The Massive Compact Halo Object (MACHO) Project Photometry Catalog

The MACHO Project was a collaboration between scientists at the Mt. Stromlo & Siding Spring Observatories, the Center for Particle Astrophysics at the Santa Barbara, San Diego, & Berkeley campuses of the University of California, and the Lawrence Livermore National Laboratory. Our primary aim was to test the hypothesis that a significant fraction of the dark matter in the halo of the Milky Way is made up of objects like brown dwarfs or planets: these objects have come to be known as MACHOs, for MAssive Compact Halo Objects. The signature of these objects is the occasional amplification of the light from extragalactic stars by the gravitational lens effect. The amplification can be large, but events are extremely rare: it was necessary to monitor photometrically several million stars for a period of 10 years in order to obtain a useful detection rate. For this purpose we built a two channel system that employed eight 2048*2048 CCDs, mounted on the 50 inch telescope at Mt. Stromlo. We have taken ~127,000 images with this system since June 1992. Analysis of a subset of these data has yielded databases containing light curves in two colors for 8 million stars in the LMC and 10 million in the bulge of the Milky Way.

MACHO项目是由斯特罗姆洛山与赛丁泉天文台、加州大学圣巴巴拉分校、圣地亚哥分校及伯克利分校的粒子天体物理中心，以及劳伦斯利弗莫尔国家实验室的科研人员合作开展的科研项目。本项目的核心研究目标是检验一项假说：银河系银晕中的大部分暗物质由褐矮星或行星这类天体构成，这类天体后来被称为大质量致密晕天体（Massive Compact Halo Objects，简称MACHO）。这类天体的观测特征是通过引力透镜效应，偶尔放大河外恒星的光线。该放大效应的强度可能很高，但相关事件极为罕见：为获取有效的探测率，需对数百万颗恒星开展长达10年的测光监测。为此，研究团队搭建了一套双通道观测系统，使用8块2048×2048像素的电荷耦合器件（Charge-Coupled Device，简称CCD），并将其安装在斯特罗姆洛山的50英寸望远镜上。自1992年6月以来，该系统已获取约12.7万幅观测图像。对其中部分数据的分析已构建出数据库，涵盖大麦哲伦星系（Large Magellanic Cloud，简称LMC）内800万颗恒星与银河系核球内1000万颗恒星的双色光变曲线。