SNIFFLES I：影响1-26 GHz射电天文学的低轨卫星的有意发射、无意发射与非预期辐射
SNIFFLES I: Intended Emission, Unwanted Emission, and Unintended Radiation from Low-Earth Orbiting Satellites Impacting Radio Astronomy from 1-26 GHz
AI总结：
SNIFFLES项目首批结果显示，Starlink等四个NGSO星座的卫星在1-26 GHz射电天文频段产生三类干扰，部分信号落入保护频段，流量密度远超天文源，威胁射电天文观测。
AI中文摘要：
我们公布了正在开展的观测项目SNIFFLES的首批结果，该项目旨在表征非地球静止轨道（NGSO）系统在1-26 GHz（L、S、C、X和K波段）射电天文接收机常用频段内的有意发射、无意发射与非预期辐射。我们使用澳大利亚新南威尔士州库纳巴拉布兰附近的22米口径莫帕射电望远镜，并结合澳大利亚望远镜致密阵列（ATCA）的一台单天线及其新型BIGCAT后端的后续观测，对四个NGSO星座（Starlink、OneWeb、Amazon Leo和Guowang）的卫星开展了4629次跟踪观测，累计望远镜观测时长375.9小时。通过将探测到的多普勒频移与预测星历进行关联，我们确认了卫星的身份。我们在四个星座中的三个星座的300多个独特频率上，探测到2345例有意发射、无意发射与非预期辐射的实例。这些探测覆盖了影响射电天文学的全部三类干扰：（1）有意发射（包括DTD）；（2）无意发射（OOBE，包括Starlink的DTD信号的最高至四次谐波，其基频约为2.6 GHz，四次谐波在约10.5 GHz处被探测到）；（3）卫星平台电子设备产生的非预期辐射。多项探测结果落入射电天文学的核心保护频段，包括受保护的羟基（OH）谱线频段内的1613.19 MHz，以及2690.76 MHz和2700 MHz。在2700 MHz处，相关卫星版本的所有观测中有76.9%探测到非预期辐射。ATCA的后续测量证实，其流量密度比典型天文源高出多达11个数量级，远超射电天文接收机的饱和阈值。
英文摘要：
We present the first results of SNIFFLES, an ongoing observational programme to characterise intended emission, unwanted emission, and unintended radiation from NGSO systems across common radio astronomy receiver bands from 1-26 GHz (L, S, C, X, and K bands). Using the Australian 22 metre Mopra radio telescope near Coonabarabran, New South Wales, with followup observations from a single dish of the ATCA interferometer and its new BIGCAT backend, we conducted 4629 tracked observations of satellites from four NGSO constellations (Starlink, OneWeb, Amazon Leo, and Guowang), amounting to 375.9 hours of telescope time. Satellite identification was confirmed by correlating detected Doppler shifts with predicted ephemerides. We detected 2345 instances of intended emission, unwanted emission, and unintended radiation at 300+ unique frequencies from three of the four systems. The detections span all three interference classes affecting radio astronomy: (1) intended emission (including DTD), (2) unwanted emission (OOBE, including up to the fourth harmonic of the Starlink DTD signal at approximately 2.6 GHz, with the fourth harmonic detected near 10.5 GHz), and (3) unintended radiation from satellite platform electronics. Several detections fall within primary radio astronomy allocations, including 1613.19 MHz within the protected OH line band, and at 2690.76 MHz and 2700 MHz. At 2700 MHz, unintended radiation was detected in 76.9 percent of all observations of the relevant satellite version. ATCA followup measurements confirm flux densities up to eleven orders of magnitude brighter than typical astronomical sources, well in excess of levels that saturate radio astronomy receivers.
