diff --git a/SGDP4.cpp b/SGDP4.cpp
index 2c64386..2b8abbd 100644
--- a/SGDP4.cpp
+++ b/SGDP4.cpp
@@ -51,14 +51,14 @@ void SGDP4::SetTle(const Tle& tle) {
     /*
      * extract and format tle data
      */
-    mean_anomoly_ = tle.GetField(Tle::FLD_M, Tle::U_RAD);
-    ascending_node_ = tle.GetField(Tle::FLD_RAAN, Tle::U_RAD);
-    argument_perigee_ = tle.GetField(Tle::FLD_ARGPER, Tle::U_RAD);
-    eccentricity_ = tle.GetField(Tle::FLD_E);
-    inclination_ = tle.GetField(Tle::FLD_I, Tle::U_RAD);
-    mean_motion_ = tle.GetField(Tle::FLD_MMOTION) * TWOPI / Globals::MIN_PER_DAY();
-    bstar_ = tle.GetField(Tle::FLD_BSTAR);
-    epoch_ = tle.GetEpoch();
+    mean_anomoly_ = tle.MeanAnomaly(false);
+    ascending_node_ = tle.RightAscendingNode(false);
+    argument_perigee_ = tle.ArgumentPerigee(false);
+    eccentricity_ = tle.Eccentricity();
+    inclination_ = tle.Inclination(false);
+    mean_motion_ = tle.MeanMotion() * TWOPI / Globals::MIN_PER_DAY();
+    bstar_ = tle.BStar();
+    epoch_ = tle.Epoch();
 
     /*
      * error checks
diff --git a/Tle.cpp b/Tle.cpp
index 62d9b63..ec7545c 100644
--- a/Tle.cpp
+++ b/Tle.cpp
@@ -3,7 +3,17 @@
 #include <cassert>
 #include <cstdlib>
 
+Tle::Tle(const std::string& line_one, const std::string& line_two) {
+
+    name_.erase();
+    line_one_ = line_one;
+    line_two_ = line_two;
+
+    Initialize();
+}
+
 Tle::Tle(const std::string& name, const std::string& line_one, const std::string& line_two) {
+
     name_ = name;
     line_one_ = line_one;
     line_two_ = line_two;
@@ -12,105 +22,48 @@ Tle::Tle(const std::string& name, const std::string& line_one, const std::string
 }
 
 Tle::Tle(const Tle& tle) {
+
     name_ = tle.name_;
     line_one_ = tle.line_one_;
     line_two_ = tle.line_two_;
-    date_ = tle.date_;
 
-    for (int fld = FLD_FIRST; fld < FLD_LAST; fld++) {
-        fields_[fld] = tle.fields_[fld];
-    }
+    norad_number_ = tle.norad_number_;
+    international_designator_ = tle.international_designator_;
+    epoch_ = tle.epoch_;
+    mean_motion_dot_ = tle.mean_motion_dot_;
+    mean_motion_dot2_ = tle.mean_motion_dot2_;
+    bstar_ = tle.bstar_;
+    inclination_ = tle.inclination_;
+    right_ascending_node_ = tle.right_ascending_node_;
+    eccentricity_ = tle.eccentricity_;
+    argument_perigee_ = tle.argument_perigee_;
+    mean_anomaly_ = tle.mean_anomaly_;
+    mean_motion_ = tle.mean_motion_;
+    orbit_number_ = tle.orbit_number_;
 }
 
 Tle::~Tle() {
 }
 
-double Tle::GetField(TleField fld, TleUnits units) const {
-    assert((FLD_FIRST <= fld) && (fld < FLD_LAST));
-    assert((U_FIRST <= units) && (units < U_LAST));
-
-    double value = fields_[fld].second;
-    double converted = 0.0;
-
-    switch (fld) {
-        case FLD_I:
-        case FLD_RAAN:
-        case FLD_ARGPER:
-        case FLD_M:
-        {
-            /*
-             * native format is degrees
-             */
-            if (units == U_RAD)
-                converted = Globals::Deg2Rad(value);
-            break;
-        }
-        default:
-        {
-            converted = value;
-            break;
-        }
-    }
-
-    return converted;
-}
-
 /*
- * get field represented as a string
- */
-std::string Tle::GetFieldString(TleField fld, bool append_units) const {
-    assert((FLD_FIRST <= fld) && (fld < FLD_LAST));
-
-    std::string str = fields_[fld].first;
-
-    if (append_units)
-        str += GetUnits(fld);
-
-    return str;
-}
-
-/*
- * get the units for a field
- */
-std::string Tle::GetUnits(TleField field) const {
-    static const std::string strDegrees = " degrees";
-    static const std::string strRevsPerDay = " revs / day";
-    static const std::string strNull = "";
-
-    switch (field) {
-        case FLD_I:
-        case FLD_RAAN:
-        case FLD_ARGPER:
-        case FLD_M:
-            return strDegrees;
-
-        case FLD_MMOTION:
-            return strRevsPerDay;
-
-        default:
-            return strNull;
-    }
-}
-
-/*
- * convert a raw string into an exponent string
+ * convert a tle raw string into an exponent string
  */
 std::string Tle::ExpToDecimal(const std::string& str) {
-    static const int kColumnSign = 0;
-    static const int kLengthSign = 1;
-    static const int kColumnMantissa = 1;
-    static const int kLengthMantissa = 5;
-    static const int kColumnExp = 6;
-    static const int kLengthExp = 2;
+
+    static const int START_SIGN = 0;
+    static const int LENGTH_SIGN = 1;
+    static const int START_MANTISSA = 1;
+    static const int LENGTH_MANTISSA = 5;
+    static const int START_EXP = 6;
+    static const int LENGTH_EXP = 2;
 
     assert(8 == str.length());
 
-    std::string value;
-    value = str.substr(kColumnSign, kLengthSign);
+    std::string value = str.substr(START_SIGN, LENGTH_SIGN);
     value += ".";
-    value += str.substr(kColumnMantissa, kLengthMantissa);
+    value += str.substr(START_MANTISSA, LENGTH_MANTISSA);
     value += "e";
-    value += str.substr(kColumnExp, kLengthExp);
+    value += str.substr(START_EXP, LENGTH_EXP);
 
     return value;
 }
@@ -119,6 +72,12 @@ std::string Tle::ExpToDecimal(const std::string& str) {
  * extract all variables
  */
 void Tle::Initialize() {
+
+    std::string temp;
+
+    /*
+     * trim whitespace
+     */
     TrimLeft(name_);
     TrimRight(name_);
     TrimLeft(line_one_);
@@ -126,104 +85,129 @@ void Tle::Initialize() {
     TrimLeft(line_two_);
     TrimRight(line_two_);
 
-    assert(!name_.empty());
-    assert(!line_one_.empty());
-    assert(!line_two_.empty());
-
-    assert(IsValidLine(line_one_, Tle::LINE_ONE));
-    assert(IsValidLine(line_two_, Tle::LINE_TWO));
+    /*
+     * check the two lines are valid
+     */
+    assert(IsValidPair(line_one_, line_two_));
 
     /*
      * line 1
      */
 
-    fields_[FLD_NORADNUM].first = line_one_.substr(TLE1_COL_SATNUM, TLE1_LEN_SATNUM);
-    fields_[FLD_INTLDESC].first = line_one_.substr(TLE1_COL_INTLDESC_A, TLE1_LEN_INTLDESC_A +
-            TLE1_LEN_INTLDESC_B + TLE1_LEN_INTLDESC_C);
-    fields_[FLD_EPOCHYEAR].first = line_one_.substr(TLE1_COL_EPOCH_A, TLE1_LEN_EPOCH_A);
+    temp = line_one_.substr(TLE1_COL_NORADNUM, TLE1_LEN_NORADNUM).c_str();
+    norad_number_ = atoi(temp.c_str());
+    /*
+     * if blank use norad number
+     */
+    if (name_.empty())
+        name_ = temp;
 
-    fields_[FLD_EPOCHDAY].first = line_one_.substr(TLE1_COL_EPOCH_B, TLE1_LEN_EPOCH_B);
+    international_designator_ = line_one_.substr(TLE1_COL_INTLDESC_A, TLE1_LEN_INTLDESC_A + TLE1_LEN_INTLDESC_B + TLE1_LEN_INTLDESC_C);
+
+    int year = atoi(line_one_.substr(TLE1_COL_EPOCH_A, TLE1_LEN_EPOCH_A).c_str());
+    double day = atof(line_one_.substr(TLE1_COL_EPOCH_B, TLE1_LEN_EPOCH_B).c_str());
+    /*
+     * generate julian date for epoch
+     */
+    if (year < 57)
+        year += 2000;
+    else
+        year += 1900;
+
+    epoch_ = Julian(year, day);
 
     if (line_one_[TLE1_COL_MEANMOTIONDT] == '-') {
-        // value is negative
-        fields_[FLD_MMOTIONDT].first = "-0";
+        temp = "-0";
     } else
-        fields_[FLD_MMOTIONDT].first = "0";
+        temp = "0";
+    temp += line_one_.substr(TLE1_COL_MEANMOTIONDT + 1, TLE1_LEN_MEANMOTIONDT);
+    mean_motion_dot_ = atof(temp.c_str());
 
-    fields_[FLD_MMOTIONDT].first += line_one_.substr(TLE1_COL_MEANMOTIONDT + 1, TLE1_LEN_MEANMOTIONDT);
+    temp = ExpToDecimal(line_one_.substr(TLE1_COL_MEANMOTIONDT2, TLE1_LEN_MEANMOTIONDT2));
+    mean_motion_dot2_ = atof(temp.c_str());
 
-    // decimal point assumed; exponential notation
-    fields_[FLD_MMOTIONDT2].first = ExpToDecimal(line_one_.substr(TLE1_COL_MEANMOTIONDT2, TLE1_LEN_MEANMOTIONDT2));
-
-    // decimal point assumed; exponential notation
-    fields_[FLD_BSTAR].first = ExpToDecimal(line_one_.substr(TLE1_COL_BSTAR, TLE1_LEN_BSTAR));
-
-    fields_[FLD_SET].first = line_one_.substr(TLE1_COL_ELNUM, TLE1_LEN_ELNUM);
-    TrimLeft(fields_[FLD_SET].first);
+    temp = ExpToDecimal(line_one_.substr(TLE1_COL_BSTAR, TLE1_LEN_BSTAR).c_str());
+    bstar_ = atof(temp.c_str());
 
     /*
      * line 2
      */
 
-    fields_[FLD_I].first = line_two_.substr(TLE2_COL_INCLINATION, TLE2_LEN_INCLINATION);
-    TrimLeft(fields_[FLD_I].first);
+    temp = line_two_.substr(TLE2_COL_INCLINATION, TLE2_LEN_INCLINATION);
+    TrimLeft(temp);
+    inclination_ = atof(temp.c_str());
 
-    fields_[FLD_RAAN].first = line_two_.substr(TLE2_COL_RAASCENDNODE, TLE2_LEN_RAASCENDNODE);
-    TrimLeft(fields_[FLD_RAAN].first);
+    temp = line_two_.substr(TLE2_COL_RAASCENDNODE, TLE2_LEN_RAASCENDNODE);
+    TrimLeft(temp);
+    right_ascending_node_ = atof(temp.c_str());
 
-    // decimal point is assumed
-    fields_[FLD_E].first = "0.";
-    fields_[FLD_E].first += line_two_.substr(TLE2_COL_ECCENTRICITY, TLE2_LEN_ECCENTRICITY);
+    temp = "0.";
+    temp += line_two_.substr(TLE2_COL_ECCENTRICITY, TLE2_LEN_ECCENTRICITY);
+    eccentricity_ = atof(temp.c_str());
 
-    fields_[FLD_ARGPER].first = line_two_.substr(TLE2_COL_ARGPERIGEE, TLE2_LEN_ARGPERIGEE);
-    TrimLeft(fields_[FLD_ARGPER].first);
+    temp = line_two_.substr(TLE2_COL_ARGPERIGEE, TLE2_LEN_ARGPERIGEE);
+    TrimLeft(temp);
+    argument_perigee_ = atof(temp.c_str());
 
-    fields_[FLD_M].first = line_two_.substr(TLE2_COL_MEANANOMALY, TLE2_LEN_MEANANOMALY);
-    TrimLeft(fields_[FLD_M].first);
+    temp = line_two_.substr(TLE2_COL_MEANANOMALY, TLE2_LEN_MEANANOMALY);
+    TrimLeft(temp);
+    mean_anomaly_ = atof(temp.c_str());
 
-    fields_[FLD_MMOTION].first = line_two_.substr(TLE2_COL_MEANMOTION, TLE2_LEN_MEANMOTION);
-    TrimLeft(fields_[FLD_MMOTION].first);
+    temp = line_two_.substr(TLE2_COL_MEANMOTION, TLE2_LEN_MEANMOTION);
+    TrimLeft(temp);
+    mean_motion_ = atof(temp.c_str());
 
-    fields_[FLD_ORBITNUM].first = line_two_.substr(TLE2_COL_REVATEPOCH, TLE2_LEN_REVATEPOCH);
-    TrimLeft(fields_[FLD_ORBITNUM].first);
+    temp = line_two_.substr(TLE2_COL_REVATEPOCH, TLE2_LEN_REVATEPOCH);
+    TrimLeft(temp);
+    orbit_number_ = atoi(temp.c_str());
+}
 
-    // update double variables
-    for (int fld = FLD_FIRST; fld < FLD_LAST; fld++) {
-        fields_[fld].second = atof(fields_[fld].first.c_str());
-    }
+/*
+ * check the two lines have matching norad numbers
+ * and that the lines themselves are valid
+ */
+bool Tle::IsValidPair(const std::string& line1, const std::string& line2) {
 
-    int year = static_cast<int> (GetField(Tle::FLD_EPOCHYEAR));
-    if (year < 57)
-        year += 2000;
-    else
-        year += 1900;
-    double day = GetField(Tle::FLD_EPOCHDAY);
+    if (atoi(line1.substr(TLE1_COL_NORADNUM, TLE1_LEN_NORADNUM).c_str()) !=
+            atoi(line2.substr(TLE2_COL_NORADNUM, TLE2_LEN_NORADNUM).c_str()))
+        return false;
 
-    date_ = Julian(year, day);
+    if (!IsValidLine(line1, 1))
+        return false;
+
+    if (!IsValidLine(line2, 2))
+
+        return false;
+
+    return true;
 }
 
 /*
  * validate a line
  */
-bool Tle::IsValidLine(std::string& str, TleLine line) {
-    TrimLeft(str);
-    TrimRight(str);
+bool Tle::IsValidLine(const std::string& str, const unsigned char line_number) {
 
-    const std::string line1_validation = "1 NNNNNC NNNNAAAA NNNNN.NNNNNNNN +.NNNNNNNN +NNNNN-N +NNNNN-N N NNNNN";
-    const std::string line2_validation = "2 NNNNN NNN.NNNN NNN.NNNN NNNNNNN NNN.NNNN NNN.NNNN NN.NNNNNNNNNNNNNN";
+    static const std::string line1_pattern = "1 NNNNNC NNNNAAAA NNNNN.NNNNNNNN +.NNNNNNNN +NNNNN-N +NNNNN-N N NNNNN";
+    static const std::string line2_pattern = "2 NNNNN NNN.NNNN NNN.NNNN NNNNNNN NNN.NNNN NNN.NNNN NN.NNNNNNNNNNNNNN";
 
-    if (Tle::LINE_ONE == line) {
-        if (!ValidateLine(line1_validation, str))
+    /*
+     * validate line against the pattern
+     */
+    if (1 == line_number) {
+        if (!ValidateLine(str, line1_pattern))
             return false;
-    } else if (Tle::LINE_TWO == line) {
-        if (!ValidateLine(line2_validation, str))
+    } else if (2 == line_number) {
+        if (!ValidateLine(str, line2_pattern))
             return false;
     }
 
-    // Last char in string must be checksum
-    // int chk = CheckSum(str);
-    // if (chk != (str[TLE_LEN_LINE_DATA - 1] - '0'))
-    //   return false;
+    /*
+     * last char in string is modulo 10 checksum
+     */
+    int chk = CheckSum(str);
+    if (chk != (str[TLE_LEN_LINE_DATA - 1] - '0'))
+
+        return false;
 
     return true;
 }
@@ -231,23 +215,49 @@ bool Tle::IsValidLine(std::string& str, TleLine line) {
 /*
  * validate line given a pattern
  */
-bool Tle::ValidateLine(const std::string& pattern, const std::string& line) {
+bool Tle::ValidateLine(const std::string& line, const std::string& pattern) {
 
+    /*
+     * check length of lines match
+     */
     if (pattern.length() != line.length()) {
         return false;
     }
 
-    std::string::size_type pos = 0;
+    std::string::const_iterator pattern_itr = pattern.begin();
+    std::string::const_iterator line_itr = line.begin();
 
-    while (pos != line.length() - 1) {
-        if (isdigit(pattern[pos]) || pattern[pos] == ' ' || pattern[pos] == '.') {
-            if (pattern[pos] != line[pos])
+    while (pattern_itr != pattern.end()) {
+
+        if (isdigit(*pattern_itr) || *pattern_itr == ' ' ||
+                *pattern_itr == '.' || *pattern_itr == '-') {
+
+            /*
+             * these characters should match exactly
+             */
+            if (*pattern_itr != *line_itr)
                 return false;
-        } else if (pattern[pos] == 'N') {
-            if (!isdigit(line[pos]) && line[pos] != ' ')
+
+        } else if (*pattern_itr == 'N') {
+
+            /*
+             * if pattern value is 'N' then either a number or a ' '
+             */
+            if (!isdigit(*line_itr) && *line_itr != ' ')
+                return false;
+
+        } else if (*pattern_itr == '+') {
+
+            /*
+             * if pattern value is '+' then either a '+' or a ' '
+             */
+            if (*line_itr != '+' && *line_itr != ' ')
+
                 return false;
         }
-        pos++;
+
+        pattern_itr++;
+        line_itr++;
     }
 
     return true;
@@ -257,14 +267,19 @@ bool Tle::ValidateLine(const std::string& pattern, const std::string& line) {
  * compute checksum
  */
 int Tle::CheckSum(const std::string& str) {
+
     size_t len = str.size() - 1;
     int xsum = 0;
 
     for (size_t i = 0; i < len; i++) {
+
         char ch = str[i];
+
         if (isdigit(ch))
             xsum += (ch - '0');
-        else if (ch == '-')
+        else
+
+            if (ch == '-')
             xsum++;
     }
 
@@ -274,28 +289,35 @@ int Tle::CheckSum(const std::string& str) {
 /*
  * trim left of string
  */
-void Tle::TrimLeft(std::string& s) {
-    if (!s.empty()) {
-        std::string::size_type pos = s.find_first_not_of(' ');
+void Tle::TrimLeft(std::string& str) {
+
+    std::string whitespaces(" \t\f\n\r");
+
+    if (!str.empty()) {
+        std::string::size_type pos = str.find_first_not_of(whitespaces);
 
         if (pos != std::string::npos)
-            s.erase(0, pos);
+            str.erase(0, pos);
+
         else
-            s.clear();
+            str.clear();
     }
 }
 
 /*
  * trim right of string
  */
-void Tle::TrimRight(std::string& s) {
-    if (!s.empty()) {
-        std::string::size_type pos = s.find_last_not_of(' ');
+void Tle::TrimRight(std::string& str) {
+
+    std::string whitespaces(" \t\f\n\r");
+
+    if (!str.empty()) {
+        std::string::size_type pos = str.find_last_not_of(whitespaces);
 
         if (pos != std::string::npos)
-            s.erase(pos + 1);
+            str.erase(pos + 1);
         else
-            s.clear();
+            str.clear();
     }
 }
 
diff --git a/Tle.h b/Tle.h
index e5b41d2..2ba7847 100644
--- a/Tle.h
+++ b/Tle.h
@@ -8,73 +8,14 @@
 
 class Tle {
 public:
+    Tle(const std::string& line_one, const std::string& line_two);
     Tle(const std::string& name, const std::string& line_one, const std::string& line_two);
     Tle(const Tle& tle);
     virtual ~Tle();
 
-    enum TleLine {
-        LINE_ZERO,
-        LINE_ONE,
-        LINE_TWO
-    };
-
-    enum TleField {
-        FLD_FIRST,
-        FLD_NORADNUM = FLD_FIRST,
-        FLD_INTLDESC,
-        FLD_SET, // Tle set number
-        FLD_EPOCHYEAR, // Epoch: Last two digits of year
-        FLD_EPOCHDAY, // Epoch: Fractional Julian Day of year
-        FLD_ORBITNUM, // Orbit at epoch
-        FLD_I, // Inclination
-        FLD_RAAN, // R.A. ascending node
-        FLD_E, // Eccentricity
-        FLD_ARGPER, // Argument of perigee
-        FLD_M, // Mean anomaly
-        FLD_MMOTION, // Mean motion
-        FLD_MMOTIONDT, // First time derivative of mean motion
-        FLD_MMOTIONDT2, // Second time derivative of mean motion
-        FLD_BSTAR, // BSTAR Drag
-        FLD_LAST // MUST be last
-    };
-
-    enum TleUnits {
-        U_FIRST,
-        U_RAD = U_FIRST, // radians
-        U_DEG, // degrees
-        U_NATIVE, // Tle format native units (no conversion)
-        U_LAST // MUST be last
-    };
-
     /*
-     * initialize from raw tle strings
+     * get raw strings
      */
-    void Initialize();
-
-    /*
-     * get field represented as a double
-     */
-    double GetField(TleField fld, TleUnits unit = U_NATIVE) const;
-    /*
-     * get field represented as a string
-     */
-    std::string GetFieldString(TleField fld, bool append_units) const;
-
-    /*
-     * get epoch of tle
-     */
-    Julian GetEpoch() const {
-        return date_;
-    }
-
-    /*
-     * compute checksum
-     */
-    static int CheckSum(const std::string& str);
-    static bool IsValidLine(std::string& str, TleLine line);
-    static void TrimLeft(std::string& str);
-    static void TrimRight(std::string& str);
-
     std::string GetName() const {
         return name_;
     }
@@ -87,28 +28,100 @@ public:
         return line_two_;
     }
 
-    double GetNoradNumber() const {
-        return GetField(Tle::FLD_NORADNUM);
+    /*
+     * get tle values
+     */
+    double NoradNumber() const {
+        return norad_number_;
     }
 
+    std::string InternationlDesignator() const {
+        return international_designator_;
+    }
+
+    Julian Epoch()const {
+        return epoch_;
+    }
+
+    double MeanMotionDot()const {
+        return mean_motion_dot_;
+    }
+
+    double MeanMotionDot2()const {
+        return mean_motion_dot2_;
+    }
+
+    double BStar()const {
+        return bstar_;
+    }
+
+    double Inclination(const bool in_degrees)const {
+        if (in_degrees)
+            return inclination_;
+        else
+            return Globals::Deg2Rad(inclination_);
+    }
+
+    double RightAscendingNode(const bool in_degrees)const {
+        if (in_degrees)
+            return right_ascending_node_;
+        else
+            return Globals::Deg2Rad(right_ascending_node_);
+    }
+
+    double Eccentricity()const {
+        return eccentricity_;
+    }
+
+    double ArgumentPerigee(const bool in_degrees)const {
+        if (in_degrees)
+            return argument_perigee_;
+        else
+            return Globals::Deg2Rad(argument_perigee_);
+    }
+
+    double MeanAnomaly(const bool in_degrees)const {
+        if (in_degrees)
+            return mean_anomaly_;
+        else
+            return Globals::Deg2Rad(mean_anomaly_);
+    }
+
+    double MeanMotion()const {
+        return mean_motion_;
+    }
+
+    unsigned int OrbitNumber()const {
+        return orbit_number_;
+    }
+
+    /*
+     * helper / validation methods
+     */
+    static bool IsValidPair(const std::string& line1, const std::string& line2);
+    static bool IsValidLine(const std::string& str, unsigned char line_number);
+    static void TrimLeft(std::string& str);
+    static void TrimRight(std::string& str);
+
 private:
     /*
-     * get units for a field
+     * initialize from raw tle strings
      */
-    std::string GetUnits(TleField field) const;
+    void Initialize();
     /*
-     * get raw value for a field
-     */
-    double GetFieldNumeric(TleField) const;
-    /*
-     * convert a raw string into an exponent string
+     * format a raw string into an exponent string
      */
     static std::string ExpToDecimal(const std::string&);
     /*
-     * validate a line
+     * validate a line against a pattern
      */
-    static bool ValidateLine(const std::string& pattern, const std::string& line);
+    static bool ValidateLine(const std::string& line, const std::string& pattern);
+    /*
+     * compute checksum
+     */
+    static int CheckSum(const std::string& str);
 
+private:
     /*
      * raw tle data
      */
@@ -117,12 +130,21 @@ private:
     std::string line_two_;
 
     /*
-     * epoch of tle
+     * extracted values all in native units
      */
-    Julian date_;
-
-    // array of tle values in native string and double form
-    std::pair<std::string, double> fields_[FLD_LAST];
+    double norad_number_;
+    std::string international_designator_;
+    Julian epoch_;
+    double mean_motion_dot_;
+    double mean_motion_dot2_;
+    double bstar_;
+    double inclination_;
+    double right_ascending_node_;
+    double eccentricity_;
+    double argument_perigee_;
+    double mean_anomaly_;
+    double mean_motion_;
+    unsigned int orbit_number_;
 
     /*
      * name line
@@ -133,8 +155,8 @@ private:
     /*
      * line 1
      */
-    static const unsigned int TLE1_COL_SATNUM = 2;
-    static const unsigned int TLE1_LEN_SATNUM = 5;
+    static const unsigned int TLE1_COL_NORADNUM = 2;
+    static const unsigned int TLE1_LEN_NORADNUM = 5;
     static const unsigned int TLE1_COL_INTLDESC_A = 9;
     static const unsigned int TLE1_LEN_INTLDESC_A = 2;
     static const unsigned int TLE1_COL_INTLDESC_B = 11;
@@ -159,8 +181,8 @@ private:
     /*
      * line 2
      */
-    static const unsigned int TLE2_COL_SATNUM = 2;
-    static const unsigned int TLE2_LEN_SATNUM = 5;
+    static const unsigned int TLE2_COL_NORADNUM = 2;
+    static const unsigned int TLE2_LEN_NORADNUM = 5;
     static const unsigned int TLE2_COL_INCLINATION = 8;
     static const unsigned int TLE2_LEN_INCLINATION = 8;
     static const unsigned int TLE2_COL_RAASCENDNODE = 17;