M31_V1's light curve is taking shape
A distant Cepheid is getting some attention for the first time in decades, thanks in part to some AAVSO observers.
Earlier this year, the AAVSO was contacted by Dr. Keith Noll from the Hubble Heritage Team at the Space Telescope Science Institute about a unique HST project. They were requesting amateur observations of the very first Cepheid discovered in M31 by Edwin Hubble. This object, M31_V1, varies between roughly V=18.5 and V=19.5 with a period of about 30.41 days. Surprisingly, the star has been poorly studied since Hubble's time, and astronomers at HST including Dr. John Grunsfeld felt that this should be remedied. The AAVSO launched a campaign on July 16, 2010 to change this. Due to the faintness of the target, fewer than half a dozen AAVSO observers have taken up the challenge of this star. However, the data collected thus far clearly show the Cepheid-like shape of the light curve, and confirm with reasonable precision a period around 30.4 days.
HST should be observing this star some time in late 2010 or early 2011. Additional ground based observations will be done by Mount Wilson and other observatories, but the AAVSO observers are doing their part. It's shaping up to be a great project, and another great AAVSO light curve!