APOD and General Astronomy Discussion Forum
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Chile’s Atacama Desert comprises over 100 000 square kilometres of arid, barren terrain. However, for astronomers working at the largest ground-based astronomical project in existence, the Atacama Large Millimeter/submillimeter Array (ALMA), some of the most important measurements occur on the scale of just a few millimetres.
The ALMA Operations Support Facility (OSF) sits at an altitude of 2900 metres above sea level in the Andes. From here, astronomers, technicians, and engineers can control each of ALMA’s individual 66 antennas, which are located over 2000 metres higher, at 5000 metres elevation, up on the Chajnantor plateau. Getting the antennas up to this plateau presents quite an engineering challenge.
Enter Otto and Lore! These huge orange beasts — one of which is seen here — were specifically designed and built in Germany to carry the 100-tonne antennas from the OSF to Chajnantor (a distance of some 28 kilometres). When they arrive, the leviathan transporters position each antenna with millimetre precision. This incredibly exact positioning is crucial to the array’s scientific operations, and enables ALMA to produce some of the world’s sharpest images of the Universe.
You can see Otto and Lore in action in ESOcast 56: Gentle Giants in the Desert.
This NASA/ESA Hubble Space Telescope image contains a veritable mix of different galaxies, some of which belong to the same larger structure: At the middle of the frame sits the galaxy cluster SDSS J1050+0017.
The gigantic mass of this cluster creates the fascinating phenomenon of strong gravitational lensing. The gravity of the cluster bends light coming from behind it in a similar way to how the base of a wine glass bends light. The effects of this lensing can be clearly seen as curved streaks forming a circular shape around the centre of the frame. Astronomers can use these distorted galaxies to calculate the mass of the cluster — including the mass of the dark matter within it — and to peer deeper into the Universe as otherwise possible. Gravitational lensing does not only distorts the views of galaxies, it also enlarge their appearance on the sky and magnifies their light.
Hubble has viewed gravitational lensing many times, and produced truly stunning images. Astronomers even set up a dedicated programme to study different galaxy clusters which show a great number of lensed galaxies: The Frontier Fields programme. This way some of the most distant galaxies in the Universe were found. With each additional cluster being observed some more distant galaxies are added to this list, slowly completing our picture of how galaxies looked and evolved in the early Universe.
I love these rich cluster and lensed galaxies images!!!bystander wrote: ↑Mon Sep 24, 2018 4:50 pm Warped and Distorted
ESA Hubble Picture of the Week | 2018 Sep 24This NASA/ESA Hubble Space Telescope image contains a veritable mix of different galaxies, some of which belong to the same larger structure: At the middle of the frame sits the galaxy cluster SDSS J1050+0017.
The gigantic mass of this cluster creates the fascinating phenomenon of strong gravitational lensing. The gravity of the cluster bends light coming from behind it in a similar way to how the base of a wine glass bends light. The effects of this lensing can be clearly seen as curved streaks forming a circular shape around the centre of the frame. Astronomers can use these distorted galaxies to calculate the mass of the cluster — including the mass of the dark matter within it — and to peer deeper into the Universe as otherwise possible. Gravitational lensing does not only distorts the views of galaxies, it also enlarge their appearance on the sky and magnifies their light.
Hubble has viewed gravitational lensing many times, and produced truly stunning images. Astronomers even set up a dedicated programme to study different galaxy clusters which show a great number of lensed galaxies: The Frontier Fields programme. This way some of the most distant galaxies in the Universe were found. With each additional cluster being observed some more distant galaxies are added to this list, slowly completing our picture of how galaxies looked and evolved in the early Universe.
Sure, the same filters I used were probably used for ESA's version. Two near-infrared (F160W, F110W) a visible orange (F606W), and a visible blue / near UV (F390W)
Ann wrote: ↑Mon Sep 24, 2018 5:07 pm
... Geck, the spacetelescope.org page credits you. You have told us before that sometimes they credit you even if you have had little or nothing to do with the image, but perhaps, in this case, you know something about it? For example, do you know what filters were used for it? ...
Thanks, Geck (and bystander)!geckzilla wrote: ↑Mon Sep 24, 2018 5:19 pmSure, the same filters I used were probably used for ESA's version. Two near-infrared (F160W, F110W) a visible orange (F606W), and a visible blue / near UV (F390W)
Note that the F160W is assigned to red, the F110W and F606W are assigned to cyan, and the F390W is assigned to blue. I recall these are quite hard to get color balanced because they are so red, hence the color assignment for each filter might seem like it doesn't make sense.
You can see more info here:
https://flic.kr/p/PJTDQy
Apparently the addition of the infrared instruments to HST were kind of an afterthought, but for some reason they (mostly) constrained the naming convention to three digits. You can think of F110W and F160W as having invisible zeroes on the end before the W. For JWST the same naming convention is retained, even though they're all >1000nm filters.Ann wrote: ↑Mon Sep 24, 2018 5:39 pmCan you explain something to me? Why are F110W and F160W infrared filters, when F390W and F606W are visible light filters? It sounds as if F110W and F160W should detect shorter wavelengths than F390W and F606W, but in reality it is the other way round. What is the logic behind that?
Thanks, Geck!geckzilla wrote: ↑Mon Sep 24, 2018 7:44 pmApparently the addition of the infrared instruments to HST were kind of an afterthought, but for some reason they (mostly) constrained the naming convention to three digits. You can think of F110W and F160W as having invisible zeroes on the end before the W. For JWST the same naming convention is retained, even though they're all >1000nm filters.Ann wrote: ↑Mon Sep 24, 2018 5:39 pmCan you explain something to me? Why are F110W and F160W infrared filters, when F390W and F606W are visible light filters? It sounds as if F110W and F160W should detect shorter wavelengths than F390W and F606W, but in reality it is the other way round. What is the logic behind that?
