Homogeneous Photometry. IV. On the Standard Sequence in the Globular Cluster NGC 2419
Homogeneous Photometry. IV. On the Standard Sequence in the Globular Cluster NGC 2419
复制标题
DOI：
10.1086/430281
复制
发表时间：
2005-03
影响因子：
3.5
通讯作者：
P. Stetson
中科院分区：
文献类型：
--
作者：
P. Stetson
我对球状星团NGC 2419进行了基于CCD的BVRI宽带测光的新分析，基于同事捐赠或从公共档案中检索的340张CCD图像。校准结果已通过我的网站提供。我将我的分析结果与Saha等人（PASP，117，37）对这些数据的一个子集进行的独立分析结果进行了比较，Saha等人发现，对于该星团中的恒星，他们的I波段测光与我的测光之间的颜色依赖差异高达0.05等。我的结论是，差异的主要部分似乎与WIYN 3.5 m望远镜上的Mini‐Mosaic（MIMO）相机中的小快门定时误差（百分之几秒）有关。对异常的较小贡献可能来自：（1）在我2004年9月的二级标准列表中，最大振幅为±0.02 mag的色标误差，以及（2）先前研究使用相对少量的标准星星观测值来确定测光转换中相对大量的拟合参数所产生的统计效应。
I present a new analysis of CCD‐based BVRI broadband photometry for the globular cluster NGC 2419, based on 340 CCD images either donated by colleagues or retrieved from public archives. The calibrated results have been made available through my Web site. I compare the results of my analysis with those of an independent analysis of a subset of these data by Saha et al. (, PASP, 117, 37), who have found a color‐dependent discrepancy of up to 0.05 mag between their I‐band photometry and mine for stars in this cluster. I conclude that a major part of the discrepancy appears to be associated with small shutter timing errors (a few hundredths of a second) in the Mini‐Mosaic (MIMO) camera on the WIYN 3.5 m telescope. Smaller contributions to the anomaly likely come from (1) a color‐scale error with a maximum amplitude of ∼±0.02 mag in my secondary standard list as of 2004 September, and (2) statistical effects arising from the previous study’s use of a relatively small number of standard‐star observations to determine a comparatively large number of fitting parameters in the photometric transformations.