Frequency of Observations for Different Variable Star Types

Visual observations of variable stars make up the largest component of the AAVSO International Database now containing over 19 million observations on thousands of variable stars. These stars are primarily large-amplitude (visual range greater than one magnitude). The types of variables include; pulsating (Mira, semiregular, RV Tauri, Cepheids), eruptive or cataclysmic (dwarf nova, nova, recurrent nova, novalike, supernova, symbiotic), R Coronae Borealis, nebular (T Tauri, flare), irregular, and suspected variables. The observations on these stars are sent directly to AAVSO Headquarters. We also have several hundred eclipsing binary and RR Lyrae stars in the visual observing program and their observaitons are sent directly to the chairmen of these special committees.

Due to the wide range of periods and magnitudes of variation from type to type, some stars need more frequent observations and require more specific reporting of their observing time than others. Below is a table that gives the suggested frequency of observations together with the digit of the Julian day their observations should be reported at to the AAVSO.

Suggested Frequency of Observations:

Cepheids Every clear night 4 decimal places
Cataclysmic var. Every clear night 4 decimal places
Mira variables Once per week 1 decimal place
Semiregular Once per week 1 decimal place
RV Tauri stars Once per week 1 decimal place
Symbiotic stars* Once per week 1 decimal place
R CrB* stars During maximum once per week 1 decimal place
R CrB stars During fadings every clear night 4 decimal places
Irregular variables Once per week 1 decimal place
Suspected variables Every clear night 4 decimal places
Flare stars Continuously for 10 to 15 minutes for rare outbursts. 4 decimal places
Eclipsing binaries Every 10 minutes during eclipse 4 decimal places
RR Lyrae stars Every 10 minutes 4 decimal places

Note: Symbiotic stars and R CrB stars may experience possible small-magnitude, short-period variability. If you are interested in looking for this, then observations should be made every clear night and reported to 4 decimal places.