Description
Return surveyed sky fraction from solid angle.
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 surveyed sky fraction from solid angle.
When to use this tool
Use Survey Solid Angle Fraction when checking the stated survey-area, bin or comoving-volume term.
How to use the tool and how it works
- Enter steradians. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read skyFraction. Use the output convention below.
Return surveyed sky fraction from solid angle. Require steradians in [0,4*pi]; skyFraction = steradians/(4*pi).1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| steradians | Steradians | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| skyFraction | Sky Fraction | Required. Finite number. |
{
"input": {
"steradians": 3.141592653589793
},
"output": {
"skyFraction": 0.25
}
}Limitations and assumptions
- This assumes geometrically nonoverlapping survey area; masks, completeness, exposure and selection effects are not measured.
- 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
Similar or alternative tools
- Angular Bin Solid Angle Weight
Return solid angle of a cosine-polar-coordinate bin.
- CMB Temperature Redshift Ratio Tool
Calculate cmb temperature redshift ratio from explicit caller-supplied inputs.