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Sirius B

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obrazell's picture
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Sirius B

I was interested in John Chuters article on Sirius B where he claims there are credible observations of Sirius B from the UK with instruments as small as 130mm. It would be interesting know to know what was the source of these credible observations and whether they were visual or imaging.. If the source of these observation is the SGL forum, probably the least credible source of any observational material known then I would question this piece and these observations given most very experienced double star observers fail to spot Srius B except with much larger instruments under exceptional conditions.

Owen

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It was decided to set this as

It was decided to set this as a challenge. I have not, or ever professed to being, an experienced visual or anything else, observer.

If it leads to a debate then that in itself is a good thing.

Let us see where this debate and the actual challenge goes before coming to any definitive conclusions.

I learn something new every day. It will be a sad day when that stops being the case.

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The Dogon

What is the current accepted position on the stories allegedly from the Dogon that they knew Sirius had companions?

http://www.unmuseum.org/siriusb.htm

Regards,

Michael.

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Dogon it!

Probably more convincing if it had also been unknown in the west at the same time.

Would love to see the artefact that proves them right.

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Visibility of SiriusB

I was using a standard cheap 150mm X 1200FL Celestron Refractor in March last year.  Being an achromat there was a huge amount of chromatic aberration.(CA)  Here is what I found visually:

with 7mm eyepiece (X171) Sirius B was intermittently visible,  with 5mm eyepice (X240) it was constantly seen, and with 2.3mm eyepiece (X522) it was very easy. I have a few not very well tracked, but quite distinct images. (I intend to take some better ones.) (Viewing from Brisbane, Australia. 27.5 deg South. 153 deg East.)

Regarding the Dogons' knowledge, skeptical analysts indicate that the Dogon's knowledge may have been contaminated by the researchers who were conducting their research shortly afterwards, as the information provided by the Dogon priests corresponds with European knowledge of the late 1920's.  Check it out with Mr Google.

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Visibility of Sirius B

Here are the images: 15 seconds at 2000 ISO with 10mm eyepiece and eyepiece projection. Sirius B is the ragged streak hard up on the left hand side of Sirius.  You will see that it is really there because the squiggle of the streak is different in each image and matches the other stars confirming that it is Sirius B.  I have since 'trained' my drive and hope to do better next time.  I have also included an image of the refractor, one of the common, garden variety, cheapie 150mm F8's.

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Sirius B

Try again

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Many thanks, Peter, for a

Many thanks, Peter, for a valuable and interesting contribution to the thread.

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Sirius B is doable in medium apertures

Hi Owen,
 About a year ago I observed Sirius B visually using a friend’s good quality 200mm APO refractor. It wasn’t easy but it was definitely observable. The refractor I was using had good contrast and colour correction which helped. Telescopes of poor contrast will struggle to show it because Sirius is magnificently bright in any aperture telescope.

Peter

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Sirius B

I would concur Peter. I have been observing double stars for about 30 years now using a variety of high quality, high contrast telescopes including a 7" F8 Mak-Newt with 1/10th wave quartz optics and 13% obstruction, an 8" F6 Mak-Newt with 18% obstruction, 1/9th wave astro sitall optics and an OMC 200 Mak-Cas, F20, 4,000mm FL with 22% obstruction. I've failed to see it in all of those scopes despite numerous attempts. I have seen it twice in my Takahashi Mewlon 300, a 12" high contrast Dall-Kirkham design and once in my 18" F4.5 Newtonian which has a superb mirror. The first time in the Mewlon was back in October 2007 when it was just below 8" separation. The seeing was excellent, the E & F stars in the trapezium stood out like there was always 6 on show but even so, the pup was just momentary glimpses in the glare of Sirius A but consistent in it's position. A check the next day confirmed I had the correct PA. The next time was a couple of years later in the 18" at Kelling Heath. Skies were claggy but seeing good so I changed my targets. Again the E & F stars stood out so I gave Sirius a go but first being a Dobsonian which always has some flexure I collimated the scope for that altitude. The observation was similar to that I'd had with the Mewlon previously. Then last month in the Mewlon, again E & F stars steady and tight (I think this is a pre-requisite in my book - if you can't see them well, don't even bother going for Sirius B). This time of course the seperation is 11" and I had an almost continuous view of the pup for about half an hour, a faint spec just below the diffraction spike from the spider. Even so the pup was very faint and almost averted vision in the glare of Sirius B. It's altitude in the UK does not help, even when the seeing is very good high up, it rarely is at the altitude of Sirius. I know an occulting bar would help but for me the beauty of observing this is seeing it against the glare of the primary and not in isolation.

Andrew

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Sirius B in small apertures
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Impressive

You can understand Owen's concern though, as (above) an experienced observer manages it twice in 30 years while using a 300mm Mewlon and some other very useful sounding instruments and yet its now being seen in scopes much smaller than that used to discover it. Yes, optics are better now and baffling has improved, but the MKI eyeball hasnt changed much (and mine could certainly do with an upgrade). 

And I'm with him on newsgroups, sometimes the content is low quality.

Raises an important question about observing dim companions of bright stars.

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Credible

I note the author did not answer Owen's question on the source of the 'credible observations' but simply removed the word credible from the article. You never said John whether or not you had observed the pup yourself, I would like to think you had before writing such an article and suggesting or implying what aperture scope it might be visible in from UK skies.

Andrew

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Pup

As mentioned it was decided to give this as a challenge by the group of people who manage the website, the ’webops’ group as we call ourselves. I volunteered to write the challenge. As you will see, challenges are put up regularly, as are tutorials etc etc. This is part of the the group‘s strategy to make the website a dymamic site that engages its members and seeks to encourage new members.

i have not personally observed the pup but then I have never tried. You are correct that I amended the article but I also said in my reply to Owen that a debate about this would be useful and that has indeed proved and is proving to be the case. I also stated that I did not regard myself as an experienced observer. Do I need to be to be a member of the BAA?  There are many reasons why people choose to be a member of the BAA. 

This does not detract from the issuing of the challenge as it is evident, to me at least, that this is not an impossible challenge with modest equipment and as is evidenced by the replies above.

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Article

Although not being an experienced observer is not necessary to be a member of the BAA or write articles a knowledge of astronomy should be. There are other issues with this article in that the orbit of the Pup is stationary and the Pup itself is at maximum elongation.  If the BAA is to be regarded as a serious organization then its website and articles on it need to be right as well and a knowledge of the subject should be a pre-requisite to write about it.. I understand that you wish to make a dynamic website but there must be a threshold before you write.

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Maintaining my membership

Maintaining my membership of the BAA is one way that I have of continually learning about this fascinating hobby. If you were able to elucidate further on your previous reply regarding the orbit etc then I and others may further learn about Sirius and it’s Pup. In this way this debate is achieving its purpose. Your reply certainly indicates that you are able to do so. In fact I am confident that you can as, of course, I am aware of who you are and your expertise in many astronomical matters.

Please note that this is designated as an Observer’s Challenge. The challenge is to try and observe the Pup, should anyone decide to try and do so. There is no compulsion. In this respect it seems that it is possibe to do so, witness images and other replies earlier in this thread. The use of the word ‘challenge’, also indicates that it is not meant to be easy.

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Pup

I remember seeing it in the late 1970's visually with a 10inch F6.5 newtonian.  It could have been 1978-79 but I'm having trouble locating that observation in my files (which is why I'm late to the discussion).  I do recall that it was a very difficult observation to make, with the separation at or near maximum distance I think.  If I find my notes, I'll come back.  Don't think I dreamt it!

Gary

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Pup

Just checking my binary calculator Gary, at the start of 1978 it would have been at a separation of 10.8" and PA 53 degrees. Ditto 1979, sep 10.5" PA 51 degrees. Brilliant getting it back then, think I only had a 60mm refractor back in the 70's and no I didn't see it with that :-)

Andrew

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Quality encouragement

I’m not sure I would have been quite as blunt as Owen, but I do agree that if the BAA is to remain the leading organisation in amateur astronomy it must be careful what it publishes. I’m not suggesting there is anything wrong in John’s observing challenge but in a wider context the BAA’s output does often get quoted in the general world of astronomy. If the BAA publishes something inaccurate, misleading or open to being misconstrued this downgrades the Association and the wider amateur astronomy world.

Perhaps the more expert and experienced amongst us need to come forward and volunteer to assist with what the BAA does?

To get back to the reason John issued the observing challenge, lets all encourage as many observers as possible to hunt out the pup before the chance of seeing it diminishes for the best part of a lifetime. (Seems Gary above is into his 2nd lifetime!)

Peter

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Agreed

I have to agree with all of this......

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Look what I found by accident

On 2018-11-30 I was imaging HL CMa, which many of you know is uncomfortably close to Sirius.  It's essential to place the latter outside the field or it dazzles both CCDs and eyeballs.  However, at least there is a bright (far too bright) guide star nearby.  A SBIG-8 camera has a small CCD for guiding purposes and it was used with the minimum possible exposure time of 0.11 seconds.  Sirius was still over exposed but, to my surprise, the Pup showed up occasionally in the autoguider window.

After taking the science data another 100 images at 0.11s were taken of Sirius.  The one from the moment of best seeing appears here.  The blooming from Sirius runs from top to bottom on the full frame, of which this is only a small crop.  It's fortunate that the camera was orientated at a good angle to the line joining the stars.

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Visual observation of Sirius B

I seem to remember seeing the Pup on (a very few) occasion(s) with the 0.275m Mak-Cas owned by the Oxford University AS.  This would have been around 1980 or so,  My memory is suspect and I no longer have access to any contemporary records so treat this report with the suspicion it deserves.

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Observing 'The Pup'

This evening there was a lull in my usual lunar occultation work and I turned my C14 onto Sirius.  Now my C14 has always suffered from a slight haze on the inside of the corrector plate, and I have never plucked up the courage to remove and clean it like I did my old C8.  Further the alignment of the secondary is tweaked to approximately correct to give good star images but is not perfect and in/out of focus images at high power will testify.  So what I am saying is the optics are not perfectly clean nor perfectly aligned. Conditions were relatively steady. So I first of all inserted a standard (40 to 60 degree field) 8mm - 24mm zoom eyepiece. At 24mm (X163) the pup was very difficult to see close to the brilliant image of Sirius. It was easier to zoom in to the 8mm focal length (X489) when it stood out so plainly with black sky all around that I was wondering whether I was looking at the correct star. Zoomed out back to X163, (now knowing precisely where to look), I was able to spot it, by moving my eye around the eye lens a little, to cause the rays emanating from nearby Sirius to avoid this area and so reveal the 'pup' very close to Sirius. Re-inserting my standard 25mm eyepiece (X156), I managed to repeat this operation.

Now my views on this are, short of using an occulting bar:  Firstly, if using a Newtonian, check that the spikes from the diagonal support will not be in the way.

Secondly, ensure that the conditions are sufficiently good to obtain a sharp and relatively stable star image.

Thirdly, don't muck around with a low magnification. Go straight to 400 or 500 so that the pup will be a reasonable angular distance from Sirius. Only when thus located, scale back and check out the lowest magnification that you can reasonably see it.  I would suspect this to be around X150 or a tad less. There is no point trying to initially pick it up at a low magnification!

As I reported earlier in this thread, these results tonight were very similar to those with my 150mm refractor last March, except that the refractor produced a much fainter image and a whole lot of colour from chromatic aberration.

I will try 150mm refractor with the 112 mm aperture stop to see if I can still pick up the pup.

Now I must confess, that tonight I did not play fair at all. Not only was I using the C14, but you probably don't want to know the altitude of Sirius at around 11hrs 30min when I observed it.  I will tell you anyway... around 65 degrees!

So whatever I have recommended should be taken with a grain of salt when you factor in its altitude from your site.

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SGL

Owen as a BAA and SGL contributor, I was interested in how you justify your comment on SGL being "the least credible source of any observational material known" ? Have you done a study or can you provide a credible reference? 

On a different tack, I suspect visual acuity is as important as telescope  aperture, seeing and other sky conditions to observations of the Pup.

Regards Andrew 

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SGL

I don't know about Owen, but I certainly find you have to take whats there with a large pinch of salt.

I just looked at a discussion in the deep sky section about whether M31 was a naked eye object and another in the imaging section on what affordable CCD camera to buy. Didnt exactly inspire confidence. 

Looking more generally, there were postings from participants that were at best naive/lazy (even some with 20,000 posts), others who slavishly followed someones opinions because they had taken some nice pics and a few were clearly just plain biased in favour of stuff they had owned. I have no doubt it also has a percentage of observers who manage to "see" rather more than their instrument actually delivered and enjoy the immediacy of the applause available.

Personally, I couldnt say its worse than CloudyNights or any other fora but, while appreciating a proportion of participants will undoubtedly know their stuff, theres very much a need to be able to filter out the noise - and that can be difficult while you are yourself inexperienced. 

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SGL

Grant , 

"I have no doubt it also has a percentage of observers who manage to "see" rather more than their instrument actually delivered and enjoy the immediacy of the applause available."   a trait shared with Percival Lowell!

Also "clearly just plain biased in favour of stuff they had owned" a passion shared on SGL by a recent President of The BAA and Takahashi!

Of course it's a forum that does not seek peer reviewed posts and us such needs care in deciding what to take as accurate. However, to condemn it as the worst without justification is committing the offence it is accused of.

There are many fine images posted there and discussions which myself, Robin Leadbeater and other BAA members have contributed to. It does not seek to replicate the BAA but engages a wide audience interested in astronomy. In my view it is better to participate and improve such a form than sit on the sidelines sniping.

Regards Andrew

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Fora

I think that, if you look back at my posting, you will find that I don't say that it is the worst. If Owen wants to defend that position, thats entirely up to him. 

If asked an opinion, I would say it is much the same as all the others, only with a more UK slant in equipment choices. But thats hardly pouring praise on it! Some discussions will be sound and informed, some average, others will be hijacked by fools.

The net gave us access to more knowledge and with that came a greatly increased supply of gibberish. I think you will find that what I said can be summed up as "The advice may only be worth what you paid for it". 

I wish good luck to those of you who do help add quality to the fora and admire your tenacity, but find that what I have to do already fills my waking hours. 

Also, I don't think its sniping to point out that a source of information may be significantly suspect.  

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Fora

Grant , I don't want to make a big issue of this but I apply Richard Feynman saying:

Have no respect whatsoever for authority; forget who said it and instead look what he starts with, where he ends up, and ask yourself, "Is it reasonable?"

rather than what it cost me.

Regards Andrew

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Agreed

Yep. Its no big deal. We disagree. It  happens.

But, should I respect that saying from Feynman more because he was an authority on quantum electrodynamics?

Ho hum. Back to the gardening.

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Yes agreed

No you should not, anymore than I should disregard your advice as it was free!

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Fora

Touche. :)

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Observing Sirius B

Last night I had another 'lull' in my occultation observing and moved over my 150mm refractor to check out whether I could see 'the pup' with the aperture stopped down to 112mm.  (The altitude was around 55 degrees.) Okay, I was a bit cocksure and this attitude (pride comes before a fall), clearly deserves what it gets. The weather has changed here and the moist south-easters are blowing. As a result, though okay for occultations, conditions are not appropriate for splitting difficult double stars. Once again I was enchanted by the exquisite diffraction disc and rings of a refractor, somewhat larger when stopped down to 112mm, but while the disc appeared to remain fairly stationary, the rings, whilst still for the most part sharp and discrete were in constant random motion. Most of the problem was the twinkling type random flashing from the central disk. I increased the magnification to X522, and knowing where to look, with the full 150mm aperture could only maybe say that I glimpsed the pup once or twice. I could not say that I really saw it. At 112mm aperture absolutely nothing.  And yet on the other occasion just a few days ago with the same instrument, same eyepieces, it was really easy at high magnification! (report above.)

Now what lesson have I learned?  Firstly to reiterate, but this time very strongly, that steady seeing (and a clear sky) are essential. Now obviously altitude will play a significant part in the opportunity to achieve this. Because good altitude is a 'given' for me, it is quite unfair to directly apply my observations to those possible from northern Europe.

From the appearance last time in the 150mm I would feel that the original claim of visibility with a 130mm instrument is 'do-able' under the right conditions. The difficulty is to get those conditions from England where Sirius at 52N latitude rises to a maximum altitude under 22 degrees even allowing for refraction.

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Thanks for the contributions

It has been pleasing to see that this challenge has generated interest, both in debate and in observations. This was always the intention and I have also learned things I was not aware of astronomically which, as mentioned, is why I’m a member etc.

The challenge was not meant as a UK based challenge and that is not inferred anywhere in my piece. So it is doubly pleasing that observations are coming in from well outside the UK.

There are always differences of opinion, both here and on other fora. The level of expertise also varies enormously but that is to be expected and not, in my opinion, something to use as a criticism of other internet fora. The more useful tack would be to correct errors and impart knowledge when it is apparent that someone doesn‘t understand something. Of course, the manner in which this is done is important. 

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Procyon B anyone?

Now that we've had several images of Sirius B posted, including today's picture of the week, does anyone fancy trying for Procyon B?  The separation is only about half that of Sirius, so it will be much more of a challenge.  Although the primary is 2 magnitudes fainter, so is the secondary.

I intend to give it a try after returning to La Palma this week.

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Nothing last night.

No joy last night.  Seeing was quite poor.

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Good challenge

You know this of course, but it is also worth saying that the greater altitude that Procyon achieves from our vantage point should help with seeing. I just need to get the Hyperstar off my C8 and put the secondary mirror back for native FL imaging. After all the faff with getting things aligned just right...

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A unique oportunity for a lucky few ?

Just spotted this on the S&T website

https://www.skyandtelescope.com/observing/will-sirius-disappear

"Monday night, February 18th. That evening around 10:30 p.m. MST (5:30 UT February 19th), there's a good probability that the 17th-magnitude 4388 Jürgenstock will occult the sky's brightest star for up to 1.8 seconds."

The event is not visible from the UK but anyone on the narrow path though North America could get (very a brief) view of Sirius B free from the glare of its bright companion. (Sirius is predicted to be totally eclipsed for just 0.2sec !)

Robin

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Revised track

I've just seen there is now a revision to the path noted at the bottom of the page.  (The original track was calculated based on the position of the centre of mass of the A-B system rather than Sirius A !

I hope you have not already made your travel plans !

Robin