乌兹别克斯坦Maidanak天文台标准星的CCD测光：变换和比较
CCD Photometry of Standard Stars at Maidanak Astronomical Observatory in Uzbekstan: Transformations and Comparisons
摘要：
标准星的观测在恒星测光中具有重要意义。我们研究了乌兹别克斯坦迈达纳克天文台UBVRI CCD测光系统的标准转换关系。所有观测都是在2003年8月至2007年9月期间使用AZT-22 1.5 m望远镜、SITE 2k CCD或Fairchild 486 CCD和标准Bessell UBVRI滤光片进行的。我们观察到许多标准恒星周围的天体赤道所观察到的SAAO天文学家。测定了各夜的大气消光系数、光度零点和光度零点的时间变化。次生消光系数和光度零点非常稳定，而原生消光系数表现出明显的季节变化。我们还确定了每个滤波器的变换系数。对于B、V、R和I滤波器，可以用直线或两条直线的组合来实现到SAAO标准系统的转换。然而，在U滤波器和Fairchild 486 CCD组合的情况下，需要高达0.08 mags的显著非线性校正项-与巴耳末跳跃的大小或巴耳末线的强度相关。我们发现我们的数据在V，B-V，V-I和R-I上与SAAO测光匹配良好。而在U-B中，零点差约为3.6 mmag，散射约为0.02 mag。我们将U-B中相对较大的散射归因于SAAO测光在U中的较大误差。我们确认了SAAO标准UBVRI系统和Landolt标准系统之间的大部分微小差异。我们还试图解释大气消光系数的季节变化的背景下，在地球大气中的散射源。
英文摘要：
Observation of standard stars is of crucial importance in stellar photometry. We have studied the standard transformation relations of the UBVRI CCD photometric system at the Maidanak Astronomical Observatory in Uzbekistan. All observations were made with the AZT-22 1.5m telescope, SITe 2k CCD or Fairchild 486 CCD, and standard Bessell UBVRI filters from 2003 August to 2007 September. We observed many standard stars around the celestial equator observed by SAAO astronomers. The atmospheric extinction coefficients, photometric zero points, and time variation of photometric zero points of each night were determined. Secondary extinction coefficients and photometric zero points were very stable, while primary extinction coefficients showed a distinct seasonal variation. We also determined the transformation coefficients for each filter. For B, V, R, and I filters, the transformation to the SAAO standard system could be achieved with a straight line or a combination of two straight lines. However, in the case of the U filter and Fairchild 486 CCD combination, a significant non-linear correction term - related to the size of Balmer jump or the strength of the Balmer lines - of up to 0.08 mags was required. We found that our data matched well the SAAO photometry in V, B-V, V-I, and R-I. But in U-B, the difference in zero point was about 3.6 mmag and the scatter was about 0.02 mag. We attribute the relatively large scatter in U-B to the larger error in U of the SAAO photometry. We confirm the mostly small differences between the SAAO standard UBVRI system and the Landolt standard system. We also attempted to interpret the seasonal variation of the atmospheric extinction coefficients in the context of scattering sources in the earth's atmosphere.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
