The Tycho Catalog Skymap - Version 2.0
- Visualizations by:
- Tom Bridgman
- View full credits
The stars are plotted as gaussian point-spread functions (PSF) so the size and amplitude of the stars corresponds to their relative intensity. The stars are also elongated in Right Ascension (celestial longitude) based on declination (celestial latitude) so stars in the polar regions will still be round when projected on a sphere. Stars fainter than the threshold magnitude, usually selected as 5th magnitude, have their magnitude-intensity curve adjusted so they appear brighter than they really are. This makes the band of the Milky Way more visible. Stellar colors are assigned based on B and V magnitudes (B and V are stellar magnitudes measured through different filters). If Johnson B and V magnitudes are unavailable, Tycho B and V magnitudes are used instead. From these, an effective stellar temperature is derived using the algorithms described in Flower (ApJ 469, 355 1996). Corrections were noted from Siobahn Morgan (UNI). The effective temperature was then converted to CIE tristimulus X,Y,Z triples assuming a black-body emission distribution. The X,Y,Z values are then converted to red-green-blue color pixels. About 2.4 million stars are plotted, but many may be below the pixel intensity resolution. The three most conspicuously missing objects on these maps are the Andromeda galaxy (M31) and the two Magellanic Clouds.
Changes from the first version #3442, The Tycho Catalog Skymap: The star generation algorithm now favors use of the Johnson magnitudes when available. This improves the star colors over the previous method. The star intensity profiles are also slightly modified to make the cores brighter with a faster intensity falloff. We have also set the color standard to SMPTE with a gamma of 1.8.
Update: This skymap has been revised. The newer version is available at Deep Star Maps.
Please give credit for this item to:
NASA/Goddard Space Flight Center Scientific Visualization Studio
- Tom Bridgman (GST) [Lead]
- Ernie Wright (USRA)
SeriesThis visualization can be found in the following series:
Datasets used in this visualization
Hipparcos Hipparcos Catalogue (Collected with the Telescope sensor)
Dataset can be found at: http://www.rssd.esa.int/index.php?project=HIPPARCOSSee more visualizations using this data set
Hipparcos Tycho Catalogue (A.K.A. Tycho 2 Catalogue) (Collected with the Telescope sensor)
Dataset can be found at: http://archive.eso.org/ASTROM/See more visualizations using this data set
Note: While we identify the data sets used in these visualizations, we do not store any further details nor the data sets themselves on our site.