Results are presented from a study of various sunspot contrast parameters in broadband red (672.3 nm) Cartesian full-disk digital images taken at the San Fernando Observatory (SFO) over eight years, 1997 – 2004, of the twenty-third sunspot cycle. A subset of over 2700 red sunspots was analyzed and values of average and maximum sunspot contrast as well as maximum umbral contrast were compared to various sunspot parameters. Average and maximum sunspot contrasts were found to be significantly correlated with sunspot area (r s=− 0.623 and r s=− 0.714, respectively). Maximum umbral contrast was found to be significantly correlated with umbral area (r s=− 0.535). These results are in agreement with the works of numerous other authors. No significant dependence was detected between average contrast, maximum contrast, or maximum umbral contrast during the rising phase of the solar cycle (r s=0.024, r s=0.033, and r s=0.064, respectively). During the decay phase, no significant correlation was found between average contrast or maximum contrast and time (r s=− 0.057 and r s=0.009, respectively), with a weak dependence seen between maximum umbral contrast and cycle (r s=0.102).
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机译：结果是对1997年至2004年八年的第23个黑子周期在圣费尔南多天文台（SFO）上拍摄的宽带红色（672.3 nm）笛卡尔全盘数字图像中各种黑子对比度参数的研究得出的。分析了超过2700个红色黑子的子集，并将平均和最大黑子对比度以及最大本影对比度的值与各种黑子参数进行了比较。发现平均和最大黑子对比度与黑子面积显着相关（r s =-0.623和r s =-0.714）。发现最大本影对比度与本影面积显着相关（r s =-0.535）。这些结果与许多其他作者的作品一致。在太阳周期上升阶段（r s = 0.024，r s = 0.033和r s = 0.064）。在衰减阶段，平均对比度或最大对比度与时间之间没有发现显着相关性（r s = − 0.057和r s = 0.009），且弱最大本影对比度与周期之间的相关性（r s = 0.102）。
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