 * Rest frame based on our galaxy's center of mass.
073 */
074 GALACTOCENTRIC,
075
076 /**
077 * Rest frame based on the our local group of galaxies' center of mass.
078 */
079 LOCAL_GROUP,
080
081 /**
082 * Rest frame based on <i>COBE measurements of dipole anisotropy</i>.
083 * (The description above was taken from the source listed in
084 * the class comments.)
085 */
086 COSMIC_MICROWAVE_BACKGROUND("CMB"),
087
088 /**
089 * An unknown rest frame.
090 * <p>
091 * This element is used to implement the
092 * <i>Null Object Pattern</i>. In situations where a method might
093 * be tempted to return <i>null</i>, this element is returned instead.</p>
094 */
095 UNKNOWN;
096
097 //private Set<String> aliases = new HashSet<String>();
098 private final String[] aliases;
099
100 private VelocityFrame(String... aliases)
101 {
102 this.aliases = aliases;
103 Arrays.sort(this.aliases);
104 }
105
106 /**
107 * Returns a default velocity frame.
108 * @return a default velocity frame.
109 */
110 public static VelocityFrame getDefault()
111 {
112 return UNKNOWN;
113 }
114
115 /**
116 * Returns a text representation of this enumeration constant.
117 * @return a text representation of this enumeration constant.
118 */
119 public String toString()
120 {
121 return EnumerationUtility.getSharedInstance().enumToString(this);
122 }
123
124 /**
125 * Returns the velocity frame represented by {@code text}.
126 * <p>
127 * For details about the transformation, see
128 * {@link EnumerationUtility#enumFromString(Class, String)}.</p>
129 *
130 * @param text a text representation of a velocity frame.
131 *
132 * @return the velocity frame system represented by {@code text}.
133 */
134 public static VelocityFrame fromString(String text)
135 {
136 //Try standard approach first
137 VelocityFrame result = EnumerationUtility.getSharedInstance()
138 .enumFromString(VelocityFrame.class,
139 text);
140 //If no match found, search aliases
141 if (result == null)
142 {
143 text = StringUtil.getInstance().normalizeString(text);
144 for (VelocityFrame elem : VelocityFrame.values())
145 {
146 //See if the parameter name is in the list of the epoch's acceptable names.
147 //NOTE: This relies on the fact that the aliases have been sorted.
148 if (Arrays.binarySearch(elem.aliases, text.toUpperCase()) >= 0)
149 {
150 result = elem;
151 break;
152 }
153 }
154 }
155
156 return result;
157 }
158 }