<p>30.0 mean &quot;variable&quot;.</p>
<p>If you click on the &quot;Ptm&quot; column header, you get a pop-up window including &quot;Note (2) : codes used for the magnitudes:&quot;; below that is a list of codes, including &quot;30.0 = variable (var. in published catalog)&quot;</p>

CC BY-SA 4.0
2021-05-19T20:31:05.853Z
converting a comment
James K
CC BY-SA 4.0
2021-05-19T20:30:56.617Z
2021-05-19T20:30:56.617Z
James K
<p>I have a problem to believe, that the visual magnitude of beta lyrae changes from 3.51 to 30 mags. Maybe 3.0 mag. I looked into the new Gaia catalogue and I am wondering about a lot of measurements. In most cases you can read N unbelievable values for one astronomical star and so on. In my opinion the Hipparcos and Tess catalogue conform better to terrestrial measurements until  2010.</p>

CC BY-SA 4.0
2021-05-13T12:29:32.123Z
"30.0 = variable (var. in published catalog)".
ProfRob
CC BY-SA 4.0
2021-05-12T21:16:34.850Z
2021-05-19T20:29:59.093Z
2021-05-19T20:29:59.093Z
Thomas Höll
<p><a href="https://en.wikipedia.org/wiki/Beta_Lyrae" rel="nofollow noreferrer">Beta Lyrae</a> (HD 174638) is ascribed visual magnitude 30.0 in the Henry Draper catalog. There are hundreds of other stars in the catalog also given magnitude 30.0. What was meant by these nominal magnitudes? Is there a resource in Vizier or elsewhere that provides corrected magnitudes?</p>
<p><a href="https://vizier.u-strasbg.fr/viz-bin/VizieR-3?-source=III/135A/catalog&amp;-out.max=50&amp;-out.form=HTML%20Table&amp;-out.add=_r&amp;-out.add=_RAJ,_DEJ&amp;-sort=_r&amp;-oc.form=sexa" rel="nofollow noreferrer">https://vizier.u-strasbg.fr/viz-bin/VizieR-3?-source=III/135A/catalog&amp;-out.max=50&amp;-out.form=HTML%20Table&amp;-out.add=_r&amp;-out.add=_RAJ,_DEJ&amp;-sort=_r&amp;-oc.form=sexa</a></p>

CC BY-SA 4.0
2021-05-09T09:52:29.070Z
If you click on the "Ptm" column header, you get a pop-up window including "Note (2)  : codes used for the magnitudes:"; below that is a list of codes, including "30.0 = variable (var. in published catalog)".
Peter Erwin
CC BY-SA 4.0
2021-05-09T09:53:00.047Z
For up-to-date magnitudes, I'd try Simbad, e.g.:
https://simbad.u-strasbg.fr/simbad/sim-basic?Ident=hd+174638&submit=SIMBAD+search
Peter Erwin
CC BY-SA 4.0
2021-05-09T13:27:05.893Z
You can also use Vizier’s photometry tool, http://vizier.u-strasbg.fr/vizier/sed/ .   The results of a search are displayed as fluxes, but if you click on individual entries you can see the underlying catalog data, which are often in magnitudes.
Eric Jensen
<magnitude><star-catalogues>
Why is magnitude of Beta Lyrae given as 30.0 in Henry Draper catalog?
Ags1
# Why is magnitude of Beta Lyrae given as 30.0 in Henry Draper catalog?

(Asked by: username_0 on 2021-05-09)

[Beta Lyrae](https://en.wikipedia.org/wiki/Beta_Lyrae) (HD 174638) is ascribed visual magnitude 30.0 in the Henry Draper catalog. There are hundreds of other stars in the catalog also given magnitude 30.0. What was meant by these nominal magnitudes? Is there a resource in Vizier or elsewhere that provides corrected magnitudes?

<https://vizier.u-strasbg.fr/viz-bin/VizieR-3?-source=III/135A/catalog&-out.max=50&-out.form=HTML%20Table&-out.add=_r&-out.add=_RAJ,_DEJ&-sort=_r&-oc.form=sexa>

**Tags:** magnitude, star-catalogues

> **Comments:**
> **username_1**: If you click on the "Ptm" column header, you get a pop-up window including "Note (2)  : codes used for the magnitudes:"; below that is a list of codes, including "30.0 = variable (var. in published catalog)".  
> **username_1**: For up-to-date magnitudes, I'd try Simbad, e.g.: https://simbad.u-strasbg.fr/simbad/sim-basic?Ident=hd+174638&submit=SIMBAD+search  
> **username_2**: You can also use Vizier’s photometry tool, http://vizier.u-strasbg.fr/vizier/sed/ .   The results of a search are displayed as fluxes, but if you click on individual entries you can see the underlying catalog data, which are often in magnitudes.  

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## 2 answers

### Answer by username_3 on 2021-05-19. Score: 2 | Accepted answer

30.0 mean "variable".

If you click on the "Ptm" column header, you get a pop-up window including "Note (2) : codes used for the magnitudes:"; below that is a list of codes, including "30.0 = variable (var. in published catalog)"

> **Comments:**
> **username_3**: converting a comment  

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### Answer by username_4 on 2021-05-12. Score: -2

I have a problem to believe, that the visual magnitude of beta lyrae changes from 3.51 to 30 mags. Maybe 3.0 mag. I looked into the new Gaia catalogue and I am wondering about a lot of measurements. In most cases you can read N unbelievable values for one astronomical star and so on. In my opinion the Hipparcos and Tess catalogue conform better to terrestrial measurements until 2010.

> **Comments:**
> **username_5**: "30.0 = variable (var. in published catalog)".  

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