Rory1942>
For some reason I am unable to change the date when using the almanac or sight. This is a new development .
Gyro Erro
Can you make the app so you can calculate the gyro error on ships
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.
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.
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Very basic and not worth money
Does the same calculations as some other free apps. It does have some good features like the trip feature for storing several sights etc. for the money I would expect the input fields to be more locked down with a selection field rather than entering manually an getting in the correct format the app requires. Also not entirely sure on all the results thus far but need to do more sights to clarify. Happy to pay for an app that is above the free stuff. But this should be about a third of the cost
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Excellent App
This app is an excellent value. I have been practicing celestial navigation for over 20 years and have programed calculators to provide almanac data and reduce sights. This app does everything you need. The Sky View feature is very nice and greatly facilitates sight planning. Touching the screen in the Sky View mode provides accurate HC and azimuth values for each body. The plotting function, however, needs improvement; the LOPs are on a small screen with a fixed scale spanning 120 NM. You can't see the area of intersection well enough to estimate the precision of the fix or identify which sights might be outliers and better deleted. Some kind of "pinch to expand" feature would be a big improvement and warrant five stars for the improved app.
The app does not have some of the nice bells and whistles like sight averaging, star ID from observed altitude and azimuth, or great circle sailing. If you want all that and more you should buy StarPilot, but it is more than twice the price. This app will serve your needs, provide plenty of practice and lots of fun, and, along with a sextant, enable a safe return from the longest voyage in the event space aliens zap all the GPS satellites. Actually, in that case you would need a chronometer too.
The app does not have some of the nice bells and whistles like sight averaging, star ID from observed altitude and azimuth, or great circle sailing. If you want all that and more you should buy StarPilot, but it is more than twice the price. This app will serve your needs, provide plenty of practice and lots of fun, and, along with a sextant, enable a safe return from the longest voyage in the event space aliens zap all the GPS satellites. Actually, in that case you would need a chronometer too.
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