Hi Roger,

As Michael suggested, you can enter it as a GSC number. The Tycho
designations were essentially "borrowed" from GSC. Alternatively, you
can use Go To... Object Name and enter any of the following:

tyc 1954 1781 1
TYC 1954 01781
Tyc2 1954 1781

or even

GSC 1954 1781

...and Guide will find that object.

The nomenclature here has gotten a little out of hand. "Tyc2"
= "Tycho-2", meaning the expanded second version of the Tycho catalog.
For star naming purposes, Tyc2 and Tyc are used interchangeably.
That's not entirely safe, since about 60% of the stars in Tycho-2
weren't listed in Tycho-1. But people do it all the time, so Guide
treats Tyc2 = Tyc. Leading zeroes are sometimes given, and Guide
ignores them.

Finally, there's the matter of a third number, a "component
designator". For single stars, this is always 1, and you can
leave it off (people usually do). If TYC 1954 1781 1 had a close
companion, it would be called TYC 1954 1781 2.

-- Bill