This app plots and animates the "Hipparcos and Tycho Sky" for a user-defined region.
The user selects the centre of the field of view and the field width (up to 35 degrees) in the bottom left corner using the fields "RA", "Dec", and "Width". A faint limiting magnitude can be set using the "V(lim)" selection. Pressing the "View" button will load the data and show the sky. Tycho stars can be included or excluded by toggling the "View TYC" button. By clicking on any star and then selecting the "Get Info" button, the Catalogue entries for that star will be returned in a browser window. A list of all the stars in the field and some summary data from the Catalogues can be obtained with the "List" button: a text window is generated containing the HIP number (ID), V magnitude (mag), coordinates (alpha and delta), parallax (par), proper motion (in RA and Dec; muA and muD), and the B-V colour-index (b-v). The "Refresh" button in the list window can be used to update the window after each new selection. The star field can also be animated by toggling the "Animate" button to show the effect of the measured proper motions. The step size for each increment in time can be varied through the "Step" field and the stars can be plotted with tails (to illustrate the positional shift with time) or without tails (giving an instantaneous sky plot for the epoch) by toggling the "Tails" button.