README

What does the function calc_total_heliocentric_mag() do?

It calculates total heliocentric magnitude as a function of heliocentric distance, separated by orbital arc and Oort group. The brightening parameters, currently hardcoded into dictionary BRIGHTENING_PARS, are median values for a sample of 200+ comets. See Lacerda et al. (2025) for details.

Installation

The function calc_total_heliocentric_mag() is included in the file calc_total_heliocentric_mag.py, which is self-contained. You can copy the function calc_total_heliocentric_mag.py into your working environment, or clone the repository into a local directory using:

git clone https://github.com/siarw/lpc_heliocentric_lightcurves.git

Usage

calc_total_heliocentric_mag(distance, orbital_arc, oort_group)

Examples

>>> print(calc_total_heliocentric_mag(5.0, "inbound", "new"))
output:  14.20233223070413

>>> print(calc_total_heliocentric_mag([1.0, 3.0, 10.0], "inbound", "new"))
output:  [ 8.28       11.49031036 18.06966458]

>>> print(calc_total_heliocentric_mag([2.3, 3.7], "outbound", "old"))
output:  [16.34842471 19.07594477]

Parameters

distance : float or array_like Heliocentric distance in au
orbital_arc : {inbound, outbound}, optional Orbital phase (inbound/outbound), default: inbound
oort_group : {new, int, old}, optional Oort dynamical group, default: new

Returns

median_total_mag : float or array_like Median total heliocentric magnitude. Convert to apparent magnitude by adding 5 * np.log10(observer distance).

Notes

Uses hardcoded values from dictionary BRIGHTENING_PARS structured as:

• Top level: Oort groups (new, int, old)
• Second level: orbital arcs (inbound, outbound)
• Third level: brightening parameters:
  • k_near: Brightening slope inside transition (3.16 au)
  • k_far: Brightening slope beyond transition
  • k1: Post-perihelion fading slope (outbound only)
  • m1: Magnitude at 1 au (phase-dependent)

Transition distance stored in TRANSITION_R (3.16 au).

References

If you use this function, please cite:
Lacerda et al. 2025, A&A, 697, A210 (DOI: 10.1051/0004-6361/202453565)

Todo

Implement user-specified parameters and transition distance.

Improvements

If you want to contribute suggestions, here is one way:

1. Fork the Repository. Anyone with a GitHub account can fork this public repository: Click the "Fork" button in the upper-right corner. Choose where to fork (your own account or organization). Wait for the fork to be created. This creates a personal copy of the repository under your account.
2. Clone and Edit the Forked Repository. Clone your fork to your computer:

git clone https://github.com/<your-username>/<repository-name>.git

Create a new branch for your changes:

git checkout -b suggestion-branch

Make and commit changes:

git add .
git commit -m "Description of changes"

Push your branch to your fork:

git push origin suggestion-branch

3. Propose Changes via Pull Request. After pushing changes, open a pull request (PR): Go to the main page of your fork on GitHub. Click "Compare & pull request" (GitHub may show this automatically after a push). Select the base repository and branch (the original repository and target branch, e.g., main). Select your fork and branch as the head repository and branch. Add a title and description explaining the changes. Click "Create pull request". This PR notifies me (the repository owner) that someone wants to merge their changes into your project.

Dependencies

• numpy
• typing if python_version < '3.5'

Author

Pedro Lacerda (2025-06-16)

What does the function plot_heliocentric_lightcurves() do?

It plots the heliocentric light curves corresponding to BRIGHTENING_PARS to produce this plot: