Questions tagged [instruments]

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What is a photoelectric scanner?

I am reading this article by Wing, Peimbert and Spinrad, where they mention the use of a photoelectric scanner. By searching online, I find that photoelectric scanners are used to scan punchcards, ...
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What exactly causes very bright sources, such as supernovae, to appear as large circles in photographs?

Consider images such as those in https://hubblesite.org/contents/news-releases/2021/news-2021-007, which show bright supernovae embedded in their host galaxies. No matter which telescope and which ...
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What is Hubbles WFC3 "UVIS 47 G200" filter? What is it used for? How to find an example?

Extensive reading for Are the dispersion directions of the prism and the grating in Hubble WFC3 UVIS G280 perpendicular? Can we call this a "grism"? With cross-disparsion? led me to ...
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Are the dispersion directions of the prism and the grating in Hubble WFC3 UVIS G280 perpendicular? Can we call this a "grism"? With cross-disparsion?

Prologue From Into the UV: A precise transmission spectrum of HAT-P-41b using Hubble's WFC3/UVIS G280 grism: The UVIS grism, however, comes with several quirks that make it difficult to observe with ...
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56 views

How to determine the color term for a filter with a systematically bluer offset than the standard

This is a hypothetical scenario in an attempt to test my understanding of the color term when performing photometric calibrations: Imagine we are observing stars through a B filter with an offset ...
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What are the pros and cons of different types of echelle spectrograph cross-dispersers?

Echelle spectrographs, operating at high resolving power, typically consist of an echelle grating with a low numbers of lines/mm, used with high diffraction orders (often $n=$50-100). To separate the ...
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Why does X-shooter use double passes through prisms for Echelle cross-dispersion instead of gratings?

The catchy title Down-the-barrel observations of a multiphase quasar outflow at high redshift: VLT/X-shooter spectroscopy of the proximate molecular absorber at z=2.631 towards SDSS J001514+184212 ...
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What was the first use of time-delay integration in Astronomy? Are there instances before GAIA?

In the context of GAIA, time-delay integration is the clocking of a CCD's charge shift register at a frequency such that it matches the linear speed across the focal plane of the actual image. So even ...
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Have avalanche photodiodes been used successfully for precision photometry? If so, in analog (charge integration) mode or just in photon counting?

This excellent answer to What would “the next GAIA”-like instrument be like? Could it simply be a 3 to 5x scaled-up version of the same beautiful system? is worth a thorough read-through, but it and ...
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What telescopes used 1000+ pixel Microwave Kinetic Inductance Detectors (MKIDs) for multispectral, single photon counting (time + energy of photons)?

This excellent answer to What would “the next GAIA”-like instrument be like? Could it simply be a 3 to 5x scaled-up version of the same beautiful system? is worth a thorough read-through, but it and ...
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Is the difference between LIGO & Virgo and their "Advanced" versions really generational, or were these just planned incremental upgrades?

I just learned the term "third generation gravitational wave detector" in answers to What would a kHz gravitational wave detector look like? (mountains on millisecond magnetars) How would it ...
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Astrophysical particle spectroscopy; narrow-line particle sources (charged or uncharged) for things other than photons? Have any been detected?

Is Cosmic Ray Astronomy a thing? Is there an equivalent of the red shift effect for cosmic rays? have got me thinking and under this answer I've commented: That's a good point; there aren't as many ...
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What would a kHz gravitational wave detector look like? (mountains on millisecond magnetars) How would it differ from LIGO/Virgo?

The abstract of Gravitational waves from mountains in newly born millisecond magnetars says: In this paper we study the spin-evolution and gravitational-wave luminosity of a newly born millisecond ...
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Are astronomers still using photomultiplier tubes for optical photometry?

In Time domain astronomy and fastest eclipsing binary ZTF J1539+5027 (+20 mag, 6.91 minutes) How to measure it's minimum brightness? I've written A logarithmic magnitude scale might tend to show ...
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Time domain astronomy and fastest eclipsing binary ZTF J1539+5027 (+20 mag, 6.91 minutes): How to measure its minimum brightness?

Per Wikipedia's ZTF J153932.16+502738.8 ZTF J153932.16+502738.8 is a double binary white dwarf with an orbital period of just 6.91 minutes. [...] The light curve shows eclipses. One dip in the light ...
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Is Sofia a radio telescope proper?

I usually think of SOFIA, the Stratospheric Observatory for Infrared Astronomy as an infrared optical telescope: SOFIA uses a 2.5 m (8.2 ft) reflector telescope, which has an oversized, 2.7 m (8.9 ft)...
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What leads an observer to choose a narrow slit over a wide one (and vice-versa) when observing?

In spectroscopy, a wide slit will lead to lower spectral resolution while too narrow of a slit will reduce incoming flux from the object. From what I read, it appears as though there is always a ...
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352 views

Why (the heck) is the basic angle of GAIA 106.5°?

This answer to Why does the Gaia space telescope have two main mirrors says: According to the GAIA FAQs which does an excellent job: http://www.cosmos.esa.int/web/gaia/faqs: Why is there an angle of ...
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Was GRAVITY built to look at one star?

GRAVITY (shown below) is a interferometric combiner of near infrared light from four very large telescopes called The Very Large Telescope in order to make careful astrometric measurements near the ...
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What happens to the Fourier Transform of the Measured Spectrum?

What happens when you double the width of the entrance slit of a spectrograph, in turn letting in twice as much light, would there be an improvement in the Fourier transform of the measured spectral ...
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Has Hubble photographed Venus in near IR? If so how does it compare to the new and exciting Parker Solar Probe image?

Phys.org's Parker Solar Probe offers stunning view of Venus includes the image below taken by the Parker Solar Probe during it's most recent gravitational assist flyby of Venus as it continues to rid ...
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Number of lenslets in wavefront sensor array

I have to do a short calculation, but, quite frankly, I have no idea how to even start... Suppose you have a 10-m telescope (f/10) with an infrared camera that observes at 10 micrometer. The seeing is ...
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Hypothetical CMB space telescope design problem, received power from extended thermal source versus receiver front end NEP?

Consider the example of a large radio dish antenna in space equipped with a heat shield protecting it from the Sun. Let's say the amplifiers front-end effective temperature (for purposes of noise ...
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How can Mercury's sodium tail be imaged?

I recently learned that Mercury has a sodium tail. Can this sodium tail be imaged with a ground based telescope? Is so, what is the minimum setup required to be able to take a picture of it? Do you ...
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How were "microshutters" or other multiplexed or multi-object techniques first used in Astronomical spectroscopy?

This answer to How will microshutter arrays be used in the James Webb and future space telescopes? explains how multiple objects can be selected so that the throughput of a spectrometer can be ...
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Is science data from astronomical telescopes analyzed with something analogous to "optical character recognition"?

Do people manually input the science data from telescopes into databases or does some software automatically collect the data from telescopes and put it in servers and databases? I'd imagine there's ...
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How do radio astronomers avoid having their receivers burned out by ground-imaging radar from satellites?

After about 34:00 in the 9th press conference of AAS 235, radio astronomer and NRAO's spectrum manager Harvey Liszt talks about Radio Astronomy in a New Era of ...
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Is there a limit to the distance of detectable gravitational wave events?

This is somewhat a follow up question to this one. This article indicates that the binaries detected have a distance between 320 and 2840 Mpc. With the current technology, is there a limit to the ...
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Requirements for an amplifier and filter for a horn antenna-based 21 cm radio telescope?

We are looking into the possibility of building a low budget horn antenna for detecting 21 cm hydrogen line radiation (~1420 MHz) and and possibly measuring its spectrum. What are the types of ...
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How was the astrometry of the famous 1919 solar eclipse confirmation of General Relativity calibrated and verified?

The new New York Times article The Eclipse That Made Einstein Famous describes several events and discussions on the hundred year anniversary of the the 1919 solar eclipse and verification of the ...
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How does ALMA produce stable, mutually coherent ~THz local oscillators for all of their dishes?

The ALMA (Atacama Large Millimetre/submillimetre Array) radio telescope's band-10 capabaility is now operational, per this answer. That's confirmed by NRAO's First Science with ALMA’s Highest-...
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What would go into the design of a simple sky quality meter, used to measure night sky brightness?

@MCG's answer mentions several methods to classify night sky quality or brightness, and goes on to say: Additionally, you could always purchase a SQM (Sky quality meter) which is a small, portable ...
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How to calculate luminosity in g-band from absolute AB magnitude and luminosity distance?

How can I calculate the (non-bolometric) luminosity $L$ of a galaxy (or a star for that matter) over a given band from its AB apparent magnitude $m_{AB}$ over that band and its luminosity distance $...
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How are the ESPRESSO Echelle spectrograph's calibration "lines" produced?

The CBC News Technology and Science Q&A This ESPRESSO machine doesn't make coffee but scans the skies for habitable planets includes a nice description of ESPRESSO (Echelle SPectrograph for Rocky ...
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How does the ESPRESSO Echelle spectrograph fold the spectrum so nicely?

The CBC News Technology and Science Q&A This ESPRESSO machine doesn't make coffee but scans the skies for habitable planets includes a nice description of ESPRESSO (Echelle SPectrograph for Rocky ...
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What is the large astronomical instrument shown in this 1918 eclipse expedition photo?

This nice video musing about (among other things) the US Naval Observatory's $3,500 expedition to Baker City or at least Baker County Oregon to observe the June 18, 1918 solar eclipse, there is a ...
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How could a 20 inch space telescope "be able to make out Earth-size planets" orbiting Alpha Centauri?

The NY Times article Telescope to Seek Earthlike Planet in Alpha Centauri System describes a proposed effort to put a telescope into orbit fairly quickly with a narrowly defined purpose - to look for ...
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123 views

How many science instruments can be used in parallel with the Hubble Space Telescope?

The Hubble Space Telescope offers a parallel obervation mode. Observing programmes such as CANDELS and CLASH use WFC3 and ACS in parallel fields. These are also the only instruments of which I have ...
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What are the dimensions of LIGO Detector evacuated chambers?

The LIGO complex is very large, but I assume that there is a very small chamber that actually does the science since they are measuring very small sheers. How big around is the actual evacuated ...
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279 views

2SB mixer in radio astronomy?

In literature about the instrumentation of radio astronomy, I frequently come across a type of mixer described as "2SB". I'm familiar with single-sideband (SSB) and double-sideband (DSB) mixers, but ...
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323 views

Can we find out whether early Venus was Earth-like or not?

It has been speculated that Venus billions of years ago could've had a much different atmosphere with liquid water on its surface and possibly life. Partly thanks to the cooler young Sun. But is it ...