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Time to get serious about Sirius


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Pretty sure I got it tonight with the 200p. Barlowed the Hyperion IV zoom at 8mm with the dedicated 2.25x at (I think) 337x. A very faint speck of light  trailing Sirius A at around the 4 o clock position Dob view.

It came and went with the seeing but I went back to it after a look around Orion and it was in the same position. 

Got the best views yet of Trapezium E&F tonight at 150x as well. 😎

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'Tis the season that Sirius is getting reasonably well positioned (well, as good as it gets here in the UK) and it is a good time to take on the challenge of splitting it and seeing the elusive "Pup"

Got the little blighter ! First time I've managed it with the ED120. Quite hard and I repeated the observation about 10 times with 2 different eyepieces to make sure. The "Pup" star was not consi

I'm very happy to say that last night (27 Feb) I finally managed to see the Pup! I'm so thrilled by it 🙂  I spent nearly 2 hours observing from 7:30 to 9:30pm and managed to see it both with or w

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6 minutes ago, Dark Vader said:

Pretty sure I got it tonight with the 200p. Barlowed the Hyperion IV zoom at 8mm with the dedicated 2.25x at (I think) 337x. A very faint speck of light  trailing Sirius A at around the 4 o clock position Dob view.

It came and went with the seeing but I went back to it after a look around Orion and it was in the same position. 

Got the best views yet of Trapezium E&F tonight at 150x as well. 😎

Excellent - well done DV :smiley:

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257x sounds about right @John  my best success has been with my Morpheus 6.5mm at 230x, but Sirius is higher in the sky down here so slightly easier to see with lower magnification.

Same for E and F  with that eyepiece too. 😁

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I'm very happy to say that last night (27 Feb) I finally managed to see the Pup! I'm so thrilled by it 🙂 

I spent nearly 2 hours observing from 7:30 to 9:30pm and managed to see it both with or without diagonal and with both 10mm and 6mm eyepieces giving 270x and 450x respectively. As other have said the position of the Pup is at 4o'clock without diagonal (Dob view) and at 2 o'clock with a diagonal (refractor or Mak view).

At these magnifications the separation is not the issue but the glare from the main star. I came to realize that my EP have too much light scatter around Sirius A which hides the Pup very well.

So here is my method, I repeated this many times and it always produced the Pup. Once I saw it I was able to follow it as it drifted across the FoV.

I'm using a manual EQ5 so my view drifts to the west. With GoTo this might be easier as you can put Sirius A anywhere in the FOV you like and it will stay there.

The idea is to hide Sirius A at the south or southwest edge of the FoV. The Pup is ENE of Sirius A so it should 'pop out' as soon as your eye adapts to the darker background. Once you get the angle correct you should have 2-3 seconds in manual mode to observe it as it drifts west. I made a small diagram:

2143236399_SiriusB.thumb.png.8570dc59d197bfa48894406ff296f50a.png

Its important to use a EP without any vignetting or edge distortion. I managed this first with the 6mm red line Svbony EPs but in retrospect could have just used a good Plossl. It worked also at 270x with the 10mm EP but it was trickier as the separation between the main star and the Pup is then visually smaller.

For tonight I will make an occulting bar at the fieldstop, orient it NW-SE and put Sirius A under it. Should give me more time to enjoy the view :)

Good luck, everybody!

Nik

 

 

 

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Excellent Nik :thumbright:

Your "cunning plan" worked a treat :smiley:

Light scatter from Sirius A is the big issue with this challenge. Last night I noticed that this was quite variable. There were times when the Sirius glare would suddenly inflate for a while masking the Pup star entirely. I assume that this is due to an unstable air mass of some sort ?. I have also found that sometimes "looking too hard" can cause the eye to become moist and that creates it's own very local Sirius scatter as well.

 

Edited by John
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Indeed, I found that straining to see works in the opposite effect. What works best is to relax your eye, even try for averted vision approach.

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Nice Nik. I tried this in my 100mm f13 last night (moving Sirius just off the ep field of view). I can't swear to split, but I was getting hints of its presence at 260x with a 5mm baader genuine ortho. Tried again at 292x with a 10mm ortho and 2.25 barlow, but if any thing that made it harder. So, I 've got closer than I've been before, but tantalisingly this is not a definite for me yet. The pup escapes again... .

I find this scope will certainly show the Rigel double and the E and F in the Trapezium (altough it struggled with this last night), and can just split Zeta Cancri (just... barely managed it last night at x260 in moments of good seeing and slightly cleaner at 292x later on when it was higher in the sky). Based on this, I think it should get Sirius B, or is 4" too small? Has anyone had any luck with a filter to reduce the glare at all?

Edited by Marki
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I've tried filters of various types but without success. While the glare from Sirius A subsides, Sirius B seems to get dimmed to the point where it just drops below visibility. Plus the filter itself adds a little more scatter to Sirius A. It seems to be a fine balancing act :rolleyes2:

Last night was the first time in a few years of trying that I've split Sirius with my ED120. The next challenge is to try to get it with the Tak FC100.

 

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After a couple of unsuccessful tries, I think i may have seen the Pup tonight. I was out around 830 before the moon came up. It was the first night that Sirius did not look like disco lights. It seemed whiter with less colours around it. Using my 8mm BST on an 8" Dob I saw the bright Sirius A with a faint star coming in and out. I could see a faint 'dot' just above the diffraction line towards the East. I spent a good 30 min observing it and the tiny dot Pup was following Sirius as it was getting out of my view. In my excitement I ran back in the house to pick up a scrap piece of paper and made a quick sketch as seen in my EP (sorry if it is not very accurate; the cross hair represent the diffraction lines). By 915-930 some light haze was coming in and sirius was dancing all over again.  Is that it?

20210301_232615.jpg

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Posted (edited)
20 minutes ago, Kon said:

After a couple of unsuccessful tries, I think i may have seen the Pup tonight. I was out around 830 before the moon came up. It was the first night that Sirius did not look like disco lights. It seemed whiter with less colours around it. Using my 8mm BST on an 8" Dob I saw the bright Sirius A with a faint star coming in and out. I could see a faint 'dot' just above the diffraction line towards the East. I spent a good 30 min observing it and the tiny dot Pup was following Sirius as it was getting out of my view. In my excitement I ran back in the house to pick up a scrap piece of paper and made a quick sketch as seen in my EP (sorry if it is not very accurate; the cross hair represent the diffraction lines). By 915-930 some light haze was coming in and sirius was dancing all over again.  Is that it?

20210301_232615.jpg

Hi,

I recognize most of your stars. I've rotated the sketch that I made with my 120 refractor to match the orientation of yours and arrowed Sirius B. Hope that helps a bit ?:

sirius270221.thumb.jpg.109693fbaadd950b7fbd57d59a6eb62b.jpg

 

 

 

Edited by John
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6 minutes ago, John said:

Hope that is some help.

Thanks, very helpful! So the star I saw at my E is not the one; I had not seen that one last time so it got me all excited. I did not realise that the separation is not that great and I spent time ignoring what was going on next to Sirius A.

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Posted (edited)
6 minutes ago, Kon said:

Thanks, very helpful! So the star I saw at my E is not the one; I had not seen that one last time so it got me all excited. I did not realise that the separation is not that great and I spent time ignoring what was going on next to Sirius A.

The separation is 11 arc seconds. You can use the separation between Rigel A and B as a rough guide to the "scale" in the eyepiece - the separation there is 9.7 arc seconds but Rigel B is on the other side.

The glare from Sirius usually extends around 10 arc seconds or more around the star, so Sirius B has to shine (well, glimmer) though that.

Edited by John
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3 minutes ago, John said:

The separation is 11 arc seconds. You can use the separation between Rigel A and B as a rough guide to the "scale" in the eyepiece - the separation there is 9.7 arc seconds but Rigel B is on the other side.

The glare from Sirius usually extends around 10 arc seconds or more around the star, so Sirius B has to shine (well, glimmer) though that.

Thanks for the advise. I will give it a try next time with Rigel A/B to get a sense of separation and revisit Sirius once I have a better understanding.

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On 28/02/2021 at 15:22, John said:

Excellent Nik :thumbright:

Your "cunning plan" worked a treat :smiley:

Light scatter from Sirius A is the big issue with this challenge. Last night I noticed that this was quite variable. There were times when the Sirius glare would suddenly inflate for a while masking the Pup star entirely. I assume that this is due to an unstable air mass of some sort ?. I have also found that sometimes "looking too hard" can cause the eye to become moist and that creates it's own very local Sirius scatter as well.

 

Exactly my experience from yesterday :thumbsup: . I was using a low power of 96× with my dob .. it was quite a bit windy so my tube would vibrate few seconds and Sirius becomes a blur . The focus was highly critical - it was the difference between a star Sirius and planet Sirius. I first split Rigel with same 96× so I went ahead for Sirius . LOL my imagination made my eye see Sirius B all over the circumference of Sirius A . But Rigel B was surely there at 96× . Sirius B was a bit of rebel but will try higher mag when conditions allow . 

@Kon As you are using a dob without tracking , allow Sirius to move in the field . Sirius B will be on the side of movement of the star .

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7 hours ago, Kon said:

Thanks, very helpful! So the star I saw at my E is not the one; I had not seen that one last time so it got me all excited. I did not realise that the separation is not that great and I spent time ignoring what was going on next to Sirius A.

Indeed there is a faint 13 magnitude star also ENE of Sirius but it's much further: 125'' away according to stelle doppie 

https://www.stelledoppie.it/index2.php?iddoppia=27939

If you can see that faint star then Siruis B at 8.4 magnitude should be doable in the Dob. The trick is to hide somehow the glare from Sirius A so your eye can adapt to the darker background and spot the companion. The usual way is the drift method, allow Sirius to drift beyond the edge of FoV, the companion will be exposed for a short period, but at 11'' separation it will take only a second for it to disappear too, which may not be long enough. 

If we exploit the fact that the Pup its not directly east but a bit north east (right now at 68 degrees from North to be precise ) and position Sirius to drift out in the south-west corner of FoV this will buy you a bit more time (2-3 seconds) to have the Pup exposed.

Last night I tried using an occulting bar ( a piece of wire across the field stop), but did not manage to position it exactly at the focal plane of the EP, the edges were too fizzy and did not work.

I wonder if a mild filter may help to suppress Sirius A and still leave the Pup visible.

 

 

 

Edited by Nik271
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3 hours ago, Nik271 said:

Indeed there is a faint 13 magnitude star also ENE of Sirius but it's much further: 125'' away according to stelle doppie 

https://www.stelledoppie.it/index2.php?iddoppia=27939

If you can see that faint star then Siruis B at 8.4 magnitude should be doable in the Dob. The trick is to hide somehow the glare from Sirius A so your eye can adapt to the darker background and spot the companion. The usual way is the drift method, allow Sirius to drift beyond the edge of FoV, the companion will be exposed for a short period, but at 11'' separation it will take only a second for it to disappear too, which may not be long enough. 

If we exploit the fact that the Pup its not directly east but a bit north east (right now at 68 degrees from North to be precise ) and position Sirius to drift out in the south-west corner of FoV this will buy you a bit more time (2-3 seconds) to have the Pup exposed.

Last night I tried using an occulting bar ( a piece of wire across the field stop), but did not manage to position it exactly at the focal plane of the EP, the edges were too fizzy and did not work.

I wonder if a mild filter may help to suppress Sirius A and still leave the Pup visible.

Thank you for the suggestions Nik. I show your earlier post about the method you described and I tried it last night, or I thought i did since I was observing that ENE star assuming it was the one.As suggested, I will try the Rigel A/B just to get more familiarised on the separation I expect to see and then revisit it.

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There are two faint stars near Sirius that I've found quite important to being able to have a chance to see the Pup star itself. I have circled them in my sketch below (refractor view). One is the one that @Nik271 refers to in his post above. If you can see these two, you have a shout at seeing the Pup star, when the glare of Sirius A is at a minimum.

Over the years I have tried filters, using the field stop edge and occulting bars but eventually it was just looking carefully under the better seeing conditions using a magnification that gave a decent image scale (250x or thereabouts seems to be good) that did the trick. As I've become more accustomed to spotting the Pup star and as the gap between it and Sirius A has gradually opened up, I've been able to see it with smaller apertures. I managed some brief glimpses of the Pup with my 100mm refractor a couple of nights ago. Rather fleeting though. If I did not know what I was looking for, I would have missed them. 

sirius270221.jpg.dd42dd8bf55925b07d13a67186a58f3f.jpg

 

 

 

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These sketches of field stars in the field of view are actually quite useful to get an idea of where to look for the pup. I noticed during my last attempts that I wasn't really sure where to look relative to the drifting Sirius A in the field. I guess that knowing exactly where to look greatly improves the chances of detecting B. So: thanks all!

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@John and @Nik271 with my Dob I managed to see the star ENE for the first time last night just above the diffraction spike as in my sketch. I can regularly see the WSW star. Would the diffraction spikes from the spider vanes make it nearly impossible to see it? Is it worth keep going?

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4 hours ago, Kon said:

@John and @Nik271 with my Dob I managed to see the star ENE for the first time last night just above the diffraction spike as in my sketch. I can regularly see the WSW star. Would the diffraction spikes from the spider vanes make it nearly impossible to see it? Is it worth keep going?

Can you rotate the tube of your scope so that the diffraction spikes are at a different angle ?

 

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2 hours ago, John said:

Can you rotate the tube of your scope so that the diffraction spikes are at a different angle ?

I am afraid not; I got a Sky-watcher Classic 200P Dob so not much room for turning.

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  • 4 weeks later...

The Pup star is visible tonight with my ED120 refractor at 225x and 257x. Nice, steady, seeing tonight :smiley:

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Looked for Sirius B last night, seeing was steady-ish although not as good as the previous night.   I was certain I'd seen a ghostly spot at roughly the right distance at around 7/8 o'clock in RACI view.  As far as I can tell though this doesn't make sense.  For a variety of reasons (detailed elsewhere on here) I didn't make a detailed sketch at the time, I could definitely see a couple of "outlier" stars & recollection of their position tallies with the below. 

I've gone back on Stellarium and made a quick sketch showing the field at 63x and the view which included my "sighting" at 150x + the FOV for which I've included as an inset circle, in which I have recorded where I saw my "ghost" .   My spatial awareness is horrible with respect to the RACI view and rotational changes (Orion was setting diagonally W at this point) so, although I was convinced I was seeing something that looked very much like a faint double, I remain confused as to whether this is a true sighting... 

 

Sirius.thumb.JPEG.7c8069484812a5459d58c57dcdf2d69c.JPEG

 

 

 

Edited by SuburbanMak
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56 minutes ago, SuburbanMak said:

Looked for Sirius B last night, seeing was steady-ish although not as good as the previous night.   I was certain I'd seen a ghostly spot at roughly the right distance at around 7/8 o'clock in RACI view.  As far as I can tell though this doesn't make sense.  For a variety of reasons (detailed elsewhere on here) I didn't make a detailed sketch at the time, I could definitely see a couple of "outlier" stars & recollection of their position tallies with the below. 

I've gone back on Stellarium and made a quick sketch showing the field at 63x and the view which included my "sighting" at 150x + the FOV for which I've included as an inset circle, in which I have recorded where I saw my "ghost" .   My spatial awareness is horrible with respect to the RACI view and rotational changes (Orion was setting diagonally W at this point) so, although I was convinced I was seeing something that looked very much like a faint double, I remain confused as to whether this is a true sighting... 

 

Sirius.thumb.JPEG.7c8069484812a5459d58c57dcdf2d69c.JPEG

 

 

 

This is the sketch I made using my ED120 refractor a little while back at 257x. The "Pup" star is on the E side of Sirius A so it trails "behind" Sirius as it drifts across an undriven refractor / mak-cass / SCT field of view:

sirius270221.jpg.6646b49ff9c345a6c0f6640534d8f3f2.jpg

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54 minutes ago, John said:

This is the sketch I made using my ED120 refractor a little while back at 257x. The "Pup" star is on the E side of Sirius A so it trails "behind" Sirius as it drifts across an undriven refractor / mak-cass / SCT field of view:

sirius270221.jpg.6646b49ff9c345a6c0f6640534d8f3f2.jpg

Thanks John - it seems for me the Pup is still out there... 

This one could run & run :) 

 

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