Redshift Bin Center Shift Tool

Description

Return the midpoint of a supplied redshift bin and its reference shift.

Survey geometry combines solid angle, radial distance and a stated coordinate or selection basis. A sky fraction, bin midpoint or thin-shell term is a local geometric quantity rather than an integrated survey volume, observed population or selection-corrected estimate.

Return the midpoint of a supplied redshift bin and its reference shift.

When to use this tool

Use Redshift Bin Center Shift when checking the stated survey-area, bin or comoving-volume term.

How to use the tool and how it works

Enter lowerRedshift, upperRedshift, referenceCenter. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read center, shift. Use the output convention below.

Return the midpoint of a supplied redshift bin and its reference shift. Require lowerRedshift > -1 and upper >= lower; center = lower/2+upper/2, shift = center-referenceCenter.^[1]

Input field	Meaning and units	Accepted input
lowerRedshift	Lower Redshift	Required. Finite number; strictly above -1.
upperRedshift	Upper Redshift	Required. Finite number.
referenceCenter	Reference Center	Required. Finite number.

Output field	Interpretation	Returned shape
center	Center	Required. Finite number.
shift	Shift	Required. Finite number.

json

{
  "input": {
    "lowerRedshift": 1,
    "upperRedshift": 2,
    "referenceCenter": 1
  },
  "output": {
    "center": 1.5,
    "shift": 0.5
  }
}

Limitations and assumptions

This arithmetic midpoint is not an observed mean, comoving midpoint or probability-weighted redshift.
Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Integrate the appropriate cosmological volume element and actual survey mask/selection function for complete coverage or number-count analysis.

References

Calculation and input contract: cosmology/redshift-bin-center-shift — tool.io

Similar or alternative tools

Galaxy Redshift Bin Rest Frame Width
Return a supplied observed width on a rest-frame basis.
CMB Temperature Redshift Ratio Tool
Calculate cmb temperature redshift ratio from explicit caller-supplied inputs.