<p>Section I. of <a href="https://arxiv.org/abs/1902.05569v1" rel="nofollow noreferrer">The Wide Field Infrared Survey Telescope: 100 Hubbles for the 2020s</a> says:</p>
<blockquote>
<p>Table 1 summarizes the WFIRST instrument suite, and Figure 1 presents the effective area of the Wide Field Instrument (WFI) as a function of wavelength for the imaging filters, grism, and prism. Minor changes to these specifications are possible as the mission design evolves; in particular, the WFI prism bandpass and resolution and some CGI parameters are still being optimized. Substantial changes are not expected. <strong>Both CGI channels have a 1024 x 1024 pixel electron-multiplying CCD (EMCCD) in the focal plane.</strong> Three of the five CGI observing modes will be fully commissioned prior to launch; support for the other two modes will be on a best effort basis. The CGI imaging modes can all be used with linear polarizers. WFIRST will operate from a Quasi-Halo orbit around the second Sun-Earth Lagrange point (L2).</p>
</blockquote>
<p>For background see Wikipedia's <a href="https://en.wikipedia.org/wiki/Charge-coupled_device#Electron-multiplying_CCD" rel="nofollow noreferrer">Charge-coupled device; electron-multiplying CCD</a>. Apparently within the silicon there are hundreds of stages of electron multiplication (similar to avalanche photodiodes) each with about a 2% probability of multiplication.</p>
<p><strong>Question(s):</strong></p>
<ol>
<li>How often are electron-multiplying CCDs used in astronomical telescope focal planes?</li>
<li>Will Nancy Grace Roman be the first use in a space telescope?</li>
</ol>

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2021-01-25T00:42:05.737Z
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2021-01-25T00:50:33.440Z
companion question: [Why does Nancy Grace Roman = 100 × Hubble? Why is the new space telescopes wide field camera so much wider than the old one's?](https://astronomy.stackexchange.com/q/41036/7982)
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<observational-astronomy><photography><charge-coupled-devices>
How often are electron-multiplying CCDs used in telescope focal planes? Will Nancy Grace Roman be the first use in a space telescope?
uhoh
# How often are electron-multiplying CCDs used in telescope focal planes? Will Nancy Grace Roman be the first use in a space telescope?

(Asked by: username_0 on 2021-01-25)

Section I. of [The Wide Field Infrared Survey Telescope: 100 Hubbles for the 2020s](https://arxiv.org/abs/1902.05569v1) says:

> Table 1 summarizes the WFIRST instrument suite, and Figure 1 presents the effective area of the Wide Field Instrument (WFI) as a function of wavelength for the imaging filters, grism, and prism. Minor changes to these specifications are possible as the mission design evolves; in particular, the WFI prism bandpass and resolution and some CGI parameters are still being optimized. Substantial changes are not expected. **Both CGI channels have a 1024 x 1024 pixel electron-multiplying CCD (EMCCD) in the focal plane.** Three of the five CGI observing modes will be fully commissioned prior to launch; support for the other two modes will be on a best effort basis. The CGI imaging modes can all be used with linear polarizers. WFIRST will operate from a Quasi-Halo orbit around the second Sun-Earth Lagrange point (L2).

For background see Wikipedia's [Charge-coupled device; electron-multiplying CCD](https://en.wikipedia.org/wiki/Charge-coupled_device#Electron-multiplying_CCD). Apparently within the silicon there are hundreds of stages of electron multiplication (similar to avalanche photodiodes) each with about a 2% probability of multiplication.

**Question(s):**

1. How often are electron-multiplying CCDs used in astronomical telescope focal planes?
2. Will Nancy Grace Roman be the first use in a space telescope?

**Tags:** observational-astronomy, photography, charge-coupled-devices
> **Comments:**
> **username_0**: [Is a charged-coupled-devices tag okay? If so, what would be good usage guidance for it?](https://astronomy.meta.stackexchange.com/q/680/7982)  
> **username_0**: companion question: [Why does Nancy Grace Roman = 100 × Hubble? Why is the new space telescopes wide field camera so much wider than the old one's?](https://astronomy.stackexchange.com/q/41036/7982)  

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