The telescope may be offset from its current position with an RA/Dec offset, for example to move an object with known offset position onto the reference point or spectrograph slit. The offset is made in the same coordinate system as specified for the input source and is currently implemented as an offset in arcseconds East and North in a tangent plane projection centred on the current tracking centre. The value of the offset is entered via the User Interface by typing:
OFFSET/RA value
OFFSET/DEC value
The values are specified in arcseconds. They are introduced into the telescope tracking when the OFFSET button on the Control Desk is pressed. The OFFSET lamp will then be lit and the value of the offset will be shown on the Information Display. Offsets are not cumulative, i.e. pushing the offset button again will not cause a further offset.
Offsets in Declination are notoriously inaccurate. Therefore, some adjustment
afterwards to the position of the translated object may be required; this
implies that that object should be visible on the TV probe. If you want to do
an offset on an object too weak to be seen on the TV probe, then it is better
to use the autoguider probe for a blind offset, as described in
section 
.