论文标题
裸眼星的准确地面天文学：美国海军天文台亮点星形标准数据库
Accurate Ground-based Astrometry of Naked-eye Stars: The United States Naval Observatory Bright-Star Astrometric Database
论文作者
论文摘要
我们介绍了美国海军天文台（USNO）Bright-Star Astrestoric Database（UBAD），这是一种电流 - 上观流高排名的星体目录。该目录由364张明亮的北半球明星组成，其中包括$ V <3.5 $或$ i <3.2 $和$ V <6 $的所有此类恒星，以及很大一小部分略微粘稠的星星；盖亚早期数据版本3（EDR3）中未包括36个最亮目录星。使用USNO，FlagStaff站，KAJ Strand 61英寸天文反射器进行观测。目标恒星通过一个小的12.5级中性密度斑点成像，而视野中的其余恒星则没有颗粒。这允许直接针对Gaia EDR3的许多较弱的参考恒星校准明亮目标恒星的不饱和图像。 2017.0目录时期的右升升和偏差，中值位置误差为1.9 MAS，其中90％的目录星的错误小于2.6 MAS；系统错误是1-3 mas。将UBAD观察结果与Hipparcos-2位置相结合可产生适当的动作，中位错误为0.045和0.049 MAS年$^{ - 1} $分别在正确的提升和偏斜中，90％的星星的恒星的错误小于0.1 MAS $^{ - 1} $;系统错误约为0.1 MAS年$^{ - 1} $。目标恒星位置的单帧精度通常为5-6个MAS。这些明亮的恒星的Gaia EDR3天文测量在Gaia观测中饱和，在幅度范围$ 2 \ lyssim g \ lyssim 6 $中得到了验证。
We present the United States Naval Observatory (USNO) Bright-Star Astrometric Database (UBAD), a current-epoch high-accuracy astrometric catalog. The catalog consists of 364 bright northern hemisphere stars, including all but five such stars with either $V < 3.5$ or with $I < 3.2$ and $V < 6$, as well as a large fraction of slightly fainter stars; 36 of the brightest catalog stars are not included in Gaia Early Data Release 3 (EDR3). Observations were conducted with the USNO, Flagstaff Station, Kaj Strand 61-inch Astrometric Reflector. Target stars were imaged through a small 12.5-magnitude neutral-density spot, while the remainder of the stars in the field of view were unattenuated. This allowed for unsaturated images of the bright target stars to be calibrated directly against much fainter reference stars from Gaia EDR3. The median position errors are 1.9 mas in both right ascension and declination at the catalog epoch of 2017.0, with 90% of catalog stars having errors less than 2.6 mas; systematic errors are 1 -- 3 mas. Combining UBAD observations with Hipparcos-2 positions yields proper motions with median errors of 0.045 and 0.049 mas year$^{-1}$ in right ascension and declination, respectively, with 90% of stars having errors less than 0.1 mas year$^{-1}$; systematic errors are about 0.1 mas year$^{-1}$. Single-frame accuracy for positions of the target stars is typically 5 -- 6 mas. Gaia EDR3 astrometry for these bright stars, which are heavily saturated in the Gaia observations, is validated over the magnitude range $2 \lesssim G \lesssim 6$.
