标题： 来自数字化巡天 plates 的 photometry 显示英文标题

标题： Photometry from online Digitized Sky Survey Plates

摘要： 我们利用在线数字巡天（DSS）资料中经过CCD测光定标的小视场资料进行了变星测光研究。我们比较了不同的源提取机制，发现即使接近灵敏度极限，尽管在线资料使用了H压缩，仍有可能在DSS-II上获得优于0\fm 1均方根精度的测光结果。我们的研究表明，测光精度强烈依赖于源提取方法。SuperCOSMOS扫描虽然具有更高的空间分辨率，但并未给我们带来更好的结果。这里介绍的方法和参数允许用户用少量亮星CCD定标器，在Schmidt底片巡天极限内，对小视场获得良好的板子测光，这些定标器可能由业余望远镜进行定标。特别是对于上述提到的事件，用于定标的新的视场测光通常存在，但这些前身星在之前没有被测光。此外，是否恒星聚集区是新发现的星团或其他类似工作也可以在不使用中型望远镜的情况下完成。这里介绍的定标是对小视场的“局部”定标。我们表明，这里提出的方法比巡天的“全局”定标（例如GSC-II、SuperCOSMOS和USNO-B）提供更高的精度。 显示英文摘要

摘要： Online Digital Sky Survey (DSS) material is often used to obtain information on newly discovered variable stars for older epochs (e.g. Nova progenitors, flare stars, ...). We present here the results of an investigation of photometry on online digital sky survey material in small fields calibrated by CCD sequences. We compared different source extraction mechanisms and found, that even down near to the sensitivity limit, despite the H-compression used for the online material, photometry with an accuracy better than 0\fm1 rms is possible on DSS-II. Our investigation shows that the accuracy depends strongly on the source extraction method. The SuperCOSMOS scans, although retrieved with an higher spatial resolution, do not give us better results. The methods and parameters presented here, allow the user to obtain good plate photometry in small fields down to the Schmidt plate survey limits with a few bright CCD calibrators, which may be calibrated with amateur size telescopes. Especially for the events mentioned above, new field photometry for calibration purposes mostly exists, but the progenitors were not measured photometrically before. Also the follow up whether stellar concentrations are newly detected clusters or similar work may be done without using mid size telescopes. The calibration presented here is a "local" one for small fields. We show that this method presented here gives higher accuracies than "global" calibrations of surveys (e.g. GSC-II, SuperCOSMOS and USNO-B)