Thanks for getting back to me on this.
I think you'll be pleased with the results, as I've not only found you
a reference for the number of research telescopes, but I also managed
to dig up a list of most of them around the world.
First, the reference to there being 400 CCD-enabled research
telescopes is here, in this transcript of a radio program on the
development of the CCD:
...We?re exploring ways that we collect and process light, using
charge-coupled devices, or CCDs.
...They?ve become the eyes of the world?s major telescopes. Leach
introduced the age of electronic imaging at SDSU, and has now extended
it to 80 observatories and more than 400 research telescopes
I wondered if 400 was a reasonable number for the world's supply of
major research telescopes, but this list from a German site seems to
confirm that, indeed, it is:
Tabellen der Astronomie
There are about 500 of the world's major research telescopes listed
here. About 100 of them are non-optical telescopes, which gets you
right into the 400 ballpark for the number of optical research
telescopes around the world.
Keep in mind, that there's no solid dividing line between a named
telescope at a well-known observatory, and a hand-held device used by
a backyard astronomer. Ultimately, the count of research-grade
telescopes could probably be expanded considerably. But as for the
major optical instruments in use, it seems that 400 is a good number
to work with.
I trust this information fully answers your question.
However, please don't rate this answer until you have everything you
need. If you would like any additional information, just post a
Request for Clarification to let me know how I can assist you further,
and I'm at your service.
All the best,
search strategy -- Google searches on:
"100..10000 research telescopes"
and a search on telescope names:
yerkes lick solar greenwich archenhold naval stromlo