Lecture: Fundamentals Of Interferometry

[Trienko]

I have uploaded my first lecture: Fundamentals I.

Fundamentals I:

• Covers basic positional astronomy (only what you need to understand lm-coordinates and derive uv-coverage)
• Briefly explains the Fourier transform and that an interferometer essentially is a 2D Fourier transform
• Explains how to derive uv-coverage from ENU coordinates

I have also added an assigment, which I think will help solidify what the lecture tries to teach.

Sphe, I haven't designed the practical yet. My idea for the practical that should accompony this lecture is to simulate simple sky models in MeqTrees. One source two sources a Gaussian etc... You can go through the lecture and assigment to see what I covered in the first lecture.

I you wish you could add the simulator you showed me...

I have also added a python notebook, which explains how to derive uv-coverage from first principals (assuming earth is a sphere, which is not how it is really done).

I am still busy with Fundamentals II.

Fundamentals II:

• Explains why an interferometer is essentially a 2D-Fourier transform
• Time and frequency smearing

I also think that the new students should do the following Python course, for which they can earn a statement of accomplishment.

https://www.coursera.org/course/pythonlearn

[Trienko]

I have just uploaded my second lecture in which I cover:

1. Why the interferometer is a 2D Fourier transform.
2. Fringes.
3. Fringe stopping.
4. Frequency and time smearing.
5. The nasty w-term [NOT WAYS OF MITIGATING IT].

I have added an assignment which has the following two outcomes:

1. Give the student a better understanding of FITS images, the relationship between the cell size, extend and number of pixels in a FITS image.
2. Given some basic properties of an interferometer like its dish size, channel bandwidth, longest baseline, observation frequency and number of antennas how to calculate its secondary properties which include, primary beam's HPBW, the angular resolution of the interferometer, number of baselines, angular radius in which the fringe washing function is negliable, field of view in which the w-term is negliable, the maximum integration time that the correlator may use.

@modhurita, I do not think I will be introducing calibration in the fundamental lectures, I think it belongs in the calibration lecture where you have a whole lecture to explain it properly and therefore it is beyond the scope of this lecture. Also I think it will be much easier to introduce these concepts after Griffen has introduced polarization.

I will now start to make the suggested corrections to lecture I.

[Trienko]

I have now uploaded my notebooks for my two lectures and made the suggested corrections.

Notebooks for fundamentals I:

• http://nbviewer.ipython.org/github/ratt-ru/ratt-interferometry-course/blob/master/ipython-notebooks/Simulation.ipynb
• http://nbviewer.ipython.org/github/ratt-ru/ratt-interferometry-course/blob/master/ipython-notebooks/aperture-synthesis.ipynb (from Marcellin)
• http://nbviewer.ipython.org/github/ratt-ru/ratt-interferometry-course/blob/master/ipython-notebooks/pyrapmeasures_ANTENNA.ipynb

Notebooks for fundamentals II:

• http://nbviewer.ipython.org/github/ratt-ru/ratt-interferometry-course/blob/master/ipython-notebooks/Fringes.ipynb
• http://nbviewer.ipython.org/github/ratt-ru/ratt-interferometry-course/blob/master/ipython-notebooks/Properties.ipynb

I have also added references to the important equations in my slides. I did not change my slides into amplitude/phase as I have done this in Simualtion.ipynb.

[Trienko]

I have now uploaded a preliminary schedule (may still change) for the fundamental lectures. I have also indicated my switching pattern between notebooks and slides.

Schedule: ########### (Trienko) Monday 12:00-12:45: Lecture Fundamentals I After page 17 run Simulation.ipynb section Skymodel After page 41 run Simulation.ipynb section uv-Coverage After page 42 run Simulation.ipynb section Visibilities After slides run aperture-synthesis.ipynb ###########

###########(Trienko) Monday 15:00-15:45: Lecture Fundamentals I Fundamentals I: Assignment 1 Homework complete assignment 1 and read INTERFEROMETRY I AND II AVAILABLE AT: http://www.cv.nrao.edu/course/astr534/ERA.shtml ###########

###########(Sphe) Tuesday 9:00-9:45: Simulation 101 Sphe does Simulation 101 with MeqTrees ###########

###########(Trienko) Tuesday 9:45-10:30: Lecture Fundamentals II After page 17 run Integration.ipynb section Averaging After page 19 run Fringes.ipynb section Fringes After page 24 run Integration.ipynb section Even Odd After page 30 run Fringes.ipynb section Fringe Washing Function After page 35 run Properties.ipynb ###########

###########(Sphe) Tuesday 11:00-11:45: Simulation 101 Sphe does w-projection smearing prac with MeqTrees If time left over we can discuss Assignment 1 memo ###########

###########(Trienko) Tuesday 11:00-11:45: Lecture Fundamentals II Fundamentals II: Assignment II ###########

[cyriltasse]

@Trienko : I quickly went through your lectures on fundamentals: very very (very) nice!