31 votes
Accepted

How hard is it to find the Sun's "sisters?"

Here are the problems/issues: Most stars are born in clusters/associations but a cursory investigation of cluster demographics with age reveals that the vast majority of clusters do not survive to old ...
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  • 118k
4 votes
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Do ASKAP and ALMA have "fast dump" interferometric modes? Can they see and perhaps report Fast Radio Bursts in real time?

Short answer: No and yes. Do ASKAP and/or ALMA have "fast dump" interferometric modes? Or do they have at least some way to extract dispersion of transient events at the millisecond level? ...
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  • 56
3 votes

How hard is it to find the Sun's "sisters?"

Stand on dune in a desert. Take a handfull of sand, all crushed from the same rock. Now close your eyes, Hold your hand up to the wind, let the wind blow all but one of the grains of sand, somewhere. ...
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2 votes
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Understanding energy loss in a telescope aperture due to atmospheric dispersion

I'm going to make the assumption that the "aperture" of the instrument refers to the width of a fibre that feeds a spectrograph (I can't think of any other plausible scenario). What you want ...
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1 vote
Accepted

When measuring the spectrum of an object at the zenith, is it better to orient the spectroscopic slit N-S of E-W?

If you are at zenith, it doesn't matter - the light coming through the atmosphere is not differentially refracted. If you are away from zenith, then the position of the star in the sky depends on ...
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1 vote

Understanding energy loss in a telescope aperture due to atmospheric dispersion

@ProfRob 's answer helped me understand what is going on, but I would like to add something. If the telescope pointing is optimized for 5000 angstrom the aperture of 2" will completely contain an ...
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1 vote

Do ASKAP and ALMA have "fast dump" interferometric modes? Can they see and perhaps report Fast Radio Bursts in real time?

Further to Surya answer, yes ASKAP can and does detect FRBs in semi-realtime. The reporting to the outside world is far from realtime, unfortunately. In summary an incoherent sum all antennas is made (...
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  • 306

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