Notes on Particular Stars

The individual brightness measurements Hipparcos made of these stars can be found on the mission's Web site. There, an interactive utility even lets you "fold" the observations back on themselves to look for repetitive changes in brightness. Thanks to these benchmark data going back a decade now, any new minima observed by readers will lead to very accurate predictions in the future.

DG Ceti is the star described at the opening of this article. Aside from the minimum on June 14, 1992, Hipparcos caught another on July 13, 1991, and part of a third on August 9, 1990. These suggest that another dip may have occurred about November 5, 1999. But the 337.4-day interval on which this prediction is based may be a multiple of the true period, so the star should be checked on other nights as well. It has an 11th-magnitude companion 5.5" to the southeast that has nothing to do with the eclipses.

DS Ceti is presumably the 9.5-magnitude primary of the visual double star at the location given in the table; the 10th-magnitude companion lies 6.7" to the west.

AL Arietis, normally magnitude 9.2, was as faint as 9.8 in two measurements made near 19:40 UT on August 9, 1991. Unfortunately, the satellite observed this star on only 49 occasions during the mission and caught no other anomalies. All bets are off as to when it will dip again.

DP Camelopardalis had six apparent dimmings during the mission. But they don't seem commensurate, and only three were tagged as reliable by Hipparcos scientists. At 77 light-years from the Sun, this is the nearest of the binaries on our list.

V1366 Orionis, lying 1 2/3° south of Rigel, was as faint as magnitude 10.7 on July 23, 1990. After recovering it was recorded at 10.4 some 47 days later.

V1125 Tauri was 0.6 magnitude fainter than normal on March 21, 1991.

FU Eridani was a half magnitude dimmer than usual on two occasions.

V366 Puppis was faint on three occasions consistent with a 39.1-day period. This star, normally about magnitude 8.4, has a 10th-magnitude companion 7.2" to its south.

UZ Volantis is a south circumpolar star, observable from the Southern Hemisphere any night of the year, all night long.