Exoplanet WASP-3b in Lyra

Dear friends ... and that guy O'Connell,

One of the latest exoplanet announcements involves WASP-3b in Lyra and which requires 160 minutes to transit its parent star and at a depth of 11.4 mmag. Given its proximity to its parent star and relatively high mass (1.76x that of Jupiter), WASP-3b is one of the largest and hottest Jupiter-like finds so far.

The ten-day old moon was a problem during the four-hr session last night and thankfully my Baader Infrared Pass filter did a wonderful job in helping improve contrast while minimizing the mitigating effects of the lunar light (pollution).

The results from last night's session are available at www.perseus.gr/Astro-Photometry-WASP-3-20080613.htm .

All systems are go for Sunday evening and a visit to another foreign world but this time in Ursa Major.

Clear skies!

Hi Anthony,

Well done on an excellent result!
Were your images bias subtracted with any stacked bias frames and flat fielded with the IR filter?
How many non-variable comparison stars did you use for this event?
What millimag precision did you obtain for this event?
Did you determine if the predicted event was on time?

Is HAT-P-7 and TrES-2 time zone doable at your location?

Eamonn A
MPC J62
www.kingslandobservatory.com

Hi Anthony,

Hi Eamonn,

Well done on an excellent result!

Glad you like the result. This was my second try at this particular exoplanet given the problems with transparency which plagued the earlier effort.

Were your images bias subtracted with any stacked bias frames and flat fielded with the IR filter?

Yes for the flat frames and which included flat-darks.

As for the bias frames, I do not use scaled darks and therefore there should be no need for a bias since it self-cancels when each image is reduced with the master dark (ditto for the flats which are reduced with the flat-darks).

How many non-variable comparison stars did you use for this event?

I always use two such stars ... one comparison and one check.

What millimag precision did you obtain for this event?

The log from AIP4Win was reporting errors between 6 and 8 mmag for the complete session.

Did you determine if the predicted event was on time?

I have no objective of doing something like this. I also have a problem with the ingress and egress predictions from TransitSearch since they do not match the transit duration they report.

Is HAT-P-7 and TrES-2 time zone doable at your location?

Yes on both counts. I already have done HAT-P-7 and I am waiting for June 26th to attack TrES-2.

I am currently working on HAT-P-3 at this moment with another 50 minutes to go but I am not happy with the intermediate results and it is something I blame exclusively on my decision to use a LUM filter as opposed to IR once again. Unfortunately it is getting slightly late for HAT-P-3 (and UMa) and I will have to wait for later this year. :evil:

Anthony, my congratulations on this observation. It is a fine example of the quality of the work which amateurs can produce.

Hi Dave,

I am delighted to learn you like the result. I have spent some time on these wonderful exoplanets and have nailed eight of them so far ( www.perseus.gr/Astro-Photometry.htm ) and which should be up to a dozen by month-end and at least twenty by the end of July.

Just the idea that photons from a star hosting a hot Jupiter are coming through your telescope is surreal.

Hi Anthony,

Regarding WASP-3b. I was curious that you only used one comparison star and one checker star.

In a previous transit I selected at least 6 non-variable comparison stars in a field in order to use differential photometry. For each exposure, I summed the fluxes of the 6 comparison stars and divided by the flux of the target star to derive the differential magnitude of the target. This summation improves the precision to some millimags. I have found the more non variable comparison stars used the better the millimag precision for the target.

Eamonn A
MPC J62
www.kingslandobservatory.com