New Variable Stars on Digitized Moscow Collection Plates. Field 66 Ophiuchi (Northern Half)

TL;DR

This study digitized and analyzed the Moscow astronomical plates to discover and characterize new variable stars, resulting in 274 new variables and detailed light element data for several types.

Contribution

It introduces a digitization and photographic photometry method for old astronomical plates, leading to the discovery of numerous new variable stars and providing detailed light data.

Findings

Discovered 274 new variable stars in the field.

Identified 2 probable Population II Cepheids and other variable types.

Provided new light elements for several known variables.

Abstract

We initiated digitization of the Moscow collection of astronomical plates using flatbed scanners. Techniques of photographic photometry of the digital images were applied, enabling an effective search for new variable stars. Our search for new variables among 140000 stars in the 10 x 5 degrees northern half of the field centered at 66 Oph, photographed with the Sternberg Institute's 40-cm astrograph in 1976--1995, gave 274 new discoveries, among them: 2 probable Population II Cepheids; 81 eclipsing variables; 5 high-amplitude Delta Scuti stars (HADSs); 82 RR Lyr stars; 62 red irregular variables and 41 red semiregular stars; 1 slow irregular variable not red in color. Light elements were determined for periodic variable stars. We detected about 30 variability suspects for follow-up CCD observations, confirmed 11 stars from the New Catalogue of Suspected Variable Stars, and derived new light elements for 2 stars already contained in the General Catalogue of Variable Stars.