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SkyBase 2000.0 SkyChart Copyright 1988 - 90 Logan R. Zintsmaster Logan R. Zintsmaster 450 Spring Hill Drive Morgan Hill, CA 95037 CompuServe 71211, 2440 SkyBase 2000.0 SkyChart User's Manual Table of Contents 1. INTRODUCTION 1 1.1 PROGRAM OVERVIEW....................................2 1.2 HARDWARE REQUIREMENTS...............................3 1.3 MANUAL OVERVIEW.....................................3 1.4 SHAREWARE RELEASE CONTENTS..........................3 1.5 RETAIL RELEASE......................................3 2. TERMS AND CONDITIONS OF USE 4 2.1 COPYRIGHT NOTICE....................................4 2.2 PROGRAM LICENSE.....................................4 2.3 WARRANTY............................................4 3. OPERATING INSTRUCTIONS 5 3.1 INSTALLATION........................................5 3.2 RUNNING THE PROGRAM.................................6 4. USING SKYBASE 2000.0 SKYCHART 7 4.1 KEYBOARD............................................7 4.2 MOUSE SUPPORT.......................................8 4.3 OPENING SCREEN......................................8 4.4 MAIN SCREEN.........................................8 4.5 CONFIGURATION SCREEN................................9 4.6 FINDER VIEW SCREEN..................................11 4.7 MAP VIEW SCREEN.....................................14 5. PLOT DISPLAY 18 6. NOTES 20 6.1 BUGS................................................20 6.2 DATABASES...........................................20 6.2.1 Star Databases....................................20 6.2.2 Non-Stellar Databases.............................20 6.2.3 Database Accuracy.................................21 6.2.4 Printer Aspect Ratios.............................21 SkyBase 2000.0 SkyChart User's Manual Copyright 1988 - 90 Logan R. Zintsmaster ALL RIGHTS RESERVED 1. INTRODUCTION SkyBase 2000.0 SkyChart was written as shareware to make sky charts that are oriented the way you need them: normal, inverted, or mirror image. The sky charts can cover the whole sky or just enough to star hop with your finder scope to the selected object. SkyBase 2000.0 SkyChart was designed to use a disk database format so you can select the database with enough data to be useful but not so much as to be confusing. Current databases are constructed from the Yale Bright Star Catalog, the Smithsonian Astrophysical Observatory star catalog, the Messier objects, a collection of "best" NGC objects, and the Saguaro Astronomy Club catalog. As new data sources become available, new databases will be added. The program can be used with a graphics-capable IBM compatible computer, including lap-tops, and can produce hardcopy on an Epson or IBM compatible dot matrix printer. - Page 1 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual 1.1 PROGRAM OVERVIEW The initial requirement for SkyBase 2000.0 SkyChart was to produce finder charts for users of telescopes which have an odd number of reflecting surfaces. This optical configuration produces a mirror image, that is, upright but left-right reversed. Conventional practice to develop finder charts is to trace the required area of the sky from a sky chart, then flip the paper over and shine a light through it. SkyBase 2000.0 SkyChart does this electronically and more. The features of SkyBase 2000.0 SkyChart include: - Generation of Finder Charts: You pick chart center and size and field of view of your finder scope or telescope. - Generation of Star Charts: You pick the Right Ascension and Declination limits. - Display either erect, inverted, or mirror image, with or without grid lines. - Selectable limiting magnitudes, objects, and databases. - Available databases include data from the Yale Bright Star Catalog, SAO Star Catalog, Messier Objects, a collection of "Best" NGC objects, and the SAC 5.0 database of non-stellar objects. - Display configurable for lap-top screens for use at the telescope. - CGA/EGA compatible with Microsoft Mouse support. - Screen oriented input with fill-in-the-blank data entry for ease of use. - Hardcopy output for Epson and IBM compatible dot matrix printers. The next question on your mind is likely to be, "But does it work?" Yes, it does. I have taken SkyBase 2000.0 SkyChart and my lap-top out to my telescope and used it to find several Messier objects. The objects were found by matching the SkyBase 2000.0 SkyChart display of the field around the object with the view in my finder scope. When I switched to the eyepiece, the object was there to be seen. In my book, that's the acid test. So much for the editorial, now enjoy the program. - Page 2 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual 1.2 HARDWARE REQUIREMENTS SkyBase 2000.0 SkyChart runs on an IBM PC or PC compatible with 512kB of memory, a CGA, EGA, or compatible display, either monochrome or color monitor, and one or two floppy disk drives (depending on the databases used), or 1 MB of hard disk space. It will also operate on an IBM compatible lap-top. 1.3 MANUAL OVERVIEW The manual for SkyBase 2000.0 SkyChart is simple and straightforward. Each of the input screens is described, as well as the plot display. The input fields in these screens are discussed and the operation presented. The special keys used on the keyboard are also explained. SkyBase 2000.0 SkyChart was designed to be easy to use, so it is hoped that this manual will not be needed often. 1.4 SHAREWARE RELEASE CONTENTS The shareware release of SkyBase 2000.0 SkyChart contains a fully functional program plus a stellar database, a non-stellar database, and a text file for producing this manual on a printer. This package is a reasonable size for downloading. Due to their sizes, the other databases are mailed upon request. Operation of SkyBase 2000.0 SkyChart is not changed, only more objects are available for plotting. 1.5 RETAIL RELEASE A retail version, SkyBase 2000.0 Plus, is also available. This version incorporates the features of the shareware release and adds on screen identification of non-stellar objects, additional hardcopy information, and stellar data to magnitude 10 (258,000 stars). The registration fee (less sales tax) for the shareware version may be applied to the cost of the retail version. Shipping and handling are $4.00 additional. - Page 3 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual 2. TERMS AND CONDITIONS OF USE 2.1 COPYRIGHT NOTICE The SkyBase 2000.0 SkyChart program and documentation are protected under the copyright laws of the United States. The Runtime module is copyrighted by Microsoft Corporation. The SkyBase 2000.0 SkyChart program, character fonts, screen displays, and databases are copyrighted by Logan R. Zintsmaster. All rights are reserved. 2.2 PROGRAM LICENSE SkyBase 2000.0 SkyChart is licensed to the user under the "shareware" concept for use on a single or subsequent computer by a single user. Non- registered users are granted a limited license to use SkyBase 2000.0 SkyChart on a trial basis. A user is authorized to make copies and distribute the program, freely, as long as no copyright or license notices are removed; all documentation is included; and no fee, compensation, or other charge is accepted or requested. SkyBase 2000.0 SkyChart may be posted on electronic bulletin board systems for downloading by their users, providing the above conditions are met. All rights are reserved by the author. Should SkyBase 2000.0 SkyChart be found useful, a license registration fee of $25.00 shall be sent to the author (CA residents, please add 7% sales tax), Logan R. Zintsmaster 450 Spring Hill Drive Morgan Hill, CA 95037 Registered users will receive a printed manual with a menu map, the latest version of SkyBase 2000.0 SkyChart, and all available databases. Retention and use of SkyBase 2000.0 SkyChart by a user shall be construed as accepting this license agreement and the terms and conditions of use specified herein. If the terms and conditions are unacceptable, a user shall destroy or erase his copy(s) of the program, data files, and documentation. 2.3 WARRANTY There are no warranties, expressed or implied, and any such warranty is expressly disclaimed including but not limited to implied warranties of merchantability and fitness for a particular purpose either with respect to defects in a supplied diskette, documentation, and the program license granted herein in particular, and without limiting operation of the program license with respect to any particular application, use or purpose. In no event shall anyone developing, using, or distributing this program be liable for any loss of profit or any other commercial damage, including but not limited to special, incidental, consequential or other damages. - Page 4 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual 3. OPERATING INSTRUCTIONS 3.1 INSTALLATION The files associated with SkyBase begin with the prefix 'SKY'. To install SkyBase 2000.0 SkyChart on a hard disk, create a subdirectory with an appropriate name, like 'SKYBASE'. For example, on the C drive, the command to do this is MD C: \ SKYBASE ----------------------------------------------------------------- ----------------------------------------------------------------- Please note that keyboard entries will be presented on a separate line, or when embedded in text, surrounded by single quotes. When making the entries, do not enter the single quote marks. All DOS commands are ended by pressing the 'Enter' key, which will not be shown, explicitly. ----------------------------------------------------------------- ----------------------------------------------------------------- Place the Program disk in your floppy drive and copy all files into the subdirectory. Next, remove the Program disk and insert any Data disks. Copy all the files to the subdirectory. For example, to copy all the files on a floppy in the A drive, use the command COPY A: *.* C: \ SKYBASE Repeat this until all data disks have been copied. When installation of the downloaded version is complete, the following files are needed for execution and should be in the subdirectory. SKYBASE.EXE SkyBase executable SKYBAS87.EXE SkyBase executable for 80x87 (registered users only) SKYBASE.CGA Font File for CGA SKYBASE.EGA Font File for EGA SKYBASE.MDA Font File for EGA on Monochrome Display SKYYLE.RND Yale Bright Star Catalog data SKYYLE.NDX Yale Bright Star Catalog index SKYMESS.RND Messier Objects data SKYMESS.NDX Messier Objects index SKYSAO.RND Star data from SAO Catalog (registered users only) SKYSAO.NDX Star data from SAO Catalog index (registered users only) SKYNGC.RND NGC Objects data (500 objects) (registered users only) SKYNGC.NDX NGC Objects index (registered users only) SKY.CFG Configuration data - Page 5 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual The following files contain the manual and user registration form, respectively. SKYBASE.DOC Shareware version manual SKYREGS.FRM Shareware registration form 3.2 RUNNING THE PROGRAM To run SkyBase 2000.0 SkyChart, change directories to the SkyBase subdirectory and start the program by using the command: 'SKYBASE'. For example, using the subdirectory described earlier the commands to start the program are: CD C: \ SKYBASE C: SKYBASE Once loaded, the copyright message is presented and the program begins execution. To try out SkyBase 2000.0 SkyChart, the following coordinates are suggested for the Finder Screen. Orion Right Ascension 5.30 Declination 0 Chart FOV 15 Big Dipper Right Ascension 12.30 Declination 55 Chart FOV 30 Sagittarius Right Ascension 18.40 Declination -30 Chart FOV 12 In the Map Screen, it is interesting set the ranges to plot the full 24 hour Right Ascension range over the full 180 degree Declination range and note the dense band of stars that constitute the Milky Way. - Page 6 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual 4. USING SKYBASE 2000.0 SKYCHART As stated in the introduction, SkyBase 2000.0 SkyChart was designed to be easy to use. This section describes the keys used to control the program, the five input screens used to control its operation, and, finally, the plotted data. 4.1 KEYBOARD SkyBase 2000.0 SkyChart is controlled by a series of fill-in-the-blank screens. To enter data, several keys are used to control the data entry process. These are discussed below. The 'Enter' key finishes a field but generally does not conclude the entry processing for the screen. This is reserved for the 'End' key on the numeric keypad (the '1' key) or the 'F10' function key. One exception is in the Main Screen where there is only one entry field. Pressing the 'Enter' key will cause the selection to be processed. The other exception is at the end of a sky plot. Pressing the 'Enter' key will return to the Main Screen. The 'End' and 'F10' function key are used to signal the end of the input to a screen. When either of these keys are pressed, the actions entered on the screen are performed. 'Del' and the 'Backspace (<-)' keys perform their usual functions. 'Del' deletes the character under the cursor. 'Backspace' deletes the character to the left of the cursor and moves the cursor one space to the left. The Insert key, 'Ins', is not implemented because the fields are small. The 'Esc' key stops the current action and returns to the previous screen. The Numeric keypad is automatically set to the cursor control mode (i.e. 'NumLock' is disabled.) During data entry, the arrow keys can be used to move within a field or from field to field. If you wish to use the keypad to enter data, press the 'Shift' key to enter numbers; release it to move the cursor. The screen fields carry default settings on program startup or the values from the previous entry. These defaults will be discussed in detail for each screen. On-screen messages are provided at the bottom of the screen as prompts. These messages explain which keys to press to accomplish the next action in the sequence. - Page 7 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual 4.2 MOUSE SUPPORT If a Microsoft compatible mouse is available, it can be used to select screen fields to be changed, enter input values, signal the end of input, and select the plotting center for a Finder Chart. It can be used in the Main Screen, Map View Screen, and Finder View Screen. It can not be used in the Configuration Screen. When entering data, clicking the left button will cycle the character under the cursor through the sequence of acceptable input values. Clicking the right button has the same effect as pressing the 'End' key. Please note that when using a Microsoft Bus Mouse with an EGA display, the mouse driver must be version 6.11 or later. Otherwise, the arrow will not appear in the Plot Screen. 4.3 OPENING SCREEN When SkyBase 2000.0 begins execution, the licensing and copyright screen is displayed. To continue, press any key. 4.4 MAIN SCREEN The Main Screen allows you to select one of three input screens in SkyBase 2000.0 SkyChart or to exit the program. Each of these selections is chosen by means of a single letter entry. When the letter has been entered in the field, press the 'F10', 'End' or 'Enter' key. The data files which are currently in use are shown on this screen for reference. They may be changed with the Configuration selection as will be described later. Also shown on the screen is the Local Sidereal Time (LST) at midnight (0 hours) Local Mean Time (LMT) for the date read from the system clock. This value of LST is used to create a default set of parameters for a full sky map centered on this time. In some cases, SkyBase 2000.0 SkyChart will be used on the evening following the calculated LST; however, this shifts the chart only 4m in Right Ascension, a tolerable amount for most uses. If desired, these default values can be changed when the Map Screen is entered. - Page 8 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual Four selections are possible in the Main Screen: C - Configuration: Configure SkyBase 2000.0 SkyChart for the selected databases, display type, and screen size. F - Finder: Display a finder chart centered around an object or a point of Right Ascension and Declination. M - Map: Display a section of the sky using Right Ascension and Declination limits. Q - Quit: Stop the program and return to DOS. Each of these selections will be discussed in detail. 4.5 CONFIGURATION SCREEN The Configuration Screen is used to tell SkyBase 2000.0 SkyChart where the database files are located and the dimensions of your display. The Configuration Screen can be entered from the Main Screen at any time during execution. The Configuration Screen consists of the following fields. Star Database File: Enter the full pathname of the file to be used for the star database. The path should start at the drive and include the file name without the file extension (i.e. the three letters after the period in the filename shown in the disk directory.) Following the installation example above, the entry for the Yale Bright Star Catalog on a hard disk system would be: C: \ SKYBASE \ SKYYLE On a floppy based system, with the data on drive B:, the command would be: B: \ SKYYLE The Notes section contains the names of the star databases that are currently available. These database file names are also shown at the bottom of the configuration screen. Non-Stellar Database File: Enter the full pathname of the file to be used for the non-stellar objects database. The path should start at the drive and include the file name without the file extension (i.e. the three letters after the period in the filename shown in the disk directory.) - Page 9 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual Following the installation example above, the entry for the Messier Object database would be: C: \ SKYBASE \ SKYMESS On a floppy based system, with the data on drive B:, the command would be: B: \ SKYMESS The Notes section contains the names of the star databases that are currently available. These database file names are also shown at the bottom of the configuration screen. Monitor: Select the type of display that you would like on the monitor. There are three selections: B - Used for single color or monochrome displays. R - Used for single color or monochrome displays but reverses black and white when plotting. May be used for backlit LCD displays, at night. C - Used for color displays, especially EGA or VGA monitors. Star magnitudes are both color coded and size coded. Horizontal Screen Size: Enter the horizontal dimension of the displayed area of the screen. Vertical Screen Size: Enter the vertical dimension of the displayed area of the screen. ----------------------------------------------------------------- ----------------------------------------------------------------- Note: These dimensions are not the screen size since the commonly quoted screen size (i.e. 14" monitor) is a diagonal, corner to corner measurement of the screen. The horizontal and vertical dimensions can be measured from the double line box displayed on the screen during execution since it is plotted at the display size limits. ----------------------------------------------------------------- ----------------------------------------------------------------- Printer Type : 1 - For Epson MX/FX 80 type printers, IBM Graphics printers, or printers which emulate these models, such as the Okidata printers with Plug 'N Play (a registered trademark of Okidata). 2 - For the Epson FX-86 and later model printers, IBM Proprinters, or models which emulate either of these printers. - Page 10 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual It is important to note the impact of screen size and printer type on the hardcopy output. In some cases, the horizontal and vertical sizes which produce a round circle on the display will produce an ellipse on the hardcopy output. This problem will be encountered when using a lap-top computer with the short, wide LCD display, like that seen on the NEC, Toshiba, and Sharp models. To determine the sizes for hardcopy output, set both the Horizontal Size and Vertical Size to 1 and make a Finder chart. Measure sides of the chart and use these values for the Horizontal Size and Vertical Size. The Notes section contains some typical values. Once these values are determined, you may use the actual screen size to obtain the correct sky mapping parameters. When you are happy with the display, enter the Configuration Screen and enter the horizontal and vertical size needed for the printed copy. The mapping parameters are held in the other screens, so it is easy to return to the previous field screen, re-plot the display, and then print it. Alternatively, you can set the screen size to the nominal size required by the printer when you begin and not worry about the elongation on the screen display while you select the mapping parameters. The printed output will have the proper shape. The screen size can also be used in the Finder View for all plot types and the Map View for the Lambert type to distort the display to meet other needs, such as a skychart for a column in a newsletter. Increasing the horizontal dimension will cause the chart to shrink in the Right Ascension axis. Increasing the vertical dimension will cause the chart to shrink in the Declination axis. When all entries are complete, press the 'End' key to return to the Main Screen. 4.6 FINDER VIEW SCREEN The Finder View Screen contains the fields for specifying a Finder Chart centered on an object or a point specified by Right Ascension and Declination. The plotted chart will contain a circle which represents the field of view entered for your finder scope, a smaller circle, 45' (arc minutes) in radius, which is used in many finder scopes for polar alignment, and cross-hairs in Right Ascension and Declination. - Page 11 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual The Finder View Screen consists of several fields used to specify the location, the size, and the type of objects plotted. The fields are described below. Viewing Center R.A.: Enter the Right Ascension for the center of the Finder Chart. The form of entry is two digits for the hour, a decimal point, and then two digits for the minutes. For example: 5.30 corresponds to 5h 30m, the nominal location of the Orion constellation. Alternatively, the number of a Messier object can also be entered, in the form ' Mnnn '. When using this form of entry, it is not necessary to enter the Declination. For example, the Andromeda Galaxy can be selected by entering ' M31 ' in the Right Ascension field. SkyBase 2000.0 SkyChart will determine the location of the object and insert the appropriate values for Right Ascension and Declination. Viewing Center Declination: Enter the Declination for the center of the Finder Chart. The entry should be in decimal degrees and include the minus sign ' - ' for the Southern sky. If the Messier number has been entered into the Right Ascension field above, an entry in this field is not required. The next set of fields are used to specify how much of the sky is plotted on the screen. Finder field of view: The entry for this field is the field of view for your finder scope, in degrees. When the chart is plotted, the Finder field of view will be shown as a circle on the chart. Inside the Finder circle is a circle whose radius is 45', corresponding to the polar alignment circle found in many finder scopes. If zero (0) is entered, the circles and cross- hairs will not be plotted. Chart field of view: The overall size of the plotted chart, in degrees, is entered in this field. This parameter may be larger or smaller than the Finder field of view, entered above. If the Chart field of view is larger than the Finder field of view, then the plotted chart can be used to star-hop to the desired location. If the Chart field of view is smaller, then it has the effect of magnifying the Finder field of view. In this case, the cross-hairs may extend past the chart limits as a reminder that the Finder field of view extends past the plotted chart. Based on these entries, SkyBase 2000.0 SkyChart calculates the needed Right Ascension and Declination limits for the plot. These limits are automatically entered in the Map View Screen, which will be discussed later. - Page 12 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual The next series of entries are used to control the plotting of the chart. SkyBase 2000.0 SkyChart has four types of plotting transformations which can be used to plot the celestial sphere data onto a two dimensional surface. The plot can be erect, mirror image, or inverted and grid lines may be added, if desired. Plot Type: Select the desired plotting transformation. R - The Rectangular Plot Type places Right Ascension along the x-axis and Declination along the y-axis without any transformation. This representation is fairly accurate for twenty (20) degrees around the Celestial Equator. But at the poles it is highly inaccurate, since it stretches the pole completely across the screen. Plotting data using this plot type is very fast. C - The Cosine Plot Type accounts for the fact that the distance between lines of constant Right Ascension converge as they approach the poles. The convergence is proportional to the cosine of the Declination. E - The Elliptical Plot Type maps the Celestial sphere onto an ellipse similar to a Mollweide projection. L - The Lambert Plot Type uses a conical transformation to generate the plot. This type of transform should be used above 45 degrees Declination, and must be used near the poles. However, it involves lots of calculation and plots slowly. Image Type: Enter the type of image display desired for the plot. N - Display a Normal image, that is, North Celestial Pole at the top, South Celestial Pole at the bottom, Right Ascension increasing from right to left. I - Display an Inverted image, that is, North Celestial Pole at the bottom, South Celestial Pole at the top, Right Ascension increasing from left to right. M - Display a Mirror image, that is, North Celestial Pole at the top, South Celestial Pole at the bottom, Right Ascension increasing from left to right. Grid Lines: Enter 'Y' for a grid lines at major axis points. Enter 'N' for no grid lines. - Page 13 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual The next series of fields are used to control the objects that are plotted. Plot NGC: Enter 'Y' to plot the objects in the non-stellar database. Enter 'N' to prevent plotting. Plot stars: Enter 'Y' to plot the stars in the stellar database. Enter 'N' to prevent plotting. Magnitude Limit: Enter the largest magnitude to be plotted. Enter '9' to plot all stars. If the database in use does not have stars to the magnitude selected here, no additional stars will be plotted. When all entries are complete, press the 'End' key to start the plotting. 4.7 MAP VIEW SCREEN The Map View Screen contains the fields for specifying a star chart which is plotted between user specified limits of Right Ascension and Declination. When this screen is entered the first time, default limits are set to center a chart on the LST of local midnight. This time is shown in the lower left corner of the screen. When a Finder Chart has been plotted, this screen will contain the Right Ascension and Declination limits used to plot the Finder Chart. The Map View Screen consists of several fields which are used to specify the location, the size, and the type of objects plotted. The fields are described below. Low limit of R.A.: Enter the Right Ascension for the right-hand side of a Normal Image Map Chart. The form of entry is two digits for the hour, a decimal point, then two digits for the minutes. For example: 5.30 corresponds to 5h 30m. High limit of R.A.: Enter the Right Ascension for the left-hand side of a Normal Image Map Chart. The form of entry is two digits for the hour, a decimal point, then two digits for the minutes. For example: 5.30 corresponds to 5h 30m. ----------------------------------------------------------------- ----------------------------------------------------------------- If the chart crosses the 23h 59m 0h 0m boundary, enter the Low Limit normally. For the High Limit, enter the desired value, plus 24 hours. For example, for a chart covering the sky from 23h to 5h, the entries would be: 23.00 and 29.00, respectively. ----------------------------------------------------------------- ----------------------------------------------------------------- - Page 14 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual Low limit of Declination: Enter the Declination for the lower boundary of Normal Image Map Chart. The entry should be in decimal degrees and include the minus sign '-' for the Southern sky. High limit of Declination: Enter the Declination for the upper boundary of a Normal Image Map Chart. The entry should be in decimal degrees and include the minus sign '-' for the Southern sky. It is not necessary to account for the negative signs in deciding which is the lower boundary and which is the upper boundary in these entries. SkyBase 2000.0 SkyChart will take care of the problem for you. The limits will be adjusted so that the North Celestial pole is at the top and the South Celestial pole is at the bottom of the chart (Normal Image). The Messier Object selection, which can be used in the Finder View Screen, can not be used in the Map View Screen. However, if a Messier Object is selected in the Finder View Screen and plotted, the Map View Screen will automatically default to the Right Ascension and Declination limits used in the Finder plot. They can then be extended or narrowed, as desired. The next series of entries are used to control the plotting of the chart. SkyBase 2000.0 SkyChart has four types of plotting transformations which can be used to plot the celestial sphere data onto a two dimensional surface. The plot can be erect, mirror image, or inverted and grid lines may be added, if desired. - Page 15 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual Plot Type: Select the desired plotting transformation. R - The Rectangular Plot Type places Right Ascension along the x-axis and Declination along the y-axis without any transformation. This representation is fairly accurate for twenty (20) degrees around the Celestial Equator. But at the poles it is highly inaccurate, since it stretches the pole completely across the screen. Plotting data using this plot type is very fast. C - The Cosine Plot Type accounts for the fact that the distance between lines of constant Right Ascension converge as they approach the poles. The convergence is proportional to the cosine of the Declination. E - The Elliptical Plot Type maps the Celestial sphere onto an ellipse similar to a Mollweide projection. L - The Lambert Plot Type uses a conical transformation to generate the plot. This type of transform should be used above 45 degrees, Declination. However, it involves lots of calculation and plots slowly. Image Type: Enter the type of image display desired for the plot. N - Display a Normal image, that is, North Celestial Pole at the top, South Celestial Pole at the bottom, Right Ascension increasing from right to left. I - Display an Inverted image, that is, North Celestial Pole at the bottom, South Celestial Pole at the top, Right Ascension increasing from left to right. M - Display a Mirror image, that is, North Celestial Pole at the top, South Celestial Pole at the bottom, Right Ascension increasing from left to right. Grid Lines: Enter 'Y' for a grid lines at major axis points. Enter 'N' for no grid lines. - Page 16 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual The next series of fields are used to control the objects that are plotted. Plot NGC: Enter 'Y' to plot the objects in the non-stellar database. Enter 'N' to prevent plotting. Plot stars: Enter 'Y' to plot the stars in the stellar database. Enter 'N' to prevent plotting. Magnitude Limit: Enter the largest magnitude to be plotted. Enter '9' to plot all stars. If the database in use does not have stars to the magnitude selected here, no additional stars will be plotted. Uniform star size: Enter 'Y' if the stars should be plotted with their size determined by magnitude. Enter 'N' if they are to plotted the same size. When 'N' is selected, the stars will be plotted at their minimum size to reduce the overlap in the chart. When all entries are complete, press the 'End' key to start the plotting. - Page 17 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual 5. PLOT DISPLAY Once all parameters are entered into either the Chart or Finder View Screen and the 'End' key pressed, the plotting begins. The grid boundaries are plotted first, followed by the stars and non-stellar objects. The plotting may be terminated at any time by pressing the 'Esc' key. Both stellar and non-stellar objects are plotted. The stars are plotted as circles which are then filled. In some cases, two stars will be plotted on top of each other and the larger circle will not be filled completely. This is a minor quirk in the screen display routines which has not yet been circumvented for CGA displays. Since EGA and VGA displays use color as well as size, this effect will not be seen. In that case, two different colored stars are plotted. It will also be noted, that objects which are plotted close to the chart boundaries will extend past the limits of the chart. This is not a problem and represents common practice for star charts. The Map View display is sized to fit all of the available screen area. In this case, the relation: "One hour of Right Ascension equals fifteen degrees of Declination at the equator" does not hold true. However, the Finder View is scaled properly in both Right Ascension and Declination and the "one hour equals fifteen degrees" relationship is maintained. When the plotting is complete, a message is displayed at the bottom of the screen. If the 'Enter' key is pressed, the program returns to the previous screen. If the 'P' key is pressed, then a hardcopy of the screen is printed. This process takes longer than the usual print screen operation since SkyBase 2000.0 SkyChart prints the screen in the portrait mode and expands the vertical lines to correct for the 8.5 by 11 inch paper aspect ratio. Pressing the 'Esc' key will stop the printing. When a mouse is present, an additional option is possible. A pointer is displayed which can be positioned with the mouse. Left to right movement of the mouse moves the pointer in Right Ascension. Up and down movement moves the pointer in Declination. The current pointer location is displayed in the lower left corner of the screen. It is important to note that the mouse pointer movement is affected by the transformation selected. For example, if the display is a Lambert plot about the celestial pole, then left-right motion for Right Acension results in a rotation about the pole and up-down motion for Declination becomes radial motion from the pole. Once a new chart center is selected, pressing the left button will replot the diagram, using the parameters set previously. If the original plot was a Map View, then the new plot will be a Finder View plotted at the selected center. If the plot was a Finder View, a new Finder View, centered on the new position, will be plotted. The display limits are updated automatically to the new center. Pressing the right button will return the program to the Main Screen. - Page 18 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual 6. NOTES 6.1 BUGS This program has been extensively tested by some pretty tricky people, but if you find a problem, please let me know. You can leave a message on CompuServe: 71211, 2440 or put the US Post Office to work. I would also like to hear your suggestions for improvements and enhancements. 6.2 DATABASES Several databases have been constructed for use with SkyBase 2000.0 SkyChart. They are listed below, along with the title of the source data used in their construction. It is important to note that much of the original data has been removed to achieve a practical size. 6.2.1 Star Databases The following star databases are available. SKYYLE: From the Yale Bright Star Catalog, 4th Edition. Contains over 9,000 stars to magnitude 6. File names: SKYYLE.RND, SKYYLE.NDX This is a good catalog to use when making charts to use for visual and binocular observations. With fewer stars, plots are faster. SKYSAO: From the Smithsonian Astrophysical Observatory catalog. Contains over 45,000 stars to magnitude 8.0 File names: SKYSAO.RND, SKYSAO.NDX 6.2.2 Non-Stellar Databases The following non-stellar object databases are available. SKYMESS: The Messier objects. File names: SKYMESS.RND, SKYMESS,NDX SKYNGC: Over 400 "Best" NGC objects from a public domain file and cross-checked against SAC 5.0. File names: SKYNGC.RND, SKYNGC.NDX SKYSAC: From the SAC 5.0 database of nonstellar objects by the Saguaro Astronomy Club of Phoenix, AZ. Contains over 10,000 entries. File names: SKYSAC.RND, SKYSAC.NDX - Page 19 - (V 4.6) SkyBase 2000.0 SkyChart User's Manual 6.2.3 Database Accuracy The databases used in SkyBase 2000.0 SkyChart have been obtained from public sources and they are believed to be accurate. However, their absolute accuracy can not be guaranteed due to the sheer number of entries. If a discrepancy is suspected, a reference sky atlas or catalog should be used for a cross-check. 6.2.4 Printer Aspect Ratios Unfortunately, the print head spacings and vertical paper movements do not match the aspect ratios of the various screen displays. Thus, it is necessary to change the horizontal and vertical sizes in the Configuration Screen to produce a correct hardcopy. The following table contains values which I have determined for several configurations. These should provide a good starting point. Printer Type 1 2 H V H V CGA Monitor 4.56 4.78 6.08 4.78 EGA Monitor 4.43 4.07 5.92 4.07 As mentioned previously, if you want to determine your own values, set the Horizontal and Vertical sizes to 1 and make a Finder View plot. Measure the sides of the chart along the axis borders and use these values for the Horizontal and Vertical sizes. - Page 20 - (V 4.6)