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  #21  
Old 02-04-2019, 05:41 PM
Dennis
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Thanks for posting this challenging project Bojan, it got me outdoors again.

I’m a little late to the game, but I managed to grab a session on Sunday night to attempt recording the companion of Procyon. Previously, I had easily split Sirius A & B but with Procyon I did not even get close.

I grabbed a few AVI’s at 1024x768 at various exposure settings, along with a full res 1936x1096 field at 10 secs to record the wider view.

I couldn’t record any stellar diffraction rings with the Mewlon 210 which was highly unusual, probably due to poor seeing.

I have also included an earlier image of Sirius A & B taken in 2018 with the same optical set up, but using a Canon 5D Mk IV as the camera.

After this one Procyon attempt, I feel it is unlikely that I will be able to image Procyon B, even with the star at a greater altitude and under good seeing conditions.

I have annotated the wider composite view with field stars that showed up consistently in the 3 x 10 sec exposures. I used the “Ruler Tool” in PS CC to measure the pixel separation from Procyon A and then multiplied those values by 0.15 to obtain an approx. separation in Arc Secs. However, I could not correlate my field stars with those listed in the database (green text top left) at the following link.

https://www.stelledoppie.it/index2.php?iddoppia=34859

Unfortunately, I did not note the orientation of the ASI 290 MM during the capture….

Cheers

Dennis
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Click for full-size image (ZWO ASI290MM_L_31032019_195145_Star_lapl4_ap1 1200.jpg)
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Click for full-size image (IMG_1088 Crop 800 Text.jpg)
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  #22  
Old 02-04-2019, 09:05 PM
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I think I caught a glimpse of it tonight.... meaning pretty sure I am.
Atmosphere was boiling a bit but it was calm from time to time.

Sirius B was easy.. and so was Trapezium, all 6 of them at ~250x.
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  #23  
Old 02-04-2019, 10:25 PM
Wavytone (Nick)
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Dennis after doing some maths tonight for your scope Procyon B will be behind the 4th diffraction ring. If you don't see it try rotating the OTA 45 degrees in case its hiding under a diffraction spike. In mine it's between the 4th and 5th.

Last edited by Wavytone; 03-04-2019 at 07:28 AM.
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  #24  
Old 03-04-2019, 09:17 AM
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mental4astro (Alexander)
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Quote:
Originally Posted by bojan View Post
and so was Trapezium, all 6 of them at ~250x.
Just 6?

There's a whole lot more, you know. Aperture and seeing is important. I've seen 10 stars in the Trapezium from my home in Sydney under exceptional seeing conditions with my 17.5". Not even from a dark site, but from deep inside Ol' Sydney Town. Trap. A, B, C, D, E & F are cannon fodder for a scope 6" and larger. The others though do need more aperture grunt and stable seeing. Aperture and seeing. A dark sky not necessarily critical.

I've been following this thread with considerable interest. Now if only the blooming clouds would bugger off I could have a go too...

Alex.
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  #25  
Old 03-04-2019, 09:28 AM
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Just 6?

I know.. It is bare minimum.. less than that and no point in even attempting Siius B.
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  #26  
Old 03-04-2019, 09:36 AM
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mental4astro (Alexander)
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Bojan, I also use the Trapezium as a quick guide to seeing conditions. How easily the smaller two of the brighter six stars can be seen is a very good guide. Seeing any more is just LUXURY!
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  #27  
Old 03-04-2019, 09:57 AM
Dennis
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Originally Posted by Wavytone View Post
Dennis after doing some maths tonight for your scope Procyon B will be behind the 4th diffraction ring. If you don't see it try rotating the OTA 45 degrees in case its hiding under a diffraction spike. In mine it's between the 4th and 5th.
Hi Nick

Thanks for that, I gave up once I realised the seeing did not support resolving any of the diffraction rings of Procyon, so settled for a series of 3x10 sec longer exposures just to tease out some of the close by field stars.

Just for info, here is Antares with companion in the Mewlon 180, an easy split under very good conditions.

I may have missed the boat this season, but will be back...

And, I'll note the orientation of the camera.

Cheers

Dennis
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  #28  
Old 03-04-2019, 10:33 AM
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Quick calculation of mag differences:

Sirius A = -1.46m, B = 8.44m, delta = 9.9
Procyon A = 0.34m, B = 10.7m, delta = 10.36
Sirius A, Procyon A delta = 1.8m
Sirius B, Procyon B delta = 2.26m

I also did simulation with Aberrator (with turbulence) for 12" aperture f/10 (and 90% obstruction, to roughly match what I saw in eyepiece), see attached screen dump below.

I think I have to give up Procyon B - unless I climb some mountain (1000metres?) with the whole setup and try from there.
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  #29  
Old 03-04-2019, 03:53 PM
Wavytone (Nick)
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What’s more in theory the brightness of the fourth diffraction ring is 0.00005 times that of the centre of the Airy disk, or a bit fainter than 10 magnitudes.

You only stand a chance at Procyon B when you can clearly see the 4th and 5th ring well enough to look for a faint star in them, assuming an 8”-12” scope.

Last edited by Wavytone; 03-04-2019 at 07:30 PM.
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  #30  
Old 03-04-2019, 07:40 PM
Dennis
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Here is a real world example of how a double (Antares) appears in a Vixen ED102S F9 4" Refractor versus a Tak Mewlon 180 (7") F12 DK.

The Vixen image was taken using a stacked x5 PowerMate and Vixen ED x2 Barlow at an efl of 9108mm at F90 using a Meade LPI back in 2005.

The Mewlon 180 image was taken with a Tak Extender x1.6 at an efl of 3456mm at F19.2 more recently in 2013.

Cheers

Dennis
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  #31  
Old 03-04-2019, 09:57 PM
Wavytone (Nick)
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That one on the right is much more like what you have to do with Procyon. BTW that Mewlon had very clean pristine optics.

Last edited by Wavytone; 03-04-2019 at 10:11 PM.
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  #32  
Old 03-04-2019, 10:58 PM
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Wow, Dennis, that shot of procyon with all companions listed is impressive! I don't usually get much into double stars, but that one was all kinds of cool.


Markus
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  #33  
Old 04-04-2019, 07:39 PM
Dennis
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Quote:
Originally Posted by Wavytone View Post
That one on the right is much more like what you have to do with Procyon. BTW that Mewlon had very clean pristine optics.
Quote:
Originally Posted by Stonius View Post
Wow, Dennis, that shot of procyon with all companions listed is impressive! I don't usually get much into double stars, but that one was all kinds of cool.

Markus
Thanks Nick & Markus, I appreciate your comments.

I finally tracked down a DSS Image (via Sky Safari Pro on my wife's iMac) and was able to make a reasonably confident correlation between some common field stars between the DSS Plate and the ASI290MM image.

Cheers

Dennis
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  #34  
Old 08-04-2019, 10:35 AM
Dennis
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Still trying to hunt down the elusive Procyon B, but so far, no success.

However, what I did notice is that Procyon A “appears” to have changed its position against the fainter background stars when I compare a crop from an up-sampled DSS Image and the Mewlon ASI 290 MM image.

I have uploaded a low-res animation (blink rate = 2 secs) to show how the centroid of Procyon appears to wander between the DSS and Mewlon images, when registered using the faint BG stars.

Could this be a simple case of Parallax based on the older DSS plate and the more current Mewlon image? Or is it more likely to be an image acquisition artefact?

Or, is the Universe expanding...

Cheers

Dennis
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  #35  
Old 08-04-2019, 10:47 AM
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How far apart (in time) are the shots?

From Wiki:
Radial velocity (Rv)−3.2[8] km/s


Proper motion (μ)
RA: −714.590[2] mas/yr
Dec.: −1036.80[2] mas/yr
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  #36  
Old 08-04-2019, 11:14 AM
Dennis
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How far apart (in time) are the shots?

From Wiki:
Radial velocity (Rv)−3.2[8] km/s


Proper motion (μ)
RA: −714.590[2] mas/yr
Dec.: −1036.80[2] mas/yr
Hi Bojan

Thanks for that.

I do not know the source details for DSS images downloaded via Sky Safari Pro on my wife’s iMac but Wiki writes:

“The term Digitized Sky Survey originally referred to the publication in 1994 of a digital version of an all-sky photographic atlas used to produce the first version of the Guide Star Catalog”

See also:

https://irsa.ipac.caltech.edu/data/DSS/

Which indicates that the source data for the digitisation program are either from the UK Schmidt or the Oschin Schmidt (Palomar) telescopes.

My Mewlon image was taken on 7th April 2019, so assuming 1994 for the DSS Plates, the gap is around 25 years, although some of the original photographic plates come from Palomar Surveys in the 1950's.

Cheers

Dennis

Last edited by Dennis; 08-04-2019 at 11:26 AM.
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