No, the word telescope is not an adverb. It is a noun, adjective and a verb.
The closest adverb form of the word "telescope" is telescopically.
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Sunspots were first observed telescopically in late 1610 by the
English astronomer Thomas Harriot and Frisian astronomers Johannes
and David Fabricius
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Most loft ladders are built like extension ladders, that is to
say they slide telescopically into sections. This means when they
are stored away they take up less space than a step ladder, but
this storage space is in the loft.