Today progress on the Prescott HERA dish took the form of building the dish hub and rim.  The hub is where all the dish supports (25′ pvc pipes) meet. The hub is made using concentric “sonotube” concrete forms in which are embedded 3″ plastic pipes set in a radial pattern.  Its basically a giant tinker toy hub made of cement. At the same time we also put up the rest of the rim support poles with their fixtures to receive the dish supports.

HERA Prescott Photo Album

Our work team today.

ECHO beam mapping is very repeatable. When we map two different antennas and subtract, the different is nearly zero. ECHO in blue, satellite measurements in grey.

ECHO beam mapping is very repeatable. When we map two different antennas and subtract, the different is nearly zero. ECHO in blue, satellite measurements in grey.

Our first paper about the drone calibrator is out on the arxiv today!  Using data from our field tests last year we measured the stability and accuracy of the beam maps. The repeatability compared well to measurements made using satellites (thats the plot on the right) and the measurements matched up well with the models. There were a few issues though. The main thing seems to be the stability of the antenna attachment to the drone. We’re sensitive to even a degree of rotation!  Overall, though the thing worked a lot better than I was expecting, quite frankly.

The paper is here: https://arxiv.org/abs/1610.02607

When building any kind of instrument its really important for the people looking at the data to understand all the little things that go into building it and from an experimental perspective its key to be able to experiment with the hardware.  With the primary construction going on in South Africa this is a challenge. Travel to site is key, but sometimes you can’t beat having your own copy.

With support from ASU, the Bowman lab, Embry Riddle,  in collaboration with ERAU Professor Andri Gretarsson we are building a HERA dish at the Radio Observatory on the ERAU Prescott campus.

Today the survey was completed and the three primary telephone poles were installed!

HERA-Prescott poles. Ellie Gretarsson for scale.

Last week the ECHO team took the (relatively) short drive from Tempe up to Prescott, Arizona and Embry Riddle Aeronautical University to do some more testing at a new location.  The Embry-Riddle Physics department has put together a very nice campus observatory which is predominantly devoted to radio science, both astronomy and aerospace. Under the leadership of Professor Andri Gretarsson, they have set up a set of three MWA tiles with which they plan to observe pulsars, and antenna elements from LWA and from LOFAR. On this trip we got shown around the site, made a preliminary map of one MWA tile, and discussed plans in the works to build a HERA dish.

Part of the ECHO team poses with an LWA antenna and the ECHO drone on the May, 31 trip to Embry Prescott, AZ. Left to right: Lauren Turner, Jacob Burba, Prof. Andri Gretarsson (ERAU), and Dr. Daniel Jacobs (ASU)

Part of the ECHO team poses with an LWA antenna and the ECHO drone on the May, 31 trip to Embry Prescott, AZ. Left to right: Lauren Turner, Jacob Burba, Prof. Andri Gretarsson (ERAU), and Dr. Daniel Jacobs (ASU; ECHO PI)

We only had a few hours in the afternoon to map the tile, so we hurried through three sorties and hoped for the best.  Getting home and processing the data we were pleased to see the expected square sidelobe pattern (shown below). The errors are still a bit high due to a low sample count, so we’ll be heading back up as soon as we can to get more data.

The beam map from this run.

The beam map from this run. It came out surprisingly well for such a quick attempt at data collection.

Here’s some great news, the first stage of the Hydrogen Epoch of Reionization Array (HERA) has been finished and is now taking data. Now, witness the might of this fully operational battlestation. Well, actually we’re far from full size, so far we’ve got 19 out of the planned 350 dishes.  Here’s a picture.hera19Each dish is 14 meters (42ft) across. The feeds are borrowed from the PAPER array (seen in the background) and hung over the dishes from telephone poles ala Arecibo. The 19 element array has about the same collecting area and sensitivity as the full PAPER array.

In a couple years time HERA will cover the rest of the field, to be about the same size as Arecibo, actually. This is a big size: for Americans think eight football fields arranged in a two by four grid, or a typical super Walmart with an extra large parking lot. If you’re thinking ahead to the olympics in Brazil, HERA will be about the same size as Maracanã stadium where the opening ceremonies will be held.

Here is the field crew that built this first stage.

H19 Crew

Now comes the fun of taking our new telescope for a test drive.  Data taking has commenced and will continue until we start building to HERA 37 in 6 months or so. The data look great; the collecting area boost is amazing.

25. August 2015 · Write a comment · Categories: research · Tags:
ASU Students make adjustment to ECHO. Left to right: Ben Stinnett, Jacob Burba, Lauren Turner

ASU Students make adjustment to ECHO. Left to right: Ben Stinnett, Jacob Burba, Lauren Turner

This week several students and I traveled to Green Bank, WV for some high precision testing of the ECHO drone.  The goal was to test our beam mapping accuracy on an antenna for which we had good models.  This was also a week reserved for focused work; its our opportunity to put in a solid amount of time in the field to work out the kinks in the mapping process.  After some rain delays on day 1 the weather was beautiful for flying. Over the course of four days we flew around 25 flights and made four complete beam maps. This is described in more detail in our field report memo:

Report on ECHO measurements of Orbcomm dipoles in Green Bank. D. Jacobs (2015)

We had a good time and learned a lot; students and  PI.  Physics student Jacob took some truly excellent photos, check out the complete album here.

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ECHO Green Bank trip 2015 Left to Right: Ben Stinnett, Danny Jacobs, Abraham Neben, Lauren Turner, Jacob Burba

About ECHO

ECHO is the External Calibrator for Hydrogen Observatories, a drone-mounted calibrator designed to help us get 1 part in 10,000 precision in cosmology telescopes targeting the first half-billion years of cosmic time. ECHO is supported by the National Science Foundation and Arizona NASA Space-Grant.

This year the Murchison Widefield Array annual December meeting was hosted by Arizona State University, here in Tempe. In celebration of over a year of active observing the meeting was opened to attendance and contributions from the wider community. The result was a rare convocation of the low frequency radio astronomy community. Topics ranged from transients and radio galaxies to 21 cm at cosmological distances. One of the highlights of the meeting was the announcement of the discovery of low altitude flux tubes in the ionosphere (Physics Today article). Remember friends, they aren’t image artifacts if they line up with the earths magnetic field lines!

The full list of participants along with most of the talk slides can be found over on mwatelescope.org.

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The meeting was also preceded by a 5 day intensive work session by the Epoch of Reionization team.

 

This week, in conjunction with the Low Frequency meeting, the MWA 21 cm science team got together to have a data crunch. A good time was had by all except the data which was severely crunched and is now much reduced from its former self.

We set up shop in a conference room, generously loaned to us by the defense folks down on 4.

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And here we all are!

MWA 21 cm group, Tempe Busy Week, December 2014

MWA 21 cm group, Tempe Busy Week, December 2014

 

 

03. December 2014 · Write a comment · Categories: research · Tags:
ECHO team members Mason Denny and Marc Leatham perform test on a scale model testbed

ECHO team members Mason Denny and Marc Leatham perform tests on a scale model testbed

This semester I start work in earnest on a new project thats been simmering in the background, the External Calibrator for Hydrogen Observatories (ECHO) an experimental method to provide an airborne calibration source for wide-field radio arrays observing Hydrogen at cosmological distances. In particular, accurate maps of the primary beam (the response of the receiver dipoles as a function of position on the sky) have been found to be crucial at multiple stages analysis of data from PAPER/MWA/LOFAR etc but have historically been measured through indirect means such as the amplitude of satellites or radio galaxies passing overhead. ECHO aims to provide a direct measurement with a system where all parameters are under the experimenter’s control.

At this point we are designing and building our transmitter (don’t need much power for a radio telescope!) and selecting a new drone platform. We’ve hired a small team of undergraduates to take point.

ECHO team members Marc Leatham and Victoria Serrano give the quad-rotor a shakedown flight. The quad is acting as a scale model and training frame for a larger platform soon to come.

ECHO team members Marc Leatham and Victoria Serrano give the quad-rotor a shakedown flight. The quad is acting as a scale model and training frame for a larger platform soon to come.

ECHO Version 1 A bicolog 5007 mounted on a Mikrokopter 8.

ECHO Version 1 A bicolog 5007 mounted on a 8 rotor Mikrokopter. An upgrade to a newer pixhawk-based platform is planned for the spring.

 

 

 

 

 

 

 

 

 

 


This project is supported by National Science Foundation and the Bowman Low frequency Cosmology lab in the School for Earth and Space Exploration.

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