Attached press-release on back states that the series "premieres this fall" which dates the distribution of the materials as prior to September 5, 1977 (the date the series premiered)
There is a date stamp of November 7, 1980 on back, which is believed to indicate the date the image was published for purposes unrelated to the promotion of the series and/or when the image was archived by the news agency - not for when the publicity materials were originally distributed for publication (the series went off the air in January 1978).
The photo has no copyright markings on it as can be seen in the links above (also see original upload).
It was created for publicity purposes-distribution to the media. The image was meant to bring attention and publicity for the personalities pictured, the program he/she was part of, and the network airing it, the same as the publicity photos for actors and actresses in the film industry were intended to do.
Film production expert Eve Light Honthaner in The Complete Film Production Handbook, (Focal Press, 2001 p. 211.):
"Publicity photos (star headshots) have traditionally not been copyrighted. Since they are disseminated to the public, they are generally considered public domain, and therefore clearance by the studio that produced them is not necessary."
"There is a vast body of photographs, including but not limited to publicity stills, that have no notice as to who may have created them." (The Professional Photographer's Legal Handbook By Nancy E. Wolff, Allworth Communications, 2007, p. 55.)
"Publicity Photos (star headshots) older publicity stills have usually not been copyrighted and since they have been disseminated to the public, they are generally considered public domain and therefore there is no necessity to clear them with the studio that produced them (if you can even determine who did)."
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.