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John

Antares Challenge

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 The clarity of the atmosphere is certainly affecting your chances of splitting Antares in the UK. It is a credit to any of you who succeed with it at such low elevations. My view of it here in Melbourne with the star at about 60 degrees elevation was steady as a rock, no drifting in and out at all. E and F in the Trapezium likewise is fairly easy with Orion also at 70 degrees up.

I get into difficulties with splitting the Double Double which cruises along just above our northern horizon, I have managed it but seeing all four is a tough challenge through the haze.

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Posted (edited)
6 hours ago, David Levi said:

Well done John. I feel a bit disappointed now as I've just come in after failing to split Antares with my Takahashi FC-100D. I tried to see the smaller partner star without knowing its location and after giving up and looking up its position I still couldn't see it or even imagine that I could see it. I was binoviewing at approx. 200x magnification. There was a bit of unsteady atmosphere at that magnification and the diffraction rings weren't helping. It was a fun challenge though and one I will return to now that your experience has shown that it is possible with a 100mm apo refractor.

I've done it in the past with an 80ED - I don't think aperture is the main issue really, it's more about seeing and as John says, having a clear S aspect (and of course having any clear nights).

This is a simulation (Aberrator) of Antares with a 180 mm Mak and a 100mm frac - you can see both can split it easily; I've added a bit of colour for fun!

Chris

 

antares - Effect of aperture.jpg

Edited by chiltonstar
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6 minutes ago, chiltonstar said:

I've done it in the past with an 80ED - I don't think aperture is the main issue really, it's more about seeing and as John says, having a clear S aspect (and of course having any clear nights).

That's good to know. My location isn't great for low declination observation. SQM is roughly 19.0 at the zenith and of course there's a lot more muck to look through low down on the horizon.

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1 hour ago, chiltonstar said:

I've done it in the past with an 80ED - I don't think aperture is the main issue really, it's more about seeing and as John says, having a clear S aspect (and of course having any clear nights).

This is a simulation (Aberrator) of Antares with a 180 mm Mak and a 100mm frac - you can see both can split it easily; I've added a bit of colour for fun!

Chris

 

antares - Effect of aperture.jpg

Thanks for that Chris. If those position angles are right then that builds my confidence more that I got the split. I'd say that last night the secondary looked a smaller blob than the primary and rather more the colour of dirty blu tack !

It was good to be observing something last night, I've not been out much due to the poor weather lately.

 

 

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Posted (edited)
11 minutes ago, John said:

Thanks for that Chris. If those position angles are right then that builds my confidence more that I got the split. I'd say that last night the secondary looked a smaller blob than the primary and rather more the colour of dirty blu tack !

It was good to be observing something last night, I've not been out much due to the poor weather lately.

 

 

The Stelle Doppie figure for PA is 277 degrees which matches what we both saw I think. The blue of the secondary may be aperture dependent as I would say with 180mm it was definitely blue-green 'ish, although of course with atmospheric refraction and seeing wobbles, colour is always a bit subjective!

On my original, the intensity ratio looks right, but shrinking the file and copying across has made the intensities look more similar. Unfortunately, my laptop was also trying to perform a couple of updates (G knows what) which corrupted the image file slightly. This is the 100mm simulation with the blue-green intensity reduced to something more like the correct ratio (it makes the colour slightly more Blu Tack'ish maybe?):-

Chris

antares 100mma.jpg

Edited by chiltonstar
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"....with atmospheric refraction and seeing wobbles, colour is always a bit subjective!...."

It most certainly is !

That image is close to what I observed in terms of scale and hues during the moments of best steadiness, which were rather few of course. The kaleidoscopic effect of the atmosphere on the primary star was doing it's best to keep the secondary a secret :rolleyes2:

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10 minutes ago, chiltonstar said:

This is the 100mm simulation with the blue-green intensity reduced to something more like the correct ratio (it makes the colour slightly more Blu Tack'ish maybe?

That's pretty much how they looked to me, maybe the secondary was a tad brighter here and more grey/green, but pretty close.

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I went out with the intention of having a go at Antares last night but cloud stopped that plan. I did split the double double and then Izar with the Equinox 80 and Nagler Zoom. I hadn’t expected to get Izar in the frac and was very pleasantly surprised. Chris’ comments on splitting Antares at 90x gives me hope of getting a split with this setup. 

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