All Questions
Tagged with apparent-magnitude photometry
9 questions
5
votes
1
answer
424
views
Surface Brightness Definition
I know the surface brightness is calculated by taking the apparent magnitude of an object and then divide by the size of the thing. But this is more of "observed" surface brightness, how do ...
3
votes
0
answers
44
views
Estimate the shape of an object based on flux curve
Is there an aproximation to know the shape of a dust cloud,etc based on the magnitude/flux curves of stars they transit? Example, can I know if the shape is (at least in 2 dimensions) elliptical, ...
- 31
2
votes
1
answer
78
views
Why must all magnitude systems have a reference point?
Let $f_*$ and $f_0$ be the observed flux of a star and a reference flux in a particular spectral band, and let $m_*$ and $m_0$ be their respective apparent magnitudes. Then the star's magnitude is ...
5
votes
1
answer
2k
views
How to convert between AB and Vega magnitudes?
This might be a bit silly, but I'm really struggling with a conversion.
I have apparent AB magnitudes: $$m_{AB} = -2.5 \log_{10}(f_\nu [\mu Jy]) + 25$$ that I would like to convert to Vega magnitudes, ...
- 1,105
8
votes
1
answer
193
views
How many photons does it take to determine the existence of a distant object?
This applies to any object, but I see the recent discovery of the oldest, most distant galaxy and it started me wondering what the limits are. Presumably you can do better with a bigger telescope and ...
- 1,429
0
votes
1
answer
165
views
Is it possible to calculate a star's apparent magnitude in another photometric band knowing its visual magnitude?
Or, in other words, is it possible to know a star's luminosity in a certain photometric band?
Proxima Centauri's Wikipedia page provides the apparent magntiude in each UBVRIJHK band (getting ...
- 2,799
0
votes
1
answer
115
views
Extinction and reddening dataset
Where can I find a dataset containing the interstellar reddening and extinction values for all globular clusters, preferably in the HST/WFC3 system.
- 333
2
votes
0
answers
175
views
Apparent Magnitude / Apparent Brightness relationship help
I'm a high-school student that is currently working on a project that describes, using mathematical notation and explanation, how scientists can find the values of each of the properties of stars, ...
- 35
3
votes
1
answer
969
views
Why do different instrumental filters use different magnitude systems (Vega vs AB)?
Suppose I wanted to construct the spectral energy distribution (SED) of an object. Further suppose I observe this object through the 9 broad-band filters using the Subaru Suprimecam (just for an ...
- 723