ASTROCLK Astronomical Clock and Celestial Tracking Program Page 1 Program Revision History ASTROCLK REVISION HISTORY Each released version of ASTROCLK uses a four digit revision code such as 8805. The first two digits indicate the year and the second two digits indicate the week of the year. In some cases, an additional letter suffix is added to distinguish changes occuring within the same week. A partial week at the beginning or end of the year is counted as a full week. Using this method, a year will typically have 53 weeks although it is possible to have 54 weeks in a leap year (1972 is an example). The current year-week revision code is shown on the Julian Date display, Display Mode 7, in ASTROCLK. This file records the recent revision history of program ASTROCLK through all of the minor twists and turns that usually accompany the evolution of such a program. (Early revision notes have been deleted from this file but are available on request.) It illustrates the tortuous process of maintaining and refining a program as ideas and problems are reported from every quarter. It may also be helpful to users who are upgrading from one version to another to find out what has changed. This file may also describe recent changes not included in the main documentation; compare the version numbers below with the main documentation. David H. Ransom, Jr. 9016 04/15/90 ----------------- -Changed ephemeris format to UTC date and time rather than local. -Added ephemeris epoch/equinox selection: Equinox of Date OR the current internal Standard Epoch (set using F8). -Added PRINT OPTION to F2 Ephemeris Generation. Printer output is sent to the DOS device "PRN". Be sure printer is ready BEFORE selecting it for output. Titles plus 55 lines of data are sent per page with auto formfeeds between pages and at the end. Note that "graphics characters" are included in the data lines; if these characters are not wanted, use FILE OPTION and edit out the unwanted characters. -Added FILE OPTION to F2 Ephemeris Generation. Data are identical to PRINT OPTION above except are sent to file. Enter complete file name when requested; default file is ASTROCLK.EPH located in ASTROCLK path. -Corrected time calculations for Minor Planets to avoid adding the correction for UTC to TDT/ET twice. -Updated file ASTROCLK.MPC with osculating elements as of 1989 OCT 1.0. Data taken from file ELEM892.MPC. -Since Minor Planet elements are often published [in Sky and Telescope, for example] with T (Time of Perihelion) rather than M (Mean Anomaly), manual data entry now requests the user to select M or T and enter the desired value. For T, use the format: DD[.DDD],MM,YYYY When the input data are displayed for acceptance, only M is displayed; if T was entered, it has been converted to M. If T is input, then the program requests q (Perihelion Distance) instead ASTROCLK Astronomical Clock and Celestial Tracking Program Page 2 Program Revision History of a (Semi-Major Axis). -Calculation of minor planet perihelion changed to date nearest the date of the osculating elements. Thus for reasonably current elements and if the minor planet is more than half way around in its orbit, the perihelion date may be in the future. -Reworked manual data reentry ("Z") for Minor Planets to show prior data of osculating elements if present (from previous manual entry or from "X" catalog entry). -Minor cosmetic changes to Precession screens for clarity. -The main documentation remains unchanged from Version 8947. 9014 04/02/90 ----------------- -Corrected a significant error in Minor Planet positions when data are read from Minor Planet Catalog ELEM891.MPC (Epoch B1950.0). For example, Mean Anomaly might be in error by as much as 0.5 degrees. The error was less serious when current data were used. Using ELEM891.MPC, ASTROCLK's J2000.0 calculated positions now agree with AA 1989 to typically less than five seconds or arcseconds. Thanks to Ward Harman for many hours of patient analysis which enabled us to pin down the problem. -Changed minor planet calculations to make sure all calculations performed regardless of display mode. Under certain circumstances the equatorial coordinates (RA/DEC) were incorrect in Mode 0. -Added "prior value" code to manual orbital data input ("Z" after "P" Planet Selection). Input routines modified to accept the usual formats for angles: DDD[.DDD] DDD,MM[.MMM] DDD,MM,SS[.SSS] Once data are entered, the values are retained and displayed on subsequent "Z" inputs. Press RETURN to leave an entry unchanged. The manually entered data are discarded when you exit ASTROCLK. -Added "/" as a valid separator for date inputs. Dates may now be input as "dd/mm/yyyy" or "dd,mm,yyyy". -Minor cosmetic changes in Minor Planet displays. -The main documentation remains unchanged from Version 8947. 9012 03/21/90 ----------------- -Versions 9007 and 9010 were limited beta releases. This is the first public release since Version 8951. The main documentation, files ASTROCLK.DC1 and ASTROCLK.DC2, remains unchanged from Version 8947. All subsequent changes are described in these notes ONLY! -Corrected color error on large digit navigation position. 9010 03/08/90 ----------------- -Added "Zone x", where "x" represents the standard international time zone letter, to the local clock title (Display Mode 1). Zone Z is Greenwich, Zones A thru M are East Longitudes, and Zones N thru X are West Longitudes. -Repaired error which could cause program to hang if navigation ASTROCLK Astronomical Clock and Celestial Tracking Program Page 3 Program Revision History is active and the key sequence F10+F2+F10 is entered to cancel navigation. -Corrected nautical mile conversion factor to 6080.2 feet. 9007 02/12/90 ----------------- -Version 9007 is a MAINTENANCE UPDATE in order to improve various navigation features and to correct several minor errors. The changes are described below and NOT in the main documentation which is unchanged from Version 8947. -Special thanks to Captain Helge Brudvik of the Royal Viking Sky for the freedom of the bridge, and to Chief Officer Magnus Bakken for his practical demonstrations of navigation at sea (as well as many hours of pleasant conversation). The changes in this version have been made during a cruise around South America and reflect what I have learned and observed during that ten week period. -Added large digit display for calculated position in navigation mode; press "N" to toggle navigation displays. -Number of star sights which may be entered for navigation fix increased from three to seven maximum to conform with Air Almanac. When last star sight entered, press RETURN to stop data entry. -Added DRIFT and DIRECTION to navigation to permit correction for combined wind and current effects. Enter using F10+F2. -Corrected UT Time entry in F10+F2 Navigation Fix entry so that RETURN leaves time unchanged rather than resetting it to zero. -Conversion factor for nautical miles corrected to 6082 feet. -Suppressed "Federal/State Taxes Due" message on calendar for Easter Sunday on April 15th. -Minor cosmetic changes in navigation functions. 8951 12/21/89 ----------------- -Version 8951 is a MAINTENANCE UPDATE in order to correct various minor errors. The changes are described below and NOT in the main documentation. -By popular request, the documentation is UNCHANGED from Version 8947. The documentation will remain unchanged until the next major revision so the full documentation need not be reprinted for minor upgrades in the program. All changes are documented in files ASTROCLK.HST and ASTROCLK.NEW only. -The default responses (pressing RETURN/ENTER only) when using F6 and SHIFT-F6 to enter new LOCAL or DESTINATION coordinates were incorrect and reset the new value instead of using the prior value. The prompts have been improved and the logic has been repaired. Note that the ELEVATION is now left UNCHANGED as the default response. Thanks to Bob Khron for the bug report! -SHIFT-F6 may now be used to review the DESTINATION coordinates and name. Press RETURN to leave all data unchanged. -When navigation is active and SPEED is non-zero, the calculated position window includes the date and time of the last navigation fix: "Fix @ 12-11-1989 15:30 UT" to remind the user when the last fix was entered or calculated. -Dead reckoning positions were calculated one second behind the current time when the clocks were ON. I sure hope nobody crashed ASTROCLK Astronomical Clock and Celestial Tracking Program Page 4 Program Revision History on account of that one! -Added Leap Second at end of 1989 to Delta AT table. 8947 11/19/89 ----------------- -Improved Apparent Geocentric Equatorial Coordinates for internal database stars and catalog stars, mean to apparent position, to include effects of nutation and annual aberration. Parallax NOT included. Apparent coordinates are now accurate to within one second/arc-second. -Added navigation function F5 to show first 20 USNO stars in view and suitable for star sights. Uses current coordinates and time. -Revised external star catalog logic. Search times halved and direct access by catalog number is now immediate. -Expanded external star catalog searches F5+F4 and F5+F5 to show list of 10 stars nearest the coordinates input. -Repaired SUB Refract to give correct answer when converting apparent to real altitudes and adjusted the navigation example data accordingly. Real to apparent was OK. -Fixed horizon dip calculation (misplaced decimal point in a constant). -Added SHIFT-F6 for entry of DESTINATION data using external city file and updated HELP. -Added '/' prefix to F6 and SHIFT-F6 city name input to allow match within name. -Improved degree input routine for small negative angles; now processes both "-0,26" and "0,-26" correctly. A minus sign anywhere flags a negative angle. -Fixed "Division by Zero" error in navigation mode when speed was set to zero. -Corrected Planetary Heliocentric Longitude to remove multiples of 360 degrees. -Corrected USNO coordinates per AA 1989. -Corrected paging problem with ephemeris if more than 40 intervals requested. -ASTROCLK.INI now always written on exit. -Reformatted these notes to use a little less paper ... 8943 10/25/89 ----------------- NOTE: Program operation with Navigation DISABLED is essentially unchanged from previous versions. See also the notes which follow and the program documentation. -MAJOR UPGRADE: F10 is now NAVIGATION. May be used to predict current position by DEAD RECKONING and by SIGHT REDUCTION of USNO Standard Navigation Stars. Added new NAVIGATION section in documentation with discussion and instructions. -Added ASTROCLK Errors 60 thru 62 if a Navigation function is requested and Naviga-tion mode has not been set up with F10. -Added ALT-F6 to set LOCAL CONDITIONS of Elevation, Temperature and Pressure. Affects apparent ALTITUDE of target object and adjusts for horizon dip with elevation. Elevation is saved but temperature and pressure are initialized to 20C (68F) and 1010mb (29.83") respectively upon startup. -Corrected calculation of Greenwich Hour Angle [GHA] on Target ASTROCLK Astronomical Clock and Celestial Tracking Program Page 5 Program Revision History Tracking Display per Nautical Almanac 1989. (How did that slip by for so long?) -Fixed minor error in SUB ZoneName so that Local STANDARD Time is displayed correctly in Dual Time displays for modes 2 thru 5. Clarified text in DUAL TIME section. -ALT-F5 now sets POLARIS as target, moved from F10. [ALT-F10 is unchanged.] -Added designation [Ho] for Apparent or Observed Altitude on Target Tracking Display. -Improved accuracy of SUB AngleDiff for very small angles. -Extensive reorganization and cleanup to add NAVIGATION mode and to relieve memory constraints with QB4 compiler. -Deleted revision notes for versions 8905 and earlier. Available on request. 8935 8/30/89 ----------------- -Changed F2 to display an EPHEMERIS of the current target object. User sets interval and number of intervals with F2. Use the "PrtSc" key to print. Added by popular request! -Added manual entry menu of orbital para-meters for planetary objects using "Z" command on planet selection menu ("P" command). -Added Day-of-Year (current year, JAN 1 = 1) to F3 date input. Any time input is ignored. Allowed DOY formats are (quantities in [] are optional): Dnnn[.nnnn] Dnnn:hh[.hhhh] Dnnn:hh:mm.mm[.mm] Dnnn:hh:mm:ss[.ss] Times are UT. The comma is also allowed as the separator. -Changed date input using F3 to allow JD with no letter prefix. Eliminated QB4 error in this case. -Removed on screen HELP from ASTROCLK code and added program ASTROHLP. Operation of help using Function Key F1 is unchanged. Saved about 10K of RAM compared to V8931, all but about 3K of which was consumed by new features. Also corrected/updated the help screens. Modified in response to user requests to reduce RAM requirements! -Added SHIFT-F9 to execute a preset DOS command or batch file. Use ALT-F10, SETTING PROGRAM OPTIONS, to set the command. The DOS command is saved in file ASTROCLK.INI. Default is no action. -Modified Interval Timer displays to include negative days. Range is now -999 to +9999 days on small window, -99 to +999 days on main window. -Clarified text for Alarm & Interval Timer. -Removed ESC key "cancel" codes except during external file searches and to quit ASTROCLK; RETURN is usually used where ESC was used before. F8 PRECESSION now requires "Y" or "y" to proceed and RETURN to cancel. Changed per user requests! -Extensive minor editing and corrections to the documentation, principally related to the new features and changes in this version. 8931 8/04/89 ----------------- ASTROCLK Astronomical Clock and Celestial Tracking Program Page 6 Program Revision History -Added most likely chart numbers for Sky Atlas 2000.0 and Uranometria 2000.0 on Target Tracking display, Display Mode 0. -Corrected Interval Timer problem: if timer is non-zero and a date >32,767 days different from the timer start date was entered with F3, ASTROCLK aborted with QuickBASIC Error 6, OVERFLOW. Another oops! -Added automatic conversion to JD for numeric dates greater than 50 entered without a prefix when using F3. Prior versions would sometimes abort in this situation.