KStars Guide the feature-rich planetarium: KStars Tools, Object Details Window, The Astrocalculator.

Object Details Window

The Object Details Window presents advanced data available about a specific object in the sky. To access this tool, right-click on any object, and select the Details... item from the popup menu.

The window is divided into a number of tabs. In the General tab, we present basic data about the current object. This includes names and catalog designations, object type, and magnitude (brightness). On the Position tab are the object’s Equatorial and Horizontal coordinates, as well as its rise, set and transit times.

In the Links tab, you can manage the internet links associated with this object. The Image and Information links associated with the object are listed. These are the links that appear in the popup menu when the object is right-clicked. You can add custom links to the object with the Add Link... button. This will open a window in which you fill in the URL and link text for the new link (you can also test the URL in the web browser from this window). Every time you add a custom URL to a certain object, you are able to choose the resource type using the Resource Type button. Keep in mind that the custom link can easily point to a file on your local disk, so you can use this feature to index your personal astronomical images or observing logs.

You can also modify or remove any link using the Edit Link... and Remove Link... buttons.

The Advanced tab (not available for all objects) allows you to query professional astronomical databases on the internet for information regarding the current object. To use these databases, double click on the desired database in the list to see the results of your query in a web browser window. The query is made using the primary name of the object you clicked on to open the Details Dialog. The following databases are available for querying:

• Set of Identifications, Measurements, and Bibliography for Astronomical Data (SIMBAD): SIMBAD is similar to NED, except it provides data about all kinds of objects, not just galaxies.

• SkyView: Provides images from All-Sky surveys that have been performed in dozens of different parts of the spectrum, from Gamma Rays to the Radio. The KStars interface will retrieve an image from any of these surveys, centered on the selected object.

• High Energy Astrophysical Archive (HEASARC): Here you can retrieve data about the current object from a number of “High-energy” observatories, which covers the Ultraviolet, X-ray and Gamma Ray portions of the electromagnetic spectrum.

• NASA/IPAC Extragalactic Database (NED): NED provides encapsulated data and bibliographic links about extragalactic objects. You should only use NED if your target is extragalactic; i.e. if it is itself a galaxy.

• NASA Astrophysical Data System (ADS): This incredible bibliographic database encompass the entire body of literature published in international peer-review Journals about astronomy and astrophysics. The database is divided into four general subject areas (Astronomy and Astrophysics, Astrophysics Preprints, Instrumentation, and Physics and Geophysics). Each of these has three sub-nodes that query the database in different ways. “Keyword search” will return articles which listed the object’s name as a keyword. “Title word search” will return articles which included the object name in their Title, and the “Title & Keyword search” uses both options together.

• Multimission Archive at Space Telescope (MAST): The Space Telescope Science Institute provides access to the entire collection of images and spectra taken with the Hubble Space Telescope, as well as several other space-based observatories.

Finally, in the Log tab, you can type in some text that will remain associated with this object’s Details window. You could use this to attach personal observing notes, for example. Your notes will be saved, such that you can easily read or use them next time when you will use KStars.

The KStars Astrocalculator provides several modules that give you direct access to algorithms used by the program. The modules are organized by subject:

Time Calculators

• Julian Day

• Sidereal Time

• Almanac

• Equinoxes and Solstices

Coordinate Converters

• Equatorial/Galactic Coordinates

• Apparent Coordinates

• Horizontal Coordinates

• Ecliptic Coordinates

• Angular Distance

• Geodetic Coordinates

Solar System

• Planets Coordinates

Julian Day module

This module converts between the calendar Date and time:, the Julian day:, and the Modified julian day:. The Modified Julian Day is simply equal to the Julian Day - 2,400,000.5.

To use the module, enter one of the three dates and the corresponding values for the other two date systems will be displayed. You can also set the Date and time to now, by pressing the Now button.

There is a batch mode for this module. To use it, simply generate an input file whose lines each contain a number of values for the input parameter: “Date and time”, “Julian day” or “Modified Julian day”. Then specify the input and output filenames, and press the Compute button to generate the output file. The output file will contains values for the other two complementary parameters. For example, if your input file contains a set of Date and time: values, then each line of the output file will contain values for Julian day: and Modified julian day:. You can read the output directly in KStars by pressing the View output... button.

Tip

Exercise:

What calendar date does MJD = 0.0 correspond to?

Sidereal Time module

This module converts between Universal Time and Local Sidereal Time. First, select a geographic location and a date for the calculation. Then the corresponding value for the other Time will be displayed.

There is a batch mode for this module. To use it, simply generate an input file whose lines each contain values for the input parameter: Compute sidereal time or Compute standard time from to left dropdown box. You can choose to set the Date: and Location: in the current window, or you can tell KStars to read these values from the Input file:. Then specify the input and output filenames, and press the Compute button to generate the output file. The output file will contains values for the complementary parameter. For example, if your input file contains a set of “standard time” values, then each line of the output file will contain values for “sidereal time”. You can read the output directly in KStars by pressing the View output... button.

Day Duration module

This module computes the length of day as well as sunrise, sun-transit (noon), and sunset times for any calendar date, for any location on Earth. First select the desired geographic coordinates and date, then the data is computed and displayed.

Equinoxes and Solstices module

The Equinoxes and Solstices module calculates the date and time of an equinox or solstice for a given year. You specify the year and the date and time of the events (Vernal Equinox, Summer Solstice, Autumnal Equinox, or Winter Solstice) are displayed.

There is a batch mode for this module. To use it, simply generate an input file whose lines each contain a year for which the Equinox and Solstice data will be computed. Then specify the input and output filenames, and press the Compute button to generate the output file. Each line in the output file contains the input year and the date of each event. You can also read the output directly in KStars by pressing the View output... button.

Equatorial/Galactic Coordinates module

This module converts from Equatorial coordinates to Galactic coordinates, and vice versa. Fill in the coordinate values in either the Galactic coordinates or Equatorial coordinates (J2000) section. Alternatively set the equatorial coordinates by selecting an object using the Find Object dialog. Then the complementary coordinates will be filled in.

The module contains a batch mode for converting several coordinate pairs at once. You must construct an input file in which each line contains two values: the input coordinate pairs (either Equatorial or Galactic). Then specify which coordinates you are using as input, and identify the input and output filenames. Finally, press the Run button to generate the output file, which will contain the converted coordinates (Equatorial or Galactic; the complement of what you chose as the input values).

Apparent Coordinates module

The Apparent Coordinates module converts the catalog coordinates of a point in the sky to its apparent coordinates for any date. The coordinates of objects in the sky are not fixed, because of precession, nutation and aberration. This module takes these effects into account.

To use the module, first enter the desired target date and time in the Target Time & Date section. Then, enter the catalog coordinates in the Catalog Coordinates section. Alternatively you can set the catalog coordinates by selecting an object using the Find Object dialog. You can also specify the catalog’s epoch here (usually 2000.0 for modern object catalogs). Then the object’s coordinates for the target date will be displayed in the Apparent coordinates: section.

Horizontal Coordinates module

This module converts from Equatorial coordinates to Horizontal coordinates. First, select the date, time, and geographic coordinates for the calculation. Then, fill in the equatorial coordinates to be converted or use the Find Object dialog in the Equatorial Coordinates (J2000) section. The corresponding Horizontal coordinates will be presented in the Horizontal Coordinates section.

Ecliptic Coordinates module

This module converts between Equatorial coordinates and Ecliptic coordinates. First, select Date and time:. Then, fill in the coordinate values in either the Ecliptic Coordinates or Equatorial Coordinates section. Alternatively set the equatorial coordinates by selecting an object using the Find Object dialog. Then the complementary coordinates will be filled in.

Angular Distance module

The Angular Distance tool is used to measure the angle between any two points on the sky. You simply specify the Equatorial coordinates of the desired pair of points, and then obtain the angle between the two points.

There is also a Batch mode for this module. In batch mode, you specify an input filename which contains a number of parameters (up to four) on each line: the initial right ascension (RA), initial declination (Dec), final right ascension and final declination. By default, each line should contain four numbers signifying the RA and Dec values for pairs of points. Alternatively, you can specify a single value for any of these four coordinates in the calculator panel (the corresponding values in the input file should be skipped if they are specified in the calculator).

Once you have specified the input filename and an output filename, simply press the Run button to generate the output file.

Geodetic Coordinates module

The normal geographic coordinate system assumes that the Earth is a perfect sphere. This is nearly true, so for most purposes geographic coordinates are fine. If very high precision is required, then we must take the true shape of the Earth into account. The Earth is an ellipsoid; the distance around the equator is about 0.3% longer than a Great Circle that passes through the poles. The Geodetic Coordinate system takes this ellipsoidal shape into account, and expresses the position on the Earth’s surface in Cartesian coordinates (X, Y and Z) or in Geographic coordinates (Longitude, Latitude and Elevation).

To use the module, first select which coordinates you will use as input in the Select Input Coordinates section: Cartesian or Geographic radio buttons. Then select an ellipsoid model and fill in the input coordinates in either the Cartesian Coordinates section or the Geographic Coordinates section. When you press the Convert button, the corresponding coordinates will be filled in.

The module contains a batch mode for converting several coordinate values at once. You must construct an input file in which each line contains up to three numbers: the input coordinate values (either Cartesian or Geographic). Then specify which coordinates you are using as input, and identify the input and output filenames. Finally, press the Run button to generate the output file, which will contain the converted coordinates (Cartesian or Geographic; the complement of what you chose as the input values).

Planet Coordinates module

The Planet Coordinates module computes positional data for any major solar system body, for any time and date and any geographic location. Simply select from the Solar system body: drop-down list, and specify the desired date, time, and geographic coordinates (these values are preset to the current KStars settings). Then the Equatorial, Horizontal, and Ecliptic coordinates of the body are computed and displayed.

There is a batch mode for this module. You must construct an input file in which each line specifies values for the input parameters (solar system body, date, time, longitude, and latitude). You may choose to specify a constant value for some of the parameters in the calculator window (these parameters should be skipped in the input file). You may also specify which of the output parameters (Equatorial, Horizontal, Heliocentric ecliptic and Geocentric ecliptic coordinates) should be calculated. Finally, specify the input and output filenames, and press the Run button to generate the output file with the computed values.

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