USPS N/JN SIGHT CHECKER This program was written to reduce the amount of time required for a Sight Checker to check the sights of students enrolled in USPS N and JN courses. Given: GHA, Dec, Ho, DR L, and DR Lo, the program will reduce a sight and display the results in the format required on the USPS sight reduction forms. Both the Nautical Almanac Sight Reduction and the Law of Cosines methods are supported. There are two versions of the program included on this disk: "NAVCHK" writes data directly to the screen memory providing the fastest possible screen updates. This is the preferred mode; however, it may not work on all machines. "NAVCHKB" writes to the screen through the BIOS which should work on almost any ibm compatable computer. Try this if "NAVCHK" does not work properly. DATA ENTRY When the program is started you will see a small window in the upper left corner of the screen into which you will enter: GHA, Dec, Ho, DR Lat, and DR Lo. The cursor will be located just to the left of the degree symbol in the GHA field. After typing in the degrees portion of the GHA you will need to advance to the minutes field. This can be done by pressing: enter, space, tab, or right arrow. The cursor should now be in the "whole minutes" field of the GHA. After typing in the whole minutes portion of GHA you can advance to the tenths of minutes field by pressing: enter, space, tab, right arrow, or the decimal point. Continue until all five arguments have been entered. South Latitude and East Longitude must be preceded by a minus sign. If a mistake is made you can use the "delete" or "backspace" keys to erase the incorrect numbers. The arrow keys can be used to move the cursor anywhere in the data entry window for corrections. LAWCOS (F2) Pressing the F2 key will compute the Law of Cosines reduction of the sight. The output is displayed in a window in the lower half of the screen in a format similar to what appears on the USPS SR89 sight reduction form. NASR (F3) Pressing the F3 key will compute the Nautical Almanac Sight Reduction of the sight. The output is displayed in a window in the lower half of the screen in a format similar to what appears on the USPS sight reduction form. The input data is rounded to the nearest minute before being used in the NASR reduction. This is in accordance with the rounding guidelines found in the N and JN course material. PRINT (F4) Pressing F4 will print the contents of the two windows displayed on the screen to a printer attached to LPT1. If your printer does not print the IBM graphics character set, the degrees symbols will probably not print correctly. A hard copy can also be obtained by printing data which has been saved to a file. This option provides some flexibility which the PRINT function does not offer. See the SAVE function description. CLEAR (F5) Pressing F5 will clear the data entry window and any output data in the sight reduction window. SAVE (F6) This function is invoked by pressing F6. It will enable you to save the data in the data input window and the displayed sight reduction window to a file. You will be prompted for the file name to which the data will be written. The default file name is "save.txt". Next you will be prompted for any comments you may want to include with the data. The comment can be up to 48 characters long and will be printed immediately before the input data field in the file. If the file already exists, new data will be appended to it. Old data in the file is never over- written. This is convenient for keeping a group of sights together, all the sights for one three body fix for example, with comments providing additional information on each sight. This file can be printed with the DOS print command or read into a word processor for further refinement. MODE (F7) The mode key selects the format the reduction will be displayed in. This version of navchk supports the SR92 and SR93 forms. Navchk defaults to SR93 when the program is started. DISCLAIMER This program has been tested a fair amount but it is very possible a bug or two remains. Under no circumstances should the information provided by this program be substituted for common sense. Bug reports and suggestions for improvement will be gratefully accepted by: Stan Roberts, N 2230 Jewel St. Longmont, CO 80501 (303) 772-0396 email: stanr@atlantis.stortek.com (work) email: stanr@sprynet.com (home) NAVCHK is free and can be copied and distributed without fear of copyright infringement. November 1, 1997 -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- A Related DOS program that is extremely useful is the Interactive Computer Ephemeris(ICE) which is produced by the U.S. Naval Observatory. The ICE is a Nautical Almanac that has all the tabular information found in the annual printed version plus several computation programs that are useful for JN/N students and checkers and even amateur astronomers. It covers a span of 250 years, 1800 to 2050. The ICE cost is minimal (approx $25 when I purchased it) which included two diskettes (3.5" and 5.25"), a comprehensive information booklet and shipping. Information on ordering the Interactive Computer Ephemeris may be obtained by writing to or calling: National Audio Visual Center 8700 Edgeworth Drive Capitol Heights, MD 20743-3701 Tel. (301) 763-1891 The ICE program is also available from: Celestaire 416 Pershing Wichita, Kansas 67218 1-800-727-9785