Observatory Visit Naomi McClure-Griffiths Australia Telescope National Facility CSIRO Vacation...
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Transcript of Observatory Visit Naomi McClure-Griffiths Australia Telescope National Facility CSIRO Vacation...
Observatory Visit
Naomi McClure-GriffithsAustralia Telescope National Facility
CSIRO
Vacation Scholar Program2 Dec 2002
What is the Observatory Trip?
• Trip to Parkes of Narrabri from Friday the 17th of January to Tuesday the 21st, 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:– 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
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
Frequency (several octaves)
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Frequency (Velocity)
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:
– http://www.narrabri.atnf.csiro.au/observering/users_guide/html/atug.html
• Parkes observing documentation:– http://www.parkes.atnf.csiro.au/documentation/documents.html
• Virtual Radio Interferometer (VRI)– http://www.narrabri.atnf.csiro.au/astronomy/vri.html
• ATCA Sensitivity Calculator– http://www.atnf.csiro.au/observers/docs/at_sens
• Parkes Sensitivity Calculator– http://www.parkes.atnf.csiro.au/cgi-bin/utilities/pks_sens.cgi
• Source Rise and Set Time Calculators– http://www.parkes.atnf.csiro.au/cgi-bin/utilities/coord.cgi (Parkes)
Reminders
• December 12 - Introduction to Radio Astronomy
• December 19 - Brainstorming Session• January 9 - Proposals Due• January 17-21 - The Trip!!• Contact:
– Naomi McClure-Griffiths:• Email: [email protected]• Phone: x4321• Room: 91b Marsfield