2014-07-19
Disappointed
Is anyone writing these 5-star reviews even using this app? I have purchased almost all of the celestial navigation apps on the app store (except StarPilot - too expensive, especially in light of its bad reviews) and Celestial is the LEAST feature rich of them all.
First off, everything is done based on UTC time. Whenever you make another sight you have to do the conversion from the current time in your head before you enter it. It does have the function to automatically produce the current UTC which helps when entering an actual sight since you can get the current UTC and update to the minutes and seconds of your sight. Way more difficult when entering data for previous data. Also, the rise and set times are only displayed in UTC and you have to do the conversion in your head. The rise and set times were a few minutes off from the times you may find on the internet, but that is probably not a big deal.
More of a big deal is the accuracy of the sight reductions. I entered 2 sights of the Sun that I had previously made and reduced by hand. Since I had done this at my home and determined the correct fix to my location I know my results are correct.
The Ha and Ho values produced by Celestial matched my hand calculations, but the Hc was way off. I assume this difference was due to Celestial not calculating from an assumed position (which must be done when your are doing a reduction via table lookup) so I can’t compare it directly to my results. The plot of the sights looked similar to mine but there is not enough detail on the plot to estimate the fix from. The fix it calculated for me was off by more than 20nm. There are no details of how this was calculated, so not idea of why.
When entering a new sight, you start with no data and have to enter everything again. When doing multiple Sun sights (as most of us do), this is extra unnecessary work when the only thing that needs to change is the sextant altitude and time. In my case it led to an error since the limb defaults to “none” and I forgot to change it on the second sight I entered. It took time to go back and figure out my error.
One of the major things Celestial is missing is the ability to make a running fix. Are we suppose to stop the boat and take down the sails every time we want to make a fix? Another major omission is the ability to compute an expected altitude that can be used to set your sextant to before making a sight. Not a big deal for the Sun and Moon, but a very big deal when you are trying to find a specific star or planet among all the others in the sky.
Celestial provides an Almanac function that produces the hourly values of GHA and Dec for the objects that match the Nautical Almanac values pretty well. They give you confidence that the internal calculations are correct, but you can’t do much else with them. You could potentially use them along with the tables from an old almanac, but since no v or d values are given that correction could not be applied when using this method - making this useless.
Overall functionality is very minimal - and in my trial the fix was simply wrong. Everything is just displayed black and white which kills you night vision when trying to use it for twilight sights. The iPad version is just a scaled up iPhone version with the help information always displayed. Some of the other apps that are available give you a lot more for your money and produce the correct results.