The Hubble Deep Field is an image of galaxies that are 13 billion years old. In the future, the Roman space telescope Nancy Grace will get a similar image, but with a field of view 100 times larger
Today we are all excited about the Webb Telescope, whose mission so far has been a huge success. We’re also eagerly awaiting the first images from this telescope, but we shouldn’t forget that Webb, while important, is just a drop in the ocean that observational astronomy needs.
Before we move on to the topic of ultra-deep field, let’s remind ourselves that…
…more famous than Hubble, but there are other space observatories too
Hubble is a backup example of a space observatory, the observations of which are talked about a lot. Until the observation web began, it remained the largest operational telescope in space, but the list is long. We had the Kepler telescope, for example, which provided us with huge databases to help us find exoplanets. Or Spitzer, designed for observing the infrared sky, which, in addition to observing galaxies and stars, has also proven useful in studying extrasolar planets.
These two telescopes are no longer active, but the Gaia space observatories (which measure the position of stars) and TESS (the search for extrasolar planets by transit method, while observing most of the sky) are still operational. The current stages of both large-scale sky surveys are scheduled to end this year.
Hubble, Webb I teleskop Nancy Grace Roman
Hubble is currently the most versatile telescope in Earth orbit. One of the few things that can also be observed in UV rays. This is one reason NASA is concerned about the condition of this telescope. Without it, one of the largest ultraviolet sky observation programs would fail.
Webb is often treated as a successor to Hubble, but it’s not exactly a good comparison. The range of wavelengths of the observed light (near and mid-infrared) would make it something between the already off Spitzer (infrared) and Hubble (visible light, near infrared).
Meanwhile, by mid-2027, the Nancy-Grace-Roman (NGR) telescope is also set to reach the L2 point near Earth, just like Webb. Equipped with a mirror diameter of 2.4 meters. The NGR is similar to the Hubble telescope in many ways, so its consideration as a telescope is largely justified.
Heart of the Nancy Grace Roman Telescope 300 Megapixels
The Wide Field Instrument is a monitoring device, the main element of which is a camera made of 18 modified CMOS arrays with a resolution of 16 mega pixels each. The overall resolution of the sensor mosaic is up to 300 mega pixels. An array of 8 monitoring filters allows light to be recorded from blue (480 nm) to near-infrared (2300 nm or 2.3 μm).
The final images will have technical breaks due to the inability to precisely connect the sensors on the base, but this is something we often encounter in the case of mosaics used in monitoring tools. Thanks to the ability to precisely locate the telescope between observations, it will be possible to remove these gaps from the final portions of the images that will be included in popular scientific publications.
Not only will the camera in the WFI instrument provide a higher resolution than the one in the Hubble telescope. The pixels will also be more sensitive and the data acquisition speed will be 500 times faster.
The main difference between the Hubble telescope and the NGR telescope is the field of view
The NGR telescope will have a different observational strategy than Hubble. There will only be two instruments on board. But not just any. One of them, the so-called Coronagraph Instrument (CGI), will allow precise observation of the vicinity of various stars. The second most emotive is the Wide Field Instrument (WFI) with its 300MP camera.
The optical design of the NGR telescope in combination with the WFI will provide a field of view 100 times greater than that of Hubble and the ACS camera while maintaining the same image resolution. In the case of infrared images taken by Hubble and WFC3 camera, it will be more than 200 times.
The NGR telescope can still see a small patch of sky, 0.28 square degrees, just slightly larger than the size of a full moon. But it was viewed simultaneously, not in multiple independent sessions as Hubble had to do. It is estimated that in its first five years of operation, the NGR telescope will cover up to 50 times the area of the sky with observations that Hubble has been able to make in more than 30 years of its career.
Hubble’s Deep Field (Hyper), i.e. images of the farthest regions of space
From the moment the Hubble telescope was launched into orbit, it was known that one of the benefits of such an observatory in orbit would be the opportunity to make very long exposures to a specific part of the sky to see very faint, and at the same time time, very distant and young galaxies.
Hubble took its first image, called the Hubble Deep Field (HDF), as early as 1995. This observation was then repeated, selecting different places in the sky, using different filters. The most cited images of this type, released to the public in 2014, are a mixture of observations from ultraviolet to near infrared. It’s a version of the Hubble Ultra Deep Field (HUDF) that was created a decade ago.
The NGR will make the ultra-deep field telescope 100 times more efficient than the Hubble telescope
The astronomers had to spend approximately 280 hours of observing time on the Hubble telescope with the help of various instruments to create the HUDF. It wasn’t a single exposure, but a series of photos put together after that. We do not include here the time required to process component images. In 2027, due to advances in computer technologies, although the amount of data from the NGR telescope increases, it will certainly be smaller.
In the future, thanks to the NGR telescope, astronomers will spend the same amount of time imagining an area 100 times larger in the sky than Hubble could do in its current configuration. In other words, it’s as if 100 Hubble telescopes were making their own ultra-deep field at the same time.
The area of sky covered by HUDF is highlighted in blue, and both are inserted into a zoomed in image of selected parts of it. The white outline is Hubble’s low-range field of view (exposure time). The golden frames depict the area covered by the NGR telescope’s sensors in a single shot
The more sky we can capture in such ultra-deep fields, the more we will know about the early stages of the universe on a larger scale. Hubble’s observations have so far helped study a specific region containing about 10,000 galaxies. A wider field of observation, but a smaller depth (observing range), in the case of Hubble, made it possible to study a community of about 265,000 galaxies.
This is what the NGR Telescope’s Ultra-Deep Field would look like
Field-of-view simulations of the NGR telescope and the WFI instrument, along with images of galaxies resulting from our knowledge of their composition, were prepared by staff from the University of California, Santa Cruz. you can watch it in full precision Pictured with zoom function.
There are approximately 10 million galaxies in the generative part of the sky. The squares on top denote the field of view of all the sensors in the NGR telescope. The following slides and entries below show the magnification of a sensor’s field of view and the galaxies visible in it. This is somewhat how astronomers expect to see space with the NGR telescope.
Benefits of the NGR Ultra Deep Field Telescope
The NGR telescope captures in a single image up to several million galaxies, including those that existed when the universe was less than a billion years old. The Roman Extremely Deep Field, as these futuristic images of deep space are called, will not only show more galaxies due to the wider field of view, but will also expand the range of observations over time, i.e. see those later in the history of the universe.
The NGR telescope’s ultra-deep field will improve our knowledge of when the largest structures of individual galaxies, their clusters, their superclusters, began to form. Hence the voids and filaments of matter, all of which are likely to contain dark matter.
It can be assumed that the NGR telescope will not be limited to a single ultra-deep field. It will monitor more and more regions of the sky to contribute to the formation of the most accurate picture of the deep universe. This will lead to a huge amount of information that astronomers will have to process in the future.
Not only the NGR telescope, but also the Euclid Observatory and Vera C. Robin
At the mention of the NGR telescope, that is, a NASA project, it is impossible to forget another space observatory, which is to enter orbit soon, because this fall, and its observations will begin in 2023. It is the European Euclid Telescope, equipped with a larger number of megapixels in the camera, but with a mirror smaller than a telescope NGR.
Its diameter is only 1.2 meters, although considering the size of all cosmic observatories, it is not very small. By the time the NGR telescope goes into orbit, the main phase of Project Euclid has been completed, including redshift measurements of distant galaxies.
In early 2022 and 2023, regular observations will also begin with the Vera C. Rubin Telescope (formerly the Large Universal Survey Telescope) located in Chile. It is a telescope with a mirror length of 8.4 meters and a very wide field of view, designed for a mass survey of the sky, where the camera resolution of 3.2 Gpix helps.
These cosmic and terrestrial observatories will complement each other to improve our knowledge of the behavior of matter, both visible and invisible, and its interaction on intergalactic scales.
Source: NASA, ESA, NGR, inf. King
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