Tutorials [ES]

Step 1: Search for candidates

In the tab Lots all the different lots are listed down, 1000 stars each one. Select a lot which is not still assigned to anyone, noting down your name in the User column. The link that appears in the column CSV List contains a file with the list of stars corresponding to that lot. You can download and open it with Excel, LibreOffice Calc or similar.

When examining the stars (following the tutorial mentioned above) you will find stars with interesting light curves. Note them down in the Candidates tab located at the spreadsheet.

Sometimes you will see there are several collaborators using the spreadsheet at the very same time. Here are some tips to avoid possible conflicts that could arise when trying to edit simultaneously the same cells:

• You can use Google Drive Chat to communicate with them.

• You can also leave blank several lines and add data below, therefore leaving some space to avoid colliding with other users.

• You can change the background color of several lines to show that you are going to be working in that area of the spreadsheet. Remember to erase that background color once you are done editing them.

When you have finished examining a lot, tick the cell Completed in the correspondent line at the tab Lots and select a new lot to continue working.

Step 2: Star characterization

Once all the K2's campaign 18 stars have been inspected, we will move on to confirm and obtain the necessary data from the variable stars that are among the easiest to identify: eclipsing, delta scuti and rr lyrae. To do this, we will follow these steps:

1. We will check and analyze all the variable stars found in lots that have been previously inspected by other collaborator from the Project. For that, we will assign those lots as we did in the Phase 1 (be careful, it is about reviewing ONLY those stars identified as variables, NOT ALL the stars in the lot again). This is how we will perform a double check.

2. For now we will only analyze variable stars catalogued as eclipsing binaries, delta scuti and rr lyrae, clearly unmistakable.

3. It is important to identify the stars that belong to the Beehive Cluster (M44) or to M67, both in the field of K2's campaign 18. For that we have to perform a search (AR and Dec) of the star at Vizier, go to the chart of Gaia DR2 and verify the star's distance and own movements. If they match the average values from this clusters' members, we might have unveiled their belonging. Here is a quick guide on how to do this.

4. Note down this values (period, AR coordinates and Dec, distance to the star, own movements and radial velocity) in the spreadsheet so we can identify the star as a member of M44 or M67.

Step 3: Light curve analysis

For the Light curve analysis we will use a couple of programs (notebooks written in Python language) specifically developed for this Project. We will use the Google Colab platform, that allows us to run the notebooks in the cloud without having to install the development environment in every computer.

These are the notebooks:

• Analysis by GLS method. For stars with a continuous variability, like pulsating, rotating or Type EB or EW binaries.

• Analysis by BLS method. For stars with relatively short transits in comparison with their period, like happens in EA type binaries or planets.

Some stars will work better with the first method and others with the second. In case of doubt it is possible to try both and choose the one that leaves a cleaner phase curve.

After running these programs we will write down at the spreadsheet the following data in the correpondent columns of the Candidates tab:

• Method used (GLS or BLS)

• Period

• T0 (epoch)

• Amplitude

Besides we will save the phase curve image in PNG format with a filename under the format EPICXXXXXXXXX_phase.png which we will after copy to this Google Drive folder.