The York College Radio Telescope

1
The York College Radio Telescope Ian OLeary, Tim
Paglione, Waynewright Joseph (York College,
CUNY)

• Organization
• The telescope was shipped to York College in
  several parts. The motors came to us
  pre-assembled and we completed the rest by hand.
  We positioned the base on the roof of the
  Academic Core building, directly above the York
  College TV studio, where the control laptop was
  located. The connection between the laptop and
  the telescope was through a vent collar in the
  roof. The cables were fed through the collar and
  connected to the motors, calibrator, and digital
  radio receiver.

• Commissioning
• We installed the SRT software on a designated
  laptop.
• This program helps control the telescope, access
  sources, correct/calibrate pointing, calibrate
  the temperature scale, track sources, examine
  spectrum and power from the receiver, and record
  data.
• We aligned the telescope by tracking the Sun.
• We tracked the Sun at different offsets and found
  where the greatest power was received.
• We rotated the electronic noise calibrator to
  maximize its power coupling to the receiver.
• -We also made software adjustments for proper
  calibration of the power-to-temperature
  conversion.
• We observed the hydrogen spectrum from the
  well-known source S8 (see figure).
• We installed Virtual Network Computing (VNC)
  software onto the main laptop to control it from
  anywhere in the York College network.
• We measured beam dimensions (resolution) by
  observing the Sun.
• -The beam full-width at half maximum, is 7
  degrees.

• Diffraction and Resolution
• Most single-dish radio telescope readings are
  blurry. The blurring stems from diffraction
  which affects all telescopes. For sharper images
  better resolution the diameter of a
  telescope's collecting area must be substantially
  larger than the wavelength of the radiation it
  detects
• Resolution ? Wavelength/Diameter of dish
• To have good resolution in the radio, one must
  have a large telescope. The ideal aperture for a
  radio telescope operating at 21 cm would be
  several kilometers, which is very difficult and
  expensive to design and construct.

Abstract We constructed, installed and
commissioned a radio telescope at York College.
The Small Radio Telescope (SRT) was developed by
the MIT Haystack Observatory and is distributed
by Custom Astronomical Support Services, Inc. A
radio telescopes main purpose is to receive
radio emissions from the universe, especially
from atomic hydrogen. We aligned the telescope,
calibrated the temperature scale and installed
computer software to complete the construction of
the SRT. We measured the pointing accuracy and
the beam size, and observed the hydrogen spectrum
of the Galactic cloud S8.

• Introduction
• Radio telescopes allow us to observe the
  expanding universe through radio waves. These
  radio waves are so low in frequency that they are
  able to pass through dusty regions that visible
  light cannot. With this, radio astronomers have
  access to the entire universe. The first radio
  telescope was constructed in 1931 by American
  scientist Karl Jansky. He realized that radio
  signals moves with the sky every day. Radio
  astronomy grew from there and has produced many
  new maps of galaxies, supernovae and the rest of
  the universe.

• Construction
• We installed the base, motors, parabolic dish,
  and the digital radio receiver on the roof of the
  Academic Core Building at York College. The base
  of the telescope is a hexagon with three-foot
  wide sides. A mast perpendicular to the ground is
  supported by six support legs. The mast supports
  the azimuth motor, which is connected to an
  adaptor pipe supporting the elevation motor. The
  elevation motor is connected to the parabolic
  dish, which consists of five parts four quarter
  pieces of the dish and an adapter ring, which
  connects the dish to the elevation drive. The
  digital radio receiver is supported above the
  dish by four feed legs.
• Each motor required a connection to a control box
  in the York College TV studio directly below the
  telescope
• Two power connections
• One pulse wire to monitor motor movement
• One ground wire
• Also connected to the telescope is an electronic
  calibrator, which allows calibration of signal
  temperatures. A control box connects to the SRT
  and laptop. The digital radio receiver connects
  to the control box by a coaxial cable.

• Radio Astronomy
• Radio astronomy is the study of the Universe in
  the radio part of the electromagnetic spectrum.
  Radio waves are a form of electromagnetic
  radiation with wavelengths that range from
  approximately 1mm and beyond. Almost all of the
  radio spectrum is accessible from ground-based
  observatories, day and night. Radio telescopes
  collect and concentrate the radio waves from an
  astronomical source. The signal received is then
  electronically processed.
• Radio waves can penetrate dust and allow us to
  measure the full extent of the universe.
• The cosmic microwave background radiation (the
  evidence of the Big Bang) is strongest in the
  radio.
• Hydrogen, the most abundant element in the
  Universe, emits in the radio at a wavelength of
  21 centimeters.
• Other unique sources of radio emission include
  normal galaxies, such as the Milky Way, radio
  galaxies and quasars, as well as supernova
  explosions.

• Status
• We are currently waiting for a replacement motor
  sensor which failed after it was exposed to rain.
• We plan to map the hydrogen emission from the
  Milky Way when the SRT resumes operation.