First Attempt at an Exoplanet

[AMcD]

I am not certain whether this post should go here or in Deep Sky Imaging, but I am tonight making my first attempt to capture the light curve of a star with a transiting exoplanet.  The chosen target is Wasp 33 (HD15082) in Andromeda, approximately 399 light years from Earth.  The planet, Wasp-33b, is a 'hot Jupiter' that has an orbital period of 1.22 days.

There appear to be a number of challenges.  First, I really should have tried some variable star photometry before diving straight into this.  Second, my 6" achromatic refractor is rather small for this sort of observation.  Third, I do not yet have any photometry filters so the comparison between the target star and the comparator stars might be somewhat challenging.  Fourth, having read the material of AstroImageJ, the software that will produce the light curve, the processing of the images is not a straightforward affair.  Fifth, the imaging run requires a meridian flip, which can make comparing the data spanning the transit tricky.  Sixth, I have a little icing on my CCD.  Finally, seeing is not brilliant tonight so guiding is not optimal.

Still, I have managed to capture data covering the ingress of the planet onto the stellar disc at 18.09hrs and am keeping my fingers crossed that the clouds stay away until after planetary egress from the stellar disc at 21.00hrs.  If it works notwithstanding the myriad of difficulties, I will post whatever light curve I manage in due course...😀

[Ian McCallum]

Not that long ago, this would have been considered science fiction!😵🧐

[Astro Noodles]

Yeah, It is totally cool. I'm eager to know if you get a result.

[AMcD]

35 minutes ago, Ian McCallum said:

Not that long ago, this would have been considered science fiction!😵🧐

It is amazing isn't it that this can now be attempted from a back garden with mostly second hand equipment.  Who would have thought it?  Certainly not me when I started out on this hobby.

[AMcD]

28 minutes ago, Astro Noodles said:

Yeah, It is totally cool. I'm eager to know if you get a result.

I have managed to capture the complete duration of the transit without the clouds rolling in (assuming that I have read the table of transit times correctly for my latitude and longitude 😳).  I now need to do flats, darks and bias for this specific imaging run and then will turn to grappling with AstroImageJ.  Hopefully I will have some results (positive or negative) in a few days...

[rl]

Best of luck with this. It's trying something on the limit...in a way I enjoy this sort of thing much more than pretty pictures. It's a bunch of fun trying even if you fail.

Do you have any estimates on the brightness dip and the photon statistics?

Please let us see the results even if there is no obvious transit signal. 

[AMcD]

1 hour ago, rl said:

Best of luck with this. It's trying something on the limit...in a way I enjoy this sort of thing much more than pretty pictures. It's a bunch of fun trying even if you fail.

Do you have any estimates on the brightness dip and the photon statistics?

Please let us see the results even if there is no obvious transit signal. 

Thanks.  I have an estimate of the brightness dip from the Swarthmore database of 12.5 ppt.   Photon statistics are a bit beyond me at the moment and I need to get my head around those (a challenge for someone who failed their maths GCSE a grand total of four times before calling it a day!!!).

[tomato]

Awesome project, as you say hard to believe that this can even be contemplated with amateur equipment. 
 

If we had a decent number of clear nights I’m sure I would give photometry a go but alas sky time is a scarce commodity in our neck of the woods. 

[Alex E]

yeah agreed, pretty mind-blowing what one can achieve in their back yard nowadays

[Muc]

That's amazing whatever the result turns out to be

[AMcD]

The software used to plot, or attempt to plot, the light curve has a steep learning curve to say the least...🤯  I am three hours in and still only at the stage of entering parameters...

[FinleyChambers]

very nice

[AMcD]

First Attempt at an Exoplanet - The Result.  Well here it is @Ian McCallum, @Astro Noodles, @rl, @tomato, @Alex E, @Muc and @FinleyChambers.   All in all I am relatively pleased.  Whilst my data is clearly not yet anywhere near good enough to demonstrate ingress and egress, and therefore nowhere near good enough to plot a proper transit light curve, it would appear that I did manage to detect a dip in the brightness of Wasp-33 as the planet crossed the stellar disc. 

I definitely need to do more work on exposure times and to acquire and understand how to use astrometry filters, rather than the narrowband filter I used to cut through my Bortle 5 sky.  I also need to get far better at understanding the various parameters that go into making up the model of the light curve.

Still, for a first attempt at exoplanets I will take it 😀

 

 

 

 

 

 

 

[Astro Noodles]

It certainly does appear that you have succeeded in detecting a drop in the light. I am very impressed.

[rl]

Well done! I am extremely impressed....

[Len1257]

Fascinating stuff, amazing that it can be achieved with relatively little eqipment. Knowing absolutely nothing about photometry is there a recommended resource out there that won't send me scurrying for cover? LOL! 

[tomato]

1 hour ago, Len1257 said:

Fascinating stuff, amazing that it can be achieved with relatively little eqipment. Knowing absolutely nothing about photometry is there a recommended resource out there that won't send me scurrying for cover? LOL! 

Firstly let me emphasise that I do not photometry,  but I did enjoy reading this introductory article:

https://www.cloudynights.com/articles/cat/articles/first-steps-into-variable-star-photometry-r3302
 

[AMcD]

4 hours ago, Len1257 said:

Fascinating stuff, amazing that it can be achieved with relatively little eqipment. Knowing absolutely nothing about photometry is there a recommended resource out there that won't send me scurrying for cover? LOL! 

This was my first attempt at photometry and I got some good tips from the AAVSO website (www.aavso.org) which contains a good introduction to the topic of photometry.  I also found a lot of assistance on exoplanet photometry from the Practical Guide to Exoplanet Observing by Dennis M. Conti and, in respect of the use of AstroImageJ, from his AIJ Cookbook (copies attached below). 

The guide itself also contains a good account of how to use AstroImageJ to create the light curve, as does the manual for that piece of software from the University of Louisiana and NASA (again, copy attached below).  Perhaps the most helpful resource for using the software however, is the YouTube video created by Chad at Patriot Astro (link below).  He explains the whole process step by step, and includes a number of stages that are not immediately apparent from the documentation that I have referred to above.

And finally a word or warning.  I became so involved in the process of analysing my data yesterday that I managed to entirely miss the fact that there was the most perfect clear night developing outside.  By the time I noticed I had missed out on a whole evening's worth of imaging in circumstances where my QHY8 requires about 6 hours to de-ice after startup 😳

Hope this of some help.

 Practical Guide to Exoplanet Observing.pdf

AIJCookbook.pdf

AstroImageJ_User_Guide.pdf

 

 

[Len1257]

37 minutes ago, AMcD said:

 

And finally a word or warning.  I became so involved in the process of analysing my data yesterday that I managed to entirely miss the fact that there was the most perfect clear night developing outside.  By the time I noticed I had missed out on a whole evening's worth of imaging in circumstances where my QHY8 requires about 6 hours to de-ice after startup 😳

Hope this of some help.

 

 

This last bit made my day! One day I'll make a tick list and won't forget to charge my (enter here whatever I have forgotten again) before I need it!

Thanks for all the information, I could easily miss a couple of imaging sessions if I get stuck into it all!