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"THE EARTH CENTERED UNIVERSE" Sky Visualization Software User's Manual Version 1.3 Shareware and Registered Versions Released in May 1992 for Microsoft(R) Windows 3.0 and 3.1 Written by: David J. Lane 4-26 Randall Avenue Halifax, Nova Scotia Canada B3M 1E2 Phone: (902) 443-5989 Compuserve E-Mail: 71601,247 Internet E-Mail: 71601.247@compuserve.com Manual Revision 1.3 1. Getting Started Thank you for choosing to try "The Earth Centered Universe", ECU for short. ECU is a Sky Visualization Program capable of simulating many of the phenomenon of the earth centered sky. This includes, but is not limited to, the stars, planets, sun, and moon, comets, and "deep sky" objects. ECU is designed as an observing tool for the observing amateur astronomer, but is equally useful to the "armchair" astronomer or other interested person. Many of the concepts and terms used in this manual are common in amateur astronomy, but may not be familiar to all users. The author recommends the purchase of a good beginner book in astronomy as a guide to the understanding of the concepts provided by this program. An excellent beginner's book is: NIGHTWATCH: An Equinox Guide to Viewing the Universe by Terence Dickinson, which is available in most well stocked bookstores or libraries. ECU is designed to operate on a PC from within the Microsoft Windows 3.0 or 3.1 environment. This environment provides all of the "tools" necessary to support a highly graphical program like ECU. This manual assumes that the user is familiar with the operation of typical Windows 3 programs. ECU was written, because of the obvious lack of good, reasonably priced astronomy programs. Most "commercial" software products (and the author has purchased three of the high profile programs) suffer from very awkward (not intuitive at all) user interfaces and ssllloooowwwww operation (especially without a math processor). ECU, therefore, attempts to fill an obvious need at the reasonable prices of shareware. 1.1 Registration of ECU A large amount of effort in software development has gone into the "The Earth Centered Universe". It currently is comprised of about 280 pages of program listing. This release, V1.3, includes a several enhancements over previous versions (ECU was first released as V1.1 in March of 1992). Prior to the first release, a round of "beta testing" was executed. The user feedback resulted in many changes and a wish list from Earth to the Moon (see section 7.). The most notable enhancements to ECU in this version are listed below: 1. The substitution of the previous star database to the use of the Yale and Smithsonian Astrophysical Observatory star catalogs; the later being optional and containing about 250,000 stars. 2. The number of comets is increased to six and their names now appear in menus. 3. A menu item has been added to center the sky display on a specified Azimuth/Altitude. 4. On screen "Speed Buttons" are added for several commonly used functions. 5. A menu item has been added to set the field size to a specified number of degrees. 6. The deep sky object symbols have been changed so they are more recognizable. In order to ensure that ECU is supported and greatly improved in the future, I ask that you register ECU. Registration will bring a laser printed manual and an enhanced version of ECU. This enhanced version includes several databases, which are too large to distribute by normal shareware methods (eg: bulletin board systems). Also, several computational enhancements (which require one of the database files) are enabled in the REGISTERED VERSION. I ensure you that the SHAREWARE VERSION is not "crippled" software. It only lacks some of the advanced features, such as catalogue identification of stars, descriptions of "deep sky" objects, ultra-high accuracy solar system calculations (lower accuracy versions are included), comets, etc. The executable file is the same. A form that can be used to register ECU is found in the file REGISTER.TXT. The author would be most pleased in hearing your comments and suggestions for improvements of ECU or this manual. I would also like to hear about any "bugs" which you detect so they can be fixed in a future release. ECU is a SHAREWARE product, thus is user supported. I can be reached at any of the addresses (post office and e-mail) listed on the cover page of this manual. 1.2 System Requirements As stated in section 1., ECU operates within the Microsoft Windows 3 environment. It will not run under DOS alone. However, it has been tested for operation in the soon to be released OS/2 2.0. The minimum system requirements are listed below: Hardware: 286/386/486 100% PC Compatible Computer Math Co-processor: 80x87 supported, but not required Software: DOS 3.x or higher Microsoft Windows 3.0 or 3.1 (standard or enhanced mode) Memory: Minimum 700K bytes free from within Windows Minimum 1M bytes free with enhanced stellar database Disk Capacity: SHAREWARE VERSION - 500K bytes REGISTERED VERSION - 2.2M bytes WITH ENHANCED STELLAR DATABASE - 5.5M bytes Graphics Card: An EGA or better graphics card (VGA recommended) Monitor: Color required for good screen displays Mouse: Windows compatible ECU has been tested with slower 286-based computers and operates perfectly satisfactorily with them. In fact it operates faster on a 286 computer than many commercial programs operate on the author's 386! The use of a math co-processor is supported, but not required. With most commercial programs, this statement means that it works, but is untolerably slow! ECU's sky drawing routines are written almost entirely in integer math, thus operate quickly with or without the math processor. During development, the author's computer did not have a math co-processor. I have one now. The math processor, however, does speed up local horizon, planet, sun, moon, and comet orbit calculations significantly. 1.2 Installation Instructions ECU is normally distributed as one file (ECUREG.EXE) in self uncompressing format. The compressed file contains the following files for the SHAREWARE, REGISTERED, and ENHANCED STELLAR DATABASE VERSIONS: SHAREWARE VERSION ECU.EXE - the main executable program file ECU.CFG - the default configuration file YBSC1.ECU - the main Yale Bright Star file SAC1.ECU - the main "deep sky" object file CONS.ECU - the constellation data file LABELS.ECU - the text labels data file LOCATION.ECU - the geographic location data file REGISTER.TXT - the ECU registration form MANUAL.TXT - this manual REGISTERED VERSION ALL ABOVE FILES PLUS: YBSC2.ECU - the secondary Yale Bright Star file SAC2.ECU - the secondary "deep sky" object file PTERMS.ECU - the orbital terms used for high accuracy calculations PINDEX.ECU - the index file for PTERMS.ECU ENHANCED STELLAR DATABASE VERSION ALL ABOVE FILES PLUS: SAO1.ECU - the primary Smithsonian Astrophysical Observatory star file SAO2.ECU - the secondary Smithsonian Astrophysical Observatory star file Installation of ECU is straight forward. The example below assumes that your hard disk is drive 'C', and your floppy disk is drive 'A'. You can install ECU from DOS or from a "DOS Window" within Windows 3. TYPE 1. Log to your hard disk: C: <return> 2. Make a directory to store ECU: MD \ECU <return> 3. Change to the ECU directory: CD \ECU <return> 4. Install the ECU program disk in drive 'A' 5. Extract the files from ECUREG.EXE: A:\ECUREG<return> 6. If you don't have the enhanced stellar database go to step 11. 7. Install the ECU SAO1 disk in drive 'A' 8. Extract the files from SAO1.EXE A:\SAO1<return> 9. Install the ECU SAO2 disk in drive 'A' 10. Extract the files from SAO2.EXE A:\SAO2<return> 11. Start Windows: WIN <return> (ignore if already running) 12. Start the "File Manager" use the mouse 13. Open the ECU directory such that the ECU.EXE file is visible. 14. Arrange the screen so that ECU.EXE and a suitable program group in the "Program Manager" are both visible. 15. Drag ECU.EXE from the "File Manager" to the "Program Manager". A colorful Icon should appear. 16. Proceed to section 1.3: Starting ECU. 1.3 Starting ECU ECU is started by double-clicking the ECU Icon. Loading ECU typically takes less than 15 seconds, however, the SHAREWARE version takes somewhat longer the first time it is started. This is because the file MATH.ECU needs to be created. This file is used by ECU to speed up its sky drawing functions. It is not distributed in the SHAREWARE version so as to reduce the "download" time (and therefore the cost) of ECU from bulletin boards. Subsequent startups will occur normally. Before the "main window" appears, several data files, plus the configuration file are loaded into memory. If any problem is encountered while loading ECU (due to bad or missing files, not enough memory, etc.), a small dialog box displaying a descriptive message is displayed on the screen. Pressing 'OK' will return control to Windows 3. If all is successful, the opening screen will appear greeting the user with a colorful display of the constellation of ORION. At this time, only one copy of ECU can be running at any one time. If the user attempts to run a second copy of ECU, a small dialog box will appear describing the problem. The ECU "main window" always begins centered on the screen, however, it is designed it operate optimally "full screen". Press the "maximize" button to facilitate this. By default, ECU always uses the configuration file "ECU.CFG" located in the current directory. If a file name is specified on the command line, ECU uses the specified file. This is useful for setting up ECU 'icons' to quickly bring up saved astronomical events. I suggest you read sections 2. and 3. next, which introduce the operation of the program, and address all of the menu selections. If you just want to explore, that's fine, too. I think you will find ECU quite intuitive. Section 4. then describes the built-in databases. 2. Introduction This section assumes that ECU is installed and is running. As indicated in Section 1.3, ECU runs optimally "full screen", which is obtained by pressing the "maximize" button. Mouse operations are integral to the operation of ECU, and will be described in Section 2.3. The on-screen controls, such as the check boxes and scroll bars will be described in Section 2.4 and the menu selections in Section 3. But first, the on-screen status displays and sky display area will be described. 2.1 The Status Display The left portion of the ECU window comprises the status display area. This area contains the following items: a) Geographic Location - the top line shows the city where the observer is located. If a city was not selected (but rather a specific latitude/longitude was entered), the message "By Lat/Long" will be displayed. Immediately below, the latitude (Lat) and longitude (Long) of the observer is displayed as degrees and minutes. Positive latitudes are North of the equator and positive longitudes are West of the Greenwich meridian. To set your geographic location, see section 3.3.2, which describes the "Set -> Geographic Location" menu selections. b) Local Mean Time (LMT) - contains the date and time of the local civil time. The date is always in the format year/month/date. The time is either displayed as hh:mm in 24 hour time or hh:mmpm in am/pm format. See section 3.3.1.4. c) Universal Time (UTC) - contains the universal date and time (that of the Greenwich meridian). The date is always in the format year/month/date. The time is always displayed as hh:mm in 24 hour time format. d) Right Ascension (RA) - contains the right ascension of the center of the sky display. It is formatted in hours and minutes as hh:mm.m. e) Declination (Dec) - contains the declination of the center of the sky display. It is formatted in degrees and minutes as +dd mm'. f) Azimuth (Azim) - contains the azimuth of the center of the sky display. The azimuth is the angle, in degrees and minutes, from the Northern horizon towards the East at the current Date and Time and Geographic Location. g) Altitude (Alt) - contains the altitude of the center of the sky display. The altitude is the angle, in degrees and minutes, measured vertically from the horizon at the current Date and Time and Geographic Location. h) Field Size (Field) - contains the number of vertical degrees currently shown in the sky display. The minimum field size is 2 degrees and the maximum is about 60 degrees. i) Magnitude (Mag) - contains the minimum magnitude for which stars are displayed in the sky display. This number is usually the same as that set in the "Set -> Magnitude Limits..." menu selection, however to keep the sky drawing speed fast, the maximum magnitude of stars displayed changes with the field size. This ranges from magnitude 5.5 for fields larger than 50 degrees to magnitude 8.5 for field sizes from 10 to 15 degrees. See section 3.4.2, which describes the "Set -> Magnitude Limits..." menu selection. 2.2 The Sky Display The right portion of the ECU window is the sky display area. The sky display area displays celestial objects using one of two "projections". These two projections were selected for the speed of their calculation, however there is some distortion at the limits of their usefulness. When displaying the sky from -45 to +45 degrees Declination, a simple modified-Mercator projection is used. This projection causes the objects at high Declinations to be distorted (spread- out), most noticeable in constellations like Ursa Major (the big dipper). This is the same distortion that makes Canada appear much larger than the United States on world maps with similar projections (Canada is only about 10% larger). When displaying the sky either North of +45 or South of -45 degrees in Declination, the Zenithal Equidistant Projection is used. This projection is quite good, but does spread out objects a bit at low Declinations. With both projections, North is always up (South is down) and East is to the right (West is to the left). The objects and items displayed in the sky display area are listed below. Each will be discussed in detail in sections 3. and 2.4 by the specific menu selection or screen resource which controls their operation. a) Grid - the coordinate grid helps illustrate the sky projections just described. Lines of Right Ascension are drawn every hour (coarse grid) or every 20 minutes (fine grid). Lines of Declination are drawn every 10 degrees (coarse grid) or every 5 degrees (fine grid). b) Stars - stars are displayed as varying sized dots according to the star's brightness. The larger the dot, the brighter the star. c) Lines - there are many lines displayed by ECU. These include the constellation lines, horizon line, and ecliptic line. Markers are also displayed at the Zenith (the overhead point) and the North and South poles. d) Labels - there are text labels displayed for solar system objects, bright stars names, Messier objects, constellation names, and labels for the ecliptic and horizon lines, and markers. e) Solar System objects - the planets, sun, moon, and comets are displayed. The sun and moon are displayed to their correct size and the phase of the moon is shown. Planets are displayed as either a point or by their standard symbol. Comets are displayed as points. Comets are not available in the SHAREWARE VERSION of ECU. f) Deep sky objects - deep sky objects are displayed in six different categories. These are Galaxies, Open Clusters, Globular Clusters, Bright Nebulae, Planetary Nebulae, and Other; each displayed using a different symbol. 2.3 Mouse Operations The mouse forms a vital part of the ECU user interface and has many uses from within ECU. The cursor (the shape of the mouse pointer) is used to inform the user of how the mouse is currently being used. If it is a cross-hair, it is used for selecting a window, identifying an object, centering, or measuring an angle. The cursor is always a cross-hair while in the sky display area. If it is an arrow, it is used for operating the scroll bars or buttons. Each mouse button will be described separately in the next two sections. 2.3.1 Left Mouse Button The left mouse button, while the cursor is in the sky display area, is used for the following functions. a) Select an object - if the left mouse button is pressed (and released) within a few pixels of the center of an object, a dialog box, called the "Identify Object" dialog box, will appear identifying and describing the object. Section 5. details the contents of the "Identify Object" dialog box. A cross-hair will appear on the screen identifying the object currently selected. The dialog box is always placed in the diagonally opposite corner from the object selected, so that it doesn't cover the object selected. The dialog box can, of course, be moved about the screen as the user wishes. If more than one object is in the vicinity, the "Next" button can be pressed to update the dialog box with new information for the next object. The dialog box can be terminated in four ways. If the "Quit" button is pressed, the dialog box will terminate immediately. If another object is selected, the current dialog box will be replaced with a new one. If the left mouse button is pressed while the cursor is not near an object, the dialog box will terminate. Finally, the <ESC> key can be pressed. b) Zoom a window - the second function performed by the left mouse button is its ability to draw a rectangle on the screen which is used to re-position and re-scale the sky display. The rectangle is drawn by positioning the mouse at one corner, dragging the mouse (with the left mouse button pressed) to another corner, and then releasing the button. The center of the rectangle defines the new display center and the vertical height is used to scale the display. 2.3.1 Right Mouse Button The right mouse button, while the cursor is in the sky display area, is used for the following functions. a) Center the mouse position - if the right mouse button is pressed (and released), the current mouse position will become the center of the sky display at the current scale. This feature is very useful for quickly "panning" about the sky. b) Measure an angle - the second function performed by the right mouse button is its ability to measure angles on the sky. Angles are measured by positioning the mouse at one location, dragging the mouse (with the right mouse button pressed) to another location, and then releasing the button. A dialog box will appear which displays the angular measure between the two points in degrees. 2.4 On-Screen Controls The on-screen controls include the scroll bars, zoom buttons, check boxes, and time step arrows and buttons. Each is described below: a) Scroll Bars - Two scroll bars are used to rapidly move the center of the sky display about the celestial sphere. The scroll bars are used in two modes as controlled by the menu selection described in section 3.4.10. 1) The vertical bar is used to change the Declination. +90 degrees is at the top; -90 degrees is at the bottom. Pressing the end arrows will move the pointer (and the sky display) by one degree and pressing along the bar will move the pointer by 10 degrees. The horizontal bar is used to change the Right Ascension. 23 hours 59 minutes is at the left; 0 hours is at the right. Pressing the end arrows will move the pointer by 4 minutes and pressing along the bar will move the pointer by one hour. When sliding the scroll bars by dragging the pointer, observe at the Right Ascension and Declination displays to know when to stop. 2) The vertical bar is used to change the Altitude with reference to the local horizon. +90 degrees is at the top (the Zenith); -90 degrees is at the bottom (the Nadir). Pressing the end arrows will move the pointer (and the sky display) by one degree and pressing along the bar will move the pointer by 10 degrees. The horizontal bar is used to change the Azimuth with reference to the local horizon. 0 degrees (North) is at the left; 358.5 degrees is at the right. Pressing the end arrows will move the pointer by 1.5 degrees and pressing along the bar will move the pointer by 15 degrees. When sliding the scroll bars by dragging the pointer, observe at the Azimuth and Altitude displays to know when to stop. b) Zoom buttons - the zoom buttons, identified as "zoom in" and "zoom out", are used to change the scale of the sky display. Each press of the respective button changes the scale by a factor of two. c) Check boxes - the six check boxes: Stars, Deep Sky, Solar System, Grid, Lines, and Labels are used to toggle whether the respective item is displayed in the sky display. Note that when operating with graphics boards providing less than 350 pixels in vertical resolution, only the Stars and Deep Sky check boxes are available. d) Time step arrows and buttons - the time buttons "+" and "-" are used to change the current time by the amount shown at the immediate left. Pressing the black arrows causes the amount at which the time changes to be altered in steps from a minimum of 1 minute to a maximum of 4 years. e) Speed buttons - the boxes in the status area, which are used to display the current settings of parameters ranging from the Geographic Location to the Stellar Magnitude Limit (see section 2.1), are also used to provide quick access to the menu items which control the respective parameter. When the left mouse button is pressed while the mouse is within one in the boxes cause the appropriate dialog box to "pop-up". For example, the left mouse button is pressed within the "Mag" box, the "Magnitude Limits..." dialog box will pop-up. 3. Menu Selections The menu selections control most of the features of ECU and are divided into seven categories as listed below. Each is described in detail in the identified sections: a) File - the file menu handles the loading and saving of the configuration settings of ECU (see section 3.1). b) Edit - edit allows the last operation to be nullified (see section 3.2). c) Set - the set menu allows the time, geographic location, sky display color, comet orbits, and calculation settings to be adjusted (see section 3.3). d) Field - the field menu controls if and how the stars, deep sky objects, planets, sun/moon, grid, lines, and labels are displayed. It also allows for various zoom settings (see section 3.4). e) Center - the center menu allows many ways to set the center of the sky display. These ways include centering on a specified Right Ascension/Declination, a constellation, a bright star, a Messier object, a Solar System object, a point on the local horizon, or by a text search of the databases (see section 3.5). f) Animation - the animation menu controls the various features of the animation mode (see section 3.6). g) About - the about menu lists the program credits, the version number, etc. (see section 3.7). Many of the common menu items have "short cut" keyboard keys to allow quick access to their features. The keys used are identified by an underline under the key used. The Alt key is to be pressed in conjunction with the identified key. Also, some menu items identify their keyboard equivalent to the right in their menu item. 3.1 File Menu The File menu allows the configuration settings of ECU to be loaded (opened) and saved. Virtually every setting in ECU is stored in the configuration file. This allows ECU to be "set up" for a particular astronomical event and this event saved to a configuration file for later quick retrieval. 3.1.1 Open... The Open... menu selection presents a dialog box allowing a new configuration file selected, then subsequently loaded. It defaults to file names with the extension ".cfg". I will not detail the operation of this dialog box, since it is identical to every other MS-Windows application that has an Open... function. 3.1.2 Save The Save menu selection saves the current configuration settings to the current configuration file name. The current file name is always displayed on the ECU Window title. 3.1.3 Save As... The Save As... menu selection saves the current configuration settings to the file specified by the file name selected in the dialog box presented. I will not detail the operation of this dialog box, since it is identical to every other MS-Windows application that has a Save As... function. 3.1.4 Exit The Exit menu selection is used to exit ECU. If the configuration settings have changed, a message box appears ensuring that the user wishes to exit without saving. ECU can also be exited by "double-clicking" on the Control- menu box or by selecting "Close" in the window's system menu. 3.2 Edit Menu The Edit menu currently has only one entry: Undo. The Undo menu selection nullifies the last operation. This is very useful when you have made a "slip of the mouse" and wish to get back to where you were. 3.3 Set Menu The Set menu allows the time, geographic location, Solar System calculation settings, comet orbits, and sky background color to be adjusted. Each is described in the sections below. 3.3.1 Time The time can be set in one of three formats: local civil time, Universal time (GMT), or set to your pc's system clock (using local civil time). The current time format used is identified in the Time menu selections sub-menu, by a check mark in front of the current mode. The following sections describe the time settings. 3.3.1.1 Enter Local Time The Enter Local Time menu selection presents a dialog box allowing the user to enter the year, month, date, hour, and minute in local time format. The year can be from 1000 to 3000 AD and the hour must be in 24 hour format. The time is always initialized to the current time. Ending the dialog box is accomplished by pressing the 'OK' button. Aborting, without changing the time, is accomplished by pressing 'Cancel'. If an error is detected when ending the dialog box, a 'beep' will sound and the cursor will be placed at the offending field. This menu selection can also be activated by pressing the left mouse button while the mouse is in either of the boxes which display the local mean date and time (LMT) in the ECU status display area. 3.3.1.2 Enter Universal Time Entering the Universal time is accomplished identically to entering the local time. This menu selection can also be activated by pressing the left mouse button while the mouse is in either of the boxes which display the universal date and time (UTC) in the ECU status display area. 3.3.1.3 Use System Time Selecting Use System Time causes ECU's time base to become synched to the pc's system clock. This will cause the sky to update automatically once per minute, therefore simulating the actual sky's movements. 3.3.1.4 Local Time Format The local mean time (LMT) display in the status area is displayed in either 24 hour or am/pm format. The Local Time Format menu selection is a sub-menu of AM/PM and 24 Hour selections, each selection setting the respective format. The current format is identified by a 'check mark'. 3.3.1.5 Daylight Savings The Daylight Savings menu selection toggles whether the current local time is to be interpreted as a daylight savings time. It is used by ECU to convert from local time to Universal time. If a 'check mark' is present, daylight savings mode is enabled. If ECU is using the pc's system clock and the daylight savings time 'check mark' is present, the pc's time should be set to the daylight savings time. 3.3.2 Geographic Location The Geographic Location menu selection provides a sub-menu containing two methods of entering a location on the Earth's surface. These are By Latitude/Longitude and By City/Town. 3.3.2.1 By Latitude/Longitude The By Latitude/Longitude menu selection presents a dialog box allowing the user to enter the latitude, longitude, and time zone of the location used in the sky display calculations. The latitude is entered as degrees (North is positive, South is negative) and minutes. The longitude is also entered as degrees (West of the prime meridian is positive, East is negative) and minutes. The time zone is entered in hours West of UTC (the time of the Grenwich meridian; enter a negative for the Eastern hemisphere). The location is always initialized to the current location. Ending the dialog box is accomplished by pressing the 'OK' button. Aborting, without changing the location, is accomplished by pressing 'Cancel'. If an error is detected when ending the dialog box, a 'beep' will sound and the cursor will be placed at the offending field. This menu selection can also be activated by pressing the left mouse button while the mouse is in either of the boxes which display the current latitude and longitude in the ECU status display area. 3.3.2.2 By City/Town The By City/Town menu selection presents a dialog box allowing the user to select the location from a set of pre-defined locations. A list box is presented containing the available list. The user is to select the desired location, then exit the dialog box. Ending the dialog box is accomplished by pressing the 'OK' button. Aborting, without changing the location, is accomplished by pressing 'Cancel'. This menu selection can also be activated by pressing the left mouse button while the mouse is in the box which displays the current city/town at the top the ECU status display area. If your location is not in the list of available locations, you can use a text editor (the Windows NotePad will do fine) to edit the file LOCATION.ECU. The file format is quite simple, as shown by the sample entries below: 49.0 59.0 3.5 Corner Brook NFLD 53.3 60.1 4 Goose Bay, LAB 47.5 52.9 3.5 St. John's NFLD 46.1 59.8 4 Sydney NS The first three entries, which are separated by spaces, are the latitude (decimal degrees North of the Equator), longitude (decimal degrees West of the Prime meridian), and time zone (hours West of UTC). The fourth entry is the name of the location. The order of lines in the file does not matter since ECU sorts the file in order when it is loaded. 3.3.3 Solar System The Solar System menu selection provides a sub-menu allowing several calculation options pertaining to the Solar System to be changed. A 'check mark' in front of a menu item indicates that it is enabled. Each menu item is described below. 3.3.3.1 High Accuracy Calculations This menu selection controls the precision of the solar system calculations. The high accuracy calculations are not available when using the SHAREWARE VERSION of ECU. 3.3.3.2 Precess to Sky Display This menu selection controls whether the Solar System object positions and the horizon line are to be adjusted (due to the effect of precession of the Earth's axis of rotation) to match the J2000.0 coordinates used by the sky display. 3.3.3.3 Nutation This menu selection controls whether the Solar System object positions (except the comets) are to be corrected for the effects of Nutation. Nutation is at maximum, a 9 arc-second wobble in the precession circle primarily caused by the gravitational pull of the Moon. Nutation can only be calculated when the High Accuracy Calculations selection is enabled. 3.3.3.4 Aberration This menu selection controls whether the Solar System object positions (except the comets) are to be corrected for the effects of Aberration. Aberration is the apparent displacement of the position of an object due to the finite speed of light (whatever that means?). Aberration can only be calculated when the High Accuracy Calculations selection is enabled. 3.3.3.5 Light Travel Time This menu selection controls whether the Solar System object positions (except the Moon) are to be corrected for the effects of the Light Travel Time. The Light Travel Time correction recognizes that the observer sees an object at where it used to be in the past. Light Travel Time corrections can only be calculated when the High Accuracy Calculations selection is enabled. 3.3.3.6 Observer's Parallax This menu selection controls whether the Solar System object positions (except the comets) are to be corrected for the effects of the Observer's Parallax. The Observer's Parallax is the effect of an apparent shift of an objects position for observers located at different locations on the Earth. This effect is what causes the Solar Eclipses and Occultations of the Moon to be only observable from certain locations on the Earth's surface. Be sure to enable this selection when simulating events which are location specific like solar eclipses. 3.3.4 Atmospheric Refraction This menu selection controls whether the local horizon, Azimuth and Altitude displays, and Rise/Set calculations are to be corrected for the effects of Atmospheric Refraction. Atmospheric Refraction causes an object to appear higher in the sky that it actually is. The bending (or refraction) of light as it passes through the Earth's atmosphere causes this effect. 3.3.5 Define Comet Orbit The Define Comet Orbit menu selection provides a sub-menu of the six comets which can be defined. Each selection is identical except for the comet number. Each sub-menu selection presents a dialog box allowing the orbital elements of a comet to be entered. The following items can be entered. a) Comet Name - a textual name that can be displayed next to the comet in the sky display. b) Date of Perihelion - the date of perihelion can be entered as either decimal years or as year, month, and decimal days. If the month is set to zero, the decimal years are used and the month and date are ignored. If the month is valid (1 to 12), the year, month, and date are used. c) Perihelion Distance - the distance of the comet to the Sun in astronomical units (AU) at Perihelion. d) Eccentricity - the eccentricity of the comet's orbit from 0 to 1. e) Argument of Perihelion - the argument, in degrees, of the perihelion. f) Longitude of Ascending Node - the longitude, in degrees, of the ascending node. g) Inclination of Orbit - the inclination of the orbit in degrees. h) Epoch of the Elements - the epoch of the elements, either B1950.0 or J2000.0. i) Magnitude Constants - the magnitude constants g and k, are used to estimate the brightness of the comet. Each comet has a different set of constants. Comet brightness predictions are notoriously extremely unreliable. g) Enable Comet - this flag enables the comet for display. Ending the dialog box is accomplished by pressing the 'OK' button. Aborting, without changing the comet orbital elements, is accomplished by pressing 'Cancel'. If a comet has a name and is 'enabled', it will be subsequently be referred to in the menus by its name instead of just "Comet 1", etc. 3.3.6 Sky Background Color The Sky Background Color menu selection provides a sub-menu allowing the sky background to be set to either black or white. I find the black background more pleasing, but the white background is required for printing of sky charts. The current mode is identified by the 'check mark'. 3.4 Field Menu The Field menu controls various parameters pertaining to the sky display. Each menu selection is described separately in the following sections. 3.4.1 Display The Display menu selection provides a sub-menu allowing the user to toggle the display of stars, deep sky objects, solar system objects, the grid lines, lines and labels on the sky display. This menu selection duplicates the on-screen check boxes. The current state of each display setting indicated by a 'check mark' in front of the menu item. 3.4.2 Magnitude Limits... The Magnitude Limits... menu selection presents a dialog box allowing the user to set the limiting magnitude for stellar and deep sky objects. The magnitude is set by dragging the scroll bars to the desired magnitude as displayed immediately below each scroll bar. The actual stellar limiting magnitude is dependant on the field size, however, the setting here sets the upper limit. If the deep sky magnitude limit is set to 20, all objects will be displayed, even those whose magnitude is unknown. Pressing 'OK' exits the dialog box and activates the new magnitude limits. Pressing 'Cancel' exits without making any changes. This menu selection can also be activated by pressing the left mouse button while the mouse is in box which displays the current Magnitude Limit in the ECU status display area. 3.4.3 Object Selection... The Object Selection... menu selection presents a dialog box allowing the user to select which types of deep sky objects are displayed. The dialog box has 7 check boxes; one for each of Galaxies, Globular Clusters, Open Clusters, Bright Nebulae, Planetary Nebulae, Other, and Unknown Magnitudes. If the check box of the respective object type is true, that type will be displayed (if deep sky objects are also 'turned on'). Note that the 'Unknown Magnitude' type allows for the display of objects whose magnitude is unknown, without littering the display with hundreds (or thousands) of faint objects, as would be the case if the limiting magnitude were set to 20 as described in Section 3.4.1. Pressing 'OK' exits the dialog box and activates the new object selections. Pressing 'Cancel' exits without making any changes. 3.4.4 Planets... The Planets... menu selection presents a dialog box which allows the user to control various display parameters for the eight planets. The three entries for each planet include a check box indicating if the respective planet is displayed, a set of radio buttons which determines if it is displayed as either a point or as the planet's symbol, and a check box indicating if the planet's name is also displayed. Pressing 'OK' exits the dialog box and activates the new planets settings. Pressing 'Cancel' exits without making any changes. 3.4.5 Sun The Sun menu selection toggles whether or not the Sun is displayed on the sky display. If marked by a 'check mark', the Sun will be displayed (assuming the Solar System objects are also 'turned on'). 3.4.6 Moon The Moon menu selection toggles whether or not the Moon is displayed on the sky display. If marked by a 'check mark', the Moon will be displayed (assuming the Solar System objects are also 'turned on'). 3.4.7 Grid The Grid menu selection provides a sub-menu allowing the resolution of the coordinate grid to be set. If 'Fine' is selected, the grid will mark every 20 minutes in Right Ascension and every 5 degrees in Declination. If 'Coarse' is selected, the grid will mark every 1 hour in Right Ascension and every 10 degrees in Declination. A 'check mark' marks the current setting. 3.4.8 Lines/Points The Lines/Points menu selection provides a sub-menu allowing the user to toggle the display of lines and points on the sky display. These include the constellation lines, ecliptic line, horizon line, zenith point, and celestial pole points. The current state of each line/point is indicated by a 'check mark' in front of the menu item. 3.4.9 Labels The Labels menu selection provides a sub-menu allowing the user to toggle the display of text labels on the sky display. These include the constellation labels, bright star labels, Solar System labels, Messier labels, horizon line/zenith point labels (N,S,E,W, etc.), and ecliptic point labels (VE - vernal equinox, SS - summer solstice, etc.). The current state of each label is indicated by a 'check mark' in front of the menu item. 3.4.10 Scroll Bars The Scroll Bars menu selection provides a sub-menu allowing the mode of the scroll bars to be set. If 'RA/Dec' is selected, the scroll bars are used to move about the celestial sphere using Right Ascension and Declination coordinates. If 'Azim/Alt' is selected, the scroll bars are used to move about the local sky display using Azimuth and Altitude coordinates. A 'check mark' marks the current setting. 3.4.11 Field Size... The Field Size... menu selection presents a dialog box allowing the user to enter the vertical size, in degrees, of the ECU sky display. The valid range is 2 to 60 degrees in integer divisions. Ending the dialog box is accomplished by pressing the 'OK' button. Aborting, without changing, is accomplished by pressing 'Cancel'. If an error is detected when ending the dialog box, a 'beep' will sound and the cursor will be placed at the offending field. This menu selection can also be activated by pressing the left mouse button while the mouse is in box which displays the current Field Size in the ECU status display area. 3.4.12 Zoom In Full The Zoom In Full menu selection causes the ECU sky display to zoom in to the minimum allowable field size, which is 2 degrees in height. 3.4.13 Zoom To 10 Degrees The Zoom To 10 Degrees menu selection causes the ECU sky display to zoom a field size, which is 10 degrees in height. 3.4.14 Zoom To 20 Degrees The Zoom To 20 Degrees menu selection causes the ECU sky display to zoom a field size, which is 20 degrees in height. 3.4.15 Zoom To 40 Degrees The Zoom To 40 Degrees menu selection causes the ECU sky display to zoom a field size, which is 40 degrees in height. 3.4.16 Zoom Out Full The Zoom Out Full menu selection causes the ECU sky display to zoom out to the maximum allowable field size, which is about 60 degrees in height. 3.5 Center Menu The Center menu allows the user to quickly center on most objects in ECU's databases. This includes centering on a specified Right Ascension/Declination, a specified Azimuth/Altitude, a constellation, a bright star, Messier object, Solar System object, a point on the local horizon, or on a text search of the databases. When an object is centered on the sky display, a cross-hair is used to mark it. Each centering menu selection is described separately below. 3.5.1 On RA/Dec... The On RA/Dec... menu selection presents a dialog box allowing the user enter a specific Right Ascension and Declination to center the sky display on. The Right Ascension is entered as hours and minutes. The Declination is entered as degrees and minutes. Ending the dialog box is accomplished by pressing the 'OK' button. Aborting, without changing the sky display, is accomplished by pressing 'Cancel'. If an error is detected when ending the dialog box, a 'beep' will sound and the cursor will be placed at the offending field. When the dialog box ends, ECU centers the sky display at the coordinates entered. This menu selection can also be activated by pressing the left mouse button while the mouse is in either of the boxes which display the current Right Ascension/Declination in the ECU status display area. 3.5.2 On Alt/Az... The On Alt/Az... menu selection presents a dialog box allowing the user enter a specific Azimuth and Altitude, with reference to the local horizon, to center the sky display on. Both the Azimuth and Altitude are entered as degrees and minutes. Ending the dialog box is accomplished by pressing the 'OK' button. Aborting, without changing the sky display, is accomplished by pressing 'Cancel'. If an error is detected when ending the dialog box, a 'beep' will sound and the cursor will be placed at the offending field. When the dialog box ends, ECU centers the sky display at the local horizon coordinates entered. This menu selection can also be activated by pressing the left mouse button while the mouse is in either of the boxes which display the current Azimuth/Altitude in the ECU status display area. 3.5.3 On Constellation... The On Constellation... menu selection presents a dialog box allowing the user to select a constellation to center the sky display on. A list box is presented containing the available list of 88 constellations in alphabetical order. The user is to select the desired constellation, then exit the dialog box. ECU then centers the sky display on the selected constellation. 3.5.4 On Bright Star... The On Bright Star... menu selection presents a dialog box allowing the user to select a bright star to center the sky display on. A list box is presented containing the available list of bright stars in alphabetical order. The user is to select the desired bright star, then exit the dialog box. ECU then centers the sky display on the selected bright star. 3.5.5 On Messier Object... The On Messier Object... menu selection presents a dialog box allowing the user to select a Messier Object to center the sky display on. A list box is presented containing the available list of 110 Messier objects in numerical order. The user is to select the desired object, then exit the dialog box. ECU then centers the sky display on the selected Messier object. 3.5.6 On Solar System Object The On Solar System Object menu selection contains a sub-menu of all the Solar System objects (Sun, Moon, Planets, and Comets). The menu item selected is centered on the sky display. 3.5.7 On Point on Horizon The On Point on Horizon menu selection contains a sub-menu of all the cardinal points on the local horizon plus the Zenith (the overhead point). The menu item selected becomes centered on the sky display. 3.5.8 On Database Search... The On Database Search... menu selection is used to search the ECU databases for a specified object. If a match is found, the specified object is centered on the sky display. The user is presented with a dialog box which prompts for a line of text. If the 'OK' button is pressed, the search commences. The line of text entered is immediately converted to upper case to avoid ambiguities and all spaces are removed. The object types which can be searched for are listed below: a) Constellations - the 88 constellations can be searched by entering their complete formal name (eg. 'Ursa Major'). b) Bright Stars - bright stars can be searched by entering their complete formal name (eg. 'Deneb'). c) Stars - any star in the Yale Bright Star (YBSC) database can be searched by entering either its Smithsonian Astrophysical Observatory (SAO) catalogue number with the prefix 'SAO', its Yale number with the prefix 'HR', or its Henry Draper (HD) catalogue number with the prefix 'HD'. For example, to find the SAO star number 49898, enter 'SAO49898'. Note that entering 'sao 49898' would be just as effective because the case of the input and spaces are ignored. This search in limited to searches of stars in the Yale Bright Star Catalogue database. SAO stars which are fainter than 6.5 magnitude (the extended stellar database) are not searched, primary due to the excessive time that it would take to search the entire SAO database of about 250,000 stars. Searching for YBSC stars is not available in the SHAREWARE VERSION of ECU. d) Deep Sky Objects - deep sky objects can be searched by entering either their primary name or 'Other Names:' as stored in the SAC deep sky database (see Section 4.). For example, the Andromeda Galaxy can be found by entering either its official name 'NGC224' or its common name (other name) 'M31'. Searching for deep sky objects is not available in the SHAREWARE VERSION of ECU. If the search is not successful, a message box will appear informing the user of this. 3.6 Animation Menu The Animation menu controls all of the functions of ECU's animation mode. The animation mode is used to simulate astronomical events which are affected by changes in the time. The animation mode has the following features. a) Time can be automatically stepped in any step from 1 minute to 4 years. b) Time can be stepped in either forward or reverse. c) The time between time steps can be set from 0 to 60 seconds. d) The trail history can be stored as either the objects Right Ascension/Declination or its Azimuth/Altitude. e) The solar system objects can be trailed with dots drawn behind them. f) The number of dots used in the trail can be set from 10 to 100. g) The sky display can be made to 'lock' on any solar system object, or point with reference to the local horizon. h) The time can be manually stepped, either forward or in reverse. i) All of the features of ECU can be used while the animation mode is running due to the multi-tasking nature of Windows, and thus of ECU. Animation mode is best learned by experimentation, however, the menu items which control the animation mode are described in the sections below. 3.6.1 Start The Start menu selection starts the animation mode. If a 'check mark' preceeds the menu selection, animation mode is running. 3.6.2 Stop The Stop menu selection stops the animation mode. The ESC key can also be used to stop the animation mode. 3.6.3 Forward One Step The Forward One Step menu selection steps the time forward by one time step. The time step is displayed to the left of the time step buttons in the status area. This menu selection can also be executed by pressing the '+' key or the '+' button. 3.6.4 Reverse One Step The Reverse One Step menu selection steps the time in reverse by one time step. The time step is displayed to the left of the time step buttons in the status area. This menu selection can also be executed by pressing the '-' key or the '-' button. 3.6.5 Trails On The Trails On menu selection enables the drawing of trails behind the Solar System objects. If the trails are enabled, a 'check mark' will preceed this menu selection. 3.6.6 Maximum Trails... The Maximum Trails... menu selection presents a dialog box allowing the user to enter the number of trails (10 to 100) to be drawn behind Solar System Objects. Ending the dialog box is accomplished by pressing the 'OK' button. Aborting, without changing, is accomplished by pressing 'Cancel'. If an error is detected when ending the dialog box, a 'beep' will sound and the cursor will be placed at the offending field. 3.6.7 Animation History The Animation History menu selection presents a sub-menu of the selections: RA/Dec and Anim/Alt. These selections control whether the animation history is saved as the Right Ascension and Declination of the object or as its Azimuth and Altitude with reference to the local horizon. The latter setting is useful for observing an object's path relative to the local horizon. A good example of this would be to plot the positions of the planet Mercury as it passes through an eastern or western elongation and becomes visible in the evening or morning sky. Beware, however, that the actual positions shown in the object trails (except for the current position) are not correct with reference to the background stars. Also, this setting operates slowly, because the computational overhead is higher. A 'check mark' will immediately preceed current setting. 3.6.8 Lock On Current RA/Dec The Lock On Current RA/Dec menu selection causes the animation mode to be locked on the current Right Ascension and Declination. In fact, it turns 'lock mode' off. If locked on the current RA/Dec, a 'check mark' will immediately preceed this menu selection. 3.6.9 Lock On Current Azim/Alt The Lock On Current Azim/Alt menu selection causes the animation mode to be locked on the current altitude and azimuth, with respect to the local horizon. This feature is very useful for 'watching' a particular horizon as the constellations rise or set, or as a planet such as Mercury crests above the horizon. If locked on the current Azim/Alt, a 'check mark' will immediately preceed this menu selection. 3.6.10 Lock On Solar System Object The Lock On Solar System Object menu selection presents a sub- menu of all the Solar System objects (Sun, Moon, Planets, and Comets). The menu item selected becomes locked to the center of the sky display in animation mode. A 'check mark' will immediately preceed the Solar System object locked. 3.6.10 Time Direction The Time Direction menu selection presents a sub-menu of the selections: Forward and Reverse. These selections control the direction in which time is stepped when the animation mode is running. A 'check mark' will immediately preceed the time direction setting. 3.6.11 Time Step The Time Step menu selection presents a sub-menu of the selections: Increase and Decrease. These selections increase or decrease, by one notch, the amount of the animation mode time step. The current time step is shown as the third sub-menu item. These two selections are duplicates of the time step arrows in the status area. 3.6.12 Animation Speed... The Animation Speed... menu selection presents a dialog box allowing the user enter the number of seconds between animation mode updates (0 to 60 seconds). Ending the dialog box is accomplished by pressing the 'OK' button. Aborting, without changing, is accomplished by pressing 'Cancel'. If an error is detected when ending the dialog box, a 'beep' will sound and the cursor will be placed at the offending field. 3.7 About Menu The About menu has two entries. The first selection, ECU..., presents a message box identifying ECU, its version number, its copyright notice, and how to contact the author. The second selection, Willman-Bell..., presents a message box identifying that ECU contains source code that which is copyrighted by Jeffrey Sax. The source code referred to, provides high accuracy astronomical calculations based on the algorithms described in the book: Astronomical Algorithms by Jean Meuss (distributed by Willman-Bell). The message given in the message box is a requirement of distributing programs containing Jeffrey's source code. 4. Databases This section will describe the databases built-in to ECU. ECU contains several databases. The databases which will be covered in this section are the stellar database and the deep sky database. Other databases include the label, constellation line, and geographic location databases. 4.1 Stellar Database The stellar database is divided into two parts. The first part, the Yale Bright Star Catalog (files YBSC1.ECU and YBSC2.ECU), is standard with the REGISTERED version of ECU. It contains 9110 stars to magnitude 6.5 with a wealth of information about each star. The other star database is the optional extended stellar database, the Smithsonian Astrophysical Observatory (SAO) Star Catalogue. The entire SAO catalog contains some 259,000 stars. The Yale stars and those with the magnitude unknown were extracted leaving a database of 245654 stars to about magnitude 9.5. Each database contains the magnitude (visual, if available), Right Ascension, Declination in J2000.0 coordinates and are displayed on the sky display using this epoch. The Yale Catalogue provides several calogue numbers and names for each star. These include the Bayer/Flamsteed identification, the Yale Catalogue number, the SAO Catalogue number, and the Henry Draper Catalogue number. The full spectral classification, color as B-V, and the proper motion of each star. The SAO Catalogue provides the SAO Catalogue number and the spectral type. The object positions in each database are stored in integer format obtaining a resolution of about 10 arc-seconds in Declination and 20 arc-seconds in Right Ascension at the celestial equator. The SHAREWARE VERSION of ECU only contains the primary data file of the Yale Catalogue which only provides the Right Ascension, Declination, and Magnitude. 4.2 Deep Sky Database The deep sky database (files SAC1.ECU and SAC2.ECU) contains a complete database of 10367 deep sky objects. The members of the Saguaro Astronomy Club (SAC) (pronounced sa-war-oh) of Phoenix, Arizona have provided much of the effort to compile this database (database version 5.2). The database includes the entire NGC catalog, plus other interesting deep sky objects. Selected fields of the SAC database were extracted for use in ECU. The object positions are stored in integer format obtaining a resolution of about 10 arc-seconds in Declination and 20 arc-seconds in Right Ascension at the celestial equator. Only the object type, magnitude, and position are available with the SHAREWARE VERSION of ECU. These fields are described below: a) Object Name - usually the NGC number, but for objects with no NGC value, other catalogs are used. The abbreviations listed below are used to represent the other catalogs. Abell - George Abell (planetary nebulae and galaxy clusters) AM - Arp-Madore (globular clusters) Antalova - (open clusters) Bark - Barkhatova (open clusters) B - Barnard (dark nebulae) Basel - (open clusters) Berk - Berkeley (open clusters) Be - Bernes (dark nebulae) Biur - Biurakan (open clusters) Blanco - (open clusters) Bochum - (open clusters) Ced - Cederblad (bright nebulae) Cr - Collinder (open clusters) Czernik - (open clusters) Do - Dolidze (open clusters) DoDz - Dolidze-Dzimselejsvili (open clusters) Dun - Dunlop (globular clusters) Fein - Feinstein (open clusters) Frolov - (open clusters) Gum - (bright nebulae) H - William Herschel (globular clusters) Haffner - (open clusters) Harvard - (open clusters) He - Henize (planetary nebulae) Hogg - (open clusters) HP - Haute Provence (globular clusters) Hu - Humason (planetary nebulae) IC - 1st and 2nd Index Catalogs to the NGC (All types of objects except dark nebulae) Isk - Iskudarian (open clusters) J - Jonckheere (planetary nebulae) K - Kohoutek (planetary nebulae) King - (open clusters) Lac - Lacaille (globular clusters) Loden - (open clusters) LDN - Lynds (dark nebulae) Lynga - (open clusters) M - Messier (all types of objects except dark nebula) Mrk - Markarian (open clusters and galaxies) Mel - Melotte (open clusters) M1 - Minkowski (planetary nebulae) NGC - New General Catalog of Nebulae & Clusters of Stars. (All types of objects except dark nebulae) Pal - Palomar (globular clusters) Pismis - (open clusters) PK - Perek & Kohoutek (planetary nebulae) RCW - Rodgers, Campbell, & Whiteoak (bright nebulae) Roslund - (open clusters) Ru - Ruprecht (open clusters) Sa - Sandqvist (dark nebulae) Sher - (open clusters) Sh - Sharpless (bright nebulae) SL - Sandqvist & Lindroos (dark nebulae) Steph - Stephenson (open clusters) Stock - (open clusters) Ter - Terzan (globular clusters) Tombaugh - (open clusters) Ton - Tonantzintla (globular clusters) Tr - Trumpler (open clusters) UGC - Uppsala General Catalog (galaxies) UKS - United Kingdom Schmidt (globular clusters) Upgren - (open clusters) vdB - van den Bergh (open clusters, bright nebulae) vdBH - van den Bergh & Herbst (bright nebulae) vdB-Ha - van den Bergh-Hagen (open clusters) Vy - Vyssotsky (planetary nebulae) Waterloo - (open clusters) Westr - Westerlund (open clusters) b) Other Name - contains other catalog designations that the object is known by. The same abbreviations as in a) are used. c) Object Type - the type of object from the list below. Asterism Bright Nebula Cluster with Nebulosity Dark Nebula Galaxy cluster Galaxy Globular Cluster Diffuse Nebula in a Galaxy Globular Cluster in a Galaxy Cluster with Nebulosity in a Galaxy Cluster with Nebulosity in the LMC Diffuse Nebula in the LMC Globular Cluster in the LMC Open cluster in the LMC Nonexistent in RNGC (means Sulentic and Tifft couldn't find it on the POSS plates for inclusion in the RNGC) Open Cluster Planetary Nebula Cluster with Nebulosity in the SMC Diffuse Nebula in the SMC Globular Cluster in the SMC Open cluster in the SMC Quasar Unverified Southern Object Multiple Star d) Position - the object's position, Right Ascension and Declination, in the J2000.0 epoch. e) Magnitude - the object's brightness to the nearest tenth. There are many objects which have no published magnitude; they are listed as ??.?. Dark nebulae obviously have no magnitude, so they are also listed as ??.?. f) Description - a visual description of the object. Most of these are from the NGC, some are from prominent amateurs. Back issues of Deep Sky Magazine, Astronomy magazine, Sky and Telescope magazine and Burnham's Celestial Handbook are used as a source of some of these descriptions. The descriptions use the abbreviations from the NGC and Burnham's. They are given below: ! remarkable object !! very remarkable object am among n north att attached N nucleus bet between neb nebula, nebulosity B bright P w paired with b brighter p pretty (before F,B,L or S) C compressed p preceding c considerably P poor Cl cluster R round D double Ri rich def defined r not well resolved, mottled deg degrees rr partially resolved diam diameter rrr well resolved dif diffuse S small E elongated s suddenly e extremely s south er easily resolved sc scattered F faint susp suspected f following st star or stellar g gradually v very iF irregular figure var variable inv involved nf north following irr irregular np north preceding L large sf south following l little sp south preceding mag magnitude 11m 11th magnitude M middle 8... 8th magnitude and fainter m much 9...13 9th to 13th magnitude g) Size - the size of the object in minutes of arc (') or seconds of arc ("). h) Class - the class of the object. Several professional classification schemes are contained here. Trumpler type for open clusters Concentration I. Detached, strong concentration toward the center II. Detached, weak concentration toward the center III. Detached, no concentration toward the center IV. Not well detached from surrounding star field Range in brightness 1. Small 2. Moderate range 3. Large range Richness p Poor (<50 stars) m Moderately rich (50-100 stars) r Rich (>100 stars) An "n" following the Trumpler type denotes nebulosity in cluster Shapley-Sawyer concentration rating for globular clusters The values range from 1 to 12, smaller numbers are more concentrated clusters. Vorontsov-Velyaminov type for planetary nebulae 1. Stellar 2. Smooth disk (a, brighter center; b, uniform brightness; c, traces of ring structure) 3. Irregular disk (a, very irregular brightness; b, traces of ring structure) 4. Ring structure 5. Irregular form similar to diffuse nebula 6. Anomalous form, no regular structure Some very complex forms may combine two types. Hubble type for galaxies E elliptical, E0 is roundest to E7 is flattest subgroups; 'd'is dwarf, 'c'is supergiant, 'D' has diffuse halo S Spiral, 'a' has tightly wound arms, 'b' has moderately wound arms and 'c' has loosely wound arms SB Spiral with central bar Ir Irregular 5. Identify Objects The identify objects dialog box contains various information pertaining to the currently selected object. The information common to all object types includes the Right Ascension and Declination, the Altitude and Azimuth with reference to the local horizon, and the time the object rises and sets. Each object type is listed below with each one's specific information displayed in the identify objects dialog box. a) Sun - the sun's distance, in astronomical units; and its size, in minutes of arc are displayed. b) Moon - the moon's distance from the Earth, in kilometres; its size, in minutes of arc; its age, in days; and its phase are displayed. c) Planets - the planet's magnitude; its distance from the Earth, in astronomical units; its size, in seconds of arc; and its phase (0 to 1) are displayed. d) Comets - the comet's magnitude; and its distance from the Earth and the Sun in astronomical units are displayed. e) Yale Bright Star Catalogue Stars - the star's magnitude; its Bayer/Flamsteed identification; its Yale Catalogue number; its SAO Catalogue number; its Henry Draper Catalogue number; its spectral classification; its color as B-V; and its proper motion. f) Deep Sky Objects - the object's magnitude (if known); its primary and other names; its description; its size; and its object class are displayed. See section 4.2. 6. Printing Star Charts ECU does not currently support the direct printing of star charts. However, the SHAREWARE graphics program "Paint Shop", produces excellent charts with ECU. The procedure that I use is listed below. a) Start up Paint Shop. b) Set up ECU as desired in "full screen" mode. c) Switch Sky Background Color to White. d) Use the Control Menu's "Switch To..." selection to Select Paint Shop. e) Use Paint Shop's "Capture" menu to grab ECU's full screen, or part there of. f) Use Paint Shop's "Print" selection to print out the results. The lack of the feature of printing high-quality star charts is the most obvious deficiency present in ECU. The next release will have direct printing of star charts as well as several other new features from the list in section 7. 7. The Future of ECU The future of ECU depends on you. If you register it, it gives me the signal that you are using it, which will give me lots more incentive to improve it (if no one uses it, why improve it?). Below is a partial list of the features, in no particular order, which are coming in future releases of ECU. - add the position angle into moon phases - draw the moon and sun on the sky exactly as it would appear, even if it look a bit odd (ie. not round) - add dialog boxes for label and lines settings - add Dreyer deep sky object description help dialog box - add an observing list output of objects currently on the screen - add Earth's shadow for simulating lunar eclipses - add ability to paste the screen to the clipboard - add direct high-quality sky chart printing - add solar system empheris printer output - provide more realistic star brightness displays using a combination of white/black and greys and possibly colors - add more common star names and cross reference them to their Yale equivalent - add common deep sky object names and cross reference them to the deep sky database - Hubble Guide Star Catalog CDROM support - add text labels on the coordinate grid - add ability for the user to add objects - add ability to set the colors of nearly everything, plus a red mode for dark adaptation in observatory use - add support for the SGT-MAX / MicroGuider digital setting circle device - allow the user to add descriptions (an observing log) of stars and deep sky objects - add display of Jupiter's moons - add display of Saturn's moons/rings - enhancements to the manual, particularily information pertaining the astronomical calculations used and information pertaining to the accuracy obtained - improve the appearance of the sky display by adding better sky projections which will allow for larger field sizes - allow the fonts used to display text labels to be set by the user - add constellation boundaries - provide facility for the identify object dialog box to precess the objects coordinates to the current date - add changing mouse pointers during the sky redrawing process which will identify what is currently happening. - add separate deep sky magnitude limits for each deep sky type