What to Do Next

Simply entering your magnitude estimates in a notebook may eventually reveal fading or brightening trends or cyclical variations in a star's light. But this effort is wasted unless you follow accepted techniques, like those just described, and communicate your findings to others who are also engaged in variable-star work.

The best way to share your results with professional astronomers and learn from more experienced observers is to join an organization like the American Association of Variable Star Observers, 25 Birch St., Cambridge, MA 02138 USA. The benefits of membership include being in the pipeline to receive the AAVSO's Alert Notices and News Flashes of novae and other stars showing unusual activity, as well as the biannual Journal. To find out how to join, call 617-354-0484 or visit its Web site. This site has links to other variable-star groups around the world.

In recent years, some 600 active amateurs in 40 countries have been sending their observations regularly to the AAVSO. Its database now bulges with nine million magnitude estimates going back to 1902 — a rich resource that professional astronomers consult whenever they need the history of a particular star's variations.

Comparison charts for the four variables listed in the table but not included in this Web article are contained within the original article, available in Sky & Telescope's online archive.

Eleven "Unsolved" Hipparcos Variables
Name	Type	(2000.0) R.A.         Dec.		V magnitude	Amplitude
FM Leo	EA	11h 12.8m	+00° 21'	8.4	0.5
HS UMa	I	11h 35.5m	+34° 52'	8.5*	0.6
TX Crv	—	12h 00.8m	-12° 09'	8.0*	0.7
KM Com	—	12h 38.9m	+13° 48'	8.8*	0.6
DK Boo	—	13h 44.0m	+21° 49'	8.2	0.7
V353 Hya	EA	14h 10.2m	-25° 24'	7.4	0.5
DR Boo	I	14h 16.0m	+34° 26'	8.3	0.5
FG Boo	L	15h 11.6m	+49° 54'	7.6	0.6
KZ Lup	SR	15h 51.7m	-38° 09'	9	0.5
V939 Her	SR	17h 10.3m	+40° 41'	7.3	0.7
GV Dra	EA	17h 53.5m	+52° 23'	8.5	0.5
Variable types tentatively assigned in the Hipparcos catalog based on a partial light curve are EA, Algol-type eclipsing binary; I, irregular; L, long-period; SR, semiregular. The magnitude given is the median of the values measured during the mission, adjusted to the V (visual) photometric band; asterisked values refer to the combined brightness of a close pair. The amplitude is the difference between the faintest and brightest magnitudes measured for the star (the actual amplitude could be even greater).