Q2 Data Release and Site Upgrades
We wanted to talk more about the changes to the site and give you all an update on the addition of Quarter 2 data. John’s already talked about the candidates page and some of the new features associated with that, so I wanted to focus on the changes specific to Q2 data release.
NASA and the Kepler team released Quarter 2 on Feb 1st and on Feb 2nd the latest results from the Kepler mission including a complete list of planet candidates and false positives for the first 2 quarters of data. You can read the paper detailing all of this here as well as the Kepler press conference site
The second data release is 90 days so we now have the first approximately 120 days of the Kepler science mission to go through. Q1 was about 35 days, we have chosen to show chunks of the lightcurve in the same size as we were for Q1. So Q2 is broken into three sections. Our aim was to have 5 days worth of overlap in each section, so that we don’t miss any transits that happen at the starts and ends of where we separated the lightcurves. We’re also uploading the Q1 data from the ~400 stars originally withheld and released on Feb 1st. We’ll keep you all posted on the progress.
We have been uploading the new data in batches to make the transition as smooth and seamless as possible. Occasionally the Talk links lag behind because we’re trying to upload as fast as you’re all going through the data. And sometimes you beat us to it
so we’ve increased how fast we’re uploading the Q2 data to keep up with your pace. We’ve appreciated all your patience during this process.
You can tell which part of the lightcurve you are looking at by the APH#. The first two numbers are quarter and section so APH22332480 is section 2 of Quarter 2. We use APH for the lightcurve sections and SPH for referring to the star itself. For the SPH numbers the first two numbers refer to what quarter the star first appeared in the public data set. so SPH21332480 first appeared is Quarter 2 Section 1.
The star source pages (like http://www.planethunters.org/sources/SPH10129795) contain all the sections of lightcurve for you to review and the x-axis is the days from the first observation, so you can look for repeat transits in other sections of the lightcurve easily. Also the downloadable CSV file now contains all the available lightcurve data. We have also updated the gap question (the first question asked) in the classify interface, so now you will now be asked the variability questions regardless of how your answer the gap question (before the variability questions were skipped if you answered yes to their being a data glitch or gap in the lightcurve)
We’ve made some changes to Talk to accommodate the Q2 data. The new planet candidates list and false positive list from the Kepler team are now identified. We’re planning in the near future of marking Planet Hunters planet candidates as well. Each lightcurve section has it’s own object page (ie http://talk.planethunters.org/objects/APH22332480). We now have group pages that gather all the available lightcurve object pages for the star (http://talk.planethunters.org/groups/SPH21332480) which you can access through the “View Star” link on any of the object pages. The “Examine Star” link will take you directly to the star’s source page.
As always we welcome feedback on the new changes, and we are listening to your comments and suggestions on Talk and in your emails. We can’t wait to see what we find in the Quarter 2 data.
Candidates and Upgrades
Hello everyone, graduate student John here. The time has finally arrived and we have the first batch of candidates up for you. To top it off, we have also managed some interface updates which should make marking transits faster and easier (yeah, Stuart!).
First, the candidates. I have a blog post coming out shortly which will explain how we made our selections so for now I will just give you the results. If you roll on over to the Candidates page, you will find that there are 132 new stars. That breaks down into 90 new potential planet candidates and 42 potential eclipsing binaries. We are still hard at work modeling these systems, so don’t have much more information than that it made the cut. We thought you would rather see them now and we will add the periods and radii as we do the fits.
Along with the new candidates, you can now see stars which you viewed which are possible planet or eclipsing binary candidates.
Which brings us to the other interface updates: transit marking. Now when you want to mark a transit on a star, you can simply drag a box around all of the points in the transit. Once drawn, the boxes work exactly as they did before. This should help us get more precise transit center information to more easily track down interesting candidates. Another perk is that clicking on any of the transit boxes will zoom you to that location on the plot.
Bring on the new data!
John M. Brewer
Our two new community collaboration websites, Milky Way Talk and Planet Hunters Talk, had some updates this week. We thought it was worth going over them in this blog post. We’ve had a lot of feedback about Talk and are working to implement the most-requested features.
The biggest difference you’ll see when logging into Talk is that your discussions are now easier to manage and track. A new, large box on the main page shows all the new and updated discussions since your last login. You can refine these using the two drop-down boxes at the top of this section. You can chose to show discussions from the last 24 hours, the last week, or since any date using a pop-up calendar. You can also chose to only see discussions that you are a part of, which should help you keep track of your conversations.
In addition to these changes, you’ll also find a lot more metadata around the discussions, telling you who last posted, how many people are taking part, and who started the discussion, where relevant. Users within these discussions are now highlighted if they are part of the development team or the science team. This is something a lot of you asked for.
The other item that has been changed with this Talk update is pagination. There are now easy-to-use buttons on the discussions, collections and objects on the front page. These mean that you can browse back through time and see more than just the most recent items. As Talk has grown more popular, this feature has become more necessary.
Another change to the front page is that we now show the most-recent items by default, and not the trending items. You can still see the trending items by clicking the link at the top. Users told us they preferred to see recent activity initially so we made the change. Similarly, the ‘trending keywords’ list now appears on the front page at all times.
On Planet Hunters Talk, when you’re viewing a light curve, Kepler Planet Candidates are now identified as a “Kepler Favorite”.
Finally, page titles are now meaningful. This means that if you bookmark or share a link, you’ll remember why. Collections are named and objects will be title dusing their Zooniverse ID (e.g. APH….). Several of you have also noted our lack of a favicon (the little icon next to the URL in your browser bar). This is coming shortly as well.
There are more changes planned for Talk, but these significant updates to the front page were worth noting on the blog. For example, we plan to start integrating social media links into the Talk sites, along with more updates as time goes by. Talk continues to evolve and we welcome feedback. Post comments and suggestions on the Feature Requests Thread or Board Upgrades thread on Talk or send us an email at email@example.com.
Downloading the Data
We’ve rolled out a new feature to the site. You now have the ability to download the lightcurve data directly from Planet Hunters. Once you’ve classified a star and submitted the transits, the download data button will appear and is available for every star on its source page (ie http://www.planethunters.org/sources/SPH10067557) as well as from the user My Star page (http://www.planethunters.org/profile) where you can download the data for all the stars you’ve classified (we’ve now paginated the My Stars page so all your favorites and all the stars you’ve classified should now be listed).
The file is in CSV (Comma-Separated Values) format which can be opened directly or imported into Excel, Numbers or the Open Office equivalent where you can then plot and manipulate the data. We provide additional info about the star properties including infrared color, specific gravity, right ascension and declination, and Kepler IDs. We also identify if the star is a Simulation (simulated transit lightcurve), a Kepler Planet Candidate (ie Kepler Favorite -a star that the Kepler team believes has a transiting planet but has not confirmed with follow-up observations) or Source (real Kepler lightcurve). For the simulated lightcurves, the CSV file will provide the planet radius in Earth radii and orbital period in days for the injected transit signal (assuming the given radius of the star).
The CSV file also contains three columns of data labeled time (days), brightness, error in brightness. The brightness values are the brightness of the star measured by Kepler per observation corrected for instrumental effects and systematic errors by the Kepler Team’s data processing pipeline. The error in brightness is simply +/- error in the reported brightness measurement. We’ve normalized the brightness values by dividing what we get from the Kepler public release data by a constant value just for convenience, so it’s easier to measure relative change in the brightness of the star. This just shifts the absolute value of the y-axis up or down for our plotted lightcurves but doesn’t change the actual depths of any transits. For more specifics about the data, see the Corrected Light Curves section of http://keplergo.arc.nasa.gov/DataAnalysisProducts.shtml.
Some times there’s a missing data point in the lightcurves the Kepler Team has released. These missing data points indicate a”no data” condition where the observation has been compromised by spacecraft operations or other anomalies that effect the quality of the measurements (examples might be the spacecraft entering safe mode or possibly a glitch with the electronics that readout for the flux measurements for that star). To indicate those data points we’ve set the brightness value to zero in the CSV file.
More star info…
Thanks again for your amazing work and feedback. We are working to keep up with you! There is now a data-download button (thanks to Chris, Arfon, Michael, and Stuart!) on the star pages. We are also integrating information about stars that are known eclipsing binaries (EB), Kepler planet candidates (PC) and false positives (FP). Here is an ascii list of light curves with this information. On this list, the APH number is given, followed by the Kepler ID and a flag (EB, PC, FP). For EB objects, D indicates detached binaries, SD is semi-detached, OC is an overcontact binary. Kepler PC stars include columns with the prospective period and planet radius (in Jupiter radii units).
One note about false positives: There are light curves that masquerade as transiting planets. For example, light from a bright foreground star is spread out over several pixels on the CCD detector. The halo of starlight is swept up into a single brightness measurement by the Kepler team’s software. However, in some cases a more distant eclipsing binary (EB) star system blends into the edges of the foreground star. Since the EB is more distant, it is fainter and contributes a smaller fraction of the light. In this case, the background eclipse produces a diluted signal that looks very much like a transiting planet. There are a couple of ways to eliminate these imposters:
- the Kepler team has software that looks for pixel contamination and identifies the star as a false positive (FP). When available, we are listing this information on the light curve and star pages.
- Follow up radial velocity measurements of the bright star will also include the background blended eclipsing binary. A large velocity signal can be a give away sign that the light curve does not arise from a transiting planet.
This follow-up is a critical effort, required to move an object from a transit candidate to a planet.