The Massive Compact Halo Object (MACHO) Project Image Archive for SIAP Service

The MACHO Project was a collaboration between scientists at the Mt. Stromlo and Siding Spring Observatories, the Center for Particle Astrophysics at the Santa Barbara, San Diego, and 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. The MACHO project data archive consists of approximately 127,000 two-colour images of fields collected between 1992 and 2003 covering the large and small Magellanic clouds and the galactic bulge and two-colour light-curves for approximately 18 million stars in the LMC and galactic bulge.

MACHO项目是由斯特罗姆洛山天文台与赛丁泉天文台、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学家联合开展的合作研究项目。本项目的核心目标为验证下述假说：银河系银晕中的暗物质有相当大的比例由褐矮星、行星这类天体构成，这类天体此后被统称为大质量致密晕天体（MAssive Compact Halo Objects，MACHOs）。这类天体的观测特征是，其引力透镜效应可偶尔放大河外恒星的光线。此类放大效果或十分显著，但相关事件极为稀有：为获得具备实用价值的探测率，我们需要对数百万颗恒星开展长达10年的测光监测。为此，我们搭建了一套双通道观测系统，在斯特罗姆洛山的50英寸望远镜上搭载了8块2048×2048像素的电荷耦合器件（Charge-Coupled Device，CCD）。MACHO项目数据存档包含1992年至2003年间采集的约127000幅两波段场图像，观测覆盖了大麦哲伦云（Large Magellanic Cloud，LMC）、小麦哲伦云与银河核球；同时存档还包含大麦哲伦云与银河核球内约1800万颗恒星的两波段光变曲线。