Astronomy:Integration time
In astronomy, integration time or exposure time is the duration for which photons from a source are collected.[1] A longer integration time means that more photons are collected in total.[2] It is analogous to the term shutter speed in photography;[1] however, astronomical observations generally require a much longer integration time than traditional photography, and the total integration time may be segmented into multiple different observations. Higher integration time results in a higher signal-to-noise ratio for an observation.[1][3][4] Integration time is particularly relevant in radio astronomy, where the signal may be much smaller than the background noise for a short observation.[5]
Integration time can also refer to the duration of time for which the photons for each pixel of an image are collected in the case of radio telescopes and charge-coupled devices, which only collect information for one pixel at a time.[5][3]
Integration time can be a challenge for astronomers trying to collect data. Often times, getting an adequate signal-to-noise ratio or level of precision in a measurement can take up to tens of thousands of hours.[6] Additionally, a long integration time can smooth out signals that vary with time and result in loss of information, particularly in contexts where a changing signal may be relevant, such as in the detection of exoplanets.[7] For some types of cameras, such as EMCCDs, increasing integration time may not necessarily lead to a higher signal-to-noise ratio.[8]
References
- ↑ 1.0 1.1 1.2 "Integration time". http://astro.vaporia.com/start/integrationtime.html.
- ↑ "Integration time". https://www.photonics.com/EDU/integration_time/d4790.
- ↑ 3.0 3.1 "CCD Noise Sources and Signal-to-Noise Ratio". https://evidentscientific.com/en/microscope-resource/knowledge-hub/digital-imaging/concepts/ccdsnr.
- ↑ Liu, Chao; Jones, Michael E.; Taylor, Angela C. (2021). "Characterizing the performance of high-speed data converters for RFSoC-based radio astronomy receivers". Monthly Notices of the Royal Astronomical Society 501 (4): 5096–5104. doi:10.1093/mnras/staa3895.
- ↑ 5.0 5.1 "Introduction to Radio Astronomy". https://www.radio-astronomy.org/pdf/sara-beginner-booklet.pdf.
- ↑ Mondal, Rajesh; Barkana, Rennan (2023). "Prospects for precision cosmology with the 21 cm signal from the dark ages". Nature Astronomy 7 (9): 1025–1030. doi:10.1038/s41550-023-02057-y.
- ↑ Morello, Giuseppe; Dyrek, Achrène; Changeat, Quentin (2022). "Is binning always sinning? The impact of time-averaging for exoplanet phase curves". Monthly Notices of the Royal Astronomical Society 517 (2): 2151–2164. doi:10.1093/mnras/stac2828.
- ↑ Daigle, Olivier; Djazovski, Oleg; Dupuis, Jean; Doyon, René; Artigau, Étienne (2014). "Astronomical imaging with EMCCDs using long exposures". High Energy, Optical, and Infrared Detectors for Astronomy VI. 9154. pp. 91540D. doi:10.1117/12.2056617.
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