The current version of AstroCC ...
AstroCC is a coordinate conversion utility for astronomy. It accepts an object designation or the coordinates of an object and calculates coordinates in alternative systems, and at different dates, times, and locations. It also provides lunar and bright planet coordinates to aid in planning observations.
The AstroCC coordinate converter user interface is shown below. The top row shows the current date and time in UT, local time, Julian Date, and local sidereal time (LST) formats. These and other items with a gray background cannot be modified by the user. Tooltips are provided for each item to describe its use and syntax. Tooltips can be disabled under the Preferences menu.
The desired Observatory ID should be selected on the second line, and the Latitude, Longitude, and Altitude fields will be updated automatically. Otherwise select “custom” as the observatory ID and enter the latitude and longitude entries directly. Press <Enter> after each entry is typed.
Enter a valid SIMBAD object ID and press enter. If the object ID and relevant data are found in SIMBAD, the Target Proper Motion Right Ascension (RA) and Declination (Dec) fields and the Standard Coordinates J2000 Equatorial RA and Dec fields will be updated automatically. A green border will be placed around those coordinate fields indicating that they are the active fields from which all other coordinates are calculated. Also, major solar system object names may be entered (Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto). The Epoch of Interest Equatorial RA and Dec fields will be updated automatically since these objects do not have a (relatively) fixed RA and Dec. While a solar system object name is entered in the Object ID field, the active coordinate fields cannot be changed. To do so, remove the solar system object name from the Object ID field.
Finally, the Epoch of Interest should be entered. Click the Now button to set the epoch of interest to your computer’s current time. Select Lock to keep the epoch of interest lock to your computer’s time every second. Otherwise, the epoch of interest can be entered as UT date and time, local date and time, Julian Day, Heliocentric Julian Day (HJD) or Barycentric Julian Day (BJD). All other date formats will be calculated from the entered format. The up/down arrows to the left of UTC time can be clicked to increment/decrement the date/time by one step. The time step can be set by right-clicking the up/down arrows or the UTC, Local, or JD time or date fields. The mouse wheel will also increment/decrement time if the pointer is located within one of those fields. Evening and morning nautical twilight start/end times are also shown for the epoch of interest. Click inside these fields or on the adjacent icons to set the current time to the corresponding twilight time. If the epoch of interest falls between evening and morning twilight, the twilight field backgrounds are changed to green.
For accurate dynamical time and coordinate calculations, leap second data must be kept current. To do so, simply press the Update button while connected to the internet and the data will be downloaded into AstroCC and stored along with other program preferences. New leap seconds may be introduced every six months at the end of the day on June 30 and December 31. New leap second announcements are made several months in advance. Simply click the Update button once every 3-6 months to check for an update. If Auto is selected, an appropriate leap second value is determined for the epoch of interest. A green Leap-secs background indicates that the displayed number of leap seconds is from the leap second table. The table is valid from 1/1/1961 though the current epoch. Outside this range, leap seconds must be estimated. To estimate leap seconds, AstroCC uses the formulae of Espenak and Meeus 2006, which cover the range from 1999 BCE to 3000 CE. If the epoch of interest is within this range, the Leap-secs background color is yellow, otherwise the background color is red. If Auto is not selected, the field background is white, and the user can enter a custom number of leap seconds.
Any coordinate pair can be used as the source to calculate all others. Simply type (or cut/paste) the desired coordinates into the appropriate pair of coordinate boxes and press <Enter>. The border for the entered coordinates will become green to remind the user which coordinates are being used as the source for the computation of the other coordinates. For convenience, both coordinates of a pair can be typed (or cut/pasted) into one of the boxes of a pair in sexagesimal format. When <Enter> is pressed, the coordinates will be automatically separated and placed into the appropriate boxes. While a solar system object name is entered in the Object ID field, the active coordinate fields cannot be changed. To do so, remove the solar system object name from the Object ID field.
The Phase-Altitude-Proximity section under Epoch of Interest shows the illuminated portion of the moon at the epoch of interest and the altitude of each solar system object (top number) and the distance from the current object coordinates (bottom number). A green background indicates that observations of the target of interest at the epoch of interest should be minimally affected by the solar system object. Yellow means the objects are near each other, and red means the objects are very near each other. A mouse click on the data field of a particular solar system body will make that object the current object of interest and its full coordinate conversions will be shown in AstroCC.
Fields with a gray, green, yellow, or red background cannot be modified by the user. Fields with a white background can be directly modified by the user. The coordinate pair with green borders indicates the active coordinate pair. All other coordinates are calculated based on the active coordinates as the source. Coordinate conversion formulae are not exact, so pressing <Enter> in a new coordinate pair (using the existing values) may result in a slight change to the other computed coordinate pairs.
RA and UT time must be entered in hours. All other coordinate numbers must be entered in degrees. Observatory latitude is in degrees (north positive) and observatory longitude is in degrees (east positive). Proper motion is in SIMBAD milli-arcsec per year (mas/yr) format. UT Date is in YYYY MM DD.DD format. Hour Angle (HA) is reported in the range -12:00:00 to 00:00:00 indicating sidereal hours until the object crosses the meridian and 00:00:00 to 12:00:00 indicating sidereal hours since the meridian crossing. All numbers except UT date can be entered in decimal format (i.e. dd.dddd) or in sexagesimal format (i.e. dd mm ss.ss). To facilitate cut and paste of coordinates from other sources, sexagesimal parsing is very lenient and treats any contiguous set of nonnumeric characters as a delimiter. For convenience, both coordinates of a pair can be typed (or cut/pasted) into one of the boxes of a pair in sexagesimal format. When <Enter> is pressed, the first coordinate will be automatically placed in the left-most box of the pair and the second coordinate will be placed in the right-most box. A decimal format number must be entered directly into its corresponding box.
Several options are provided under the Preferences pull-down menu at the top of the user window. After closing the program for the first time, a new file named “AstroCC_Prefs.txt” will be created. On Microsoft Windows computers, the file is saved in the same directory as the AstroCC.jar file (AstroCC should be installed in a directory with user write access). On Linux systems, the preferences file will be saved at user/home/astrocc/AsctroCC_Prefs.txt. On an Apple Mac computer, the file is saved at user/home/Library/Preferences/AstroCC_Prefs.txt. This file will automatically reload on startup and allows preferences, leap seconds, and other settings to be maintained across sessions.
Field-specific help displayed after hovering mouse over a field.
Observatory data is stored in a file named "observatories.txt" within the AstroCC.jar file structure. Using an unzip program, a copy of the file can be extracted and placed in the same directory as the AstroCC.jar file. If this file exists, it will be read with priority over the version in the jar file. The file is a simple tab-delimited file.
New entries should be added separated by tabs in the following sequence on one line:
All numeric entries should be entered as decimal numbers (not sexagesimal). Latitude is in degrees (positive north). Longitude is in degrees (positive east). Altitude is in meters above mean sea level.
Availability: AstroCC is open source software and is distributed under the terms of the GNU General Public License.
Credits: Parts of AstroCC are based on XmTel, WCSTools, Nuvola icons, and ImageJ open source software packages. Solar system object coordinate calculations and internal HJD/BJD calculations are based on code adapted from JSkyCalc which was written by John Thorstensen of Dartmouth College. BJD values may also be retrieved from http://astroutils.astronomy.ohio-state.edu/time/utc2bjd.html which is based on Eastman et al. 2010. Coordinate data are obtained from SIMBAD. Leap second data is obtained from the U.S. Naval Observatory at http://maia.usno.navy.mil/ser7/tai-utc.dat. The observatory data were compiled from the ESO website at http://www.eso.org/~ndelmott/obs_sites.htm which credits the U.S. Naval Observatory and the H.M. Nautical Almanac Office. The lunar phase images are adapted from Lunar_libration_with_phase_Oct_2007.gif from Wikimedia Commons (submitted by Tom Ruen).