<p>I believe that is a typo. In Tables 4 and 5 of the same document, &quot;UVIS 47&quot; is listed as &quot;g280&quot;, which is the grism you are curious about.</p>
<p>A perusal of several other <em>HST</em> documents (e.g., various <em>Wide Field Camera 3 Instrument Handbooks</em>) turns up no mention of a &quot;G200&quot; element, and searches of the <a href="https://mast.stsci.edu/search/hst/ui/#/" rel="nofollow noreferrer">HST archive</a> turn up nothing if &quot;G200&quot; is entered in the &quot;Filter/Grating&quot; field. (Entering &quot;G280&quot; turns up observations with that grism.)</p>

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2021-10-15T14:16:30.903Z
nice detective work, thanks!
uhoh
CC BY-SA 4.0
2021-10-15T12:28:32.867Z
2021-10-15T12:28:32.867Z
Peter Erwin
<p>Extensive reading for <a href="https://astronomy.stackexchange.com/q/47075/7982">Are the dispersion directions of the prism and the grating in Hubble WFC3 UVIS G280 perpendicular? Can we call this a &quot;grism&quot;? With cross-disparsion?</a> led me to <a href="https://www.stsci.edu/files/live/sites/www/files/home/hst/instrumentation/wfc3/documentation/instrument-science-reports-isrs/_documents/2003/WFC3-2003-02.pdf" rel="nofollow noreferrer">Instrument Science Report WFC3 2003-02; WFC3 UVIS Filters: Measured Throughput and Comparison to Specifications</a>.</p>
<p>Table 1: &quot;UVIS Filter Performance Specifications from Version D JPL Spec or CEI&quot; lists near the bottom</p>
<pre><code>Fnumber  Fname   Lam0   FWHM  lam -50 ... lam +50 ... Description
-------  -----  ------  ----  -------     -------     -----------
UVIS 47  G200   2775.0  1850    1800  ...   3650  ...   UV prism
</code></pre>
<p><strong>Question:</strong> What is Hubbles WFC3 &quot;UVIS 47 G200&quot; filter? Is it just a prism or is it a combination of a prism and a filter?</p>
<p>What is it used for?</p>
<p>How can I find an example of how it has been used in practice?</p>

<observational-astronomy><spectroscopy><hubble-telescope><instruments>
What is Hubbles WFC3 "UVIS 47 G200" filter? What is it used for? How to find an example?
uhoh
# What is Hubbles WFC3 "UVIS 47 G200" filter? What is it used for? How to find an example?

(Asked by: username_0 on 2021-10-15)

Extensive reading for Are the dispersion directions of the prism and the grating in Hubble WFC3 UVIS G280 perpendicular? Can we call this a "grism"? With cross-disparsion? led me to Instrument Science Report WFC3 2003-02; WFC3 UVIS Filters: Measured Throughput and Comparison to Specifications.
Table 1: "UVIS Filter Performance Specifications from Version D JPL Spec or CEI" lists near the bottom
Fnumber  Fname   Lam0   FWHM  lam -50 ... lam +50 ... Description
-------  -----  ------  ----  -------     -------     -----------
UVIS 47  G200   2775.0  1850    1800  ...   3650  ...   UV prism

Question: What is Hubbles WFC3 "UVIS 47 G200" filter? Is it just a prism or is it a combination of a prism and a filter?
What is it used for?
How can I find an example of how it has been used in practice?

**Tags:** observational-astronomy, spectroscopy, hubble-telescope, instruments

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## 1 answers

### Answer by username_1 on 2021-10-15. Score: 3 | Accepted answer

I believe that is a typo. In Tables 4 and 5 of the same document, "UVIS 47" is listed as "g280", which is the grism you are curious about.

A perusal of several other *HST* documents (e.g., various *Wide Field Camera 3 Instrument Handbooks*) turns up no mention of a "G200" element, and searches of the [HST archive](https://mast.stsci.edu/search/hst/ui/#/) turn up nothing if "G200" is entered in the "Filter/Grating" field. (Entering "G280" turns up observations with that grism.)

> **Comments:**
> **username_0**: nice detective work, thanks!  

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