My second exoplanet detection

[Dave Smith]

My second exoplanet detection.
This one is called Qatar-1b and is in the constellation of Draco. The predicted drop in magnitude was 0.0204 mag. Averaging my values I get a drop of 0.017, so am very happy with that. The graph shows V-C which is the difference in magnitude between the variable and a comparison star. The red lines indicate the approx start and finish of the transit. This is using my Megrez 90 with Johnson V filter and Atik 460EX camera. I also include the results of a t-test as shown to me by Robin.

Dave

[Freddie]

That’s excellent Dave. Are you able to draw a line of best fit on the graph as that really helps to clearly show the dip.

[JeremyS]

Well done Dave - great result!

[Dave Smith]

Thanks Freddie and Jeremy. I will give your idea a go Freddie.

Dave

[Dave Smith]

3 hours ago, Freddie said:

Are you able to draw a line of best fit on the graph as that really helps to clearly show the dip.

Does this help? Lines drawn purely by eye.

Dave

[Freddie]

I was more thinking to use whatever software you used to plot the graph to do a proper statistical line of best fit.

[Merlin66]

The AAVSO have all the tools you need........

[Dave Smith]

The software I have been using, Muniwin, does not have that as a feature. On the AAVSO site I have found AstroimageJ,  which is what I presume you were referring to Merlin, which does seem to have the ability to do that. I'm going to be fairly busy in the coming week but will investigate it further. Thanks for the suggestion.

Exoplanets are not my main interest, apart from anything else I don't think a 90 mm refractor is the best tool for the job. I was simply curious as to whether I could detect an exoplanet. My main interest is currently variable stars. I will however investigate AstroimageJ.

Dave

[Chris]

Well done, Dave, cracking stuff!

[Olli]

Great stuff Dave, hope you keep making these posts very interesting.

[Whirlwind]

On ‎06‎/‎05‎/‎2018 at 13:56, Dave Smith said:

The software I have been using, Muniwin, does not have that as a feature. On the AAVSO site I have found AstroimageJ,  which is what I presume you were referring to Merlin, which does seem to have the ability to do that. I'm going to be fairly busy in the coming week but will investigate it further. Thanks for the suggestion.

Exoplanets are not my main interest, apart from anything else I don't think a 90 mm refractor is the best tool for the job. I was simply curious as to whether I could detect an exoplanet. My main interest is currently variable stars. I will however investigate AstroimageJ.

Dave

NASA has an online tool to fit transits - https://exoplanetarchive.ipac.caltech.edu/cgi-bin/ExoFAST/nph-exofast

You could try this.  Just to note though you need the data in normalised flux (not relative magnitudes)

 

 

[Ruud]

Oo, Dave, I'm terribly impressed!

Congratulations on the observation!

[Dave Smith]

17 minutes ago, Whirlwind said:

NASA has an online tool to fit transits - https://exoplanetarchive.ipac.caltech.edu/cgi-bin/ExoFAST/nph-exofast

You could try this.  Just to note though you need the data in normalised flux (not relative magnitudes)

 

 

Many thanks - I'll give it a try.

Dave

[Owmuchonomy]

Another great result Dave!

[Dave Smith]

I've had a quick play with the NASA online tool but just can't get it to accept my data file. I have normalised the magnitudes and made it a txt file but no go.

I've also downloaded AstroImageJ but that seems rather a big learning curve which I will not pursue at the moment. I am happy that I have detected an exoplanet (or two) which is all that I wanted to do. Back now to variable stars 

Thanks for all the interest and suggestions.

Dave

[Whirlwind]

On ‎08‎/‎05‎/‎2018 at 20:26, Dave Smith said:

I've had a quick play with the NASA online tool but just can't get it to accept my data file. I have normalised the magnitudes and made it a txt file but no go.

I've also downloaded AstroImageJ but that seems rather a big learning curve which I will not pursue at the moment. I am happy that I have detected an exoplanet (or two) which is all that I wanted to do. Back now to variable stars 

Thanks for all the interest and suggestions.

Dave

How have you created the text file?  It loads better if it is tab separated not comma separated.  Also be wary of using Excel or other Microsoft programs for creating such files.  They tend to add in invisible characters into the text/csv files.  Most professional astronomy software is based on unix which creates clean text files and hence it can cause all sorts of problems if there are hidden characters inserted by the Microsoft.

There is another implementation here:-

http://astroutils.astronomy.ohio-state.edu/exofast/exofast.shtml

This gets you to enter in the data points 'manually' which usually clears hidden characters.

Otherwise you can post the file and I can see if I can get it working.

Ian

 

[Dave Smith]

4 hours ago, Whirlwind said:

How have you created the text file?

Ian

 

Thanks Ian. I did eventually get a text file that worked. I had normalised the magnitude ok but had forgotten to normalised the errors. However I then found that I could generate a similar graph to that above but no means of getting a line of best fit.

Dave

[Whirlwind]

What were you getting when you ran the application.  Was it throwing up any errors?

I've just ran it with photometry only data using the example HD 17156b data and following the guide

https://exoplanetarchive.ipac.caltech.edu/docs/exofast/exofast_recipe_1.html

And I am getting the following output in the results tab

 

 

[Dave Smith]

Many, many thanks Ian for your help on this. I have finally managed to get it to work. Here is the result.

Dave

[Dave Smith]

I have since found an alternative on the actual exoplanet transit database which gives the following. This seems to be an improvement as it works with the actual magnitudes.

Dave

[bish]

Excellent, exciting stuff.