Isoplanatic Field Margin
Compare a requested correction field with the measured isoplanatic angle.
Description
Isoplanatic field margin compares a requested angular radius with a supplied isoplanatic angle.
Isoplanatic field margin compares a requested angular radius with a supplied isoplanatic angle. The ratio summarizes relative field size.1
Compare a requested correction field with the measured isoplanatic angle.
When to use Isoplanatic Field Margin
Use this tool to compare a requested correction field with the measured isoplanatic angle.
Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
How to use Isoplanatic Field Margin and understand its results
- Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
- Enter isoplanaticAngleArcseconds, requestedFieldRadiusArcseconds using the field table and calculation rules, then run the tool.
- Read angularMarginArcseconds, fieldToIsoplanaticRatio, withinIsoplanaticField. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| isoplanaticAngleArcseconds | Isoplanatic angle (arcsec) | number; minimum: 0 | Required |
| requestedFieldRadiusArcseconds | Requested field radius (arcsec) | number; minimum: 0 | Required |
Enter positive isoplanatic angle and nonnegative requested radius in arcseconds. Return margin, ratio and inclusive field flag.
margin=isoplanatic−requested; ratio=requested/isoplanatic Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| angularMarginArcseconds | Angular correction margin (arcsec) | number |
| fieldToIsoplanaticRatio | Field-to-isoplanatic ratio | number; minimum: 0 |
| withinIsoplanaticField | Within isoplanatic field | boolean |
{
"input": {
"isoplanaticAngleArcseconds": 10,
"requestedFieldRadiusArcseconds": 8
},
"output": {
"angularMarginArcseconds": 2,
"fieldToIsoplanaticRatio": 0.8,
"withinIsoplanaticField": true
}
}Limitations and assumptions
No altitude turbulence profile, Strehl map or guide-star geometry is calculated.
Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.
Alternative or Complementary methods
Use MCAO Field Coverage: Estimate MCAO corrected area and science-field coverage. For a complementary task, use Fried Seeing Conversion: Convert Fried parameter to seeing angle at a supplied wavelength.
References
-
Isoplanatic Field Margin — tool.io
Similar or alternative tools
- MCAO Field Coverage
Estimate MCAO corrected area and science-field coverage.
- Fried Seeing Conversion
Convert Fried parameter to seeing angle at a supplied wavelength.