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Hipparcos: Sky Plot

Instructions for use

Click here to begin the skyplot java applet. (This will open a second window so you may need to resize the windows if you want to view both the instructions and the image.)

Input the coordinates of the centre of the region (RA, dec) in degrees, and choose the field size (in the range 1-20 degrees), then press the "VIEW" button. A sky plot will be returned showing first the Hipparcos Catalogue objects in red, followed by the Tycho Catalogue objects in white. Tycho Catalogue objects also in the Hipparcos Catalogue are finally shown in blue.

You can select stars brighter than a magnitude V(lim) to plot. V(lim) is the V magnitude given in the Hipparcos and Tycho Catalogues (Field H5/T5). This cutoff limit is applied to both the Hipparcos and Tycho stars.

The Tycho Catalogue objects can be suppressed (or added to the field again) using the "VIEW TYC" button.

Magnitudes used are the V magnitudes taken from Field H5 of the Hipparcos Catalogue, or from Field T5 from the Tycho Catalogue. In cases of slight differences in the V magnitudes from the two catalogues, these will show as circles of slightly different sizes. The magnitude scale adopted is shown at the top of the plot.

Using the cursor to click on a star image returns the HIP (single digit) identifier if the star is in the Hipparcos Catalogue (and possibly also in the Tycho Catalogue), i.e. if the object is red (HIP only) or blue (HIP+TYC). It will return the TYC (3-digit) identifier if the object is ONLY in the Tycho Catalogue (white). The V magnitude is also given. Any number of stars can be annotated in this way. Note that the labelling starts at the star image, except for stars at the right of the display where the labelling is moved to the left and for stars at the top of the display where the labels are moved to below the star.

Click on the same star image again to suppress the label.

Having activated a label, press the button "GET INFO" to spawn a new window with the catalogue information (HIP or TYC, with related links to annexes where appropriate) displayed. Move the windows if required so that "GET INFO" for a new star refreshes the catalogue data alongside the sky plot.

The position of the cursor is tracked in RA/dec (in degrees, and sexagesimal) to the right of the sky plot.

Note that the projection adopted here is a simple xy projection using RA and dec as the coordinate axes. Be aware that this is schematic, and will be (particularly) unreliable at the poles.

To print the sky plot you will need to use a screen capture program (for example, xv or snapshot) to capture and then print the image.

Here are some interesting regions you could examine (the field is centered on the named star):

NameRADecsuggested width (degrees)
Sirius (brightest star)101-16.73
Arcturus (brightest variable star) 21419.03
Barnard's Star (highest proper motion)269.5 4.6 2
Closest stars (in the same sky plot):
alpha centauri A & B (4.40 ly)
Proxima Centauri (4.22 ly)



(center plot on the above coordinates)
A crowded region (54 stars)174 -61.01
An empty (relatively) region (7 stars)17430.01

     Copyright © 2015 European Space Agency. All rights reserved.
This page was first created on 16 April, 2007 and was last updated on 18 July, 2007.
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