图像系列中超新星的Photometry：超新星遗产调查的方法和应用（SNLS）
Photometry of supernovae in an image series : methods and application to the Supernova Legacy Survey (SNLS)
摘要：
我们提出了一种技术来测量时变点源的光变曲线的空间结构的背景下，从成像数据。该技术是为了测量SNLS超新星的光变曲线，以推断它们的距离而开发的。该测光技术在图像系列上的相同天空位置处执行同时PSF测光。我们描述了两种实现的方法：一个是重新采样图像测量通量之前，和一个不。在这两种情况下，我们勾勒出所涉及的关键算法，并提出了验证使用半人工源引入实像，以评估相对于周围恒星的超新星通量测量的准确性。我们描述了锚定这些PSF通量校准孔径目录所需的方法，以获得SN幅度。我们发现一个轻微的显着偏差的2毫微克的后rescue的方法，并没有偏见的毫微克的准确度的非rescue的方法。鉴于周围的恒星的星等，我们确定的SN星等的系统不确定性小于1.5毫等，这代表了目前的光度校准不确定性影响SN测量的三分之一左右。SN测光提供了几个副产品：亮星PSF通量测量的重复性约为0.6%，对于孔径测量，我们测量了相对天体测量位置，对于单图像亮星测量，噪声基底为2.4 mas;我们表明，在MegaCam仪器的所有波段中，恒星在整个亮度范围内表现出随流量线性加宽约0.5%的轮廓。
英文摘要：
We present a technique to measure lightcurves of time-variable point sources on a spatially structured background from imaging data. The technique was developed to measure light curves of SNLS supernovae in order to infer their distances. This photometry technique performs simultaneous PSF photometry at the same sky position on an image series. We describe two implementations of the method: one that resamples images before measuring fluxes, and one which does not. In both instances, we sketch the key algorithms involved and present the validation using semi-artificial sources introduced in real images in order to assess the accuracy of the supernova flux measurements relative to that of surrounding stars. We describe the methods required to anchor these PSF fluxes to calibrated aperture catalogs, in order to derive SN magnitudes. We find a marginally significant bias of 2 mmag of the after-resampling method, and no bias at the mmag accuracy for the non-resampling method. Given surrounding star magnitudes, we determine the systematic uncertainty of SN magnitudes to be less than 1.5 mmag, which represents about one third of the current photometric calibration uncertainty affecting SN measurements. The SN photometry delivers several by-products: bright star PSF flux mea- surements which have a repeatability of about 0.6%, as for aperture measurements; we measure relative astrometric positions with a noise floor of 2.4 mas for a single-image bright star measurement; we show that in all bands of the MegaCam instrument, stars exhibit a profile linearly broadening with flux by about 0.5% over the whole brightness range.
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