50 replies to this topic

[caballerodiez91]

Hi guys,

 

I detected my first exoplanet (hd 189733 b) and made a video about it showing step by step how I did it. I thought it could be useful for the people interested in the topic or already starting with transit photometry.

 

The star has an apparent magnitude of 7.7 and the exoplanet produces a drop of 2.8% during almost 2 hours.

 

I used a tele-photo lens (the Pentacon 135 mm f 2.8), a CMOS camera (ZWO ASI 120 MM) and an equatorial mount (Skywatcher EQ3-2)

 

I also have a dual-axis motor drive, but a simple one that only controls the right ascension would be enough.

 

I bought most of the items second-hand from Ebay and I spent around 300 euros.

 

To set up the tele-photo lens and the camera I have a couple of guide rings and in order to focus the tele-photo lens, I have to separate it 33 mm from the camera by using for example 2 M42 extension rings, one of them 28 mm long and the other one 5 mm. 

 

Now, the steps to detect the exoplanet are the following: 

 

                                      1. Find out when is the exoplanet going to transit the star with the Exoplanet Transit Database.

 

                                      2. With a program called SharpCap, take for example 5-second exposures with a gain of 1 for 3 hours. 

 

                                      3. Once the transit has finished, with a program called ‘AstroImageJ’ open all the images, select the target star and for example a couple of reference stars, and perform

                                          multi-aperture photometry to detect the light curve. 

 

I think it is better explained with a video: https://www.youtube....uZinoGtUGEOankw

Edited by caballerodiez91, 12 October 2018 - 03:10 PM.

[TOMDEY]

That's wonderful! Thanks for sharing; your video is Very Thorough.  Tom

[caballerodiez91]

That's wonderful! Thanks for sharing; your video is Very Thorough.  Tom

Welcome and thanks !

[cguvn]

i did it a couple time on nights with bad seeing/ way too much moon and it is super fun. 

 

highly recommend it

[Bart Declercq]

Awesome project! Thanks for posting.

[AstroCatinfo]

Superb! Very clear and shows that with very cheap equipment you can detect deep transits. Congrats and thanks for your work.

[JohnW*]

Thanks for the quick youtube tutorial and explanation.  Tonight I was actually learning AstroimageJ using the plate solve on an image of NGC 7635.  AstroimageJ is an incredibly powerful program as freeware.  I am looking forward to actually trying this myself.  Another great resource for beginners is :  A Practical Guide to Exoplanet Observing by Dennis M. Conti.

 

John

[akulapanam]

Hi guys,

 

I detected my first exoplanet (hd 189733 b) and made a video about it showing step by step how I did it. I thought it could be useful for the people interested in the topic or already starting with transit photometry.

 

The star has an apparent magnitude of 7.7 and the exoplanet produces a drop of 2.8% during almost 2 hours.

 

I used a tele-photo lens (the Pentacon 135 mm f 2.8), a CMOS camera (ZWO ASI 120 MM) and an equatorial mount (Skywatcher EQ3-2)

 

I also have a dual-axis motor drive, but a simple one that only controls the right ascension would be enough.

 

I bought most of the items second-hand from Ebay and I spent around 300 euros.

 

To set up the tele-photo lens and the camera I have a couple of guide rings and in order to focus the tele-photo lens, I have to separate it 33 mm from the camera by using for example 2 M42 extension rings, one of them 28 mm long and the other one 5 mm. 

 

Now, the steps to detect the exoplanet are the following: 

 

                                      1. Find out when is the exoplanet going to transit the star with the Exoplanet Transit Database.

 

                                      2. With a program called SharpCap, take for example 5-second exposures with a gain of 1 for 3 hours. 

 

                                      3. Once the transit has finished, with a program called ‘AstroImageJ’ open all the images, select the target star and for example a couple of reference stars, and perform

                                          multi-aperture photometry to detect the light curve. 

 

I think it is better explained with a video: https://www.youtube....uZinoGtUGEOankw

This is fantastic!  Great work

[StarmanDan]

Wonderful work!  I do exoplanet transit observations with my club's observatory but never thought to try it with my own equipment.  We also use AstroImageJ.  It is very powerful and you can set it up to plot the light curve live as images come off the camera.  Here is a plot of Wasp-80b.  It has a similar drop in brightness as HD189733b (the y axis scale doesn't represent percent drop).  I'd be interested in seeing what the smallest percent drop you could record with your setup.  

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[Quaternion]

Wow !!! Thanks for posting this.

Edited by Quaternion, 15 October 2018 - 10:37 AM.

[StarmanDan]

Would it be possible to share your data?  I believe you could make a much cleaner plot in AIJ than what you created in the video.  Did you do any calibration of the images before hand?  

[JohnW*]

Wonderful work!  I do exoplanet transit observations with my club's observatory but never thought to try it with my own equipment.  We also use AstroImageJ.  It is very powerful and you can set it up to plot the light curve live as images come off the camera.  Here is a plot of Wasp-80b.  It has a similar drop in brightness as HD189733b (the y axis scale doesn't represent percent drop).  I'd be interested in seeing what the smallest percent drop you could record with your setup.  

Dan,

 

What equipment did you use at your clubs observatory to generate this data?  Pretty incredible when you think about it.  Today we can use amateur equipment to "see" exoplanets.  I was amazed back in the 80's when Geoffrey Marcy confirmed the first found exoplanet and found two others with his team. I still hold him in high regards for this achievement, even tho his personal life has been quite questionable.

 

John

Edited by JohnW*, 15 October 2018 - 11:54 AM.

[StarmanDan]

Dan,

 

What equipment did you use at your clubs observatory to generate this data?  Pretty incredible when you think about it.  Today we can use amateur equipment to "see" exoplanets.  I was amazed back in the 90's when Geoffrey Marcy confirmed the first found exoplanet and found two others with his team. I still hold him in high regards for this achievement, even tho his personal life has been quite questionable.

 

John

Here is what my club's observatory has in it.  That's a 24" f/9 RC in a 24' Ash Dome.  We are preparing to upgrade all of the instruments and control hardware on the telescope in the next month.  We already have a new camera, it's a Princeton Instruments Pyxis 2048 and is a significant upgrade from our old camera.

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Edited by StarmanDan, 15 October 2018 - 12:00 PM.

[Mert]

Wow, that is very interesting and I love the way you have

taken advantage of economic equipment and obtained such

a nice result!

Thanks for sharing!!

[JohnW*]

Here is what my club's observatory has in it.  That's a 24" f/9 RC in a 24' Ash Dome.  We are preparing to upgrade all of the instruments and control hardware on the telescope in the next month.  We already have a new camera, it's a Princeton Instruments Pyxis 2048 and is a significant upgrade from our old camera.

I am impressed, what a great setup.  I noticed the error bars on your transit data were very tight, hence the question.  Does AstroimageJ actually calculate the statistical variation on each data point by calculating the base star variabilty, or does it use another method.  Again impressive data.

 

I may have hijacked this thread, my apologies.  Maybe I should private message you Dan if that is OK?

Edited by JohnW*, 15 October 2018 - 01:08 PM.

[StarmanDan]

John, I haven't delved into  AIJ that heavily yet as I'm still learning to use it myself.  This article provides a good overview of using AIJ for exoplanet work and may answer your question.

 

http://iopscience.io...8-3881/153/2/77

 

Our old camera was still good enough that we were able to detect .005 delta mag exoplanet transits.  

[akulapanam]

Out of curiosity what other programs do people use besides astroimagej for this?

[JohnW*]

John, I haven't delved into  AIJ that heavily yet as I'm still learning to use it myself.  This article provides a good overview of using AIJ for exoplanet work and may answer your question.

 

http://iopscience.io...8-3881/153/2/77

 

Our old camera was still good enough that we were able to detect .005 delta mag exoplanet transits.  

Thanks for the link Dan

[StarmanDan]

Out of curiosity what other programs do people use besides astroimagej for this?

AIJ is pretty much the defacto software for this.  There are others, here is a good list.

 

http://maravelias.in...variable-stars/

[caballerodiez91]

Thanks a lot for your kind words! I really appreciate them

[caballerodiez91]

Out of curiosity what other programs do people use besides astroimagej for this?

I use SharpCap

[akulapanam]

I use SharpCap

It looks like PixInsight aperturephotometry would work too and there is a R package too. More or less all you are doing is taking a series of exposures, calibrating then, and measuring the brightness in a given set of pixels or against another set of pixels for comparison.

Would be interesting to try on this on satellites like Exoanalytic

[caballerodiez91]

It looks like PixInsight aperturephotometry would work too and there is a R package too. More or less all you are doing is taking a series of exposures, calibrating then, and measuring the brightness in a given set of pixels or against another set of pixels for comparison.

Would be interesting to try on this on satellites like Exoanalytic

Thanks for the advice !

[NorthField]

Pinning this thread = great decision

[555aaa]

MPO Canopus does asteroid and exoplanet light curves but I would say the learning curve is steeper for the former. AstroimageJ doesn't seem to handle a moving target as well however.