The home page of the Hallo Northern SKY planetarium program.

Welcome to the web page of the semi professional free planetarium program HNSKY for MS-Windows and Linux. This program can control your telescope via the ASCOM or INDI interface, has a comprehensive up to date deep sky database with 30.000 objects and detailed descriptions. A star database with millions of stars and hundreds of Deep Sky Survey images which blends in accurately. Additional the program can access the online version of the Deep Sky Survey allowing online update of the asteroid and comet databases and it can search on linein professional astronomical databases. Is provided with menu's in 21 languages and it is totally free without any advertisement or restriction!!

Free with 30.000 deep sky objects and native star databases up to magnitude 16. Online access to GAIA DR1, UCAC4 en NOMAD star catalogues or download the complete GSC 1.2 up to magnitude 15 or the USNO UCAC4 up to magnitude 16. The Sun, Moon, the planets and their major moons are all displayed with surface features. It maps the position of comets and asteroids with online updating. It is provided with hundreds of DSS deep sky images which will blend in at the correct size and orientation. It has a powerful animation menu. and an integrated deep sky observations help file with and 21 non-English menus. The MS-Windows version contains both 32 bit and native 64 bit versions. In can control almost any telescope using the ASCOM interface program. Works flawlessly together with programs like EQMOD and MaximDL. Downloading of additional DSS images via the Internet is fully integrated. Just select an area and select download.After a few second the DSS image will blend in the HNSKY map at the correct size and orientation. The comet or asteroid database can be updated online with just one click. Online database search for objects in the selected area. Numerical integration for asteroids to achieve highest accuracy positions years in the future or past. The error is less then 1" after 10 years !!! So an asteroid orbital elements from 10 years ago will after numerical integration allow position calculation within 1" accurate!! So also 10 years in the future. The program can use Jet Propulsion Laboratory Development Ephemeris like the DE431 covering years –13,000 to +16,999 for planetary positions.

HNSKY popup menu HNSKY



MS-Windows version:
HNSKY version 3.3.3 (installer, 74 MB, dated 2017-4-14) Including the magnitude 12.5 star database. Additional you could download the U16 star database up to magnitude 16  from below

Linux version:
HNSKY version 3.3.3_FPC (74 mbytes 7z archive, dated 2017-4-14, Linux AMD64 executable file name is "hnsky" An "hnsky.exe version" for MS Windows is included. Unpack somewhere at your home folder. Including the magnitude 12.5 star database. Additional you could download the U16 star database up to magnitude 16  from below.
Manual install version

MS Windows version 3.3.3 complete in a rar archive for manual installation (70 mbytes rar archive, dated 2017-4-14) Extract (and overwrite if required) these files to the HNSKY program directory or an other folder. The 64 bit version file is hnsky64.exe. Including the magnitude 12.5 star database. Additional you could download the U16 star database up to magnitude 16  from below. This version contains the new type .290 stars files. Remove the older obsolete .d32 files manually.

 History    HELP file    FORUM   GUESTBOOK    Screen shots of HNSKY.        

Star databases:
Local star databases
Name Abbreviation Magnitude limit Type Size Maximum
Proper motion Description and download link
Local files, native 290-10 format
50 MB
360° No, epoch
Native HNSKY star database up to magnitude 12.5 containing 4.7 million stars. Compilation from TYCHO-2 & UCAC4. Included with the program and installed.
Local files, native 290-9 format 206 MB RAR
360° No, epoch
Native HNSKY database up to magnitude 15 containing 39 million stars. Compilation from TYCHO-2 and UCAC4. Compressed in a RAR archive the size is 192 mbytes. Contains the Tycho and UCAC star identifiers/designation. Unpack in the program directory, typically c:\program files\hnsky.
16 Local files, native 290-5 format 419 MB RAR 360° No, epoch
Native HNSKY database up to magnitude 16 containing 113 million stars. A compilation of UCAC4 and Tycho-2. RAR file of 437 mbytes). No Tycho-2 or UCAC identifers are available due to small the 5 byte record size. Instead an IAU style designation based on the position is used. Unpack in the program directory, typically c:\program files\hnsky
Local files, native 290-5 format 647 MB 360° No, epoch
Native HNSKY database up to magnitude 17 containing 164 million stars. Note that Gaia DR1 is missing some stars so is less suitable for star maps. Unpack in the program directory, typically c:\program files\hnsky
Local files, external USNO
8.4 GB
2.6x1.3° Yes
UCAC4:You can download the 113 million stars, 8.5 Gbytes large USNO UCAC4 from HNSKY can access this catalog directly. Download Z001 to Z900 from the U4b directory and add to the same directory file u4index.unf from U4i. This UCAC4 and Nomad are the catalogues where HNSKY will use proper motion for maximum accuracy. See HNSKY UCAC screenshots.
GSC 1.2
Local files, external format
303 MB
16x14° No, epoch 1982 & 1975
Obsolete: GSC, HST Guide Star Catalog: The GSC_ACT or (catalog 255) GSC 1.2 (catalog 254) of 15 million stars to about magnitude 15 isavailable at CDS in the compact binary format (303 MB).

Alternatively download the older GSC 1.1 / GSC 1.1 (catalog 220) in the compact binary format (303 MB)
Online catalogues Name
Abbreviation Magnitude limit Type
Size Maximum
Proper motion Description
2.6x1.3° Yes
The USNO UCAC4 includes positions, proper motions and magnitudes for 113 million objects
1.4x0.8° Yes
Gaia DR1
1.4x0.8° Yes
NOMAD is merged catalog compiled by the USNO, with positions and magnitudes for 1.1 billion stars from several source catalogs, including Hipparcos, Tycho-2, UCAC 2, and USNO-B 1.0
1.4x0.8° Yes
By USNO, northern sky only, extends down to Declination -15°.228 million objects

More asteroids/minor planets 

For more asteroids you have to download and import the huge uncompressed MPCORB.DAT file from the Minor Planet Center. This file contains the orbital element contains about 710.000 numbered asteroids and size is uncompressed 140 mbytes. Save this file as MPCORB.DAT. Open this file in Wordpad or any editor and keep the first 30.000 asteroids or so and  remove the rest. Open the MPCORB.DAT file in the internal HNSKY asteroid editor. HNSKY will then convert format. To  make permanent save to HNS_AST1.AST. HNSKY will  only read the numbered asteroids. 

Alternatively conversion of MPCORB.DAT to supplement format can be done with this small DOS program
Additional supplements

HyperLeda_980.000_galaxies supplement Dated 2015-1-5 (10 MB) demo image using 65 mm telescope.  Extract the rar archive in the HNSKY directory under DOCUMENTS.
HyperLeda_2.440.000_galaxies database.rar (type hnd)  or .zip Dated 2016-7-13 (26 MB) This is a deepsky database not a supplement. Unpacked size is 103 mbytes.  Place this huge deepsky database in the HNSKY PROGRAM directory. You have to select either this one or one of the three deepsky databases.
World map supplement: World map supplement version 3.0 dated 2000-10-22. World map and 2700 cities with there location and relative brightness. Scale 1 : 5.000.000. See screen shot of version 2.0. Included a conversion program to convert coastlines to a supplement.
GCVS 4.1 variable star supplement. Complete 37382 star version. In this supplement the GCVS is displayed as labels so you can easily cross check with Tycho or UCAC2. To get Tycho star info switch off the supplement. (The smaller 7800 star version is included to the basic package)
Additional FITS images Extra  large Mars map (Color 1000x500 pixels) , large Mercury maps (1440x720 pixels) based on Mariner 10, SVTS and large Jupiter maps (Color 600x300 and 1200x450 pixels) . Use the large maps only if you have a fast computer or some patience. The planetary FITS files should be placed in your FITS directory.

45 hand made drawings/sketches (880 Kbytes) of Bill Ferris, Todd Nowlan and Rainer Töpler as FITS files. These can blended inside the map. They should be put in an other directory as the Realsky images otherwise they are blend with the Realsky images.

Other languages non-English help files and language  modules. If you  want create a new language module start modifying the English one .
CD covers Some designs by volunteers: or or or or
Conversion tools
Star catalog conversion tool with Delphi source  290 conversion. (Dated 2016-9-25)
SAO PPM conversion tool with Delphi source,  DAT conversion.   (Version 2015-6-4 )
SKY_TOASTER, program for conversion to the TOAST projection,with Delphi source.  v0.0 2016-3-28



Realsky and DSS image viewer using HNSKY DDE link (HNS_REAL)  Manual or DDE controlled Realsky image viewer. Click on an object and get the realsky image (you have to own the Realsky or DSS CD's). Click on the Realsky image and to center to get cross at HNSKY at the same place. Version 2.0.0c,  Dated 2015-8-11. Here are the instructions and screen shot demo's If your FITS directory in HNSKY is set to the HNS_REAL directory, you will get every result blended in the next screen refresh. HNS_REAL can also be used in batch programs to create several images. Complete with Delphi and C source. Can also batch wise convert FITS to BMP. An other possibility is to control HNS_REAL from the provided Excel table. Contains GETDSS source code version 1.1plus dated 11 august 2015. See also
HNS_FITS version 1.4.0 dated 2003-9-19. Utility program to create FITS files from BMP files with the correct WCS header by entering the position of two reference stars. Screen shot and describtion. This is a great tools to blend your own pictures inside the HNSKY sky map. With three added example files.
Miscellaneous The following Windows program ORB_DEB is a simple windows program which calculates the orbital elements of a minor planet based on three observations/positions using the Gauss method: Download ORB_DET.ZIP version 1.02.  Contains a win16, win32 and win64 and Linux (AMD64 bit) version.

Here are some Pascal routines as used inside the HNSKY program. If you have any suggestion to improve them, please let me know: Pascal source code for some astronomical routines and constellation arrays as used in HNSKY program.
PDF map Example printed PDF map, format A2, 1200 DPI, azimuthal equidistant projection,  from declination +90 degrees to -50 degrees. Stars up to magnitude 8.5 and 253 deepsky objects. Zoom in to 1200% to see deepsky objects.. Text searchable.

Questions, suggestions regarding the HNSKY program you could email directly to me han kleijn's email address(in English, Dutch or German) or better post them in the Yahoo group HNSKY:

view messages at ►
Join:                     ►
post a message:    ►  

To post a  message and to get an answer send back by e-mail you have to join this yahoo group. To prevent too much spam/junk mail there is approval which can take a day or so. This is just there to detect that your are an human being and not a stupid spam producing robot program filling our email boxes.

If you afraid to ask a trivial question at such a place, please do not hesitate and send it to my email address directly.

You also welcome to fill my GUESTBOOK

Some stuff to read:

Review by software informer,    
► 2016 German review of HNSKY Hallo Northern Sky Download downloaden    
► 2015 German review of HNSKY
► 2015 review of HNSKY
► 2015 review of HNSKY free-planetarium-program-windows-hnsky
► 2015 review of HNSKY
► 2015 review of HNSKY
► 2015 review of HNSKY
► 2015 review of HNSKY
Reports  of HNSKY running under Linux using emulators Please send any new report or information to
► Only for the very advanced specialists, some conversion programs used to create the star databases  Number of stars versus magnitude.
►  Collecting satellite positional data using video frames and HNS_FITS by Greg Roberts.
The README.TXT of the new Saguaro Astronomy Club SAC 7.2 deepsky database
The quest for the ideal planetarium star database by Bill Anderson. Comparison of Tycho, Tycho reference and Tycho-2.
Star chart quality and accuracy by Raymond Bruton Limitation of star catalogs and humans
The creation story of HNSKY by Han Kleijn
An evaluation of HNSKY by Bill Anderson
An accuracy evaluation of HNSKY by Giuseppe Matarazzo
Errata or correction list for SAC 7.2 Han Kleijn

Here are some links and source codes for ephemerides calculation and some other interesting astronomy programs:

An absolute excellent tutorial how to calculate planetary positions by Paul Schlyter.
Pascal, Basic, C source code and Lotus (or Excel) spreadsheet for ephemerides calculation (low accuracy) of the moon and planets.
Not used in HNSKY. Excel table routine for correcting the position of stars and deepsky objects caused by the precession (the shift of the Earth axis and ecliptic), for example equinox B1950 to J2000. - - Implemented in Excel as a visual basic routine using the rigorous method, so the accuracy around the poles is optimum. Can be used to convert star/deepsky databases in Excel. File dated 2002-8-22.
► Rotation of Jupiter's red spot at Web page about Great Red Spot transit times by Bill Gray's of project Pluto.
► The orientation of planetary axis and rotational elements of planets and satellites can be found in the following  IAU-IAG report or updated at, local copy the IAU-IAG report. (great information source)

Counter since 2015-2-27:

Visitor map: