29th Annual Report (2016-17)

138 Hydrogen line from our galaxy Amajor limitation of radio astronomy is noise, either man-made or naturally occurring. Hence, we require new techniques to reduce noise from our detector. The horn antenna is a high performance, high gain and low noise antenna, specially designed for detection of 21 cm Hydrogen line. The antenna is able to pick up radiation from the Hydrogen clouds in our galaxy, while suppressing terrestrial interferences due to the low side lobes of the antenna. The antenna is easy to handle and is superior to a parabolic dish in terms of noise performance. The horn has enabled us to study hydrogen line profiles from the galaxy. The spiral structure of the galaxy can be estimated. It is also possible to estimate the rotation curve of the galaxy. The antenna is a dual mode conical horn. It is easy to construct as compared to other antennas with similar noise performance. Software Defined Radio (SDR) receivers were used with great success. SDR is a new advancement in radio technology. The limitation of the conventional radios is its inability to configure the hardware. SDR can be configured to serve any purpose of the user. Such a receiver was implemented successfully for detection of Hydrogen line. Important techniques like Dicke switching were implemented with SDR. This has made the telescope low cost, and hence accessible to amateur radio enthusiasts. The antenna has proven to be very reliable. It will be used in M.Sc. practical in radio astronomy as well as in forthcoming Radio Astronomy Winter Schools. The antenna has also been used to demonstrate principles of radio astronomy to amateurs as well as for public outreach. Metre DishAntenna forRadioAstronomy The newly installed 3 metre dish antenna at RPL is being used for experiments in radio astronomy. Experiments like detection of 21 cm Hydrogen line, and observation of solar activities are regularly carried out with this antenna. It has a control system, which enables one to point and track celestial objects. The antenna will be used in educational activities at RPL. Hydrogen line from our galaxy