<p>I know it is necessary to convolve its spectrum with the transmission curve of a filter.</p>
<p>Are there any online tools or codes available for calculating a BB's magnitude in any specific band (e.g., UBVJHKugriz) when its surface temperature and radius are provided?</p>
<p>What I need is not a table. A table usually does not encompass all stellar types, let alone cover the entire range of temperatures. Besides, BB does not necessarily mean a main sequence star.</p>

CC BY-SA 4.0
2024-03-21T17:44:14.743Z
Are you looking for the colour-magnitude or hertzsprung-russel diagramme?
planetmaker
CC BY-SA 4.0
2024-03-22T02:54:49.197Z
temperature and radius. it has nothing to with CMD or HR diagram.
questionhang
CC BY-SA 4.0
2024-03-22T08:36:43.580Z
colour is immediately representative of the temperature as stars are black bodies. And for main sequence stars colour, temperature, magnitude, radius and mass are not independent variables.
planetmaker
CC BY-SA 4.0
2024-03-22T13:42:17.583Z
OK. I have changed the title.
questionhang
CC BY-SA 4.0
2024-03-22T16:32:57.983Z
Does this answer your question? [Query spectral type for absolute magnitude](https://astronomy.stackexchange.com/questions/57102/query-spectral-type-for-absolute-magnitude)
planetmaker
CC BY-SA 4.0
2024-03-22T16:38:53.380Z
No.  arbitrary band, arbitrary temperature and radius. Not necessarily main sequence stars.  Either convolution or on-line tools or codes.
questionhang
<photometry><magnitude>
magnitude calculation if a blackbody's radius and temperature are provided
questionhang
# magnitude calculation if a blackbody's radius and temperature are provided

(Asked by: username_0 on 2024-03-21)

I know it is necessary to convolve its spectrum with the transmission curve of a filter.

Are there any online tools or codes available for calculating a BB's magnitude in any specific band (e.g., UBVJHKugriz) when its surface temperature and radius are provided?

What I need is not a table. A table usually does not encompass all stellar types, let alone cover the entire range of temperatures. Besides, BB does not necessarily mean a main sequence star.

**Tags:** photometry, magnitude

> **Comments:**
> **username_1**: Are you looking for the colour-magnitude or hertzsprung-russel diagramme?  
> **username_0**: temperature and radius. it has nothing to with CMD or HR diagram.  
> **username_1**: colour is immediately representative of the temperature as stars are black bodies. And for main sequence stars colour, temperature, magnitude, radius and mass are not independent variables.  
> **username_0**: OK. I have changed the title.  
> **username_1**: Does this answer your question? [Query spectral type for absolute magnitude](https://astronomy.stackexchange.com/questions/57102/query-spectral-type-for-absolute-magnitude)  
> **username_0**: No.  arbitrary band, arbitrary temperature and radius. Not necessarily main sequence stars.  Either convolution or on-line tools or codes.  

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