AAVSO ALERT NOTICE 336 (April 4, 2006)

Subject: CCD CAMPAIGN TO OBSERVE 1059+23 AH LEO

Coordinates: 11:05:05.30 +23:21:08.0 (2000.0)

AAVSO Council member Dr. Pamela Gay, Harvard University, has requested our
assistance in observing the RR Lyrae variable star AH Leo closely this spring
and early summer. She is studying the Blazhko cycle and other periodicities in
this star, and precise, well time-sampled observations are essential.


Here is an excerpt from Dr. Gay's Variable Star of the Season presentation on
AH Leo that has been posted on the AAVSO website (www.aavso.org/vstar/vsots/):

"AH Leo rises from and falls back to a minimum magnitude of about V = 14.35
every 0.466 day, a period that appears to be evolving. Roughly every 25 days AH
Leo's Blazhko cycle repeats itself, causing the star's amplitude to vary from
deltaV = 0.5 to 1.2 magnitudes. To understand the star's every rise and fall,
we need to observe each of these two cycles in detail. Perhaps most
importantly, by covering the Blazhko cycle for multiple consecutive cycles we
can say with certainty what repeats (or fails to repeat) when, and identify any
additional, previously unknown, longer periodicities.

"While observations of RR Lyrae stars often focus on the ascending branch and
maximum light, we ask that observers please obtain images of the star during
all phases so that Fourier analysis can be used to fit the star's light curve.
This method works best when the entire curve is well sampled. We are also very
interested in any bumps that may appear during the descending branch of the
light curve, and changes in the shape of the light curve during minimum light."

V-band CCD observations are preferred, but filtered observations in all optical
bands are welcome. Please observe AH Leo as much as you can until the end of
its observing season in June, and submit your observations to the AAVSO using
\the appropriate CCD upload tool.

An AAVSO chart for AH Leo will be posted to the following URL:
http://www.aavso.org/cgi-bin/searchcharts3.pl?name=ah%20leo

Report observations to the AAVSO as: 1059+23 AH LEO

This campaign is being coordinated by E. Waagen (eowaagen@aavso.org).

Many thanks for your valuable astronomical contributions and your efforts.

Good observing!

Elizabeth O. Waagen
Senior Technical Assistant

SUBMIT OBSERVATIONS TO THE AAVSO

Information on submitting observations to the AAVSO may be found at:

http://www.aavso.org/observing/submit/

If you cannot access this URL, please contact us for submission details. You
may also use our charge-free number (888-802-STAR = 888-802-7827) or our fax
(617-354-0665) to report your observations.