- Addition of monthly libration graphs (option 7 from main menu). The libration graph shows either geocentric or topocentric lunar libration for a whole month with corresponding lunar phases.
- Planetary positions now plotted and labelled on starcharts (RA/Dec) and skycharts (Alt/Azi). The position of Pluto is not very accurate for dates *before* 1890 CE.
- For remote years, the positions of the stars/constellations are precessed from the base epoch of J2000 using a fast routine, so that plotted star positions are more accurate for remote years (at a slight slow-down of screen updates).
- Magnetic declination reference data updated for epoch 2000 (previously epoch 1995) providing accurate data for 1995-2005. Accuracy declines outside these limits but a declination value will be given for years in the range 1990-2010.
- Tabulation of a Hijri calendar for a single location for a whole year showing Hijri/Gregorian date conversions (option 6). The calendar is based on predicted crescent visibility for that location. Any of the supported visibility criteria may be used to predict the crescent visibility.
- Tabulation of a trizonal (regional) Hijri calendar for a whole year showing Hijri/Gregorian date conversions. The world is divided into three large zones (West, Central, East) and a calendar is predicted for each zone depending on crescent visibility in that zone. Any of the supported visibility criteria may be used.
- Correction of eclipse bug - this simple programming bug previously missed out some eclipses from the list.
- Other minor bug kills.
MoonCalc 5 - new features
Released: 29th August 1999
- Support for SVGA resolutions 800 x 600 and 1024 X 768 if your graphics card, monitor (and eyes!) are up to it.
- Displays local Magnetic Declination i.e. direction of magnetic north relative to true north (east is positive). The magnetic field model used gives accurate data for 1990 to 2000. Accuracy declines outside these limits but a declination value will be given for years in the range 1985-2005.
- Displays Delta T (Terrestrial Dynamical time - Universal time) using a combination of empirical equations and look-up tables.
- Displays lunar Apogee and Perigee data: date, time and Julian Ephemeris Day.
- Displays Solar and Lunar eclipse information for any year.
- On starchart (RA vs DEC) the brightest stars and ecliptic are labelled and there is an option to show the constellation lines/labels.
- On the horizon view (Alt vs Azi) the brightest stars are labelled with an option to show the constellation lines/labels.
- Traditional "circular" skychart view added, again with bright star labelling and constellation lines/labels. You can flip between horizon view and circular view by pressing "v" after choosing option 3.
- Yallop's criterion (1997-8) for crescent visibility added - criterion can be applied at sunset, when sun is at -5 degrees or at "best time" (see below). Now MoonCalc supports 13 crescent sighting criteria.
- When Yallop's criterion is used, the "best time" for crescent visibility is shown in the tabulated data (screen 3 of 4). Best time = sunset + (4/9)* moonset lag.
- SAAO criterion tweaked as per latest information from SAAO (1998).
- Bruin's criterion tweaked.
- When crescent visibility map is drawn, the locations of most easterly sighting *and* earliest sighting are displayed together with crescent properties at respective local sunsets.
- Displays lunar magnitude at entered time, sunset and when sun is at - 5 degrees.
- On moon "close-up" screen, selenographic sun latitude, longitude and co-longitude are displayed.
- At last, the major seas/craters on the near side of the moon can be labelled on the close-up screen (press 'N' for Name). This features works best on the higher resolutions (less crowding of labels).
- The crater database has been tweaked to give a more realistic image of the moonface.
- Topocentric libration (lat/long) data now more accurate.
- The calculations have been optimised so that the tables of data are generated faster.
- "Runtime error 200" bug fixed (this was a compiler bug which caused a crash on fast computers).
- "1899 bug" eliminated.
- "Eastbourne bug" eliminated - thanks to Eastbourne Astronomical Society (UK) for pointing out the bug. This was a problem with displaying longitudes in the range 0 to 1 E.
