SAGA

The SAGA Survey is a spectroscopic survey that aims to determine dwarf galaxy satellite systems around 100 Milky Way analogs down to the brightness of the Leo I galaxy (Mr < −12.3).

This SAGA package contains code to generate and access SAGA data catalogs. This package is intended for SAGA internal use, but it is licensed under the MIT license. If you use this package or part of it in your research, please considering citing SAGA II paper (Mao et al., 2021).

• Visit yymao/FoFCatalogMatching if you are looking for the friends-of-friends sky catalog matching code.
• Visit yymao.github.io/decals-image-list-tool/ if you are looking for the web app for listing cutouts from the Legacy Surveys.
• Visit sagasurvey.org for the most up-to-date SAGA results!

Installation

To install the code, run:

pip install https://github.com/sagasurvey/saga/archive/master.zip

To force an update, run

pip install --upgrade --no-deps --force-reinstall https://github.com/sagasurvey/saga/archive/master.zip

As of April 2022, this code base is compatible with Python 3.7 and above.

Dependencies

All required dependencies will be installed automatically. There are two optional dependencies that require manual installation:

1. casjobs OR sciserver

   You need to install casjobs or sciserver to download SDSS catalogs.

   • To install casjobs:

     pip install https://github.com/dfm/casjobs/archive/master.zip

     (Note: Do NOT use pip install casjobs as the version on PyPI is outdated.)

   • To install sciserver (recommended):

     pip install "git+https://github.com/sciserver/[email protected]#egg=sciserver&subdirectory=py3"

   In both cases you need to set environmental variables to store your credentials. (CASJOBS_WSID and CASJOBS_PW for casjobs; SCISERVER_USER and SCISERVER_PASS for sciserver).

2. Extreme Deconvolution

   You only need to install Extreme Deconvolution if you want to build GMM (you don't need it to use GMMs).

   pip install https://github.com/jobovy/extreme-deconvolution/archive/master.zip

Usage

When using SAGA, your code would almost always start with this block:

import SAGA
saga = SAGA.QuickStart('/path/to/saga/dropbox/folder', '/path/to/saga/local/folder')

You can then load various datasets:

# load host list
hosts = saga.host_catalog.load()

# load base catalogs of Paper I hosts
base_paper1 = saga.object_catalog.load(hosts='paper2', return_as='list')

# count number of satellites
for base in base_paper1:
    print(base['HOSTID'][0], '# of satellites =', saga.is_sat.count(base))

You can find more examples at https://github.com/sagasurvey/examples/tree/master/notebooks

You can also find the schema for the host list and for object catalogs at SCHEMA.md.