Binocular Variable Stars

The AAVSO Binocular Program comprises 153 stars distributed across the northern and southern hemispheres. Predominantly semi-regulars and Miras, with a sprinkling of other types, these stars generally fall within the 3.0 to 9.5V magnitude range and are best observed using handheld binoculars.

Specially curated sequences for these stars have been tailored for binocular use. The "Binocular Charts" are designed to exclusively showcase the comparison stars selected for each star's sequence. Initially, you may need to plot your own finder charts or refer to a star atlas to locate these stars in the sky. However, as you become familiar with them, the provided comparison star charts will suffice for your observations.

For stars whose minima take them below 9.5V, it is recommended to observe them using regular telescopic charts when they reach such faint magnitudes. In such cases, the binocular sequences, which extend only to 9.5V, may not provide adequate visibility for stars with lower magnitudes during their minima. Utilizing regular telescopic charts ensures a more comprehensive observation of these fainter stars in the program.

The spreadsheet includes essential information such as the star name, constellation, coordinates, type, period, range, suggested Field of View (FOV), and limiting magnitude for charts and notes. While there are additional variable stars within the range of binoculars not covered by the AAVSO Binocular Program, there are currently no plans to expand the program to include more stars. It is recommended to focus efforts on the stars outlined in the program to maximize the experience and observations within the specified criteria.

Important:

• Equipment:** Any binoculars can be used, and wider angles are preferable as they allow more comparison stars into the field. 7×50 binoculars are a good choice.

• Charts:** When printing charts using the Variable Star Plotter (VSP), start with the chart parameters to the right of the list of Binocular Program Stars, which are recommended starting values that can be adjusted based on your observing style. For observers in the northern hemisphere, select North up and East left for the proper chart orientation. Southern hemisphere observers will need to use alternative orientations.

• You may need a reliable star atlas to find the general vicinity of your Binocular Variable. Preparation is crucial, so locate your variables in your star atlas or other aids before heading outside. AAVSO provides some constellation charts that can be useful: AAVSO Online Resources http://www.aavso.org/online-resources.

• Other Information:** In the field, use a red light to review your charts and maintain dark-adapted eyes. A log sheet is attached for tracking your observations, or you can create your own method.

• Practice memorizing star patterns to minimize the need to refer back to your charts. With more observations, you'll improve and become more efficient. Soon, you'll be out-observing your old friends and recording data in just a few minutes using charts for comparison star values.

• Note the recommended minimum time between observing variables as described on the AAVSO website http://www.aavso.org/suggested-observing-cadences-variable-star-types.