> Begin forwarded message:
>
> Carl,
>
> Thanks very much! I looked at the attachments and the four experiments
> including the write-ups are an excellent introduction to radio
> astronomy.
>
> A question about OH. You mention <1K antenna temperature on the strongest?
> maser source, W49. Is this with the 4.5m telescope or with an older,
> smaller telescope? I assume we would need narrow bandwidth, probably 5
> kHz, and with a 100K Tsys it will take many minutes of integration to see
> the signal. We also have RFI around 1667 and it will be a challenge to
> get the filtering and dynamic range. On the other hand, the polarization
> and multiple lines, make this a very instructive venture.
>
> I think we have had talks at URSI about educational radio telescopes but
> maybe should devote a session to this at the 2017 meeting.
>
> Sandy
> -----Original Message-----
> From: Carl E. HEILES [mailto:hei...@berkeley.edu] On Behalf Of heiles
> Sent: Tuesday, August 18, 2015 4:08 PM
> To: Sander Weinreb <swein...@caltech.edu>
> Cc: heiles <hei...@astro.berkeley.edu>; 'DAVID DEBOER'
> <ddeb...@berkeley.edu>; 'Alan Rogers' <arog...@haystack.mit.edu>; 'Han'
> <st...@kasi.re.kr>; 'Steve Smith' <ste...@caltech.edu>; 'Monroe Ryan M'
> <ryan.m.mon...@jpl.nasa.gov>; 'Gregg Hallinan' <g...@astro.caltech.edu>;
> 'Andrew Janzen' <ajan...@caltech.edu>; 'Ahmed Akgiray'
> <ahmed.akgi...@ozyegin.edu.tr>; asoli...@caltech.edu; 'Hamdi Mani'
> <hamdi.m...@gmail.com>; 'Joe Bardin' <jcbar...@gmail.com>; 'glenn.caltech'
> <glenn.calt...@gmail.com>; 'GLENN WEINREB' <gwein...@gwinst.com>; 'Anthony
> Readhead' <a...@astro.caltech.edu>; 'Shri Kulkarni' <s...@astro.caltech.edu>
> Subject: Re: FW: Educational 6m Radio Telescope at Caltech
>
> hi sandy...
>
> in our undergrad radio astro lab, we currently do four major experiments,
> the writeups for which are attached.
>
> the first lab is devoted to bench experiments and learning about digital
> sampling. the lab in in two halves, and in fact we treat it as two separate
> labs. the first half uses test equipment; the second uses a horn on the
> roof, baseband complex sampling with the students writing their own software
> to get the power spectrum fromthe time series. i regard this first lab,
> which covers the basics of sampling and Fourier tranforms, as absolutely
> crucial for anybody who intends to pursue a technical career, and also
> everything that follows in the lab course.
>
> the second lab uses our 12 GHz interferometer (freq chosen so that we can
> look at the strong methonal masers--which we haven't gotten to yet).
> baseline is about 12 m. students do vlbi fringe fitting to determine
> accurate declinations of sources like Ori A (well, more accurately, the
> combination (baseline times cos delta). also look at fringe amplitude
> modulation to determine angular diameters of the sun and the moon.
>
> the third lab uses our 4.5m dish located about a half hour away to map HI
> 21-cm line, look at OH, and look at pulsars. Haven't done OH successfully
> yet because of equipment problems, but hope to do so this coming year, and
> include polarization. hope to get to pulsars this coming year, but that
> requires some programming for our FPGA spectrometer and might not happen
> this year.
>
> generally, course philosophy is that students must write their own software.
> we use IDL. these days, Python would be more approppriate, but at my age I'm
> not going to learn yet another language. anyway, the programming experience
> gained helps the students a lot in REU research programs and getting a
> flavor of instrumentation for later career use.
>
> if you desire, you can find some more info (handouts, writeups, etc) on my
> web page astro.berkeley.edu/~heiles/
>
> it strikes me that if you can't do OH simply because of resolution of your
> spectrometer, then this is an excellent project for them to do direct
> voltage sampling on and they could do their own FT power spectra with
> arbitrary resolution. this would be very instructive.
> bandwidths can be small so you can keep up with the data rate and disk files
> don't need to get too big. many OH masers are highly polaarized, so a good
> excuse for them to learn polarization basics. W49 is a particulary good
> example. Also there are very strong OH masers associated with IR stars, also
> polarized.
>
> our telescopes are pointed now by commercial motor controllers, thanks to
> dave deboer. doing this well (or even at all) is difficult. i suspect alan
> has a simpler and cheaper alernative. also, our telescopes are home grown;
> the hardest part is the pointing hardware and software...
>
> good luck and have fun! there are some other similar labs...i know UW at
> madison has one. we ought to convene a get-together so we can exchange
> ideas...
>
> --c
>
> On Sun, 16 Aug 2015, Sander Weinreb wrote:
>
>>
>> (Corrected email address for Heiles)
>>
>>
>>
>> From: Sander Weinreb [mailto:swein...@caltech.edu]
>> Sent: Sunday, August 16, 2015 10:31 PM
>> To: carl heiles (hei...@vermi.berkeley.edu)
>> <hei...@vermi.berkeley.edu>; Alan Rogers (arog...@haystack.mit.edu)
>> <arog...@haystack.mit.edu>
>> Cc: Dave Deboer (ddeb...@berkeley.edu) <ddeb...@berkeley.edu>; 'Han'
>> <st...@kasi.re.kr>; Steve Smith (ste...@caltech.edu)
>> <ste...@caltech.edu>; Monroe, Ryan M (382F)
>> <ryan.m.mon...@jpl.nasa.gov>
>> Subject: Educational 6m Radio Telescope at Caltech
>>
>>
>>
>> Carl and Alan,
>>
>>
>>
>> I need some advice from old salts about how to demonstrate radio
>> astronomy observing techniques to new graduate students.
>>
>>
>>
>> We are paying some attention to the 6m telescope on the roof of the
>> EE building at Caltech and are trying to make it into a good
>> teaching instrument. The front-end covers 1.3 to 1.7 GHz with about
>> 100K Tsys on two linear polarizations and we recently installed a
>> Roach 1 spectrometer with two 500 MHz bandwidth channels and 60 kHz
>> resolution. There is much RFI and a lesson we want to teach is how to work
> around it.
>>
>>
>>
>> Our weakest link is the software to integrate telescope pointing with
>> receiver output. We are working on developing a convenient system
>> but I wonder if it already exists on other small telescopes. Do you
>> have any suggestions for integrated telescope and data taking
>> control system we should look at?
>>
>>
>>
>> A second topic is what to observe with the telescope as
>> educational demonstrations. We can certainly map galactic hydrogen
>> and look at the stronger continuum sources. The spectrometer can
>> cross correlate the two linear polarizations and we could get into
>> polarization measurements. Do you have suggestion for observations?
>>
>>
>>
>> I would like to observe OH (again, since I have not observed it or
>> followed what has been done since 1963 !). Where is a good summary
>> of the observations? I think our 60 KHz resolution is too broad
>> and we will need to improve it by a factor of 10 or more.
>>
>>
>>
>> Sandy
>>
>>
>>
>
