SNDATA_ROOT for SNANA software

Environment for the Supernova Analysis software package (https://github.com/RickKessler/SNANA). This environment Includes public light curve data sets, filter transmissions, primary SEDs, calibration files, models for SNIa & CC, cadence and host-galaxy libraries for simulations, etc ...超新星分析软件包（https://github.com/RickKessler/SNANA）的配套运行环境。该环境涵盖公开光变曲线数据集、滤光片透射曲线、主光谱能量分布（Spectral Energy Distribution, SED）、Ia型与核心塌缩（Core-Collapse, CC）超新星模型、校准文件，以及用于模拟的观测节奏库与宿主星系库等。