Commissioning of the WWFI for the Wendelstein Fraunhofer Telescope

Gössl, Claus; Bender, Ralf; Fabricius, Maximilian; Hopp, U.; Karasz, Adolf; Kosyra, R.; Lang-Bardl, Florian

doi:10.1117/12.926341

Cited by 3 publications

(4 citation statements)

References 6 publications

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“…In Sect. 3.1 we used the analytical method introduced in Gössl et al (2012) that successfully allows us to consider data points at high count rates in our photon-transfer analysis even when the photon noise of the masterflat begins to dominate. We found reasonable results for the gain compared to the manufacturer's estimation (Table 3).…”

Section: Discussionmentioning

confidence: 99%

“…We used the method introduced in Gössl et al (2012) to correct for this additional noise, the following description closely follows the derivation therein.…”

Section: Gainmentioning

confidence: 99%

“…Both cameras have (2k) 2 , 15 µm pixel, back illuminated 5 Polycold PCC Compact Cooler is a trademark of Brooks Automation Inc, Chelmsford, USA 6 I.e. AMiGo, a two channel CCD-camera for the former 80 cm telescope of the Wendelstein Observatory (Gössl 2007).…”

Section: Pcc Compact Coolersmentioning

confidence: 99%

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The 64 Mpixel wide field imager for the Wendelstein 2m telescope: design and calibration

et al. 2014

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The Wendelstein Observatory of Ludwig Maximilians University of Munich has recently been upgraded with a modern 2m robotic telescope. One Nasmyth port of the telescope has been equipped with a wide-field corrector which preserves the excellent image quality (< 0.8" median seeing) of the site (Hopp et al. 2008) over a field of view of 0.7 degrees diameter. The available field is imaged by an optical imager (WWFI, the Wendelstein Wide Field Imager) built around a customized 2 × 2 mosaic of 4k × 4k 15 µm e2v CCDs from Spectral Instruments. This paper provides an overview of the design and the WWFI's performance. We summarize the system mechanics (including a structural analysis), the electronics (and its electromagnetic interference (EMI) protection) and the control software. We discuss in detail detector system parameters, i.e. gain and readout noise, quantum efficiency as well as charge transfer efficiency (CTE) and persistent charges. First on sky tests yield overall good predictability of system throughput based on lab measurements.

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Section: Discussionmentioning

confidence: 99%

“…We used the method introduced in Gössl et al (2012) to correct for this additional noise, the following description closely follows the derivation therein.…”

Section: Gainmentioning

confidence: 99%

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The 64 Mpixel wide field imager for the Wendelstein 2m telescope: design and calibration

et al. 2014

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“…• ghost images, which appear as diffuse secondary images of bright stars and can be masked automatically only if accurate knowledge about reflecting surfaces and positions of bright stars is available; charge persistence of bright stars causes similar problems and can depend on several factors (Gössl et al 2012), and…”

Section: Introductionmentioning

confidence: 99%

Implementation of Robust Image Artifact Removal in SWarp through Clipped Mean Stacking

Seitz¹,

Bernstein²

2014

Publications of the Astronomical Society of the Pacific

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We implement an algorithm for detecting and removing artifacts from astronomical images by means of outlier rejection during stacking. Our method is capable of addressing both small, highly significant artifacts such as cosmic rays and, by applying a filtering technique to generate single frame masks, larger area but lower surface brightness features such as secondary (ghost) images of bright stars. In contrast to the common method of building a median stack, the clipped or outlier-filtered mean stacked point-spread function (PSF) is a linear combination of the single frame PSFs as long as the latter are moderately homogeneous, a property of great importance for weak lensing shape measurement or model fitting photometry. In addition, it has superior noise properties, allowing a significant reduction in exposure time compared to median stacking. We make publicly available a modified version of SWarp that implements clipped mean stacking and software to generate single frame masks from the list of outlier pixels.

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