All Questions
Tagged with units observational-astronomy
8
questions
0
votes
1
answer
45
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What is the unit of the correlation function between logarithmically rebinned galaxy spectrum and stellar template spectrum?
Assume I have a logarithmically rebinned galactic spectrum $G(x)$ and a stellar template spectrum $S(x)$, where $x = \ln{\lambda}$. When $[\lambda] = 1 Å$, then $[x] = 1 Np/Å$. The fourier transformed ...
- 849
3
votes
1
answer
649
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Conversion to Jy of Hubble WFC3 units (electrons/s) and of Spitzer IRAC (MJy/sr)
I am trying to figure out how to convert the units of some FITS files to Jy. These files refer to observations in different bands using different instruments. I list them below with my way of ...
- 61
7
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1
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566
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What does par. lines mean in relation to a telescope aperture in 19th century German astronomical publications?
I am trying to understand what is meant by par. lines in an 1867 article "The Aberration of the fixed stars after the wave theory" by Prof. W. Klinkerfues of Royal Astronomy Works of ...
- 121
2
votes
1
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83
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How to calculate an infrared SED from the specific intensities?
I have values of total infrared fluxes (SED) in literature expressed in Jy (Jansky) for galaxies. I want to assure that my infrared radial profiles of the same galaxies in MJy/sr (and other in Jy/...
- 23
4
votes
1
answer
252
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Flux density from brightness map
This is a naive question. I have a temperature map of radio emission at 1420 MHz, in Kelvin. I want to extract the flux density (in Janskys) from an extended region of this map.
Is the flux density ($...
- 73
1
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1
answer
4k
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How are people converting intensities in Janskys to Kelvin?
I'm reading some ALMA proposals and I am often seeing a conversion from Jy to Kelvin when, for example, people quote noise levels or source flux.
For example on their sensitivity calculator
(https://...
- 190
1
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0
answers
181
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${\rm W/m}^2$ to Jansky [duplicate]
Lets assume I have a source and receive $8 \times 10^{-20}$ ${\rm Wm}^{-2}$ in (400-750) nm filter. How do you convert this received flux to the unit Jansky, is there a formula? (Ultimately, I want to ...
- 11
3
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148
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How often and over what period is Earth’s rotation averaged to compute UT1?
I understand that UT1 (and for that matter UT0, UT2, etc.) are based on averages of actual earth rotation, and serve as a form of mean solar time. However it’s not clear to me when these averages are ...
- 341