zh_scraper

Python tool to scrape mean extinction (Av) and standard deviation values from the Zaritsky & Harris extinction maps of the SMC and LMC.

It queries data from the MCPS data products webpage: https://www.as.arizona.edu/~dennis/mcsurvey/Data_Products.html

Please cite Zaritsky, Harris, Thompson, Grebel, and Massey 2002, AJ, 123, 855 (SMC) and/or Zaritsky, Harris, Thompson, and Grebel, 2004, AJ, 128, 1606 (LMC) if you use the data obtained from this package.

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Requirements

• Python 3.12.11 or higher (tested)
• Dependencies below listed in requirements.txt:
  • requests 2.31.0 or higher (tested)
  • beautifulsoup4 4.12.3 or higher (tested)

Install dependencies using pip:

pip install -r requirements.txt

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Installation

Clone the repo and install dependencies:

git clone https://github.com/AnnaOG/zh_scraper.git
cd zh_scraper
pip install -r requirements.txt

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Function Overview

Function:

get_extinction(galaxy, ra, dec, radius, teff='all')

Inputs:

• galaxy (str): "LMC" or "SMC"
• ra (float): Right Ascension in units of hours (decimal, e.g., 5.25 for 5h15m)
• dec (float): Declination in units of degrees (decimal, e.g., -69.5 for -69°30′)
• radius (float): Search radius in arcminutes (maximum 12)
• teff (str): 'all', 'cool', or 'hot' (default = 'all')

You can convert your coordinates to the correct units using the units and coordinates functions in the astropy package, or by using Jan Skowron's flexible converter website.

Returns:

• (mean_av, stdev_av) as floats.
• Raises ValueError if no stars are found within the radius or if inputs are invalid.

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Usage Options

1. Command-Line Interface (CLI)

Run the script directly from a terminal:

python zh_scraper.py --galaxy SMC --ra 1.168 --dec -72.614 --radius 3 --teff all

For help and argument details:

python zh_scraper.py --help

2. Python Notebook or Script

Import and use the function in a Python notebook or script:

from zh_scraper import get_extinction

mean_av, stdev_av = get_extinction('SMC', 1.168, -72.614, 3, teff='all')
print(mean_av, stdev_av)

To view the function docstring:

help(get_extinction)