Exoplanat WASP-2b

[Dave Smith]

The last 4 nights looked very promising with a high around but the first three clouded up at the wrong time. Last night it surprisingly went well until after I had finished.

My main interest is with variable stars but have taken a temporary interest in detecting exoplanets. I still feel that is amazing that with amateur equipment they can be detected.

This particular star has normal magnitude quoted as 11.98 in V band with a drop of 0.0216 mag while the planet transits. The duration of the transit is predicted as 107.9 minutes. Last night this was due to occur between 1900 and 2048 GMT.

My results shown here captured using SGPro and processed using AstroImageJ (an excellent piece of FREE photometry software). The scope used was a Celestro 11" EdgeHD with 0.7x FR and an Atik 460EX CCD camera with a V filter.

Dave

[saac]

Dave that is amazing. I wonder without going to too much trouble would you be able to give a brief outline of what the process is.  Is data capture a similar routine to what you would do for straightforward imaging; I mean is it long exposure of  multiple subs or video capture?  And how do you extract the photometry data ?  I love to have a go at this and wonder even if it something I could use for the classroom. Would my one shot colour Starlighexpress CCD be suitable? Grateful for any advice  

Jim 

[Dave Smith]

Hi Jim

I will try to briefly explain. The first stage is to take a series of images of the region of interest in such a way that the star is not saturated and also stars that may be used as comparison stars must not be saturated. In this case I used 60 seconds. The ti.e depends very much on the star brightness and the telescope used. The target star was found using SGPro and cenralised using plate solving. As soon as an image was downloaded the next was started. That is the easy bit. As in imaging darks and flats have to be applied. I use a mono camera but your camera should be ok as long as it stores the time etc in the FITS header. For the photometry there are 3 ways I have used. My first attempts were with MaximDL. That program is very expensive so don't try that unless you already have it. Then i tried Muniwin and recently AstroImageJ. Both are easily found on the net together with help files.

I would suggest that before going for an exoplanet, you try a variable star such as an eclipsing binary star as that will give you more confidence with the procedures. If you look at the variable star section of the BAA website you will find loads of advice and suggested targets. Learning the techniques is not easy but for me has been great fun. Once you can produce a reasonble light curve then would be the time to try for an exoplanet.

If at any time you have questions on this topic do not hesitate to ask.

Dave

[saac]

Dave thanks for that, really appreciate your advice. I found AstoImageJ using your link and it looks like very capable software. I've downloaded a copy and I can see it will take some time to familiarise myself with its operation. I think you are right about starting with a variable star, that makes a lot of sense.  I'm really captivated by what you have achieved above,  it really is amazing.  I've been looking for some time to do some proper measurement/analytical astronomy with a long term view of maybe introducing some of the data collection and processing into the classroom.  Even if I don't get to the stage of capturing a transit  light curve (just how cool that must be) I do see a lot of potential in photometry itself.  I'll let you know how I get on and certainly come back with questions along the way.  Thanks again.  

Jim 

[Dave Smith]

Hi Jim

Here are a few links you may find useful.

https://www.astro.louisville.edu/software/astroimagej/guide/AstroImageJ_User_Guide.pdf

Richard Lee's tutorial on AstroImageJ

https://britastro.org/sites/default/files/Tutorial_AIJ_Photometry_v2.05.pdf

BAA VSS website where there are many useful links

http://www.britastro.org/vss/

Dave

[saac]

Thanks Dave, I've got the two pdfs printed off now; my reading list for the weekend   

Jim