What are the uncertainty values for my corrected magnitudes?

AI Thread Summary
The discussion focuses on calculating the errors in corrected apparent magnitudes for a star observed in two wavebands, g-band and r-band. The Colour Excess is given as 0.36 with an uncertainty of 0.01, and the extinction values for the bands are 1.1890 for g-band and 0.8226 for r-band. The corrected apparent magnitudes are calculated as 13.7337 for g-band and 13.0952 for r-band, with associated errors of 0.033030 and 0.022850, respectively. There is uncertainty regarding the correct placement of brackets in the error calculation equation, although no functional difference is noted. The discussion emphasizes the importance of accurate error propagation in astronomical measurements.
Thomas Smith
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Homework Statement


I need to work out the errors of my corrected apparent magnitudes.

The Colour Excess is 0.36 with uncertainty = 0.01

The star was observed in two wavebands.
r-band = 2.285
g-band = 3.303

The 2.285 and 3.303 are the ratios R_V for the SDSS (Sloan digital sky servery) r and g bands.

The measured Apparent Magnitudes and Uncertainties.
g-band = 14.9228 uncertainty = 0.0003
r-band = 13.9178 uncertainty = 0.0002

The amount of extinction for g-band = 1.1890
The amount of extinction for r-band = 0.8226

g-band apparent magnitude extinction corrected = 13.7337
r-band apparent magnitude extinction corrected = 13.0952

Homework Equations



Colour Excess Uncertainty = a
Colour Excess = b
Measured Apparent Magnitude Uncertainty = x
Ratio of the band = y
##\Delta Q = 1.18908 × \sqrt{((a/b)^2 + (x/y)^2)}##[/B]

The Attempt at a Solution


Error in Corrected g band ##\Delta Q = 1.18908 × \sqrt{((Δ0.01/0.36)^2 + (Δ0.0003/3.303)^2)}## = 0.033030

Error in Corrected r band ##\Delta Q = 0.8226 × \sqrt{((Δ0.01/0.36)^2 + (Δ0.0002/2.285)^2)}## = 0.022850[/B]
 
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Thomas Smith said:

Homework Statement


I need to work out the errors of my corrected apparent magnitudes.

The Colour Excess is 0.36 with uncertainty = 0.01

The star was observed in two wavebands.
r-band = 2.285
g-band = 3.303

The 2.285 and 3.303 are the ratios R_V for the SDSS (Sloan digital sky servery) r and g bands.

The measured Apparent Magnitudes and Uncertainties.
g-band = 14.9228 uncertainty = 0.0003
r-band = 13.9178 uncertainty = 0.0002

The amount of extinction for g-band = 1.1890
The amount of extinction for r-band = 0.8226

g-band apparent magnitude extinction corrected = 13.7337
r-band apparent magnitude extinction corrected = 13.0952

Homework Equations



Colour Excess Uncertainty = a
Colour Excess = b
Measured Apparent Magnitude Uncertainty = x
Ratio of the band = y
##\Delta Q = 1.18908 × \sqrt{((a/b)^2 + (x/y)^2)}##[/B]

The Attempt at a Solution


Error in Corrected g band ##\Delta Q = 1.18908 × \sqrt{((Δ0.01/0.36)^2 + (Δ0.0003/3.303)^2)}## = 0.033030

Error in Corrected r band ##\Delta Q = 0.8226 × \sqrt{((Δ0.01/0.36)^2 + (Δ0.0002/2.285)^2)}## = 0.022850[/B]
I'm unsure about the brackets in the equation. Is this correct? ## \sqrt{((a/b)^2 + (x/y)^2)}##
Or should it be ## \sqrt{(a/b)^2 + (x/y)^2}##
 
Thomas Smith said:
I'm unsure about the brackets in the equation. Is this correct? ## \sqrt{((a/b)^2 + (x/y)^2)}##
Or should it be ## \sqrt{(a/b)^2 + (x/y)^2}##
I don't see a functional difference.
 
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