Sight Calc app for iPhone and iPad
Developer: NUVOCOM INCORPORATED
First release : 31 Jan 2012
App size: 1.42 Mb
Sight Calc is a specialized calculator for calculating sight reductions via the "Law of Cosines" method. It does not use Nautical Almanac data, so you must first compute LHA (Local Hour Angle) and declination, and determine your approximate latitude. It is designed particularly for students learning celestial navigation, such as the Celestial Navigation courses taught by the United States Power Squadrons®. If you are unfamiliar with how to do sight reductions, some good resources are available from the United States Power Squadrons® at www.usps.org. In particular, this calculator is useful in conjunction with Form SR96a, www.usps.org/eddept/n/files/sr96a.pdf
Inputs may be entered as two numbers:
Degrees - left column
Minutes - right column
Or enter as decimal degrees (e.g., 44.48833).
Sight Calc will prompt you to enter six number in sequence:
LHA (degrees)
LHA (minutes)
Lat (degrees)
Lat (minutes)
Dec (degrees)
Dec (minutes)
In v 2.0 you may enter values in any sequence. Hc, Z and Zn are continuously computed and displayed.
Be sure to enter North Latitude as a positive number and South Latitude as a NEGATIVE number. Sight Calc will take the absolute value of Latitude in the law of cosines formula, but needs the hemisphere to calculate azimuth (Zn). Similarly, enter Declination as positive if North and negative if South. (Note: this differs from version 1.x of Sight Calc.)
If you want to do repeated calculations with some of the same numbers, just enter the changed numbers.
To start over fresh at any time, press "C" to clear everything. "CE" key clears the Current Entry. Optionally, use the "o" key to convert minutes to decimal degrees, add that to the degrees field, and clear the minutes field. This has no effect on the calculation.
Please report any bugs or suggestions to:
[email protected]
Latest reviews of Sight Calc app for iPhone and iPad
I love this App! It looks like it has been out for a while and had a lot of good reviews. Im only putting this as a 2-star review at this time to bring attention to the fact that using this App when you are lost at sea may get you lost even further! From my testing the result Hc and Z is spot on! But will the sailors using an app like this know the difference between Z and Zn? If you assume that the result Z value is your azimuth and graph your sight based on that value, you are going to be lost at sea. Another correction is required to determine the azimuth. You have all of the inputs to make this correction, why not provide the azimuth output? As documented in the Ho229 tables: Latitude SAME Name As Declination - N. Lat, LHA < 180 .... Zn (azimuth) = 360-Z Latitude CONTRARY Name to Declination - S. Lat, LHA < 180 .... Zn (azimuth) = 180+Z The app is very easy to use and does the basic calculations correctly. Please calculate and output the azimuth and I will gladly update this to a 5 star review!
This is a great App for doing sight reductions using the law of cosines. I would give it a five star rating except it has compatibility issues with iOS 10.
Easy to use. Calculations are accurate. Ive been using it for a month doing Sight Reductions.
User friendly and accurate. Saves a lot of time
A real timesaver when reducing sights using the USPS forms. Eliminates the need to find and program a scientific calculator. Well done!