Crowdfunding, Exoplanets, and Devils in London (not that London)

Posted by admin on April 6, 2016
Posted in: Brian's Presentations. Tagged: , , , , , .

IMG_3637Had a wonderful visit to London, Ontario last week, home of the University of Western Ontario. Weather wasn’t quite as nice as here in Boise, but the city was just as beautiful.

My friend and colleague Catherine Neish arranged for me to give three talks while there — one on our crowd-funding effort, one on my exoplanet research, and one on our dust devil work.

I’ve posted two of the talks and abbreviated abstracts below. The dust devil talk, “Summoning Devils in the Desert”, is a reprise of a previous talk, so I didn’t include it below.

Crowdfunding To Support University Research and Public Outreach
In this presentation, I discussed my own crowdfunding project to support the rehabilitation of Boise State’s on-campus observatory. As the first project launched on PonyUp, it was an enormous success — we met our original donation goal of $8k just two weeks into the four-week campaign and so upped the goal to $10k, which we achieved two weeks later. In addition to the very gratifying monetary support of the broader Boise community, we received personal stories from many of our donors about their connections to Boise State and the observatory. I’ll talk about our approach to social and traditional media platforms and discuss how we leveraged an unlikely cosmic syzygy to boost the campaign.

On the Edge: Exoplanets with Orbital Periods Shorter Than a Peter Jackson Movie
In this presentation, I discussed the work of our Short-Period Planets Group (SuPerPiG), focused on finding and understanding this surprising new class of exoplanets. We are sifting data from the reincarnated Kepler Mission, K2, to search for additional short-period planets and have found several new candidates. We are also modeling the tidal decay and disruption of close-in gaseous planets to determine how we could identify their remnants, and preliminary results suggest the cores have a distinctive mass-period relationship that may be apparent in the observed population. Whatever their origins, short-period planets are particularly amenable to discovery and detailed follow-up by ongoing and future surveys, including the TESS mission.

Visiting Jupiter for Spring Break

Posted by admin on March 26, 2016
Posted in: Observing. Tagged: , .

Among other fun things I did this week during spring break, I practiced using one of the Physics Dept.’s new telescopes. It’s a lovely little 127-mm Maksutov-Cassegrain with a robotic mount. I also used a NexImage 5 camera. While the telescope is a joy to use, the camera is a pain, and I can’t convince it to return color images.

In any case, I took advantage of the clear night on Friday and imaged Jupiter from the middle school baseball field across the street from my house. In spite of the fact that neither the seeing nor tracking were great, some post-processing with Registax returned a nice little image.

Jupiter, from my backyard.

Jupiter, from my backyard.

Next steps: I need to do a better job with the tracking (probably need some new gear to improve the telescope alignment). A new camera might also be in order.

 

 

 

 

Looking for Endor

Posted by admin on March 23, 2016
Posted in: Brian's publications. Tagged: , , , , , .

UPDATE (2016 Mar 24): The paper is now available for free on astro-ph.

The Astrophysical Journal published today a paper by my colleagues and myself investigating in detail a way to look for moons around transiting exoplanets.

The discoveries of thousands of planets and planetary candidates over the last few decades has motivated a parallel effort to find exomoons. In addition to providing a base of operations for the Empire, exomoons might actually be a better place to find extrasolar life than exoplanets in some ways.

This technique for finding exomoons, called the Orbital Sampling Effect, was developed by René Heller and involves looking for the subtle signature of a moon’s shadow alongside the shadow of its transiting planet host, as depicted in the image below.

At epoch (1), a satellite’s transits just before the planet. At epoch (2), the planet's transit begins, inducing a large dip the measured stellar brightness. At epoch (3), the satellite modifies the planet's transit light curve slightly but measurably.

The dark cloud shown around the planet represents the exomoon’s shadow, averaged over several orbits. At epoch (1), a satellite transits just before the planet. At epoch (2), the planet’s transit begins, inducing a large dip in the measured stellar brightness. At epoch (3), the satellite modifies the planet’s transit light curve slightly but measurably.

This simple technique has advantages over alternative exomoon searches in that it doesn’t require significant computational resources to implement. It can also use data already available from the Kepler and K2 missions. However, on its own, the technique can’t provide a moon’s mass, only its size, and it requires many transits of the host planet to find the moon’s quite subtle transit signature.

No exomoon has been found yet in spite of tremendous efforts to find them, so the search continues.

 

A little planet in a little orbit around a little star

Posted by admin on March 3, 2016
Posted in: Journal Club. Tagged: , , .
Artist's conception of cloudy GJ 1214 b. From http://www.nytimes.com/2014/01/07/science/space/the-forecast-on-gj-1214b-extremely-cloudy.html.

Artist’s conception of cloudy GJ 1214 b. From http://www.nytimes.com/2014/01/07/science/space/the-forecast-on-gj-1214b-extremely-cloudy.html.

At journal club this week, we discussed the recent discovery using data from the K2 mission of the sub-Neptune planet K2-28.

This planet, roughly twice the size of Earth, circles a very small M-dwarf star so closely that it only takes two days to complete one orbit. Even though the planet is very close to its star, the star is so cool (3000 K) and so small (30% the size of our Sun) that the planet’s temperature is only 600 K. (A planet in a similar orbit around our Sun would be 1200 K.)

The authors of the discovery paper point out that this planet is similar in many ways to another famous planet, GJ 1214 b. Like GJ 1214 b, K2-28 b is member of this puzzling but ubiquitous class of sub-Neptune planets — planets that fall somewhere between the Earth and Neptune in size and composition and do not exist in our solar system*. Both planets also orbit relatively nearby M-dwarfs, which means, like GJ 1214 b, K2-28 b might be amenable to follow-up observations.

Previous follow-up observations of GJ 1214 b indicated that planet’s atmosphere is very cloudy or hazy. So K2-28 b could provide another very important toehold along the road toward understanding this strange class of hybrid planet.

*unless Planet Nine turns out to be real

 

What Did the Black Holes Say As They Merged?

Posted by admin on February 18, 2016
Posted in: BSU Journal Club. Tagged: , , .
From http://www.redshift-live.com/binaries/asset/image/25908/image/Graviational_Waves.jpg.

From http://www.redshift-live.com/binaries/asset/image/25908/image/Graviational_Waves.jpg.

Nothing. They just waved.

Led by physics major Tyler Wade, this week’s astronomy journal club discussed the very exciting result from the LIGO collaboration, the first detection of gravitational waves.

Einstein predicted the existence of gravitational waves back in 1916. (If your differential geometry and German are any good, you can read the original paper here.) Essentially, gravitational waves are a consequence of that fact that mass can distort the shape of space (that’s what we call gravity).

The upshot of this is that any massive object in motion can excite gravitational waves, but only very massive objects (like, black hole-sized) produce waves big enough that we have any hope of measuring them.

And so for the last few decades, the LIGO project, along with other gravitational observatories, has been monitoring the space-time continuum, looking for tiny distortions due to rapid, oscillatory motion of massive celestial bodies.

LIGO attempts to detect these distortions by sending two laser beams, one each, out and back along two orthogonal 4-km tunnels. By measuring the travel time for each laser beam down each tunnel, they can determine their lengths to a ridiculous precision. A passing gravitational wave would VERY slightly modify the tunnel lengths in a particular way.

How slightly? The signal reported last week by LIGO corresponds to a change in the tunnel length by 0.0000000000000000000001 meters. That’s the equivalent of a change in the width of the Milky Way galaxy by 1 meter.

At two different observatory sites, one in Washington state and the other in Louisiana, the LIGO collaboration measured the distinctive signature of gravitational waves generated by two black holes, many times the mass of the Sun, as they completed their death spiral, merging into an even bigger black hole and radiating an enormous amount of energy.

Why is this important? Well, seeing gravitational waves is not going to allow us to control gravity (at least not yet), and the fact that they exist is not surprising. Instead, LIGO has provided us a brand-new way of doing astronomy.

It’s as if, up until now, we were doing astronomy colorblind, and suddenly LIGO built a color telescope. Of course, being able to see in color would open up vast and unexpected vistas on the universe. The detection of gravitational radiation is the same kind of revolutionary achievement.

NYT has a really great animation and video describing how the detection worked, which I’ve embedded below.

Little, Disintegrating Planet Observed by Little Telescopes

Posted by admin on February 11, 2016
Posted in: BSU Journal Club. Tagged: , , .
The red dots show the observations, with the dips due to asteroid chunks transiting the white dwarf. The inset shows an artist's conception of the disruption process.

The red dots show the observations from this study, with the dips due to asteroid chunks transiting the white dwarf. The inset shows an artist’s conception of the disruption process.

For our second journal club meeting this semester (didn’t manage to blog the first one), we discussed a study from Saul Rappaport and colleagues on observations of the white dwarf WD 1145+017, which continues to show evidence that it is eating a small asteroid.

A study last year from Vanderburg and colleagues (which we discussed last semester) presented observations from the K2 Mission showing distinctive but highly-variable transit signals coming from WD 1145+017. That group conducted follow-up observations that pointed to the presence of an asteroid very close to the star, being ripped apart by the star’s gravity.

As crazy as it sounds, the idea that some white dwarfs are eating asteroids is fairly well-established, but Vanderburg’s study was the first to present observations of the process clearly in action. The variability of the transit signals indicates that the violent process is dynamic and complicated.

This new study from Rappaport and colleagues continues the saga of WD 1145+017 and finds that the disruption process persists more than a year after the initial observations. And using the apparent drift rates of the different chunks of asteroid, Rappaport is able to constrain the mass of the parent asteroid to be about 1% that of Ceres in our solar system.

One of the most exciting aspects of this study for me is that the observations were made using a network of small, amateur telescopes. Some of the scopes used in the study were 25-cm, and so I’m hopeful that, in the near future, we will be able to use Boise State’s own Challis Observatory to conduct follow-up. Just gotta wait for a clear night.

Aerospace Day at Boise State

Posted by admin on February 5, 2016
Posted in: Public Outreach. Tagged: , , .

Boise State’s Institute for STEM and Diversity Initiatives is hosting Aerospace Day here on campus today, a day to explore the science, engineering, and applications of aerospace technology.

I volunteered to give a talk on our group’s research looking for short-period exoplanets, and it seemed well-received. Lots of interesting questions afterward. I’ve posted the talk below.

During my talk, I mentioned the planethunters.org website, where the public can help find new exoplanets using data from the Kepler mission.

Thanks to Christine Chang Gillespie, Donna Llewellyn, and all the other organizers for the invitation to speak.

OCR OC-gain

Posted by admin on January 20, 2016
Posted in: Data Science. Tagged: , .

My PHYS341 students were interested to see how the OCR routine processed their attendance sheet, so I applied it, as shown below.

IMG_3707_orig-scannedThe left panel shows the original, the right the transformed version. The routine did a reasonable job of un-distorting the page (although it wasn’t too bad to begin with).

And here’s what the routine returns as text:

zolto J:)o<-&\
Qfick ${‘bt\L . .
1ZWrW(\ DQVCS
Onras Tkomag
Jam; I-Em!
De»-UV1, ?I‘L\M‘ovV\QJ3€,v'
Ia./I B,a,C/IHMC .
V.o\3 \3<<I°\Ser&eck
jengifcr Brigga
}VK°'('3E\V1c-rad LULAA
Mby Ouersfreci’ '
Tm (jivws ‘
gj)/VIOI/I  ‘
$030-4 “10u\J ‘
{NC /I/1a.V,,,,',q '
O”AKe So/ares
Skwm \<reyc}~e '

…not great.

I’m not totally sure what went wrong. Maybe I should have them write their student numbers instead.

UPDATE: 2016 Feb 5

Here’s another go with a different attendance sheet. Not much better.

IMG_3784_scanned

I‘/\0,;/{¢r\(~  VETEK BROWN
E ? RICH/W} WLMC/(
“$2114!/~, lZoAr.‘%o Pratt.‘
D“""‘ 8'3"’ ' g/"It; /Vlar,//'/1
 Lolpef‘
kpdkl/n\‘f 2011/(IE
ANN <5©<J\M) Vfxit %'L0V\€z &}"-:5 _)_La/\/MAS _ Karm I>q'v‘-5
\Tou—o0l Hand _
'Dz\m/L ?\c\n'ksvvuu‘ev*
Ian I3/¢«'-Ckfia/If ¢
94% \5<<k*?l6<:x\.cLl¢ Jennifer BH995 N\o+‘\'V\c\.6 Luv\0\ . \/\0\\)y 0\,ers+reeJr ’\".m C"\\/Ens _ 51 m cm E 1: Y Jason May A ZPM > M
PIJW1 figu//
jam 5°0W'/J
34681 \4'€y¢}~¢>/

Uniform Circular Motion Animation in Python

Posted by admin on January 6, 2016
Posted in: Teaching, Uncategorized. Tagged: , , .

I’m prepping for my classical mechanics course, scheduled to start next week. One of the first things we discuss is uniform circular motion and how it looks projected along the x- and y-axes, so I thought it would be useful to have an animation showing that. I found a few animations online, but none really showed the x and y projections I was looking for.

So I decided to create my own using my go-to language of choice Python. Fortunately, python guru Jake Vanderplas has created a very nice animation module usable in iPython Notebooks.

Based on his example here, I put together the following code to generate the desired animation:

Scanning and OCR-ing a Paper Receipt

Posted by admin on January 2, 2016
Posted in: Data Science.

I spent the morning kludging together a python script to convert a grocery receipt into a spreadsheet as part of one of my New Year’s resolutions. There seem to be a few options out there for scanning and recording receipts, but it’s not clear that they apply an OCR technique to automatically convert them to spreadsheet.

Here’s the receipt I used:

IMG_3497This website provided some python source code to detect edges in the image then the outline of the receipt and transform out any foreshortening or other viewing distortion —

(left) Edge detection, (center) Outline detection, (right) Scanned version.

(left) Edge detection, (center) Outline detection, (right) Scanned version.

To detect edges, the code converts the color image to grayscale and applies the Canny edge detection scheme, which involves applying a Gaussian blur to suppress noise, calculating image derivatives, and looking for large values. The result is shown in the image above on the left, and more details on the algorithm here.

Next, the code finds the outline of the receipt by using the OpenCV‘s findContours, sorts the contours by area, and finds the contour with the largest area but with four vertices.

The code then applies a four-point transformation to warp the receipt to give it a rectangular shape and finally thresholds the grayscale to enhance the contrast. The rightmost panel in the above image shows the final result.

To convert the image to a table of text, I used PyTesseract, which provides OCR capabilities. I installed the package Tesseract using homebrew: “brew install tesseract”.

Then I just grabbed the code from this website to convert the final result into a text table:

st = pytesseract.image_to_string(Image.open(save_filename), config="-psm 6")

The “psm=6” option was required to return the text properly.

Unfortunately, the OCR analysis wasn’t perfect. For example,
IMG_3497_scanned_linewas converted to
‘*CRESgENT R01 1 1800000401 4.82 IF

The prices on all lines came back fine, but the description was often distorted. I decided I cared more about the price anyway. Fortunately, the WinCo receipt had “TF” or “TX” at the rightmost side, so I performed a regex search to find the beginning of that string and grabbed the characters to the left of that.

Finally, I converted the strings into a list of comma-separated values to load into Excel or Google Sheets, leaving a space between the corrupted description and price so I could enter my own description, giving
CRESgENTR0111,  , 4.82

On the off-chance it will be useful to someone else, I’ve posted the code here. Using my script will also require the source code for pyimagesearch, which requires submitting an e-mail address.