机构

• 长春光学精密机械与物... [1]
• 高能物理研究所 [1]

采集方式

• OAI收割 [2]

内容类型

• 会议论文 [1]
• 期刊论文 [1]

发表日期

• 2020 [1]
• 2009 [1]

学科主题

筛选

浏览/检索结果: 共2条，第1-2条 帮助 条数/页： 5101520253035404550556065707580859095100 排序方式： 请选择题名升序题名降序提交时间升序提交时间降序作者升序作者降序发表日期升序发表日期降序 No pulsed radio emission during a bursting phase of a Galactic magnetar 期刊论文  OAI收割 Nature, 2020, 卷号: 587, 页码: 63-65 作者:  HXMT   |  收藏  |  浏览/下载：44/0  |  提交时间：2022/02/08 Astrophysics - High Energy Astrophysical Phenomena  Abstract: Fast radio bursts (FRBs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances1-3. It has long been speculated that magnetars are the engine powering repeating bursts from FRB sources4-13, but no convincing evidence has been collected so far14. Recently, the Galactic magnetar SRG 1935+2154 entered an active phase by emitting intense soft íray bursts15. One FRB-like event with two peaks (FRB 200428) and a luminosity slightly lower than the faintest extragalactic FRBs was detected from the source, in association with a soft íray/hard-X-ray flare18-21. Here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-X-ray) data. During the third session, 29 soft-íray repeater (SGR) bursts were detected in íray energies. Throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of SGR bursts, but unfortunately we were not observing when the FRB was detected. The non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of FRB 200428. Our results suggest that FRB-SGR burst associations are rare. FRBs may be highly relativistic and geometrically beamed, or FRB-like events associated with SGR bursts may have narrow spectra and characteristic frequencies outside the observed band. It is also possible that the physical conditions required to achieve coherent radiation in SGR bursts are difficult to satisfy, and that only under extreme conditions could an FRB be associated with an SGR burst.   Space camera imaging gain in-orbit adjusting strategy (EI CONFERENCE) 会议论文  OAI收割 2009 2nd International Conference on Intelligent Computing Technology and Automation, ICICTA 2009, October 10, 2009 - October 11, 2009, Changsha, Hunan, China 作者:  Wang J.;  He X. 收藏  |  浏览/下载：17/0  |  提交时间：2013/03/25 A Multi-Step Gain Adjusting Strategy (MSGAS) of space camera was proposed  which was used to get higher SNR (Signal-Noise Rate) image. When the space camera working in poor light condition  the CCD signal was so weak that it's difficult to get a clear image  to reduce the quantization noise and improve the SNR  we must amplify the CCD signal first and then quantize. The MSGAS was achieved by adjusting the gain of the CCD (Charge Couple Device) signal processor step by step  the upper limit and lower limit were set  if the MDN (Mean Digital Number) of a fixed length image data was not between the lower and upper limit  the gain was adjusted step by step. In the experiment  the upper limit  lower limit and the step were set  and the result of the experiment showed that MSGAS was robust and SNR was improved from 28 to 39. 2009 IEEE.