Science Images are Ugly

One of the questions that comes up often enough is what do the pictures look like? And that question is followed by… Where can I see them.

A raw widefield 1.2um NIRC2 image of Jupiter taken 21July2006, credit Imke de Pater, UC Berkeley
A raw widefield 1.2μm NIRC2 image of Jupiter taken 21July2006, credit Imke de Pater, UC Berkeley

The problem… Science data is usually pretty ugly.

Keep in mind that the astronomers are often pushing the telescopes and instruments right to the limit. This means that the data is barely there, a trickle of photons that have come from unimaginably distant sources.

I have been in the observing room as the data comes in. I have watched over the telescope operator’s shoulder. It is strange to see folks so excited over a smudge.

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Astronomy Team Releases Planet-Search Data

UC Santa Cruz press release

An international team of astronomers has released the largest ever compilation of exoplanet-detecting observations made using a technique called the radial velocity method. By making the data public, the team is offering unprecedented access to one of the best exoplanet searches in the world.

Planet Hunters Paul Butler and Steve Vogt
UCSC astronomer Steve Vogt (foreground) with collaborator Paul Butler at the W. M. Keck Observatory in Hawaii. Photo by Laurie Hatch
The data were gathered as part of a two-decade planet-hunting program using a spectrometer called HIRES, built by UC Santa Cruz astronomer Steven Vogt and mounted on the 10-meter Keck-I telescope at the W. M. Keck Observatory atop Mauna Kea in Hawaii.

“HIRES was not specifically optimized to do this type of exoplanet detective work, but has turned out to be a workhorse instrument of the field,” said Vogt, a professor emeritus of astronomy and astrophysics. “I am very happy to contribute to science that is fundamentally changing how we view ourselves in the universe.”

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The Keck Observatory Archive

The data produced by the W. M. Keck Observatory is available for anyone to view. This may come as a surprise to some who assume that astronomers hoard their precious data and jealously deny any access. I have also seen claims by anti-TMT activists who claim that telescope data is secret and access is restricted to some authorized group. It is a common theme I have seen repeated quite a few times during the Astronomy on Mauna Kea debate.

Saturn NIRC2 dePater
An image of Saturn taken in infrared light by NIRC2, image credit KOA/dePater

“There is an appointment signup of experts of bureaucrat choosing and the findings disappear amongst the grant supported or institutions we have no knowledge about” – Claire Templeton in a Facebook comment 16Aug2015

The idea is at least understandable. Much of modern astronomy is fairly arcane to the layman, not easily understood and seemingly mysterious. It does not have to be that way, the images and data are fully public. A small community, including astronomers and amateur astronomers, has learned to use the data to do science, or to simply peruse for their own edification. All it takes is an evening of educating yourself and you have access to a huge array of data.

The astronomers do guard their data and deny others access, but they are only allowed to do this for a limited period of time. This gives the astronomer exclusive use of their data long enough to complete the research and publish the paper. The amount of time they have exclusive use varies by telescope and institution, but it is usually a year or two. For the W. M Keck Observatory the data is usually embargoed for 18 months. Once the exclusive period expires the data is available to anyone and is posted in the online public archive.

Keck’s archive is known as KOA, or Keck Online Archive. Also a nice reference to the beautiful Koa forests that are common on the windward slopes of Mauna Kea. Here you can search and peruse twenty years of Keck data.

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Raspberry Pi, Python and SPI

It has only taken me much of the day to get it working. Hours spent reading documentation, searching for postings on the same issue, ripping up the code and trying completely different approaches. Hours of frustration mixed with some solid learning.

Victory was seen in three bytes.

Three bytes shown on the logic analyzer display and in the Python console window. The same three bytes… The hardware and software agreed. The serial timing also looked great, chip select going low when it was supposed to, a 500kHz clock, all of the edges just as the data sheet specified.

Victory is connecting an eight channel A/D converter IC to a Raspberry Pi computer with the hardware SPI module. Four channels for voltages, four channels for temperatures. The project is coming along nicely. Will talk about what in a later posting. Meantime my thanks to Connor Wolf, Louis Thiery, and Brian Hensley. It was their method and SPI code that worked!

A small victory, another step forward, this is what hackers and makers do…

Raspberry Pi Data Acquisition
A Raspberry Pi computer set up with an A/D daughterboard