The Comet Book clearly shows when Comets can be viewed and in which direction. The direction and elevation of a Comet can change ably in a day due to its fast apparent motion. The moon and a bright planet may be convenient as a guide to find the comet though they have large apparent motion, too.
According to the antivirus report, this application is safe and secure. 株式会社 ビクセン is the official developer of the app which can be found in the Educational category. The developer rolled out a new version of the tool on Dec 18, 2018 and over 50K users downloaded and installed Comet Book.
The average user rating of this application is 3.9. You can get the .apk setup package of Comet Book 2.0.3 free of charge and take a look at users' reviews on Droid Informer. This file size doesn't exceed 2 MB and the app runs flawlessly on Android 5.0 and higher.