Light Curve Comparison
Load several comet/return selections with explicit formula models and compare their observations in one normalized plotting workspace.
Source-verified Comparison-script syntax, type and return selection, axes, corrections, model plotting and R28 file-dialog stability were checked against the current implementation.
Comparison script
Click Comparison script to open the script editor. Each non-empty line defines one comet and uses semicolons between fields:
Designation;Colour/group number;Types;Returns;Formula(s)The editor can add comets from a comma-separated list, load a saved script, save the current script and run it. Cancelling Load Script or Save Script returns immediately without trying to open an empty filename; script files are read and written as UTF-8. Add from list fills the default type code vcmn, leaves returns unrestricted and copies the comet's currently stored magnitude formulas. When a listed comet is missing, the Add Comet dialog is opened; KOPR reloads the comet afterwards and safely skips it if it was not added.
Script fields
| Field | Meaning |
|---|---|
| Designation | Short comet identifier that exists in local elements and observation files. |
| Colour/group number | Numeric index into KOPR's plotting colour list. It controls the comet colour, not a scientific grouping calculation. |
| Types | v visual; c CCD including the CCD variants; m MPC total; n MPC nuclear. Combine letters without separators. |
| Returns | Perihelion years separated by /. Leave empty to use all known returns. |
| Formulas | One or more H0=..., n=... [from,to] formulas separated by /. |
Example from the application:
103P;0;vcmn;2010/2023;H0=9.46 mag, n=10.15 [-232.9, 0.0]/H0=8.71 mag, n=5.05 [0.0, 472.6]Run and update a comparison
- Open the script editor and prepare one line per comet.
- Click Run Script. KOPR loads valid local ICQ observations for each comet, assigns them to the nearest selected perihelion return and plots the requested types.
- Use Settings and selections to exclude types or observers.
- Edit axis ranges and press Refresh.
- Use Default to reload the script formulas and automatic data ranges after manual edits.
A malformed line produces a generic script error. Check semicolon count, numeric colour index, return years and formula punctuation.
Axes and model lines
The same x-axis choices as Analyzer are available: Date, Days from T, r and Log(r). Y can show observed magnitude or mag − 5 log(Δ). Comparison starts by default in Log(r) versus reduced magnitude.
For Date and Days from T, all points share one graph. For r and Log(r), pre- and post-perihelion observations are shown in separate panels. Each comet's formula lines are calculated from the orbital elements of each selected return and drawn in that comet's colour.
The entered axis fields define exact numeric/date limits. The Matplotlib toolbar can save the figure, but toolbar zoom does not rewrite the fields.
Settings and selections
| Tab | Controls |
|---|---|
| Settings | Apply personal coefficients; Marcus dust phase function and d_90; correct observed magnitudes or enhance light-curve models; Bortle survival limit. |
| Exclude | Exclude uncertain, negative and border observations. |
| Types | Enable/disable visual, CCD and MPC types and choose their markers. |
| Observers | Include or exclude observer codes across the loaded comets. |
The comparison module has no Returns tab because return selection is explicit in each script line. Personal coefficients and phase corrections change the plotted relation; the graph adds a note describing the active phase mode.
Practical script patterns
Compare the same return type for several comets
2P;0;vc;;H0=...
9P;1;vc;;H0=...
10P;2;vc;;H0=...Compare two returns of one periodic comet
103P;0;vcmn;2010/2023;H0=...Restrict to visual observations
C/2023 A3;0;v;;H0=...Replace the abbreviated formulas with complete valid lines. The examples illustrate structure only; KOPR does not infer missing H0 or n.
Interpretation and limits
- Direct apparent-magnitude comparison mixes geocentric-distance effects; reduced magnitude is generally more suitable for intrinsic brightness comparisons.
- Different magnitude types, apertures, observers and catalogues can create systematic offsets.
- A single colour per comet can conceal differences among returns; inspect the script and selected return years.
- Formula validity ranges are part of the model and should not be extended beyond their evidence without review.
- MPC total and nuclear magnitudes are distinct data types; do not combine them uncritically with visual total-coma estimates.
Related chapters
Derive formulas for one comet · Observation Planner · Script and observation formats · Troubleshooting