Note: This guide is for an outdated version of the app (v1.0.2). Here are the new directions for Android and iOS.
This is a step by step guide to using the Loss of the Night app. I have tried to make it as complete as possible, so if anything is unclear, please let me know in the comments and I will revise the instructions.
Android phone running at least Android 2.1, but preferably Android 4 or higher.
The phone must have a compass and GPS.
A location with a light polluted sky.
A friend to accompany you while you are doing observations.
The ability to see at both near and far distances without removing glasses.
Before you start:
The Loss of the Night app is meant to be used outside at night. For safety's sake, inspect the area where you plan to do your observation during the day, and make sure that it has level ground where you can move around safety.
People using mobile phones are less aware of their surroundings, which is why texting while driving is dangerous. You should never use the app alone outdoors at night! Always take a friend to watch out for potential hazards while you are using the app. These could include tripping hazards, vehicles, dangerous weather, and crime. If for some reason it's not safe to do an observation, turn off the app and leave the area immediately!
Installing the app:
To install the app, do a search in the play store for "Loss of the Night". Alternatively, type this address in your browser: http://tinyurl.com/vdn-app
|or go to the page by scanning this QR code|
Running the app:
When you first open the app it will display the privacy policies and terms and conditions. To go further, you will need to read the conditions and then click "accept" at the bottom right hand of your screen. (If you are using a device running an Android version lower than 4 or a device with a very small screen, the button may not be visible. We are sorry, but such devices are not supported.)
When you click "accept" you are brought to a screen with information about light pollution. Click "next" to go on.
Next comes a screen titled "USE". We would appreciate it if you would register and tell us something about your vision. Click "Register Now" or just "Continue as a guest".
If you choose to register, you will be asked to indicate your approximate age (use the up and down arrows to change), and you can click the buttons to tell us whether you wear glasses, etc. We also ask you to provide a username and your email. If you provide your email, we will send you a thank you email within about a month of your observation. In extremely rare cases we contact a user if we have questions about their data. Click "save" when you have entered your data.
Next comes a welcome screen, click "Continue" to go on.
Making an observation
The app will now go into measurement mode. (If the sun has not set or the moon is in the sky, the app will give you a message that it's not dark enough. Click "Measure anyway" if you'd like to test out the app.)
A button that says "Start observing stars" then pops up in the center of the screen. Click it to go on.
Your phone's GPS will now try to determine your location. This can often take up to a minute, and sometimes a bit longer. While this is happening, your eyes will hopefully be getting adjusted to the dark! (If several minutes go by and the app still hasn't found your location, there could be something wrong with your phone's GPS. Try using an app like "GPS Status" to check if your phone's GPS is working.)
Once your phone has identified your GPS location, you will be asked to input the current weather conditions. Click the relevant symbol, and then when you come to the next screen click "Continue".
You now come to a screen that says "Start measurement". Click "OK" to go on.
The app will now try to direct you to one of the brightest stars in the sky. Turn your body in a circle and watch how the arrow changes direction. Tilt your arm down so that your app is pointed toward the ground, and it will show you the stars that are under the Earth. Tilt your arm up to the sky, and it should show you the stars that are currently in the sky. It is very important that while looking at the stars in the sky you keep the phone oriented perpendicular to your body!
Now search for the star the app is asking you to look for. Turn your body until the arrow points straight up, and then raise your arm until you see a star with a flashing crosshair on it. When you find the star, the circle will expand to fill most of the screen and two buttons will appear at the bottom of the screen.
Your job is to decide whether the star the app pointed you to is visible to your naked eye or not. If you can see the star, then click "Star is visible" on the bottom right. The app will then suggest a new star.
If you cannot see the very first star, there may be something wrong with your phone. The app always starts with one of the very brightest stars in the sky, which should be visible even inside of large cities. The most likely problem is that your compass is not working properly. If your phone is in a carrying case that has a magnetic clasp, you will need to take the phone out of its case and then recalibrate the compass.
If the stars on the screen don't match the stars on your phone, then try calibrating your compass. Download a free compass app like "compass", and then wave your phone in a figure 8 at least three times while running the app. If the stars appear to be bouncing around a lot, you may be in a location near a magnetic material or an area with strong electromagnetic fields (e.g. overhead powerlines). It's best to try to use the app in a grassy area, like a park. Finally, it's possible that the compass or GPS from your phone is not working properly, and if this is the case the app will not work on your phone.
Continuing your observation
Each time you find a star, the app will ask you if it's visible or not. If you can't see the star for some reason, click on "Not visible or unsure". You will then be brought to a menu that gives you four options for why you can't see the star. Choose the option that is most appropriate.
Once you have made a decision on a total of 7 stars, the app will pop up a message that says "Measurement complete". You will have the option to quit ("send data"), "Register" (if you haven't done so already), or "Continue observing". We would really appreciate it if you observed a few additional stars, because observing more stars improves the accuracy of your measurement.
If you "continue observing" the app will keep suggesting stars without any more interruption. Simply click the "back" button when you are ready to end your observation. When you end your observation, the data is automatically sent to a server hosted by the GLOBE at Night project if your phone has internet access. If you have a data plan, this will happen immediately, otherwise, it will be transferred the next time you have a WiFi connection.
Accessing your data
If you would like to see the results of your observations, click on "User data" in the "MAIN MENU". On the screen "USER DATA" click "My measurements". A screen will come up showing the dates that you did observations, and a summary of the results of your observations (how many stars, and what the faintest star you were able to observe was). You can use the following table to relate the faintest star you were able to see to approximately how many stars you can see in the sky from your location:
mag: stars in sky
If you click on an observation, then the app will show you the names and brightnesses of the stars that you looked for. (Stars with smaller magnitudes are brighter.)
As the year goes on, different stars appear in the night sky over your head. If you enjoy using the app, feel free to use it as often as you like!
The app contains a lot of information about light pollution that you might find interesting. You can access this information by clicking on "Project information" in the main menu.
You can also switch between "Day mode" and "Night mode" in the main menu. Please use the Night mode when making observations, because it is designed to have less of an effect on your night vision.
If you have a Sky Quality Meter, you can submit data taken with the device as well. From the main menu, click "Submit data from SQM" and then use the scroll wheels to enter the SQM value.
More information about the Loss of the Night app project is available on our blog.
If you'd like to read a paper that demonstrates the scientific value of citizen observations of naked eye star visibility, you can access it for free here.
Thank you for taking part in this project! Your data will help us understand how the brightness of the night sky is changing around the world. Because we are interested in understanding long-term changes, the most valuable data are observations taken at the same place each year.