1999A&A...350..491R

We report on a total of 20 sources observed in the near infrared in the course of routine lunar occultation programs at the TIRGO and Calar Alto observatories. The results consist either in discoveries of new binaries, or in re-observations of known or suspected binaries where only incomplete information was previously available. For the first time, a companion has been detected around the following 6 stars: DO 2779, SAO 162001, SAO 93083, IRC -20444, SAO 162521, and GCVS 980 (read: GSC 01301-00102). Additionally, SAO 93746 is discovered to be a triple system, with projected separations at the 0.01" level. For the following 7 stars, our observations confirm previous reports of binarity and provide complementary information in the infrared: SAO 96746-A, SAO 161202, SAO 94060, AG+16403, SAO 98270, SAO 93950 and SAO 94554. Finally, for the following 4 stars, a companion had been previously observed or suspected, but we could not detect it for various reasons: SAO 96810, SAO 93961, SAO 93975 and SAO 93981. The projected separations in our positive results range from 0.01" to 0.57", and the brightness ratios up to ΔK=4.4mag. In addition, two visual doubles, namely SAO 184176 and SAO 94002, have also been observed and their projected angular separations and infrared brightness ratios are reported here. This paper is the fourth in a series, bringing to 58 the total number of binary sources studied by our group by means of lunar occultations.