论文标题
光度法测试：NGC 3370 ACS场的情况
Tests of photometry: the case of the NGC 3370 ACS field
论文作者
论文摘要
对获得点扩散功能（PSF）光度法的不同方法进行了批判分析和比较。使用四种不同的方法降低了NGC3370的深度ACS观察结果。这些减少探索了许多方法论上的差异：软件包（Daophot和Dolphot），输入图像（单个和堆叠帧），PSF模型（合成和经验）以及孔径校正方法（自动和手动）。光度法的比较导致以下结果：1）单个减少之间的光度不完整性仅显示最小的差异（<10％）。 2）在堆叠帧的Daophot运行中，统计错误比单个帧上的Dolphot运行小20％至30％。 3）直接由光度法代码分配的统计误差比根据人工恒星测试测得的误差小25％至50％。 4）系统错误取决于大小，并且在微弱的末端变得更大，在$σ_s\ sim0.1 $ mag的级别上。 5）Dolphot中的自动孔径校正例程会导致严重的系统误差（$σ_s\ sim 0.05 $ mag）。 6）当通过人工恒星测试正确纠正系统误差时，单个降低在0.02 MAG级别上符合良好的一致性。降低之间的合理一致性导致重要的含义：i）i）在亮度距离尺度和ii）堆叠的框架光度法可以降低到1％的水平，这是研究外部星系中非变异星的好方法。
A critical analysis and comparison of different methods for obtaining point spread function (PSF) photometry are carried out. Deep ACS observations of NGC3370 were reduced using four distinct approaches. These reductions explore a number of methodological differences: software packages (DAOPHOT and DOLPHOT), input images (individual and stacked frames), PSF models (synthetic and empirical), and aperture correction methods (automatic and manual). A comparison of the photometry leads to the following results: 1) Photometric incompleteness between individual reductions shows only a minimal difference (<10%). 2) Statistical errors are 20% to 30% smaller for DAOPHOT runs on stacked frames than DOLPHOT runs on individual frames. 3) Statistical errors assigned directly by the photometry codes are 25% to 50% smaller than the errors measured from artificial star tests. 4) Systematic errors are magnitude dependent and become larger at the faint end, at the level of $σ_s\sim0.1$ mag. 5) The automatic aperture correction routines in DOLPHOT result in a significant systematic error ($σ_s \sim 0.05$ mag). 6) Individual reductions agree well at the 0.02 mag level when the systematic errors are properly corrected through artificial star tests. The reasonable agreement between the reductions leads to important implications that i) the reduction dependent errors can be reduced to a 1% level in the luminosity distance scale, and ii) the stacked frame photometry can be a good means to study non-variable stars in external galaxies.
