User Guide

Welcome to Observer Pro! Observer Pro helps you discover the best objects for your observing or imaging, factoring in your location, horizon, date, lunar phase, and object position. There's also access to an astronomical weather forecast tailored to your location.

In order to keep your observing life somewhat organized, Observer Pro provides a Favorites List, Observing List, and a view of your Observing History. Not sure what to observe? Check out the Featured List. This is a list of objects that are prime for observing right now.

If you are having problems with Observer Pro or have some feedback, go to “Feedback” in the Observer Pro settings screen.

Visibility Charts

At the heart of Observer Pro are its Visibility Charts. They take on several forms, but they all convey the same basic information.

Simplified 24-hour Visibility Chart

The Simplified 24-hour Visibility Chart is shown in the object listing screens (such as Catalogs, Favorites, and Observing List). This chart gives you a simple representation of the object's visibility over a 24-hour period that starts at noon on the currently set date and goes to noon the following date.

The primary aim of this chart is to get a view of when the object is above your local horizon and when it is positioned for good visibility (more on what is considered 'good' below). The orange part of the chart represents the object while it is visible (unobstructed by your measured horizon profile) and the green section displays the window of good visibility. The thickness of the orange/green visibility band represents the object's zenith distance (how close the object is to straight overhead). This makes it easy to see which objects get high in the sky and which ones only graze above your horizon. The background color of the chart shows the brightness of the sky over the chart's 24-hour period. In all Visibility Charts, a vertical red line represents 'now', your device's set date and time.

Standard 24-hour Visibility Chart

When an object's row is tapped, the Detail Screen for that object is displayed. This screen gives access to the object's detailed properties, a larger image, and the other, more specific, Visibility Charts.

The Standard 24-hour Visibility Chart shown here corresponds to the Simplified 24-hour Visibility Chart shown above. This chart plots the object's altitude within the current 24-hour period (the start-date and end-date are displayed in the top corners of the chart). This is the solid orange line. Also displayed is the Sun's altitude (yellow dashed line) and the Moon's altitude (gray dashed line). These altitude curves provide a reference for the object's Visibility Curve which is also shown in this chart.

The object's Visibility Curve represents the object's contrast with the background sky. Many complex factors are included in this calculation. An object's contrast (and therefore visibility) can be good either because the sky is dark (night time, no moon) or because the object has an inherently high surface brightness. The thin horizontal green line in this chart shows the contrast threshold that determines whether the object has good visibility or not (Optimum Visibility Threshold). By default the threshold is 10% contrast, but it can be changed in the Settings Screen. If the object's contrast is above this threshold, then its Visibility Curve is drawn in green. This also corresponds to the green part of the Simplified and Standard 24-hour Visibility Charts shown in the catalog listings.

Month and Year Visibility Charts

The Month and Year Visibility Charts summarize the information contained in the 24-hour Charts into a view of the current month and year. The Month Chart displays the number of hours that the object is above the Optimum Visibility Threshold ('in the green') for each day of the month. The Year Chart shows the average number of hours per day that the object is above the Optimum Visibility Threshold for each month.

The effect of the Moon on the object's visibility is easy to see in the Month Chart. This particular month Full Moon was on the 14th.

Horizon Obstructions in Visibility Charts

All of the Visibility Charts, including the Month and Year Charts, are computed using your Local Horizon Profile (go to Site Settings to measure the horizon profile for your site). Below is an example of the Standard 24-hour Visibility Chart for an object at an Observing Site that has obstructions (in this case my house and backyard trees).

Sky Map

The Sky Map is accessed by tapping on the object's photo on the Detail Screen. The same color-coding convention used in the Visibility Charts is also used in the Sky Map for the object of interest. The Sky Map shows a wide view of the sky, your Local Horizon, the object's location and current position, and the path that the object will take through your sky.

Looking at this Sky Map, it's easy to see where the gap in visibility in the above chart comes from (a tree in this case). A slider is provided at the bottom of the Sky Map to set the time within the current 24-hour period. There is also an action menu at the top of the screen with commands to set the time to object rise, set, and transit, as well as setting the time to 'now'.

Other Features and Tips

Organizing Objects

There are currently three actions that can be taken on objects in Observer Pro: Add to Favorites, Add to Observing List, and Log Observation. Each of these actions can be accessed in various ways depending on which screen you are in. In list views, there are three ways to perform these actions: using the "three dot" menu button on the top bar, swiping an object row to the left, and long pressing an object row to reveal a larger image and an action menu.

These actions also affect the badge icons that appear next to object information on the object list and detail screens. If the clock badge is highlighted, it means an observation has been logged for the object. If the check mark icon is highlighted, the object is currently in your observing list. If the star icon is highlighted, that means the object is marked as a favorite.

Local Horizon Measurement

If your device has a magnetometer, gyroscope, and location services are enabled for Observer Pro, the Observing Site detail screen has an option to measure your horizon. Tap on the Local Horizon row in the site settings screen for further instructions.

Object's Time of Transit

The time that is displayed in the info panel at the top of the Object Detail Screen (right above the object's image) is the object's time of transit. This is the time when the object will be highest in the sky. The Sky Map is initialized to this time when it is displayed for an object.