Exoplanet Light-Curves with OSCAAR - Photometry for Everyone!

For our astrophysics club we have been doing some observations on Faulkes North over on Maui and managed to capture half of a transit before the weather shut down the telescope. At this observation session, we went through some tutorials on generating light-curves and discussed the general methodology (read about our Observation Observations) but I had wanted to find a more robust, and ideally easier, way for members to be analyzing the data in the future. After flirting with the idea of writing a comprehensive program I got some better sense and went looking for someone else who already had. Lo and behold, OSCAAR.

OSCAAR is a simple-to-use GUI that assists in the development of light-curves for exoplanets (and other eclipsing events). In their words, "oscaar is an open source project aimed at helping you begin to analyze observations of transiting extrasolar planets with differential photometry," and, "oscaar is useful for observers at small and large observatories alike, and users with any level of coding experience. No coding experience or PhD in astrophysics necessary!" Or, like the title says, "Photometry for Everyone!"

However, since the software is still in development (2.0-beta at time of writing) there are inherently some problems and I very quickly encountered these. Here are some initial notes about using and solving these problems, which will continue on into the future.

• Initially the program required dark frames and flats. I created an Issue regarding this limitation, to which the authors immediately started working on a fix. Within a week or so this was adjusted to create a dummy dark and flat image (basically an array of same size as image consisting of 1s and 0s, respectively). The interface could probably use some work and will be contacting authors regarding this issue but overall I was very please and happy with the quick response. Thanks!
• Region file must be in coordinate system (format: saoimage) or dies with bad error. This was not obvious nor the DS9 default so there was some confusion and digging on my part.
• Exposure time is set in header as ‘DATE-OBS’, which should be selected (?) automatically. Had to go into Extra Observatory Parameters and select ‘DATE-OBS’ (which was the only option given) for it to work.
• If selecting Tracking Plots and/or Photometry Plots, plots are given as running and seems to work well (see pretty pictures).

  

  Tracking and Photometry plots being generated while running.

    
  
• When trying to do a fit a bunch of array output is given and then an error. Digging into it, it is a dimension error. Something about the comparison stars when doing a np.dot versus what is passed into the leastsq. Digging into the problem, it seems to be related to the issue seen here, with leastsq not knowing how to properly optimize a multi-dimensional array.
• Well, after digging around for a while, it turns out that I just needed to use less comparison stars. I’m not sure if this is a bug or designed that way and will contact authors. Documentation refers to using as few as possible in order to increase speed but seems like an error should be handled a little better.

• 

  Half a light curve with fit for TrES 3-b

  After processing, I see a graph displaying my light-curve (well, I only have half a curve). The dialog box for the Dark and Flat are still displayed, which is a little confusing, it should close earlier. Then I am taken to a box asking for my result file names with a button for an MCMC Fit. I’m just accepting the default values for all the parameters, of which there are a lot.
• This gives me an error finding analyticalTransitModel.so, which is a linked library, so might just be a problem with me running from the repo directory rather than installing.

• Trying again the next day, I used the previously installed copy of OSCAAR (instead of the version from the repo) and had no problems with the analyticalTransitModel.so. I was able to download a copy of the exoplanets database (by entering Planet Name and choosing Update Parameters). This ran for 100 iterations, looking fancy and science-like, but then gave me an AssertionError saying that there was not successful optimization and to try new Beta values. Certainly, the error reporting could be a lot more user friendly. It suggests updating the Beta parameters but I really have no idea how to adjust them to get more (or any) appropriate results.

MCMC fit and plot. This is in the middle of the process which eventually errors out.

All in all I am impressed with the work done so far and look forward to working with the authors to help improve OSCAAR. I think there is some general clean-up work that could be done with the GUI (I notice there is a branch for a new GUI) in terms of using as well as when giving errors. I would also like to see a python3 version. The website talks about the dependencies but I think the only thing not ported to python3 directly is PyFITS and that has been rolled into astropy and should be working well so perhaps the port to python3 could happen soon (yes, that is sort of me volunteering).

2013 Lunar Science Virtual Forum Overview

You can't sequester science.

At least that's the idea coming out of the 2013 Lunar Science Forum from the  NASA Lunar Science Institute (NLSI). The 6th annual forum saw a number of changes, starting with a (budget-enforced) switch to being a completely virtual forum all the way to the announcement that the Lunar Science Institute is now the Solar System Exploration Research Virtual Institute (SSERVI). One can extrapolate from the organizational name change that the focus will not only be the Moon (think small-bodies like asteroids) but will also be virtual from here on out. My thoughts are that this is a good thing as the NLSI really seems to be trying to bridge the work between scientists, universities, and governmental organizations. There were a few questions throughout the forum asking about co-operation with the private sector although that discussion was, perhaps surprisingly, limited.

The SSERVI crew posing after a well-run virtual forum.

This being an all-virtual forum there were naturally some challenges and issues. Overall, the folks at SSERVI (I believe most of them were at AMES) did a really great job with most of the technical issues while the problems seemed to stem from participants who failed to pay attention to instructions. The agenda includes links to the entire archived conference, which can play back in real-time including all the chat features and user blunders. It's kind of cool actually. Definitely one of the advantages to an all virtual conference is that things like a complete archive of all the session is readily attained. Indeed, you can even check me out in the Lightning Talks here. :)

One can easily garner the gist of current research and focus by looking over the agenda titles with lunar geology dominating most of the sessions (naturally), although there was a fair sprinkling of volatiles, exospheres, human exploration, heliophysics and other misc. items scattered throughout. The individual speakers ranged from extremely fascinating to hard-to-understand-for-various-reasons to dry-n-pedantic and the variation was largely independent of the subject matter.

The basic format was to have one or two general speakers do an introduction of sorts to the subject matter for the day. These were largely interesting and well done, giving brief overviews of the relevant issues and subject matter. For instance, the second day opened up with some quick introductions to geology and volatiles as they are present on the moon. Dana Hurley, of the John Hopkins Applied Physics Lab, began with an insight about how when she started in the field 15 years ago the questions would have been about whether or not water existed on the Moon, a question we now have thoroughly answered. The questions now, she asks, are: 1) What are the present day abundances of volatiles and 2) what is the actual composition of these volatiles? You can see her concise overview talk here but it seemed to reflect the general consensus that we have learned a whole lot recently and are about to learn a whole lot more.

Throughout the forum (I keep wanting to say conference) there was a lot of talk about LADEE, which is natural as it is about to launch (window opens Sept. 6 - see launch details) and will give a lot of science to most of the people attending the forum. It's interesting to see all the different components with LADEE and I can't seem to shake the feeling that everyone is trying to simultaneously pat each other on the back as well as up-sale the LADEE mission in an effort to convince people it is worthwhile. Actually, this is more the feeling I get out of everything that comes from NASA these days, which makes sense as they face large budget cuts and a public that is skeptical of spending money on things they don't understand. Including the need for lunar forums.

On a personal end, and as mentioned, I did participate in the Lightning Talks, with Krystal giving a good overview of the hard work she has been doing that I have been helping volunteer with. I also gave a quick summary of some of my plans to create an easy to use data acquisition black-box kind of thing for the lunar impact monitoring (details later). Overall, it was nice to get the (brief) exposure and a good chance to tout both PISCES and UH-Hilo.

SSERVI's concluding note highlights a few areas of interest, including the awards ceremonies, and links to the relevant areas. Below are a few talks that I thought were cool, in no particular order:

• Dan Lester, Putting Telepresence on the Moon [video]
• Elliot Sefton-Nash, Thermal Extremes in Permanently Shadowed Regions at the Lunar South Pole [video]
• William Bottke, On The Formation Age of South-Pole Aitken Basin [video]
• Danielle Moser (on behalf of Robert Suggs), Large Meteoroid Impact on Moon on 17 March 2013 [video - this gives a good overview of lunar impact monitoring, which is what I have specifically been doing)]
• Citizen Science and Professional Development - Brian Day and Noah Petro [video]  

Imiloa Talk - Observing the Center of the Milky Way at 45,000 feet

Having lived in Hilo for the last couple of years, and on the Big Island for over four years now, it is a bit saddening that I have never bothered to become a member of the Imiloa Astronomy Center nor really attend many of the awesome events they regularly put on. Today, however, I had the opportunity to change that by attending an interesting talk by Ryan Lau, a graduate student out of Cornell University and a native Hawaiian resident, discussing his graduate work with infrared astronomy aboard NASA's SOFIA, a modified 747 designed to operate at 45,000 feet.

One of SOFIA's recent flight plans

Lau did a really great job of giving a brief overview of his work and of infrared astronomy in general, opening with an anecdote about his realization that the Sagan Walk, which originates at Cornell University, has the final piece of installation - representing the nearest star to our sun, Alpha Centauri - right here at the Imiloa Center, a project just completed this last December. As I reflect on it afterward, it is interesting to me that his diagram of the Sagan Walk, with the diagram arrows stretching nearly 8000km across the United States, ended up looking similar in spirit to his later slide depicting the flight paths taken by SOFIA as it flies across the United States. The contrast, of course, being that while we have mastered the ability to fly ourselves easily across our own globe, the thought of travelling to our nearest star, let alone something like the galactic center, still remains as daunting of a concept as the flat world was to initial explorers.

Any talk that is given to the general public about a highly advanced and specialized subject necessarily skips over a lot of the details but I thought that Lau did a really good job both in his presenting style, his ability to answer questions, and in his overall format of the speech. As he highlighted in the beginning, he wanted listeners to come away from the hour with three key points:

• Infrared is awesome.
• Airborne astronomy is awesome.
• The galactic center is awesome.

A look inside SOFIA. Lau is in bottom left.

With that in mind, Lau guided us through a brief but thorough overview of infrared astronomy, including the current ground and space based systems (R.I.P. Herschel) as well as the problems associated with each, with atmospheric conditions mostly affecting the former and prohibitive cost/effectiveness the latter. So onward to the second key point, that of airbone astronomy and SOFIA.

There is literature out there (follow the links above) describing SOFIA so I won't go into too much detail other than to say that it appears to be a pretty cool setup. Flight times are typically on the order of 10 hours, with nearly 5 hours of science accomplished on each flight. A typical session will last about 3 weeks, with 2-3 flights happening each week, for a total of 10-15 flights per session. The latest session, which Lau was on the plane for, had ended the previous week and had included some exciting new images of the galactic center, which is the thrust of Lau's work and his third key point.

The Galactic Center is Awesome

Specifically, Lau has been using the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST - playing fast and loose with acronyms) to look at two main regions of the galactic center, that of the inner 10 light years and the gaseous torus of dust that surrounds the black hole there, as well as that of The Sickle, which is a dense region of recent massive star formation and the site of three identified Luminous Blue Variables, extremely bright stars that can undergo unpredictable and radical shifts in brightness and spectra. In addition to being extremely bright, these stars are also extremely rare, with only 20 of them having ever been confirmed. To have three of them in one area of focus is quite extraordinary and the latest pictures generated by Lau also showed some pretty exciting properties that have never been observed.

One of the really fascinating things for me when I see stuff like this is that the science is a work in progress. Lau had literally taken these images last week and revealed some pretty incredible and awesome pictures of the two focus areas - images which aren't released to the public yet - and is still in the active process of interpreting and analyzing the results. While I would love to spill the beans on this by talking about these cool properties, I'll go ahead and wait until Lau has published his work before highlighting anything. Needless to say I thought it was pretty cool.

As mentioned, Lau did a good job of explaining these concepts and some of his results and overall just did a really thorough and concise job of giving a run-down of his recent work. Thanks again to Ryan Lau and the Imiloa Astronomy Center for the opportunity.

Dr. Buzz Aldrin and the Aldrin Cycler

I attended a Space Studies seminar yesterday up on campus in which they were watching a private video of a speech given by Dr. Buzz Aldrin to a group of PISCES members and supporters during the annual PISCES conference. This last year featured Dr. Aldrin speaking at the Waikoloa resort about a number of ideas, but mostly focused on the ideas of a united space policy, across all sectors and countries, as well as a tour and discussion of the Aldrin Cycler, again with some political asides on the part of Buzz being Buzz.

Artist depiction of an Aldrin Cycler. via

Throughout the video Buzz seemed lively and excited, often pausing to collect his thoughts and really appear to be speaking with genuine interest about the subject. He remarked early on about how he was without a teleprompter and took this opportunity to make his first jab at the President. Most of his remarks were off the cuff and of good-natured humor but he clearly has some gripes with the administration, past and present, and the lack of continued interest in the space program in general and things like the Apollo Missions in particular.

The talk was split into two main areas, the first in which Dr. Aldrin spoke in general terms about his ideas for space exploration going forward. As he stated, the idea is to "explore commercially developed and permanently settled space" He started right out by citing three core ideas of any space policy going forward: 1) strong leadership, 2) a sustainable path, and  3) long-term ambitions. Interestingly enough, I thought Dr. Aldrin's discussion about strong leadership and a united space policy, while all around interesting and full of nothing that be considered negative, still seemed to be confused, almost pandering to both sides about what a space program should look like going forward. And what are those two sides Buzz is pandering to? On the one hand, he repeatedly used words like "united," "collaboration," "coming together," and "cooperation" while speaking of public, private, international, and, frankly, all sectors and peoples that will be interested in space in the coming century. And everything he calls for is sound and logical, as it is important that we have united in policy and ideas going forward.

Yet, on the other hand, most of his speech was essentially about how the USA can maintain "leadership" in the coming years, and about how we don't want to send astronauts to the Moon, "only to find the Chinese already there." Overall, his general idea was that while other countries are focused on returning humans to the lunar surface, we need to start concentrating on how to get to Mars, thus staying one step ahead of the competition, as it were. Interestingly, Buzz, having had his chance to leap about the lunar surface, does not advocate directly sending humans to Mars although that is definitely part of his long-term plan and a critical feature of the Aldrin Cycler. But, "if we're not sending people [to a planetary surface]  than how can we be leaders? We do it by knowing more than anybody else."

Here Buzz seemed to be spot on in his assessment, namely that we are going to fail, we are going to make mistakes, but we just need to start trying. We (here implying the USA) need to maintain our leadership with this ability to try and fail, while all the while learning.

The first half of the talk was filled with these kind of  practical orations. "Today, collaboration [international, public, government, state, private, etc.] is an essential element for our success." We must, "[take] into account all the other countries space policy objectives." "I'm going to talk to you about a unified space exploration."

PISCES was also given its requisite amount of fan-fare: "As the space faring community comes together to embark...PISCES will lead in a unique and critical role in this vital new enterprise in space." "Begin with PISCES and extend to cislunar space and beyond." "But even more important, PISCES is to lead the construction of the lunar base."  And so on.

The second half of the talk Buzz focused on the Aldrin, or Mars Cycler, and practical attempts and methods to actually start getting to Mars. Dr. Buzz Aldrin actually has his PhD in Orbital Mechanics, so it's not just some guy who has walked on the Moon speaking here, he does actually know what he is talking about. Again, the central theme here seemed to be that we just need to start doing it and stop being afraid. There was a fair amount of modestly technical information about the Cycler, which refers both to the synodic period as well as the actual spacecraft Buzz envisions. [Details can be found on  Buzz's site.]

There was actually a lot more to the talk and I have a good page of pithy quotes given by Buzz. All in
all, it was actually a very interesting talk and always good to see an 80-year-old Buzz Aldrin still just as excited about humans getting into space.

A few items to share:

• On unity: Buzz wants to create a United Strategic and Space Enterprise foundation to foster this internal and global unity. That's right, it does have the name USS Enterprise, and this is, obviously, on purpose.
• On outreach and the public: "We really need to get philosophers, [and] people that are historians, to really think and look at what the earth is capable of doing. It is capable of taking humans beings and putting them on another surface in our solar system."
• On our legacy: "Thousands of years from now we will look back on the leader that committed a group of people to [reach the surface of Mars]."
• And, "That's why they're going to be the pilgrims."

Back in School

Well, after a summer hiatus where not much was done on the astronomy front, I am back in school this semester. Originally I had planned to take just two course, ASTR 180 and 260.

ASTR 180 is the introduction to astronomy for astronomy majors but is also open to general students who need to fulfill a science credit and don't want to go the biology or chemistry route. As such, there was a 10 min warning on the 'difficulty' expected in college courses as opposed to high school courses as well as a thorough warning of the type of intensive math we are going to expect to see. You know, like given an equation and one missing variable, solve for variable. You know, like high school algebra.

ASTR 260 is a computational astronomy course. It sounds interesting and is mostly (computer) lab based, so I was hoping to get some good programming. Due, however, to the constant waxing and waning of the moon, the class is actually being cancelled. Something about there being too many people, not enough professors or computers, and a general lack of coherence regarding what is going on this semester in the department (the department has, unfortunately, been inflicted with two unexpected casualties recently).

The current thinking is that 260 will become 294 and go from 3 credits to 1 credit. My hope is to actually do this as a directed study and continue my Hoku'kea camera work in lieu. My Hoku'kea camera work, however, has basically been out to the loo for the summer. While I had high hopes of getting a lot of it done in reality not much happened with it. My always-and-ever-more demanding work simply took too much of my time, much to my chagrin.

So, that frees up my schedule just a little bit. I ran into my friend Ben who is in my 180 class (we both skipped it last year to take more advanced courses so we have to go back to the Intro) and he informed me of an upper level physics class that looks really interesting. Physics 394 - Physics and Chance. I picked up the book before I left (headed to NYC for a wedding my first week of classes) and read the first two weeks of readings on the plane. The course is a Writing Intensive course and is discussion based, so should prove interesting. Of particular interest to me are the discussions regarding the irreversibility of time (time asymmetry) although the entire material appears interesting (and esoteric to boot!).

Faulkes Observing

Tomorrow night (weather permitting) I am going to be doing my remote observation run for my Observational Astronomy class. Check out this article over at Universe Today for an overview of the how's, what's, and why's. We are using the same telescope, Faulkes North, as in the article, which is generously available to Hawaii students.

This observation run is the main project that we do for the class. Given a choice of project ideas (or one of our own), the idea is to pick a project, write up and submit an observation proposal, do the observation, and then do all the processing and calculations after depending on which project we have selected. Most people who want to do an observation run will have to have their proposal accepted by a telescope committee; luckily, we students fall under the rubric of our professor's time, so we are more or less guaranteed time on the scope. We will be having an in-class telescope committee to do a mock review of the proposals which, actually, will be after I do my actual run. :)

For my project I am going to be measuring the atmospheric extinction and filter transformation coefficients, both of which are used in various calculations when doing astrometry. I selected this project because I thought it would be interesting and useful, with the numbers that I end up calculating hopefully going toward improving other student's measurements. Ideally, they would be sound enough numbers to give them back to Faulkes for general public usage.

More will be coming throughout the semester as I actually proceed with the project.

Mauna Kea Telescope Tour

A view of Mauna Loa from the HP.

Recently, I had a great opportunity to visit some of the telescopes up on Mauna Kea as part of my Observational Astronomy class. While it is certainly possible for any one to go up the mountain, and perhaps even get a basic tour, we were given an insiders tour into both the Gemini and CFH telescopes. I also had my first opportunity of checking out Hoku Ke'a, the new student telescope for us Astronomy students at UHH. Special thanks to Dr. Josh Walawender, my prof who arranged the trip and took us up there.

Looking toward Hoku Ke'a and Mauna Loa.

We started the day by taking a tour of the Hoku Ke'a dome. I would say "telescope" except for the fact that the telescope isn't really there. Unfortunately, this new scope, which is being build specifically as a student telescope, is many years behind schedule, both from the original construction and installation as well as from problems discovered after it had been installed. While the scope was supposed to be operational many moons ago the hope is to start doing some actual observations by the end of the summer. Too bad for all the students who came before, excellent timing for me. As a matter of fact, I am helping Josh out with some aspects of getting the scope running (more on that later).

Josh explaining the worm gear. We are standing underneath
where the mirror itself would be placed. Note that the mount
is currently rotated 180° since the mirror is absent.

Since Hoku Ke'a is in a non-operational state, we were able to get a closer examination of the mount structure that is being used. Josh pulled off some panels to explain the worm gear that is used. Basically, the larger gears which drive the RA and Dec are controlled by the smaller worm gear, which allows for precision control, something on the order of arcseconds. One of the goals for the large(r) scopes is to have total information about the scope, dome, environmental conditions, etc. As more and more scopes go toward remote observations, which is the plan for Hoku Ke'a, it becomes increasingly important to know the state of nearly every component. One such example is the plan to install monitors on the worm gear such that we can know the exact position of the gear itself and how that relates to the RA/Dec of where the telescope is pointed. Another example is the project I am actually working on now, which will have some cameras pointed at the actual scope itself so we can do some image analysis on the conditions that exist inside the dome at any given moment. More on Hoku Ke'a will certainly be forthcoming as I write more on this project (and hopefully more) that I will be working on.

After a lunch at the summit (thanks to the summit crew for providing a vegan option for me!) we were taken inside the Gemini scope. To say that being inside the dome and seeing the inside of Gemini was incredible would be a vast understatement. This is a very vast structure consisting of many, many parts, all delicately intertwined. Complex Systems is the word they like to use.

Underneath the primary mirror at Gemini North.

Lately I have been struck by just how incredible some of our (human beings) engineering accomplishments are and it was truly remarkable to be literally standing inside one of the engineering marvels. Not to mention really, really cold. Since everything has a latent thermal energy, including the glass (it's not really glass, but still) of the mirror itself, it is critical to keep the inside of the dome at a constant temperature with respect to the viewing conditions. So, this means keeping everything inside the dome at the same temperature as the outside night air, when observations are done. So, this mean cold. Really cold.

We were given a tour of the casing room, where they do work on the mirror when needed. We saw the inside of one of the four control rooms (one is down by the University and the other two are, I assume in Chile at Gemini South), which very seriously looked super high-tech. No doubt, that is what a Science room should look like, with monitors and dials and images and lights and bells and whistles. Later, as we toured CFH, it was interesting to see their summit control room, which is slightly older and looks like serious Science from the 60s. It's kind of like the difference between Kirk's Enterprise and Picard's.

We were also taken up onto the 5th floor, looking down onto the primary mirror. It was, of course, covered in the daytime but we got to walk around the rafters and get a close-up look at the area. While we were on this tour they were doing some maintenance work on the dome itself and I managed to snag a good photo of the partially open dome looking out toward a beautiful crescent moon.

Opening of the dome inside Gemini North with a beautiful
crescent moon positioned in just the right spot.

Control room for CFH. You can almost hears the beeps, bings,
and whirs of Science! Note even the analog dials.

Our tour of CFH was equally remarkable. CFH is one of the older scopes on the summit but because of aggressive, and intelligent, maintenance and updates by their engineering crew, they are still producing incredible images and remain a significant player. However, it was very telling to see the difference in technology that can happen in 10-20 years time. While Gemini was very clean and controlled, CFH was more of a working-engineers paradise, with exposed wires and machines, grease in the corners, old paint on the walls. Also, because CFH has gone completely to remote operations, as opposed to Gemini which is still mainly classical observation, it was rather strange since there was not a single other person in the whole building. While Gemini crawled with some astronomers and day-crew and people doing things, CFH sat silent and dark. Again, this is not a reflection on the actual science coming out of either of these scopes as they are both incredibly remarkable and productive; just an interesting note on the differences between the two.

CFH primary mirror with the MegaCam installed
in place of a secondary mirror. Also a good view
of the horseshoe mount.

There were many more details and I learned a lot on the tour. Again, it was incredibly fascinating and an outstanding opportunity for me. Special thanks to Josh for arranging everything as well as the crews of Gemini and CFH! Watch the sky!