Constellation Guide

 

Introduction

 

"Constellation Guide" is designed to view night sky map in general as well as in details. The program was designed mainly for amateurs, that is why it is containing reference number and some information from Yale Bright Star Catalogue like star names and star magnitudes. Special attention was paid to constellation boundaries, static (connected with observer) grid and dynamic (connected with catalogue coordinates) grid. In other words, the main objective of our program is to simplify observation of the night sky in general. Indeed one could easily find all specific information using a displayed catalogue number. There is no unified appearance of  constellation lines, so we chose one of the possible.

 

Sky view and map coordinates.

 

One way to display spherical data is a stereographic projection. The next picture illustrates how that projection to be constructed

Fig.1  is the image of  on a stereographic projection.

So if on the sphere there is a grid then on a stereographic projection it will look like:

 

Fig.2 Coordinates on the static grid.

So, for observer on the plane the grid on the sphere has such an appearance. That grid (static) is connected just with the observer. Indeed, sky objects are moving, but that grid allows an observer to

Because of Earth rotation sky objects are moving around the Earth axes. Next picture illustrates that rotation for different geographic latitudes. From this picture becomes clear that the less is observers latitude the more stars is available for him.

Fig 3.Sky rotation depends on an observer latitude

a) for observer on the pole    b) for observer at about 40 latitude    c)observer on the equator

 

If one projects a grid (moving grid) connected with the sphere on a stereographic projection then for the above picture it is:

 

a)                                               b)                                             c)

Fig. 4 Coordinates on the moving (with the sky) grid for the above cases.

Certainly, central zoomed picture will look like:

 

 

Fig. 5 Coordinates on the zoomed moving (with the sky) grid for the b).

 

Data Sources:

 

The Yale Bright Star Catalogue (BSC) is widely used as a source of basic astronomical and astrophysical data for stars brighter than magnitude 6.5. The catalogue contains the identifications of included stars in several other widely-used catalogues, double- and multiple-star identifications, indication of variability and variable-star identifiers, equatorial positions for B1900.0 and J2000.0, galactic coordinates, UBVRI photoelectric photometric data when they exist, spectral types on the Morgan-Keenan (MK) classification system, proper motions (J2000.0), parallax, radial- and rotational-velocity data, and multiple-star information (number of components, separation, and magnitude differences) for known non-single stars. In addition to the data file, there is an extensive remarks file that gives more detailed information on individual entries. This information includes star names, colours, spectra, variability details, binary characteristics, radial and rotational velocities for companion stars, duplicity information, dynamical parallaxes, stellar dimensions (radii and diameters), polarization, and membership in stellar groups and clusters.

 

It is available at:

http://amase.gsfc.nasa.gov/amase/MissionPages/YALEBSC.html

 

 

Constellation boundaries are computed based on the following catalogue

http://xml.gsfc.nasa.gov/archive/catalogs/6/6049/

 

 

 

Program controls

 

Installation prc file is to be installed in a usual way. Release version is to be installed without deleting the Demo version to have already chosen preferences.

 

Program designed to make possible to customize appearance of the picture and to view in details any part of the sky. Control buttons are at the left side of the screen.

                         

Fig 6. Two examples of the main screen of the program

 

The top button  is for moving screen image. Hold the pen on the screen moving from begin to end points.

 is for getting information about an object you tap. If besides BSC number and magnitude the  button appears you by tapping it you could get additional information about the sky object. By tapping  you will move the object to the center of the screen for zoom purpose. The  and  buttons are for zoom. Zoom operation works in away that the center of the picture is not moved.

The  button is for preferences. The next screenshot gives appearance of the preferences.

 

Fig. 7 Preferences screenshot.

Tip!  The less items are displayed the faster program works. Moreover, if there is no zoom (x1) to many marked items makes screen image overloaded and not readable.

 

The  button is for location, date and time settings.

 

Fig. 8 for location, date and time settings.

To set the desired value, please, tap on selector or push button.

 

 

 

 

Menu bar allows besides to find full constellation name in the CONSTELLATION LIST

Fig. 8 Menu bar.

Also it is possible use any available zoom with menu bar.

 

 

 

 

 

 

Because English is not our primary language we would be very grateful for any comments concerning improvements of this manual.

 

 

 

Vlad Yudin

Dmitry Nikolayev

 

July 17, 2003                             Dubna, Moscow region.