Welcome to the repository for tools developed by the LASEX/OV group during observations at the Observatório do Pico dos Dias (OPD), specifically for the SPARC4 instrument on the 1.6m telescope.
This repository is intended to assist current and future observers in efficiently planning, selecting, and analyzing extragalactic targets.
Extragalactic Astrophysics is one of the most active fields in contemporary Astronomy, and at the Valongo Observatory we created the LASEX (Laboratório de Astrofísica Extragaláctica) group in 2013 to foster collaboration among students, postdocs, and faculty.
We work observationally across almost the entire electromagnetic spectrum — from radio to X-ray — and our research covers galaxy formation, evolution, and the role of dark matter, among other key topics.
LASEX researchers are actively involved in projects at major observatories like Keck, VLT/ESO, and ALMA.
Learn more about our group here: lasex-valongo.com
SPARC4 (Simultaneous Polarimeter and Rapid Camera in 4 bands) is a new instrument installed on the 1.6m telescope at OPD, developed through a collaboration between INPE and LNA.
Since its first light in 2022, SPARC4 has been successfully commissioned and is now fully operational, offering simultaneous imaging in four optical bands (griz) and polarimetry capabilities.
A full data reduction pipeline in Python is available, and the instrument is now an official facility of OPD starting from semester 2024A.
Our observing program focuses on studying 50 Milky Way analog galaxies to better understand the distribution of dark matter in galaxies similar to our own.
By combining SPARC4's multi-band imaging with deep infrared data, we perform detailed stellar population analyses to decompose rotation curves and isolate the dark matter contribution.
We currently provide three Jupyter Notebooks, each designed to streamline a specific part of the observing and data preparation workflow:
| Notebook | Purpose | Link |
|---|---|---|
| Finders | Generate finder charts for galaxies to preview morphology and size before observations. | Finders.ipynb |
| OPDsample | Filter and select galaxies for the sample, excluding targets already observed in previous cycles. | OPDsample.ipynb |
| Counts | Calculate the exposure time needed to achieve the desired signal-to-noise ("contagem") for each target. It needs to be no less than 20% of 60000 maximum at OPD (i.e. 24000) and no more than 60% of this value (36000). The closer to 36000 counts you get, the better signal-to-noise you achieve. | Counts.ipynb |
In addition to the notebooks, we provide supporting documents:
| Resource | Description | Link |
|---|---|---|
| S4G Galaxy List | The list of galaxies from the S4G survey, used in the Finders tool. | S4G_1.csv |
| Example Spreadsheet | A template to guide users in structuring their own target lists for observations. |  |
| Written Tutorial | Tutorial collaboratively developed by the group, with final writing and formatting done by Maria Clara. | SPARC4 Tutorial (PDF) |
Contributions to this repository are very welcome!
You can:
- Open Issues with feature requests, bugs, or suggestions.
- Submit Pull Requests with improvements, new notebooks, or corrections.
- Fork the repository and adapt the tools for your own observing runs (just don't forget to give credit).
Future upgrades may include new tools for data reduction and advanced planning features.
For questions, feedback, or collaboration opportunities, feel free to contact the maintainers or reach out to the group:
Or open an Issue directly here on GitHub.
- Gabriel Pampolha
- Juan Maldonado
- Maria Cavalcante
- Thiago Bueno
Clone the repository and install the dependencies listed in requirements.txt:
git clone https://github.com/Astro-cat-mistry/OPD-LASEX-GMTJ.git
cd OPD-LASEX-GMTJ
pip install -r requirements.txt
Clone the repository and install the dependencies listed in `requirements.txt`:
```bash
git clone https://github.com/Astro-cat-mistry/OPD-LASEX-GMTJ.git
cd OPD-LASEX-GMTJ
pip install -r requirements.txt