On February 28, 2024, which is celebrated as National Science Day in India, the Inter-University Center for Astronomy and Astrophysics ( IUCAA, Pune, India ) hosted an open house event. The occasion featured various initiatives and demonstrations that attracted a wide array of individuals from different backgrounds and age groups. Highlights of the event included exhibits like the Cosmic Ray Muon Detector, Antenna Trainer Kit, S.U.I.T. of Aditya L1, and the Horn Antenna. Among the demonstrations was the ASRT(Affordable Small Radio Telescope) with a full experimental setup. This particular demonstration was led by Anas Ansari , Sahil Sawant , under the expert supervision of Jameer Manur . This report aims to provide an overview of the Affordable Small Radio Telescope demonstration conducted at IUCAA during the National Science Day open house.
[Glimpses of NSD’24 at IUCAA, Pune]
Introduction:
Radio spectrum is the part of the electromagnetic spectrum ranging from 1 Hz to 3000 GHz (3THz). Electromagnetic waves in this frequency range, called radio waves, have become widely used in modern technology, particularly in satellite communications. The range of frequencies in the electromagnetic spectrum that makes up the radio spectrum is very large. The radio spectrum of frequencies is divided into bands with conventional names designated by the International Telecommunication Union (ITU).
Different parts of the radio spectrum (RF bands) are allocated by the ITU for different radio transmission technologies and applications. The ITU divides the radio spectrum into 12 bands (as shown in the table below), each beginning at a wavelength which is a power of ten (10n) metres, with corresponding frequency of 3×108−n hertz, and each covering a decade of frequency or wavelength. Each of these bands has a traditional name. Then there’s further classification of the microwave range (30 Mhz - 300 Ghz). This includes the Ku band.
(Radio frequencies used for satellite communication)
Ku-band is best known for its use in satellite broadcast communications. The Ku-band (which stands for Kurz under) falls in the middle in terms of frequency, utilising the approximate range of 12-18GHz of radiofrequency. This results in bandwidth in the mid-range.
The Affordable Small Radio Telescope works in the Ku range, which extends from 12 to 16 GHz. As the name suggests, the cost of the radio telescope is minimal and it is designed such that it can be replicated by anyone and everyone. The cost of building has been kept low by using off the shelf equipment which is easily available anywhere in the world.
Purpose:
The telescope is primarily intended to observe the sun in this band viz. 10.7 to 12.75 GHz. but can just as easily be used for observing radiation from compact fluorescent lamps, human body, boiling water etc. as well. Although the radio telescope is easy to build and operate, that doesn’t limit the science that can be done with it as it can be used to carry out several scientific endeavours both basic as well as advanced.
The Sun is the nearest star to Earth. Information gathered about processes on the Sun helps us understand more remote, and often more exotic, stars as well. The Sun emits light in every wavelength in the electromagnetic spectrum – from gamma rays to radio waves. For our work, we focused on radio and the mechanisms responsible for it.
Sun is the strongest source in all electromagnetic bands, especially in radio. The mechanism responsible for radio emission from the sun is free-free emission, gyro resonance emission, and plasma emission. All of these mechanisms are operational at different layers of sun and hence act as probes.
Using ASRT, a simple measurement of temperature provides us information about the chromosphere of the sun.
ARCHITECTURE:
It mainly involves the following components.
1. Satellite dish antenna with receiver.
2. Satellite finder.
3. Mechanical stand for mounting the antenna.
4.Coaxial wires and TVsetup box.
WORKING:
1.Satellite Antenna
The satellite dish antenna has a LNB (Low noise block) and a parabolic dish reflector. This dish reflects the incoming radiation towards LNB. LNB provides the signal amplification without adding much noise.
2.Satellite Finder
The satellite finder is a tool used by DTH system service engineers for detecting the satellite signal strength. It may be analog or digital. We have used commercially off the shelf available analog satellite finder.
3.Mechanical mount :
to mount the entire dish setup.
4.Electrical connections
· Run a coaxial cable (RG6) from your TV receiver to the satellite dish.
· 2.Fix the Type F connector on both the ends.
· 3. Take another piece of coaxial cable from LNB to Sat-Finder and fix the
· type F connector on both the ends.
· 4. Now connect the output of LNB to ”LNB In” at satellite finder.
· 5. Connect Receiver to another end of satellite finder.
Result from the readings:
Drift scan:
Well from the word we can guess that an object passing over something. In this Solar drift scan first we need to calculate where will be position of the Sun in the sky after a particular time interval. Knowing the position of the Sun is easy using a planetarium software (Stellarium/ Sky Gazer/ Kstars etc).From this graph we see a peak at the centre which actually tells us that the Sun was just over the antenna at this time and what we assumed that Sun will be there at that time becomes true.
CONCLUSION:
The ASRT demonstration at IUCAA showcased the potential of affordable and easily replicable radio telescopes for scientific research. By using off-the-shelf components, the ASRT provides a cost-effective means for observing solar and other radio emissions, making advanced scientific endeavors accessible to a broader audience.
Indian Institutes for Solar Observations:
Indian Institute of Astrophysics (IIA), Bangalore: IIA operates the Kodaikanal Solar Observatory, which has contributed significantly to the study of the solar atmosphere and sunspot cycles.
Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital: ARIES focuses on solar and stellar observations, contributing to the understanding of solar dynamics and space weather.
Udaipur Solar Observatory (USO), Udaipur: USO is known for its high-resolution observations of the sun, particularly in the areas of solar magnetic fields and solar seismology.
Physical Research Laboratory (PRL), Ahmedabad: PRL conducts research on solar physics, including solar radiative output and its influence on the Earth's climate.
Extra:
National Solar Observatory (NSO), USA: NSO operates advanced facilities like the Daniel K. Inouye Solar Telescope, contributing to high-resolution studies of the sun’s surface and magnetic fields.
Solar and Heliospheric Observatory (SOHO): ESA's SOHO has provided critical data on solar wind, solar flares, and the sun’s interior.
