Observatory Visit Naomi McClure-Griffiths Australia Telescope National Facility CSIRO Vacation Scholar Program 2 Dec 2002

What is the Observatory Trip? Trip to Parkes of Narrabri from Friday the 17 th of January to Tuesday the 21 st, inclusive. Half students will go to Narrabri and half to Parkes observatories. 36 hours telescope time allocated at each observatory. Suggest that you form about 6 groups (3 people per group; 3 groups per observatory), with each group getting 12 hours of observing time each.

Basic Aims Give you “hands-on” experience in using a world-class telescope Give you some insight into various engineering issues as well as physical and astrophysical principles Give you an idea of what it’s like to propose and carryout a scientific experiment Have fun!

What will happen that weekend? Friday: Drive to Narrabri or Parkes. Friday afternoon and Saturday morning: Observatory tour, observer and safety training. Saturday midday to Sunday midnight: Observing (Three 12hr shifts) and data reduction. Monday: More data reduction and finishing up. Tuesday morning: Drive back to Sydney.

What happens before then? December 12 - Introduction to Radio Astronomy lecture December 12 – 19 - Start setting up groups and thinking of reasonable projects –To keep in mind: Which telescope is good the type of project you want to do? Can you complete the project in 12 hours? Can you reduce the data when you get it? December 19 - Project brainstorming session

What happens before then? January 9 - Written project proposals due. The proposal (~1 or 2 pages) should include: –Names of group members. –Aim of project and a justification for why this is appropriate. –The observatory and equipment required. Note any special hardware or software than might be required. –Observing frequencies/velocities and source coordinates where relevant. January 9 – 17 - Prepare observing schedules January 15 - Final briefing for the trip

Some Things You Might Need to Know Astronomical and telescope coordinates: Where is that source? What is sidereal time? And how to figure out when a source is in the sky How (very generally!) a single dish or interferometer works. How long it will take to get a result. How (in a practical sense) to observe and reduce data.

The Telescopes Parkes:Parkes –64 meter diameter single antenna –Frequency from 440 MHz to 22 GHz –Low resolution, but large collecting area Australia Telescope Compact Array (ATCA): –Six 22 meter diameter antennas operate as an interferometer –Antennas spread along a 6 km rail –Frequencies from 1.4 Gz to 110 GHz –High resolution, but less collecting area

Parkes Observatory

ATCA (Narrabri)

Interferometry Interferometer is like a single dish broken into two parts Delays are inserted to compensate for the different path lengths to each antenna. Interferometers give much higher resolution and are less susceptible to a number of systematic errors Interferometers fail to measure broad scale structure and are more complex devices. Correlator

Earth rotation synthesis 15 min 4 hrs 12 hrs

What can we observe in the radio? Emission types –Continuum emission –Spectral lines (frequency varying) –Time varying Emission mechanisms –Thermal – HII regions –Non-thermal – SNRs –Coherent – Pulsars

Electromagnetic windows

Devising reasonable projects Choose a question and then devise an experiment that can answer that question Choose something interesting –Has it been done before? –Are you interested in a source or the instrument? Is your project do-able? –Can you detect the source(s)? –Have you chosen the right instrument? Do you want to detect it? Image it? Monitor it? –Will your source be up? Talk with each other, your supervisor, Naomi, anyone!

What sorts of astronomy? Solar system –Sun –Jupiter and other planets Nearby stars –Masers –Pulsars –Active stars (episodic) The Milky Way (our Galaxy) –HI –Galactic Centre –HII Regions –Supernova remnants –Molecular clouds Magellanic Clouds Nearby galaxies Distant galaxies –Radio galaxies –AGN –Gravitational lensing Early universe –Cosmic microwave background

Engineering experiments Atmosphere/radiometry –phase stability –22 GHz water line Antennas –Focus effects –Spillover measurements –Distant sidelobes –Polarimetric response –Pointing –Holography/aperture illumination Receivers –Receiver calibration –Hot/cold load tests Radio frequency interference –Mobile phones –Microwave ovens –Computers –Satellites

More on Science Match your project to the telescope: –Parkes sees a large area with a broad beam It is ideal for imaging large objects, measuring flux values, or looking at pulsars –Narrabri sees a relatively small area with a narrow beam It is ideal for imaging regions with small detail, looking at small (extragalactic) objects –If you want to look at a a large area, Parkes is it –If you want to look with high detail, Narrabri is it

Last Year’s Projects as Examples Narrabri: –Characterise site generated interference –Image the massive star Eta Carina at 12mm –High resolution imaging of HIPASS detected galaxies Parkes: –Detecting Ammonia in cold interstellar clouds –Detect and measure the velocity, acceleration of the Galileo probe –Confirm pulsar detections from the Parkes pulsar survey

Useful Observing Tools ATNF observing documentation: – htmlhttp:// html Parkes observing documentation: – Virtual Radio Interferometer (VRI) – ATCA Sensitivity Calculator – Parkes Sensitivity Calculator – Source Rise and Set Time Calculators – (Parkes)

Reminders December 12 - Introduction to Radio Astronomy December 19 - Brainstorming Session January 9 - Proposals Due January The Trip!! Contact: –Naomi McClure-Griffiths: Phone: x4321 Room: 91b Marsfield