Jacobus Kapteyn Telescope

Coordinates of the JKT
Latitude:	28° 45' 40.1" N (+28.761°)
Longitude:	17° 52' 41.2" W (-17.878°)
Ground floor height:	2364 m

The Jacobus Kapteyn Telescope (JKT) has a parabolic primary mirror of diameter 1.0 m with two interchangeable secondaries. There is a choice of two secondary mirrors. The f/8.06 Harmer-Wynne system uses a spherical secondary and a doublet corrector to give a field of 90 arcmin diameter for photographic astrometry over a wide field. The other secondary is a hyperboloid, which gives a conventional f/15 Cassegrain focus. The JKT normally operates in f/15 mode.

It is equatorially mounted, on a cross-axis mount, which allows operation east or west of the pier. Normally it is east of the pier. Current operational range is as follows:

• Zenith distance < 84 
• -6 h < hour angle < +18 h (telescope East of pier) 
• -18 h < hour angle < +6 h (telescope West of pier) 

There are no explicit declination limits. The fully-lowered windshield which sits on the dome lintel sets a further limit. Because of the asymmetry of the telescope, the limits are different east and west of the pier.

A more detailed description of the optics and the mounting of the JKT is available in the Observers' Guide. For more information about the Telescope Control System please see the JKT TCS manual.

For other facts on the JKT see the public information web pages.

The JKT was offered to visiting astronomers with the 2k × 2k SITe2 CCD camera and the JAG autoguiding box (this instrumental configuration is also referred as JAG CCD). The camera provides an unvignetted field of view of 10 × 10 arcmin, with a pixel sampling of 0.33 arcsec.

For applying for observing time and preparing observations, please visit the ING Astronomy web pages. lpss10 is the machine hosting the observing system at the JKT. The data taking (UltraDAS); the instrument control (ICS) and data inspection (IRAF) are all on this machine. The ALPHA station lpas1 is running the TCS.

As of March 4, 2002, engineering support is withdrawn from the JKT after 23.00 - so the DE should not be called after that time for technical problems that affect observing. They should still be called in their role of Incident Officer to safeguard people or equipment. In case you need technical help after 23:00, please consult with the INT (tel. 640), or WHT TO (tel. 559).

IMPORTANT:

• A Basic User Guide is available to facilitate telescope and instrument operations
• At ZD>45-50 degrees in the west the JKT show jumps that appear as double images on the CCD. Because of this the JKT is practically useless for HA>3. Please be aware of this when planning your observations!

For more information, the JKT User Manual can be found here: Observers' Guide to JKT JAG-CCD imaging

The following plots of the reflectivity of the JKT mirrors are available:

• A plot of scattering and reflectivity of the JKT primary
• A plot of scattering and reflectivity of the JKT secondary