<p>It is arbitary, it is the Roman numeral for one.</p>
<blockquote>
<p>The first five main regions that have been identified in the infrared received the names
NGC 6334-I to NGC 6334-V (see Persi &amp; Tapia 2008). <a href="https://arxiv.org/pdf/1911.06579.pdf" rel="noreferrer">https://arxiv.org/pdf/1911.06579.pdf</a></p>
</blockquote>
<blockquote>
<p>Large-scale surveys made at different
wavelength ranges have identified these very young spots and, because not all of them
emit in all wavebands, several name sets have been proposed and this has contributed to
some confusion. In particular, Roman numbers I to V were assigned to the far-infrared
peaks by McBreen et al. (1979) and letters A to F to the radio sources by Rodr´ıguez,
Canto &amp; Moran (1982). The nomenclature adopted here is an extension of Kraemer ´
and Jackson’s (1999, Appendix) identification scheme. <a href="https://www.aspbooks.org/publications/905/456.pdf" rel="noreferrer">https://www.aspbooks.org/publications/905/456.pdf</a></p>
</blockquote>
<blockquote>
<p><a href="https://i.sstatic.net/YF0p5S6x.png" rel="noreferrer"><img src="https://i.sstatic.net/YF0p5S6x.png" alt="enter image description here" /></a></p>
<p>The 40-250 ¡im map of NGC 6334. The effective wavelength is 69 pm for a source temperature of 70 K. Roman numerals I-VI
indicate the peak source positions. The contour unit is 7.5 X 10-17 W m~2 Hz-1 sr-1
. The locations of the other sources shown include:
crosses, 40-350 pm peak source positions; dotted crosses, 1.95 cm continuum peak positions; diamonds, 6 cm continuum positions; triangles,
H20 maser sources; squares, OH maser sources; star, 2-20 pm source; open squares, 1 mm continuum peak positions. In the lower right
corner the beam size and chopper throw are shown.
<a href="https://articles.adsabs.harvard.edu/pdf/1979ApJ...232L.183M" rel="noreferrer">https://articles.adsabs.harvard.edu/pdf/1979ApJ...232L.183M</a></p>
</blockquote>

CC BY-SA 4.0
2024-04-23T21:17:06.510Z
An interesting misinterpretation of $\mu$ from the scan-to-pdf there under the plot. Never seen that one before.
Jon Custer
CC BY-SA 4.0
2024-04-23T20:18:19.560Z
2024-04-23T20:18:19.560Z
James K
<p>The Wikipedia page on <a href="https://en.wikipedia.org/wiki/NGC_6334#cite_note-10" rel="nofollow noreferrer">NGC 6334</a> has a photo identifying NGC 6334I as a star-forming region or protocluster in the Cat's Paw Nebula. The reference to an <a href="https://www.eso.org/public/images/potw1712a/" rel="nofollow noreferrer">ESO Newsletter</a> from 2017 stated that &quot;...this new image from ALMA shows a massive protostar, nestled deep within this dust-filled stellar nursery, that is undergoing an intense growth spurt, most likely triggered by an avalanche of gas falling onto its surface. This new material feeding it is causing the protostar to shine nearly 100 times brighter than before.&quot;</p>
<p>The newsletter does not reference a paper.</p>

CC BY-SA 4.0
2024-04-23T20:37:04.343Z
2024-04-23T20:37:04.343Z
amateurAstro
<p>I've just encountered (in <a href="https://iopscience.iop.org/article/10.3847/2041-8213/ad37ff" rel="nofollow noreferrer">an article</a> about the detection of 2-methoxyethanol in interstellar space) references to an object called NGC 6334I. It seems that the object is a protostellar cluster.</p>
<p>When I Google &quot;NGC 6334I,&quot; it turns up a few papers, like <a href="https://arxiv.org/abs/2402.13913" rel="nofollow noreferrer">this</a> and <a href="https://iopscience.iop.org/article/10.3847/1538-4357/abad38" rel="nofollow noreferrer">this</a>, but these sources only <strong>use</strong> the name; they don't explain its construction.</p>
<p>Similarly, when I search for &quot;NGC 6334I&quot; in <a href="http://spider.seds.org/ngc/ngc.html" rel="nofollow noreferrer">The Interactive NGC Catalog Online</a>, it returns <a href="http://spider.seds.org/ngc/ngc.cgi?CatalogNumber=NGC+6334" rel="nofollow noreferrer">the entry for NGC 6334</a>. So their search mechanism seems to strip off the trailing letter 'I', but my intuition tells me that these papers' authors would not have included the suffix if it weren't significant. To put it differently, I am not comfortable assuming that &quot;6334&quot; and &quot;6334I&quot; refer to the same object.</p>
<p>I've tried all sorts of Google searches to learn about the format (syntax) for the identifiers used in the NGC, but have turned up nothing.</p>

<ngc>
What does a final letter I mean in a New General Catalogue (NGC) identifier?
Paul Tanenbaum
# What does a final letter I mean in a New General Catalogue (NGC) identifier?

(Asked by: username_0 on 2024-04-23)

I've just encountered (in [an article](https://iopscience.iop.org/article/10.3847/2041-8213/ad37ff) about the detection of 2-methoxyethanol in interstellar space) references to an object called NGC 6334I. It seems that the object is a protostellar cluster.

When I Google "NGC 6334I," it turns up a few papers, like [this](https://arxiv.org/abs/2402.13913) and [this](https://iopscience.iop.org/article/10.3847/1538-4357/abad38), but these sources only **use** the name; they don't explain its construction.

Similarly, when I search for "NGC 6334I" in [The Interactive NGC Catalog Online](http://spider.seds.org/ngc/ngc.html), it returns [the entry for NGC 6334](http://spider.seds.org/ngc/ngc.cgi?CatalogNumber=NGC+6334). So their search mechanism seems to strip off the trailing letter 'I', but my intuition tells me that these papers' authors would not have included the suffix if it weren't significant. To put it differently, I am not comfortable assuming that "6334" and "6334I" refer to the same object.

I've tried all sorts of Google searches to learn about the format (syntax) for the identifiers used in the NGC, but have turned up nothing.

**Tags:** ngc


---

## 2 answers

### Answer by username_1 on 2024-04-23. Score: 5

It is arbitary, it is the Roman numeral for one.

> The first five main regions that have been identified in the infrared received the names
> NGC 6334-I to NGC 6334-V (see Persi & Tapia 2008). <https://arxiv.org/pdf/1911.06579.pdf>

> Large-scale surveys made at different
> wavelength ranges have identified these very young spots and, because not all of them
> emit in all wavebands, several name sets have been proposed and this has contributed to
> some confusion. In particular, Roman numbers I to V were assigned to the far-infrared
> peaks by McBreen et al. (1979) and letters A to F to the radio sources by Rodr´ıguez,
> Canto & Moran (1982). The nomenclature adopted here is an extension of Kraemer ´
> and Jackson’s (1999, Appendix) identification scheme. <https://www.aspbooks.org/publications/905/456.pdf>

> [![enter image description here](https://i.sstatic.net/YF0p5S6x.png)](https://i.sstatic.net/YF0p5S6x.png)
>
> The 40-250 ¡im map of NGC 6334. The effective wavelength is 69 pm for a source temperature of 70 K. Roman numerals I-VI
> indicate the peak source positions. The contour unit is 7.5 X 10-17 W m~2 Hz-1 sr-1
> . The locations of the other sources shown include:
> crosses, 40-350 pm peak source positions; dotted crosses, 1.95 cm continuum peak positions; diamonds, 6 cm continuum positions; triangles,
> H20 maser sources; squares, OH maser sources; star, 2-20 pm source; open squares, 1 mm continuum peak positions. In the lower right
> corner the beam size and chopper throw are shown.
> <https://articles.adsabs.harvard.edu/pdf/1979ApJ...232L.183M>

> **Comments:**
> **username_2**: An interesting misinterpretation of $\mu$ from the scan-to-pdf there under the plot. Never seen that one before.  

---

### Answer by username_3 on 2024-04-23. Score: 2

The Wikipedia page on [NGC 6334](https://en.wikipedia.org/wiki/NGC_6334#cite_note-10) has a photo identifying NGC 6334I as a star-forming region or protocluster in the Cat's Paw Nebula. The reference to an [ESO Newsletter](https://www.eso.org/public/images/potw1712a/) from 2017 stated that "...this new image from ALMA shows a massive protostar, nestled deep within this dust-filled stellar nursery, that is undergoing an intense growth spurt, most likely triggered by an avalanche of gas falling onto its surface. This new material feeding it is causing the protostar to shine nearly 100 times brighter than before."

The newsletter does not reference a paper.


---

