标题： 超新星2002ap - 第一个月 显示英文标题

标题： Supernova 2002ap - The First Month

摘要： M74中的超新星（SN）2002ap于2002年1月29日被发现。作为近几十年来最靠近的（10 Mpc）超新星事件之一，并且光谱上与所谓的“高能超新星”1997ef和1998bw相似，两者都可能与伽马射线暴（GRBs）有关，因此它具有极大的兴趣。在它的发现后不久，我们启动了对该事件的密集光度和光谱监测活动，这里我们报告了第一个月观测的结果。我们使用我们的UBVRI测光数据来估计峰值亮度的大小和日期。我们的数据显示，该天体的B波段亮度峰值可能出现在2月7.1（-1.3）（+2）UT。基于其与1998bw的相似性，我们估算出可能与SN 2002ap相关的GRB的日期范围。根据最近的报告，我们发现它可能包括所有可用伽马射线数据已密集扫描的时间框架之外的日期。SN 2002ap在峰值亮度时的绝对星等（M_B = -16.9）表明它明显比SN 1998bw或普通的Ia型超新星暗弱，但与SN 1997ef相似。我们的光谱观测证实了SN 2002ap与SNe 1998bw和1997ef极为相似。我们简要描述了这个天体的光谱演化。为了帮助其他观测者并激发理论模型，我们将整个数据集以数字形式公开发布。 显示英文摘要

摘要： Supernova (SN) 2002ap in M74 was discovered on January 29, 2002. Being one of the nearest (10 Mpc) SN events in the last decades, and spectroscopically similar to the so-called ``hypernovae'' 1997ef and 1998bw, both possibly associated with gamma-ray bursts (GRBs), it is of great interest. Shortly after its discovery, we launched an intensive photometric and spectroscopic monitoring campaign of this event, and here we report the results of the first month of observations. We use our UBVRI photometry to estimate the magnitudes at, and dates of, peak brightness. Our data suggest that this object reached its peak B-band luminosity on Feb. 7.1(-1.3)(+2) UT. Based on its similarity to SN 1998bw, we estimate the range of possible dates for a GRB that may have been associated with SN 2002ap. We find that it may include dates outside the time frame for which all available gamma-ray data have been intensively scanned, according to recent reports. The absolute magnitude at peak brightness of SN 2002ap (M_B = -16.9) shows that it was significantly fainter than SN 1998bw, or normal type-Ia SNe, but similar to SN 1997ef. Our spectroscopic observations confirm that SN 2002ap is strikingly similar to SNe 1998bw and 1997ef. We briefly describe the spectral evolution of this object. To assist other observers and to stimulate theoretical models, we make our entire data set publicly available in digital form.