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HOPS user manual

  1. A computer with any operating system: Windows, MAC OSX or Linux.
  2. A minimum RAM of 4 GB.
  3. Free space of about 4 GB to install Python and HOPS.

Python Installation
If you have Python installed on your computer, you can skip this step. Otherwise:
  1. visit the ANACONDA WEBSITE,
  2. click on “Download” under Python 3.7 version.
For Windows users, during installation, be careful to:
  1. install Python for you only (as recommended),
  2. use any destination that you prefer (if the default is not suitable for you),
  3. add python as a system variable (despite not being recommended).

HOPS Installation
If you have HOPS installed on your computer, you can skip this step. Otherwise:
  1. download the code from GITHUB,
  2. unzip the file "",
  3. double click on one of the appropriate files inside the subfolder "hops", depending on your operating system: "", "osx_installer.command", or "windows_installer.cmd",
  4. after installation, an executable file named "hops" ("hops.cmd" for Windows, "" for Linux, "hops.command" for MAC OSX) will be created on your desktop.
  5. Double-click on the executable file named "hops" ("hops.cmd" for Windows, "" for Linux, "hops.command" for MAC OSX) to start the program.
For Windows users, if windows_installer.cmd is not working, this means that Python is not installed as a system variable, either because you missed the last step of Python installation or you didn't install Python through Anaconda. In this case, either try installing Python again with Anaconda, or include Python to your system variables manually.

Data Analysis

We have produced a step-by-step VIDEO of the data analysis process and the detailed explanation is as follows:

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1. Starting the program

Double-click on the executable file named hops.x, created on our desktop during the installation. The next time you will run the program, all the choices you make will be displayed as the default.

2. Selecting a directory

The first window that appears on the screen is where you select the folder with your data. Clicking on the button next to “Directory” opens a search window through which you can select the folder of your choice.

3. Selecting the science and reduction frames

In the same window you should give the name identifiers of the different file types (observation files, bias frames, dark frames, flat frames) to the corresponding input boxes next to the following:

  • Name identifier for observation files
  • Name identifier for bias frames
  • Name identifier for dark frames
  • Name identifier for flat frames

You will see that the input boxes are already filled in. These options are either some typical ones or, if you have analysed the specific dataset in the past, the latest values you used.

For your convenience, there is the “Show files” button, which opens a list of all the files in your folder.

Next to each box there is an indication of how many files of each type exist in our folder, we cannot move to the next step if the observation files are 0 (for the rest of the files there is no limitation).

4. Selecting field coordinates

The program automatically tries to locate the field coordinates and displays the result next to “Detected target RA DEC”. If the program does not automatically detect the field coordinates, we must enter the coordinates in the input box next to “Manual target RA DEC” (according to the example hh: mm: ss +/- dd: mm: ss). If the program automatically detects the field coordinates but we do not want to use them, we can deselect “Use detected values” and enter the coordinates in the input box next to “Manual target RA DEC” (according to example hh: mm: ss +/- dd: mm: ss).

5. Selecting Header keywords

Finally, we are asked to provide some header keywords (about exposure time, date of observation and observation time) in the corresponding input cells next to the following:

  • Exposure time header keyword
  • Observation Date header keyword
  • Observation Time header keyword

Again, we will find that the import boxes are already filled, following the same logic as before. There is an indication next to each box that this header exists within our files. We cannot move unless all keywords have been found. Again for our convenience, there is the “Show header” button at the bottom of the window, which opens a window-list of all header keywords and their values in one of the field images.

  • Note: Many times in .fit files the date and time are in the same header keyword. When we enter the header of the date keyword, the program automatically detects whether this includes the time as well. As a result, the program disables the entry of the header keyword next to the cell “Observation Time header keyword”.

6. Running reduction and alignment

As soon as we click on the button “REDUCTION & ALIGNMENT”, the program performs these procedures: clearing and aligning the field images. In the beginning, a window appears with the rate of completion of image cleaning (no need to do something here).

Then, a window appears showing us the counts of the sky as a function of time. This helps us detect the damaged images and exclude them from the process. To see an image, we have to double click on the point of the chart that interests us (a red arrow will point the point). To exclude it as damaged, we double-click on the right (the point becomes red). To do so, we do a double right click (the point will turn black again).

Finally, a window with the alignment rate of the images will appear. In this window we see how the positions of specific reference stars are located in the field. If a picture is damaged and the reference star cannot be found, the program will ask us if we want to exclude it from the process. If a picture is too shaky or inverted, the program will ask us if we want to exclude it, we must select the option “NO”.

7. Selecting the targets - photometry

When the alignment of the images is completed, a new window titled “Photometry” opens in which we can select the star we are studying - Target -, as well as the comparison stars - Comparison1,2,3 … and so on. In this window we select the “show FOV” icon to display the window with the original image of the field.

To define a star (Target for example) we must first select it from the list in the “photometry” window. Then we have to double-click on the star in the field image (FOV window). We can magnify the field by clicking on the magnifying glass located at the bottom left. Zooming makes it easy to select stars. To return the field image to its original dimensions (without magnification), click on the icon on the lower left. If we want to replace the star (perhaps because we were wrong), we can double-click on another star. If we want to delete our selection, we can double-click outside the image boundaries (but always in the window).

The location selection is done automatically and appears next to the star name. Next to the star’s position there is a box in which we enter the aperture, that is, the area around the star, from which the total light will be calculated. When we change this value, the field image is automatically updated to help us easily find the right size of the box. We follow the same procedure to select the comparison stars

To calculate the light curves, close the window with the field image (FOV) by pressing the button “RUN PHOTOMETRY”. The “photometry” window does not close so we can easily run another calculation with different comparison stars if we want it.

When the photometric calculation process is finished (usually takes a few minutes), the light curves - one with our goal - and the other comparison star comparison curves (depending on how many comparison stars we have chosen) automatically appear in a new window.

Again with the magnifying glass icon at the bottom left of the window, we can magnify in the light curves to get a first idea (usually to check if there is a decrease in brightness and hence if the mapping of the planet’s passage ahead from the star was successful).

8. Modelling

Once we have completed the photometry process, we close the window with the light curves and in the “photometry” window click on the icon that says “PROCEED TO FITTING”.

At this stage, a new window titled “Fitting” opens. We notice that there are various boxes of information about the star, the planet and our observation. However, in most of these we do not need to intervene, as the code receives this information automatically from directories.

Fill in the box next to “Filter” which is usually R (red). Then, we select “Show / Update Preview” and we show a first model of our reading in a new window. In this window, with the blue color we are given the model of the passage based on the information obtained from the catalogues, and with the red color the model of our data. This helps us to distinguish the degree to which two models fit. In the box next to “scatter limit” we can change the value and then selecting “Show / Update Preview” again, we notice the modelling changes according to the value. As we lower the value (to one), the more points are discarded by the curve.

After testing different values and ending up with what we want, close this “light-curve” window and press “RUN FITTING”. When the modeling process is completed (a few minutes), our final window opens with the light curve of our target. In this window there are also a number of items related to the star target and the exoplanet.

  • Note 1: By pressing “RETURN TO PHOTOMETRY” we are given the option to return to the photometry window and repeat the process by changing some parameters. So we do not have to shut down windows and spend time.
  • Note 2: The user can change the information either for the star or the planet if he notices that the blue model does not respond to the red model.