HNSKY Files

Compact star databases for HNSKY, ASTAP and Skychart/CDC program.


The databases are provide as an installer for Windows, RAR or ZIP files. The .290 files should be placed in the program directory. For HNSKY this is c:\Program Files\hnsky or for Linux /opt/hnsky. For ASTAP this is c:\Program Files\astap  or for Linux /opt/astap. 


Clear skies, Han

The  mono star databases contain a single unmodified Gaia BP magnitude. The colour versions contains the calculated Johnson-V magitude and the blue BP minus red RP magnitude difference. If your a visual observer, download the G16 colour or G17 colour version containing Johnson-V magnitude and star colour information. If your an astrophotographer download the G17 or G18 with the photographic BP magnitude. Epoch is calculated to year 2025.


* V16	COLOUR, Gaia eDR3 up to Johnson-V magnitude 16, containing 60 million stars, including star colour information, native 290-6 format, 346 MB, epoch 2025.

* V17	COLOUR, Gaia eDR3 up to Johnson-V magnitude 17, containing 120 million stars,  native 290-6 format, 695 MB,epoch 2025

* G17	Gaia eDR3 up to BP-magnitude 17, containing 105 million stars,  native 290-5 format, 503 MB,epoch 2025

* G18	Gaia eDR3 up to BP-magnitude 18, containing 205 million stars, native 290-5 format, 996 MB RAR,epoch 2025

* TUC	Tycho2 & UCAC4 up to magnitude 15, containing 39 million stars including abbreviations, native 290-9 format, 341 MB, epoch 2017 (obsolete)

* U16	Tycho2 & UCAC4 up to magnitude 16, containing 113 million stars, native 290-5 format, 544 MB RAR, epoch 2017 (obsolete)


The compact 290 file format is described at:
http://www.hnsky.org/help/uk/hnsky.htm#database

Note that in this Gaia star database for stars with unreliable BP (blue) and RP (red) magnitudes the colour information has been removed. The unreliable colour is caused by straylight especially for close doubles closer then 1.7 arcseconds. This was achieved by calculating the C factor equals equals (BPflux+RPflux)/Gflux. If this C factor is much larger then one, the  BP and RP magnitudes are too low due to straylight. For these stars (about 0.5%)  the G magnitude is larger then the BP or RP magnitude. A substitute BP magnitude is then calculated by BPsubst:=G+0.5. This "BP en RP flux excess problem" is discussed in chapter 6 of the Gaia documentation "Gaia Early Data Release 3 Photometric content and validation". For this database the fluxes are calculated from the magnitudes rather then Gaia database fluxes. 

This are an extract of the Gaia star catalog eDR3 by European Space Agency  Science & Technology in a special format developed for the HNSKY planetarium program and ASTAP program . We acknowledge the usage of the Gaia database. See for more details the file "acknowledgement of databases.txt"  which is installed with the HNKSY program.


The best compression for above files is achieved with the RAR format. However for universal compatibility the ZIP format was selected.



In addition:

* HyperLeda_galaxies. Data of 2.1000.000 galaxies from http://leda.univ-lyon1.fr/  This is a deepsky database not a supplement. Unpacked size is 103 mbytes.  Place this huge deepsky database in the HNSKY PROGRAM directory either c:\program files\hnsky or for Linux /opt/hnsky. You have to select either this one or one of the three deepsky databases.  

* HyperLeda_980.000_galaxies An HNSKY supplement with data of 980.000 galaxies from http://leda.univ-lyon1.fr/. Extract this archive to the HNSKY directory under DOCUMENTS or in Linux under ~/.hnsky.