本帖最後由 WCYue 於 2022-4-25 11:10 編輯
有關使用 eVscope 觀測數據在偵測 WASP-148b 系外行星
We simultaneously observed the transit of WASP-148b with seven 4.5-inch Unistellar eVscopes (Marchis et al. 2020) operated by three professional astronomers (one of whom operated two eVscopes) and three amateur astronomers. Six were located in suburban and urban sites across California, and one was located in North Carolina. All eVscopes shared the same design: a Newtonian reflector with a 4.5-inch aperture and a Sony IMX224LQR CMOS sensor at the prime focus. The sensor has a pixel of scale 1.71 pixelᐨ¹ and a 36.98’ x 27.68’ field of view, with a Bayer color filter array producing a mosaic of pixels with spectral responses peaking at blue, green, and red visible wavelengths. Individual images were recorded with exposure times of 3.97s and digital sensor gains of 25dB (0.129 e- ADUᐨ¹).
Using the Unistellar/SETI Institute data reduction pipeline (SPOC) to process each data set individually, raw images were dark-subtracted and mutually aligned. These individual cali- brated frames were then background-subtracted and averaged in groups of 30 into stacked images with 119.0 s of integration time each, increasing stellar S/N and time averaging over the pixel-dependent Bayer matrix response. Barycentric corrections to BJDTDB were made to all image timestamps. Adaptively scaled elliptical apertures were then used to extract the fluxes of the target star and one comparison star to produce the differential light curve (via SExtractor’s FLUX_AUTO feature; Bertin & Arnouts 1996).
Of the seven light curves obtained using eVscopes, we ultimately combined the three most complete light curves to provide our final light curve, shown in the rightmost panel of Figure 2. Three other light curves were relatively incomplete due to imprecise pointing precision and/or cloud coverage, while the remaining telescope experienced technical issues. Before combination, the light curves were detrended for differential airmass extinction. Although we successfully detected the transit, we did not include the resulting light curve into the global fitting in Section 4 because of its limited precision.
Figure 2 |
發表於 2022-4-25 10:53:32