Update readme

README.md

@@ -1,2 +1,60 @@
-# polpy
-A universal tool for X-/gamma-ray polarimetry. Based on polarpy ([Burgess and Kole et. al. 2019](https://www.aanda.org/articles/aa/abs/2019/07/aa35056-19/aa35056-19.html)). Currently under active development, stable version will be released soon!
+# PolPy
+
+`polpy` is a universal tool developed to analyse high-energy polarization data from scattering polarimeters. Based on [3ML](https://github.com/threeML/threeML), it is a generalization of the `polarpy` ([Burgess, Kole et al. 2019, A&A](https://www.aanda.org/articles/aa/abs/2019/07/aa35056-19/aa35056-19.html)) tool that was developed for POLAR analysis. It can be used for current and future scattering polarimeters, provided standardized data and response format ([`docs/Data_and_Response_Format_For_PolPy.pdf`](docs/Data_and_Response_Format_For_PolPy.pdf)) and a defined coordinate convention are followed ([`docs/Coordinate_Defintions_and_Transforms_For_PolPy.pdf`](docs/Coordinate_Defintions_and_Transforms_For_PolPy.pdf)).
+.
+
+## Contents
+
+- [Installation](#installation)
+- [Package layout](#package-layout)
+- [Quick start](#quick-start)
+- [Data and response file formats](#data-and-response-file-formats)
+- [Citing](#citing)
+- [License](#license)
+- [Authors](#authors)
+
+## Installation
+
+`polpy` is available on PyPI and uses modern Python packaging via `pyproject.toml`. We recommend installing it inside a virtual environment (using `conda`, `venv`, or your preferred environment manager) to prevent dependency conflicts.
+
+### Standard Installation
+
+To install the latest stable version directly from PyPI, run:
+
+```bash
+pip install polpy
+```
+
+## Package layout
+
+```
+polpy/
+├── polpy/
+│   ├── poldata.py            # PolData: read raw polarization event files, compute PA offset
+│   ├── polresponse.py        # PolResponse: read + interpolate the polarization response
+│   └── polarizationlike.py   # PolarizationLike: the 3ML plugin (likelihood, fitting, display)
+├── docs/
+│   ├── Data_and_Response_Format_For_PolPy.pdf
+│   └── Coordinate_Defintions_and_Transforms_For_PolPy.pdf
+├── examples/
+│   ├── example.py                 # loading and corner-plotting saved fit results
+│   ├── polar_GRB170114A.py        # full joint POLAR + Fermi/GBM spectro-polarimetric fit
+│   └── verify_czti_pol_fit.py     # cross-check of CZTI polarization fit against direct simulation
+└── tests/                    # pytest unit tests
+```
+
+## Data and response file formats
+
+Two reference documents ship with the repo:
+
+- [`docs/Data_and_Response_Format_For_PolPy.pdf`](docs/Data_and_Response_Format_For_PolPy.pdf) — layout of the `POLEVENTS` event FITS extension and the `.prsp` response FITS extensions (`INEBOUNDS`, `SABOUNDS`, `INPAVALS`, `SPECRESP POLMATRIX`, `SPECRESP UNPOLMATRIX`)
+- [`docs/Coordinate_Defintions_and_Transforms_For_PolPy.pdf`](docs/Coordinate_Defintions_and_Transforms_For_PolPy.pdf) — instrument reference frame, local-tangent-plane frame, and the IAU polarization-angle offset convention used by `PolData.get_pa_offset()`
+
+
+## License
+
+[GPL-3.0](LICENSE).
+
+## Authors
+
+Sujay Mate, Hancheng Li, Utkarsh Pathak, Yashowardhan Rai, Nicholas De Angelis, Merlin Kole, Varun Bhalerao.