Speckle Interferometry at the OAN-SPM Mexico: Multiband Astrometry of Double Stars Measured in 2018 and 2019

In this paper we present multiband speckle interferometric measurements of double stars performed at the 2.1 m telescope of the Observatorio Astronomico Nacional, San Pedro Martir, Mexico. We focused our efforts on objects from the Washington Double Star Catalog that were observed during five runs allocated in 2018 and 2019. We report here 2101 astrometric and 2027 photometric measurements of 631 pairs, with angular separations ranging from 0.'' 05 to 6.'' 09, including 1622 measurements with separations smaller than 1 '', and a magnitude difference up to 5.99 mag through the V filter, 5.46 mag for the R filter, and 5.85 mag for the I filter. We estimated a mean error in separation of 12 mas, 1.degrees 1 in position angle, and 0.14 mag for the magnitude difference. We confirmed 58 double stars discovered by Hipparcos. For the first time we are presenting astrometric measurements for 7 systems listed at the Washington Double Star Catalog as being suspected binaries, which did not have a secondary confirmation, and 15 stars with only one published measurement. We identified a new close companion with a mean angular separation of 0.'' 10, detected in a previously known pair. Finally, we present a correction to two previously published orbital solutions of two visual binaries.