The AAVSO is working with www.transitsearch.org to coordinate observing campaigns of two transit windows in late December, 2004 and early January, 2005. The two objects of interest are HD 74156 and HD 37605, both stars were recently detected to have orbiting planets and are visible to both hemispheres.

As the campaigns begin in a couple of weeks we will post progress reports, light curves, tips and more to this web page. Stay tuned!

Last updated: Wed Feb 23 14:19:29 EST 2005

Artistic impression of an extrasolar planet. © David A. Hardy/www.astroart.org

HD 74156 and HD 37605 Campaign Details

Planet	Peak Window	Depth	Duration
HD 37605b	17:00 UT December 29, 2004 (UT)	1.78% (~0.02 mag)	435 min
HD 74156b	20:00 UT January 1, 2005 (UT)	0.69% (<0.01 mag)	415 min

Histogram of central transit times computed using self-consistent orbital fits to published radial velocity data, combined with a bootstrap Monte-Carlo method to compute transit times.

Excerpt of text from CCD Views #328, December 2, 2004:

New Exoplanet Campaign Announcement: HD 74156 & HD 37605
(or All I want for Christmas is an Exoplanet Transit)

The Transitsearch.org/AAVSO collaboration marches on. The next campaign will be a challenging one taking place over the holiday season. The target stars are HD 74156 (Hydrae) and HD 37605 (Orionis), observable from both hemispheres so everyone can be involved in this one.

The combined transit window begins on December 26, 2004 and lasts until January 3, 2005. We have put online a histogram of the distribution of combined transit times at this URL:

http://www.aavso.org/news/transithist.png

This will be a tough campaign. Millimag photometric precision will be needed for HD 74156 while HD 37605 will be easier with an estimated transit depth of ~0.02 mag. Both stars are fairly bright so SNR should not be a problem, but scintillation will be. Read CCD Views #324 Section 4. for a good discussion of short exposure photometry:

http://www.aavso.org/publications/ccdviews/324.shtml

The campaign will be coordinated at this URL, bookmark it and visit often!

http://www.aavso.org/news/transits.shtml

Since we have two stars with overlapping windows it will be important to coordinate observing. When you begin to observe a star please post a message to the aavso-photometry discussion group (or e-mail me if you are not on the group and I will relay the message) with your target, start time (UT) and estimated stop time (UT).

Chances of a positive detection are slim - an estimated 6% for the combined systems. However, as before, non detections are also valuable as they can restrain the dynamics of the system. So all data is useful! Also, the first amateur to discover an exoplanet transit is probably in for some nice publicity and exposure. How many other such opportunities ever come your way? We plan to do more of these campaigns in 2005. So what you learn here will be valuable down the road. So why not participate?