Peculiar Velocity versus Local Standard of Rest Residual Calculator

Add independent solar motion to already consistently oriented heliocentric UVW then subtract caller LSR reference; no automatic coordinate transform or Galactic orbit. Caller independently establishes frames, units, epoch, covariance and instrument context; not an identity, association or astrometric quality certification.

Description

A local-standard-of-rest comparison requires consistent UVW axes and solar-motion conventions.

A local-standard-of-rest comparison requires consistent UVW axes and solar-motion conventions.^[1]

Residual vector length does not identify the source of a star's peculiar motion. Use Peculiar Velocity versus Local Standard of Rest Residual Calculator to evaluate the supplied inputs under the model explained below.

When to use Peculiar Velocity versus Local Standard of Rest Residual Calculator

Use Peculiar Velocity versus Local Standard of Rest Residual Calculator to evaluate the supplied inputs under the model explained below. Establish the units, measurement scope and model assumptions before entering values.

How to use Peculiar Velocity versus Local Standard of Rest Residual Calculator and understand its results

Establish the units, measurement scope and model assumptions before entering values.
Enter Observed heliocentric uvw km per second, Caller solar motion uvw km per second, Caller reference lsr uvw km per second using the field table and validation rules below, then run the tool.
Read Residual uvw km per second, Peculiar speed km per second; interpret the units, signs, ordering and unknown-value placeholders described below.
Correct reported input errors and rerun. Apply successful results according to their specific meanings and check the assumptions before using them in a decision.

Input field	Meaning	Value type	Requirement
observedHeliocentricUvwKmPerSecond	Observed heliocentric uvw km per second	array of number	Required; constraints below
callerSolarMotionUvwKmPerSecond	Caller solar motion uvw km per second	array of number	Required; constraints below
callerReferenceLsrUvwKmPerSecond	Caller reference lsr uvw km per second	array of number	Required; constraints below

Enter exactly three finite UVW components each for observed heliocentric velocity, solar motion and reference LSR, all km/s in one declared convention. Compute observed+solar−reference componentwise and return its Euclidean speed. No axis convention, solar correction or orbit model is selected.

residualUVW=observedUVW+solarMotionUVW−referenceLSRUVW; speed=hypot(residual)

Use the field order, units and branch conditions described above.

Output field	Meaning	Value type
residualUvwKmPerSecond	Residual uvw km per second	array of number
peculiarSpeedKmPerSecond	Peculiar speed km per second	number

json

{
  "input": {
    "observedHeliocentricUvwKmPerSecond": [
      10,
      20,
      30
    ],
    "callerSolarMotionUvwKmPerSecond": [
      1,
      2,
      3
    ],
    "callerReferenceLsrUvwKmPerSecond": [
      0,
      5,
      0
    ]
  },
  "output": {
    "residualUvwKmPerSecond": [
      11,
      17,
      33
    ],
    "peculiarSpeedKmPerSecond": 38.716921365211874
  }
}

Limitations and assumptions

Residual vector length does not identify the source of a star's peculiar motion. Apply the exact scope and assumptions explained above.

All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse arrays fail validation. Domain-specific bounds, alignments and supported tokens are explained above; extremely large inputs or outputs can also be rejected. Input errors differ from successful false results, empty match lists and unknown-evidence placeholders.

Alternative or Complementary methods

Use Relative Parallax to Absolute Correction Adder for a related task: An absolute-parallax correction adjusts a relative parallax under a calibrated reference frame.

Use Spectroscopic Photometric Parallax Cross-Check Delta Calculator for a related task: Comparing two parallax estimates needs an independently established uncertainty for their difference.

References

Peculiar Velocity versus Local Standard of Rest Residual Calculator — tool.io

Similar or alternative tools

Relative Parallax to Absolute Correction Adder
An absolute-parallax correction adjusts a relative parallax under a calibrated reference frame.
Spectroscopic Photometric Parallax Cross-Check Delta Calculator
Comparing two parallax estimates needs an independently established uncertainty for their difference.