MS20 parts question

[Greg Montalbano]

Looking over my old MS20 schematics (haven't owned one in over 20 years,
but the modules are fun to clone & modify) & noticed the Modulation VCA,
which uses some sort of photocoupler (listed on the parts sheet as
"HTV-P873-G35-201B").
Anyone have the slightest idea what this might be, and what equivalents (or
close enough) might be available these days?

If so, thanks.

If not, too bad for me.