In looking for GSC 780:424, I did a more deeper search, and found that the star is listed in The HST Guide Star Catalog, Version 1.1 (Lasker+ 1992), and 1.3 (GSC-ACT) but the catalogued epoch date is 1984.889, while the GSC 1.0 says 1982! Yet in the VizieR search for the star in version 1.0, I now get the error ;
The following problems were encountered in this VizieR run:
****SIMBAD Error for object 'GSC 0078000424': This identifier is not present in the database: GSC 00780-00424
Bizarre.
Furthermore in the GSC 2.2, 2.2.1, 2.2.3, the star no longer exists and seems the deletion has not been documented! So I'd say this is simply an error.
Checking again using asteroid ephemerides for 1984.889, there seems no bright asteroid of 11.7 magnitude anywhere near this location.
The last option is to look for the plate for 1984.889 - but perhaps tomorrow!