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WASP-3b transit (I know, enough is enough)

paulobao

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paulobao

paulobao

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Ok, maybe I'm pushing it a bit but I love transit (no, I don't i run my bike almost all the time to my working place).

From last night. Same gear.

180 frames of 60s (1.06 GB of data to calibrate and process photometrically...).

This one, have a magnitude depth of only 0.012 mag (TrES-3 have a depht of 0.029 mag so, more than the double).

I promise that I don't bore you anymore with this kind of stuff !

Regards,

paulo

The host star:

jdv1245688255j.jpg

The WASP-3b transit (each point is a mean of 6 fits). Begin and End dates/time predictions from the Exoplanet Transit Database (which correlates well with my data):

jdv1245688653p.jpg

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daz

daz

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Absolutely not!! You keep them coming Paulo!!!

They are just amazing. I too didn't realise you could do this sort of stuff!!

Do you have a picture of the transit itself Paulo?

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paulobao

paulobao

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Do you have a picture of the transit itself Paulo?

Hello Daz,

No one ever saw (visually) a transit of an exoplanet :).

The transit method (photometric) it is the only way we have to detect the exoplanets. It is an indirect method to "see" it.

It is the method used by the professional astronomers to discover the exoplanets.

regards,

paulo

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barkis

barkis

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I echo the sentiments of Daz. and Ant. Paulo.

What you are doing is very exciting stuff. Particularly as one day, a light dip around some star may be indicating a planet with life of some sort. There is no reason to say that it is not a possibility.

As long as you plot these light curves, the majority of SGL members will want to see them.

Ron.:):icon_salut:

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paulobao

paulobao

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Hello,

I was out for a couple of days (I spend 4 whole nights making photometry and astrometry so I nedded to rest a little :). But I'm back).

Ok, I will post my next LCs here in the forum.

There is lots of targets. If you want to try one I would recommend this one next 29th:

HD189733 b (Vul)

RA (J2000): 20 00 43.713, DE (J2000): +22 42 39.07,

V = 7.67 mag, dV = 0.028 mag, duration = 109.6 minutes

it is a easy target with a "huge" mag depth of 0.029.

The transit itself it will begin at : 00:39 UT (58º alt) and it will end at 2:29 UT (62º alt). So please start 1 hour before and end 1 hour after.

And don't forget, time is UT not local.

Just point to V452 Vul (aka TYC 2141-972, HD189733, HIP98505, etc, I don't know the catalogs you have in your planetarium software!).

Pay attention to not saturate your CCD pixels. You should have something like 20000 or less ADUs (if you have a NABG CCD). Of course in a star of mag 7.7 the ccd will saturate rapidly so, defocus until you have this kind of counts in a 60-120s exposure (you will need to defocus a lot).

Regards,

paulo

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Doc

Doc

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Let me get this right in my head.

We are seeing the star that the planet revolves around. We are not seeing the planet itself. So we are detecting a dimming of the star (sun) when the exoplanet transits in front of it's own sun.

Can this dimming be seen without the use of cameras and ccd's.

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lunator

lunator

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Doc

I don't think visual observing will enable you to see this.

The change in magnitude is only 0.029.

The is roughly about 10 times less than you would expect to be able to see visually.

Cheers

Ian

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paulobao

paulobao

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Let me get this right in my head.

We are seeing the star that the planet revolves around. We are not seeing the planet itself. So we are detecting a dimming of the star (sun) when the exoplanet transits in front of it's own sun.

Exactly.

Can this dimming be seen without the use of cameras and ccd's.

Like...at naked eye? See, the maximum depth in magnitude for this one (and it is huge compared with some) is only 0.029 mag. And this occurs gradually from the begin of the transit to the center of it, in this case one hour or so after it begins. Can you detect a 29 milimag variation without any instrument? :)

Cheers,

paulo

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Doc

Doc

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Exactly.

Like...at naked eye? See, the maximum depth in magnitude for this one (and it is huge compared with some) is only 0.029 mag. And this occurs gradually from the begin of the transit to the center of it, in this case one hour or so after it begins. Can you detect a 29 milimag variation without any instrument? :)

Cheers,

paulo

LOL

I see you point guys. It still not going to stop me having a look at the star so I can imagine an exoplanet going in front of it.

Do we know how large the orbit is for the exoplanet. Is it in the so called "Goldilocks position".

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daz

daz

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More questions - sorry Paulo!

When I said an image of the transit, I mean to compare the transit image with a non-transit image to see if the drop is noticeable on screen. I understand you can image the transit of the planet!!

The filter you use - this is a special filter needed for this type of work?

Do you need it, or would the results not work properly without it?

Presumably you have to calibrate the software (Maxim??) to correctly record the magnitude?

Sorry, but I'm finding this really quite fascinating!

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paulobao

paulobao

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Hello daz,

My pleasure to answer (I will try) your questions:

about your questions:

- "I mean to compare the transit image with a non-transit image to see if the drop is noticeable on screen"

you may do that but...you must guarantee that all sky conditions are exactly the same (transparency, turbulence, etc) and the airmass are exactly the same and that would be quite a challenge :headbang:. And then you must have a high visual acuity to detect a slow drop (during time) of only a few mmags!

-"The filter you use - this is a special filter needed for this type of work?"

yes it is a calibrated photometric filter (Bessel type and R). But you don't need a filter to detect the transit itself.

-"Presumably you have to calibrate the software (Maxim??) to correctly record the magnitude?"

you don't need to know any accurate magnitude of the surounding stars because what will do is differential photometry (not absolute magnitude LCs). In the software (MaXIm DL will do that) you will need to "mark" the target star and at least one reference star at the vicinity of the target star. The software will than compare the variation of the TS to the RS in all your fits and plot that variation.

Ok, if you want to experiment I have my calibrated, aligned and croped TrES-3b transit files (in zipped format) here :

4shared.com - online file sharing and storage - download TrES-3b_Transito_de_20090621_Paulo_Lobao_J15.zip

and here the target star where the transit will occur (TrES-3) and some reference stars:

viu1246099681i.jpg

Enjoy :),

paulo

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