Analysis of the Principle and Observations for State-of-the-Art

Telescopes

Yichen Gu

Ulink High School of Suzhou Industrial Park, Suzhou, China

Keywords: Large-Aperture Telescope, Radio Interferometry, Deep-Space Observation, Event Horizon Telescope, James

Webb Space Telescope.

Abstract: As a matter of fact, the advancement of astronomical technology has enabled unprecedented observations of

the universe in recent decades. With this in mind, this study explores the principles, instrumentation, and

landmark discoveries of three major state-of-the-art telescopes, i.e., FAST, the Event Horizon Telescope

(EHT), and the James Webb Space Telescope (JWST). To be specific, each facility represents a unique

approach to astronomical observation, from large single-dish radio detection to global interferometry and

deep-space infrared imaging. FAST has revolutionized pulsar and FRB research, while the EHT captured the

first image of a black hole, confirming predictions of general relativity. At the same time, JWST is unravelling

the early universe and characterizing exoplanet atmospheres. According to the analysis, comparative analysis

highlights the complementary strengths of these observatories and discusses the technological and

observational limitations they face. Overall, the study concludes with prospects for future telescope

development and the broader significance of these facilities in advancing cosmic understanding.

1 INTRODUCTION

The telescope stands as one of humanity's most

pivotal inventions in the quest to understand the

universe. Since Galileo Galilei first turned a

rudimentary telescope skyward in the early 17th

century, the field of astronomy has undergone

revolutionary developments (Tyson, et al., 2016).

Telescopes have evolved from simple optical

instruments to highly sophisticated arrays and space-

based observatories that observe electromagnetic

radiation across the entire spectrum. They have

enabled the discovery of planets, stars, galaxies, and

cosmic phenomena that were previously beyond the

reach (Durrant, 2019). The ability to look deeper into

space not only expands the understanding of celestial

bodies but also offers insights into the fundamental

laws governing the universe (Trimble, 2018).

In recent decades, technological advancements have

led to the construction of large-scale and high-

precision telescopes, significantly enhancing the

observational capabilities. Notably, the Five-

hundred-meter Aperture Spherical Telescope (FAST),

the Event Horizon Telescope (EHT), and the James

Webb Space Telescope (JWST) represent the

forefront of this astronomical leap. These facilities

offer diverse methodologies: from radio wave

detection and very-long-baseline interferometry

(VLBI) to near- and mid-infrared imaging. Each one

plays a vital role in different areas of astrophysical

research, such as the detection of fast radio bursts

(FRBs), black hole imaging, and deep field

cosmology (Smith, 2020; Jiang, et al., 2019).

The Event Horizon Telescope gained global

attention in 2019 when it produced the first direct

image of a black hole's event horizon in the M87

galaxy, marking a watershed moment in both

astronomy and general relativity (Event Horizon

Telescope Collaboration, 2019). Similarly, FAST has

been instrumental in detecting new pulsars and fast

radio bursts, while JWST, launched in 2021, is

unveiling the structure of the early universe and

characterizing exoplanet atmospheres with

unprecedented clarity (Gardner, et al., 2006; Smirnov,

2011).

The motivation behind this study is to synthesize

and analyse the operational principles, technological

frameworks, and groundbreaking findings of these

three flagship observatories. While they differ in

design, objective, and location—ground-based vs.

space-based—they are all united in the pursuit of

understanding cosmic origins and mechanisms. This

Gu, Y.

Analysis of the Pr inciple and Observations for State-of-the-Art Telescopes.

DOI: 10.5220/0013833800004708

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 2nd International Conference on Innovations in Applied Mathematics, Physics, and Astronomy (IAMPA 2025), pages 595-599

ISBN: 978-989-758-774-0

595

paper first presents an overview of different telescope

types and their observational targets. It then delves

into the design, instrumentation, and observational

outcomes of FAST, EHT, and JWST. The subsequent

sections compare their strengths and limitations and

discuss the future prospects of telescope technology.

This structured analysis not only highlights the

individual accomplishments of each facility but also

underscores the synergistic nature of modern

astronomical research. By integrating radio, optical,

and infrared data, scientists can approach cosmic

phenomena from multiple angles, facilitating a more

comprehensive understanding of the universe.

2 DESCRIPTIONS OF

TELESCOPES

Telescopes are instruments designed to collect and

magnify electromagnetic radiation from distant

celestial objects, enabling astronomers to observe

phenomena beyond the naked eye. They can be

broadly categorized based on the portion of the

electromagnetic spectrum they observe and their

physical design. The two primary categories are

optical telescopes and radio telescopes, with newer

subcategories including infrared, ultraviolet, X-ray,

and gamma-ray telescopes.

Optical telescopes operate in the visible spectrum

and are commonly divided into refracting and

reflecting types. Refracting telescopes use lenses to

bend light, while reflecting telescopes use mirrors.

The Hubble Space Telescope, for instance, is a space-

based optical telescope that has contributed

significantly to the understanding of galaxy formation

and expansion.

Radio telescopes, on the other hand, detect radio

waves emitted by cosmic sources such as pulsars,

quasars, and interstellar gas clouds. These telescopes

typically feature large parabolic dishes, like FAST,

which is the largest filled-aperture radio telescope in

the world. Arrays of radio telescopes can also

function together through interferometry, as

exemplified by the Event Horizon Telescope, to

achieve extremely high resolution.

Infrared telescopes detect heat signatures and are

especially useful for observing objects obscured by

interstellar dust or located at great distances. The

James Webb Space Telescope operates primarily in

the near- and mid-infrared ranges, allowing it to look

back to the earliest epochs of the universe and study

the atmospheres of exoplanets (Wright, 2008).

Each telescope type is specialized to observe

different phenomena and contributes uniquely to the

understanding of the universe. Optical telescopes are

ideal for studying stars and galaxies; radio telescopes

uncover pulsars and cosmic microwave background

radiation; and infrared telescopes probe the cold,

dust-enshrouded regions of space. Together, these

instruments offer a comprehensive toolkit for modern

astronomical research.

3 FAST

The Five-hundred-meter Aperture Spherical

Telescope (FAST), located in Guizhou Province,

China, is the world’s largest filled-aperture radio

telescope. Commissioned in 2016 and fully

operational since 2020, FAST represents a significant

advancement in radio astronomy. Its massive dish,

spanning 500 meters in diameter and composed of

4,450 triangular panels, enables it to collect weak

radio signals from distant cosmic sources with

unprecedented sensitivity. The principle is listed in

Fig. 1 (Nan, et al., 2011).

Figure 1: Working principle of FAST telescope (Nan, et al.,

2011).

FAST operates in the frequency range of 70 MHz

to 3 GHz and employs an active surface capable of

adjusting to different observational configurations. Its

design allows the feed cabin, suspended by cables, to

move and align with different sky positions,

effectively simulating a smaller parabolic dish across

a vast spherical surface. This provides FAST with a

remarkably wide field of view and high sensitivity to

low-frequency radio emissions (Li, et al., 2018; Nan,

et al., 2011).

A major scientific contribution of FAST is its role

in pulsar detection. Since its commissioning, FAST

has discovered over 500 new pulsars, significantly

enriching the known pulsar population. These

discoveries are vital for understanding stellar

evolution, neutron star physics, and for potential use

IAMPA 2025 - The International Conference on Innovations in Applied Mathematics, Physics, and Astronomy

596

in gravitational wave detection via pulsar timing

arrays (Wang, et al., 2021). In addition, FAST has

detected multiple fast radio bursts (FRBs), including

both repeating and non-repeating types, contributing

to the ongoing investigation into the origins and

mechanisms of these mysterious cosmic phenomena

(Zhang, et al., 2022).

The facility also supports research in interstellar

medium studies, galaxy evolution, and dark matter

exploration through neutral hydrogen line

observations. FAST’s high precision and sensitivity

have positioned it as a cornerstone of international

radio astronomy collaboration.

Despite its strengths, FAST faces some

limitations. Due to its fixed location and single-dish

design, its sky coverage is limited to within 40

degrees from the zenith. Nonetheless, its unparalleled

sensitivity ensures its continued relevance in time-

domain astronomy and low-frequency surveys.

Ongoing upgrades and software improvements are

aimed at enhancing observation efficiency and data

processing throughput.

4 EHT

The Event Horizon Telescope (EHT) is a

groundbreaking international collaboration aimed at

imaging black holes by creating an Earth-sized virtual

telescope through Very Long Baseline Interferometry

(VLBI). This array links multiple radio observatories

across the globe to achieve angular resolutions fine

enough to observe the event horizon of supermassive

black holes. The EHT operates in the millimeter

waveband, specifically around 230 GHz (1.3 mm),

which allows it to penetrate the gas and dust

surrounding black holes (Event Horizon Telescope

Collaboration, 2022).

Figure 2: Images of black hole from EHT (Event Horizon

Telescope Collaboration, 2022).

A major milestone in EHT's history was the

capture of the first image of a black hole’s event

horizon in the M87 galaxy in 2019. This image

confirmed key predictions of Einstein’s General

Theory of Relativity, particularly the shadow caused

by gravitational lensing near the event horizon. In

2022, the EHT collaboration followed up with an

image of Sagittarius A*, the supermassive black hole

at the center of the own Milky Way as seen from Fig.

2 (Event Horizon Telescope Collaboration, 2022).

These accomplishments mark the first time humans

have directly observed black hole silhouettes,

offering empirical insights into extreme gravitational

environments.

The EHT's instrumentation relies on synchronized

atomic clocks at each participating observatory and

collects petabytes of data, which are then transported

to centralized processing facilities for correlation and

image reconstruction. The sparse sampling of the

Fourier space is addressed through sophisticated

algorithms, such as regularized maximum likelihood

and Bayesian methods, allowing for the generation of

high-fidelity images (Fish, et al., 2014).

The global array includes facilities such as the

Atacama Large Millimeter/submillimeter Array

(ALMA) in Chile, the South Pole Telescope, and the

James Clerk Maxwell Telescope in Hawaii. The

project’s success is heavily dependent on weather

conditions and precise synchronization across the

network, making observational campaigns complex

and infrequent.

Despite these challenges, the EHT has opened

new frontiers in astrophysics by directly probing the

innermost regions of black holes. Its ongoing

upgrades aim to improve resolution, increase the

number of participating telescopes, and extend

observation to multiple frequencies. These

improvements will enhance the ability to study black

hole dynamics, jet formation, and accretion physics,

making the EHT a cornerstone in the study of high-

energy astrophysical phenomena (Steinhardt, et al.,

2021).

5 JAMES WEBB SPACE

TELESCOPE (JWST)

The James Webb Space Telescope (JWST) is a space-

based infrared observatory that represents the next

generation of space telescopes, following the legacy

of the Hubble Space Telescope. Launched in

December 2021 and positioned at the second

Lagrange point (L2), approximately 1.5 million

kilometres from Earth, JWST operates in a thermally

stable environment shielded from solar and terrestrial

radiation. This unique vantage point allows it to

Analysis of the Principle and Observations for State-of-the-Art Telescopes

597

achieve extremely sensitive observations in the near-

and mid-infrared spectrum (Pontoppidan, et al., 2022).

Figure 3: The telescope components of JWST (McElwain,

et al., 2023).

JWST's primary mirror consists of 18 hexagonal

segments coated with gold to optimize infrared

reflection, collectively forming a 6.5-meter aperture

as given in Fig. 3. Its instruments include the Near

Infrared Camera (NIRCam), Mid-Infrared Instrument

(MIRI), Near Infrared Spectrograph (NIRSpec), and

Fine Guidance Sensor/Near InfraRed Imager and

Slitless Spectrograph (FGS/NIRISS), which together

enable high-resolution imaging and spectroscopy

across a wide spectral range (McElwain, et al., 2023).

One of JWST’s core scientific goals is to study the

formation of the earliest galaxies, providing a glimpse

into the epoch of reionization. Through deep field

observations, JWST has already detected candidate

galaxies at redshifts greater than 13, suggesting their

formation within the first few hundred million years

after the Big Bang. These discoveries offer new

insights into galaxy evolution and the nature of the

early universe.

Another major objective is exoplanet

characterization. JWST employs transit spectroscopy

to analyze the atmospheres of exoplanets, identifying

chemical compositions, cloud structures, and

potential biosignatures. Observations of systems like

TRAPPIST-1 and WASP-96b have already yielded

significant data on atmospheric water content and

molecular features.

JWST is also instrumental in stellar and planetary

formation studies, capturing detailed images of star-

forming regions like the Carina and Orion nebulae.

By penetrating dense clouds of gas and dust, JWST

provides crucial data on protostar development and

protoplanetary disk dynamics. These observations

help bridge the gap between star formation and

planetary system evolution.

Despite its breakthroughs, JWST faces limitations

such as finite mission lifespan, cooling system

constraints, and a lack of in-orbit servicing

capabilities. However, its impact on astronomy is

transformative. Ongoing and future programs aim to

maximize its scientific output, with coordinated

campaigns alongside ground-based observatories and

upcoming missions like the Nancy Grace Roman

Space Telescope.

JWST's unprecedented capabilities make it a

cornerstone of 21st-century astronomy, pushing the

boundaries of human knowledge about the cosmos.

Its role in addressing fundamental questions

regarding the origin of galaxies, stars, and potentially

life-bearing planets marks a new era in observational

astrophysics.

6 COMPARISON, LIMITATIONS,

AND PROSPECTS

The three telescopes analysed in this paper—FAST,

EHT, and JWST—represent different designs,

operating environments, and observational objectives

as listed in Table 1. FAST is unparalleled in its

sensitivity to low-frequency radio waves, allowing it

to discover numerous new pulsars and fast radio

bursts. Its massive single-dish design offers a wide

collecting area but limits sky coverage and angular

resolution. EHT, in contrast, uses a global network of

telescopes to achieve high spatial resolution capable

of imaging the event horizon of black holes. However,

it is limited to very specific high-frequency

observations under stringent atmospheric conditions.

JWST, as a space-based infrared observatory,

overcomes atmospheric interference entirely and

captures light from the early universe. It has enabled

transformative discoveries in galaxy formation and

exoplanetary atmospheres.

Table1: Comparison of the telescopes

Paramete

FAST EHT JWST

Wavelengt

Radio(0.

1-3GHz)

Submillimet

Infrared(0.6

-28μm)

Strength High

sensitivit

Ultra-high

resolution

Atmospheri

c-free IR

Limitation

Limited

sky

coverage

Weather-

dependent

Fixed

mission

lifespan

While each telescope has unique strengths, they

also share common limitations. FAST, though

sensitive, lacks the resolving power for detailed

imaging. EHT has limited temporal coverage due to

logistical coordination and weather dependence.

JWST faces constraints on operational lifespan, data

transmission rates, and solar shielding degradation.

IAMPA 2025 - The International Conference on Innovations in Applied Mathematics, Physics, and Astronomy

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Nonetheless, these instruments are complementary:

FAST excels at survey science, EHT focuses on

extreme gravity, and JWST offers deep spectral

analysis. Future advancements may include hybrid

systems combining radio and optical/infrared

capabilities, space-based interferometers for high-

frequency VLBI, and AI-driven data processing.

These innovations will enhance sensitivity, resolution,

and survey efficiency. Multi-messenger astronomy,

integrating gravitational waves and neutrino

detections, will also expand the scope of

observational astronomy. Collectively, these

developments promise deeper insights into cosmic

origins, structure, and evolution.

7 CONCLUSIONS

To sum up, this study analysed the principles,

instrumentation, and contributions of three cutting-

edge telescopes: FAST, EHT, and JWST. These

facilities represent a leap forward in observational

capacity, from detecting faint radio emissions and

capturing black hole silhouettes to observing the early

universe in the infrared spectrum. The study

compared their capabilities and limitations,

highlighting their complementary roles in modern

astronomy. Looking ahead, innovations in telescope

design and data integration promise to further unravel

the mysteries of the cosmos. The continued

development and deployment of such observatories

are vital for advancing both theoretical and applied

astrophysical science.

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