Sirius and Pup separation over the years

[Stu]

There was some discussion about the difficulty of observing the Pup recently on a thread of mine, so I thought I would look at the current separation vs how hard it has been in the past, and what is happening as we go forward.

Back in 1993, the separation was a tiny 2.5", which I imagine would make it all but impossible given the brightness of the primary, but perhaps with an excellent scope and an occupying bar it was possible. Does anyone have accounts of visual observations at this time?

In 2005 it was around 6.8", and is currently 11.2" so is much easier than it has been. Despite this, it still represents one of the most difficult observing challenges there is, requiring the right kit, conditions and experience to see.

Moving forward, the largest separation is about where we are now, 11.3" in 2023, it will be 6.2" in 2038 and back to 2.5" in 2043.

So, I guess we've never had it so good in terms of being able to observe the Pup, but those who were observing it 10 or more years ago can rightly say 'when I were a lad it was a proper challenge' 😉

Any input for those who observed it back then would be really interesting to hear. What kit did you use and how did you achieve it?

[Dinglem]

@stu that's very interesting thanks for sharing. So what would be the best type/size of scope to be able to see the seperation, from a back garden in a bortle 5 area?

[Wiu-Wiu]

1 minute ago, Dinglem said:

@stu that's very interesting thanks for sharing. So what would be the best type/size of scope to be able to see the seperation, from a back garden in a bortle 5 area?

I've been able to see it in my 12" dob last year but it needed perfect collimation, excellent eyepieces, and most of all: a perfect seeing. 

[Dinglem]

@Wiu-Wiu thanks for the reply, not going to see it through any of my scopes then. Must get to a Star Party and have a look through one of those big Dobs.

[Wiu-Wiu]

Afraid so.. but I've seen reports of seeing it through a 150mm achromat.. 

[John]

I've seen the pup with my 130mm triplet refractor. Its easier with my 12 inch dob though. I'm trying to think back to when I first managed it - probably around 5 years ago when I first got the 12 inch dob up and running. I don't fancy my chances between 2040 and 2048 ! (and I'll be in my 80's as well )

[markse68]

Any idea how it’s position should be  relative to position of Rigel b Stu? For some reason SkySafari doesn’t show Rigel b 🤷‍♂️ Last night I was out for about 3hrs under clear skies and spent a lot of that time just staring at Sirius wishing the pup into existence but of course it stayed in hiding. Rigel b was at 12 o’clock and obvious. Relatively where should the Pup be? It wasn’t the best seeing though- I couldn’t see trap E star which I’ve seen before a few times.

 

[orion25]

I managed to see it through my 127mm Mak-Cass with a variable polarizer to dim the glare of Sirius A. Yes, excellent seeing is a must, as well as high magnification (around 250X plus).  I waited until Sirius reached maximum elevation to cancel out any atmospheric effects. I didn't use any tracking and just let the star system drift across the field to make sure I wasn't seeing a ghost image. I read recently that the separation between Rigel A-B is similar to where Sirius A-B is right now. Thanks for the info, Stu!

Regards,

Reggie  

[Captain Scarlet]

2 hours ago, markse68 said:

Any idea how it’s position should be  relative to position of Rigel b Stu? For some reason SkySafari doesn’t show Rigel b 🤷‍♂️ Last night I was out for about 3hrs under clear skies and spent a lot of that time just staring at Sirius wishing the pup into existence but of course it stayed in hiding. Rigel b was at 12 o’clock and obvious. Relatively where should the Pup be? It wasn’t the best seeing though- I couldn’t see trap E star which I’ve seen before a few times.

 

We were obviously mirroring each other. I too spent much time staring at Sirus last night, and for perhaps a second I imagined might've seen something, around 4 o'clock position by how I was seeing but it was an 8" newt on an EQ mount, so could've been anywhere depending on orientation of the tube I guess. It may well have been imagination. I also failed to see the E star in the Trapezium, though. I had intended to use my Mak 150 but given that it was already covered in dew before I'd even got it on to the mount, I reverted to my newt. Rigel B was easy though, as a consolation, and Castor was nice too.

M

Edited January 18, 2020 by Captain Magenta

[markse68]

34 minutes ago, Captain Magenta said:

but it was an 8" newt on an EQ mount,

Hi Magnus, yes indeed I’m never really sure what’s up down east or west looking through mine (also 8” newt) I’m going to check on stellarium when I get to a pc next- does that give accurate positions of orbiting double stars though 🤔 So my thinking is use Rigel as a reference for both separation and an angular offset position for where to concentrate efforts and to turn scope tube to ensure diffraction spikes (very strong on Sirius!) are not obstructing where it should be. Will have another crack tonight at Flamsteed meet-up where hopefully there’ll be some big fracs too- I’m not giving up 😉

[Stu]

3 hours ago, markse68 said:

Any idea how it’s position should be  relative to position of Rigel b Stu? For some reason SkySafari doesn’t show Rigel b 🤷‍♂️ Last night I was out for about 3hrs under clear skies and spent a lot of that time just staring at Sirius wishing the pup into existence but of course it stayed in hiding. Rigel b was at 12 o’clock and obvious. Relatively where should the Pup be? It wasn’t the best seeing though- I couldn’t see trap E star which I’ve seen before a few times.

I've not been able to find a good reference to the angular position for Rigel, although the separation is similar to Sirius as has been said.

[markse68]

15 minutes ago, Stu said:

I've not been able to find a good reference to the angular position for Rigel, although the separation is similar to Sirius as has been said.

Thanks for looking Stu- guess what we need is for someone to actually see it tonight and give the rest of us the info 😉

[Stu]

49 minutes ago, markse68 said:

Thanks for looking Stu- guess what we need is for someone to actually see it tonight and give the rest of us the info 😉

Yes, wouldn't that be a novelty!! Skies look ok tomorrow for me.

[John]

This is how it appears with my 12 inch dobsonian if that is any help. The Pup star trails Sirius as it drifts across the undriven field of view. The position angle has changed just a little since this sketch was made a year ago (to the day !):

 

[John]

Ooops - I mean 11 months ago - I'm wishing January away too quickly !

 

[markse68]

49 minutes ago, John said:

This is how it appears with my 12 inch dobsonian if that is any help.

Great thanks John- is that it there?

[John]

Yes - it appears as a tiny dimly gleaming point of light that shows through the glare from Sirius A. It needs steady seeing do see it at all and very steady seeing to see it steadily. Its visibility comes and goes as the seeing fluctuates. 

The usual things apply such as a well collimated scope, well cooled and an eyepiece that keeps light scatter to a minimum. There will be plenty of sessions where it wont show even though your gear is capable of showing it, because the seeing is just not steady enough.

Tricky little blighter !

 

 

 

[Barry-W-Fenner]

Evening all

I feel such a plonker, I was looking  at Sirius around 2am today trying to split  these two stars in my 200p with various  bst  eye pieces. I never realised it was such a difficult thing to do. You have to admire my enthusiasm though. Total lemon 😀😀😀

 

Baz

[Barry-W-Fenner]

1 hour ago, John said:

This is how it appears with my 12 inch dobsonian if that is any help. The Pup star trails Sirius as it drifts across the undriven field of view. The position angle has changed just a little since this sketch was made a year ago (to the day !):

 

That's a pukka sketch john . 

 

Baz

[John]

I've been trying Sirus tonight with the 12 inch dob but cant get the split. There is just a bit of thin cloud knocking around and the seeing is OK but no more. Star images are not really optimally crisp from here. Everbodys got their central heating on full blast in that direction I reckon !

Nice views of some other deep sky stuff though so can't complain

[chiltonstar]

Ditto here - a half hour spent Pup hunting tonight without success, although not surprising as the seeing to the SW was barely average. On the occasions I have spotted the Pup, the seeing has been excellent+ and it has usually been late Autumn when Orion is in a better position for me, well away from houses and heating.

Chris

[Les Ewan]

HI Chris,

I spent half an hour also with my 16" Newt also without success.I left it till Sirius was at its highest (16 deg)but seeing was terriable. I have thought that I have glimpsed Sirius B in the past with 8" and 12" Newtonians but haven't been at all sure and in all honesty have had to admit defeat. Managed Porrima and Izar just after 4am but the seeing was still pretty bad but it was nice seeing Izar's bluish companion through the bubbling glare.

[markse68]

23 hours ago, John said:

This is how it appears with my 12 inch dobsonian if that is any help. The Pup star trails Sirius as it drifts across the undriven field of view. The position angle has changed just a little since this sketch was made a year ago (to the day !):

 

Hi John, had another fruitless look at Sirius last night but I'm a bit confused as I’m not seeing the surrounding stars like in your image. Is this a magnitude thing? I looked in sky safari and can’t see the line of stars either.  I guesstimated your fov and played around with magnitude settings - was there something else in your fov that wasn’t a star/s? 🤔

[John]

6 hours ago, markse68 said:

Hi John, had another fruitless look at Sirius last night but I'm a bit confused as I’m not seeing the surrounding stars like in your image. Is this a magnitude thing? I looked in sky safari and can’t see the line of stars either.  I guesstimated your fov and played around with magnitude settings - was there something else in your fov that wasn’t a star/s? 🤔

I observed Sirius last night and the field stars were the same as my sketch but last night the seeing was not as good so Sirius B was not seen. The fainter stars shown are really quite faint so the sketch probably shows them as relatively too bright.  

The sketch shows the field with a Pentax XW 5mm eyepiece which has a 70 degree AFoV so shows a true field of a touch less than 1/4 of a degree.

Hope that helps.

 

 

[markse68]

Had another go tonight. What with the record high pressure we’re in and clear skies forecast I reckoned it would be a good session so I had a “take your scope to work“ day- leaving it in the car all day to make sure it was nice and cool. Paid off in a way- scope was firing on all cylinders straight out the car with nice tight stars and almost perfect star testing 👌. As I’d hoped seeing was really excellent tonight- probably the best I’ve ever had. And no wind 😳 which really helped a lot. I saw e and f stars in the trapezium quite clearly- first time for f! I was able to split Rigel easily with a 20mm ep- just 80x mag! Sirius was a nice tight image too- by 10pm it was reasonably high and not the usual disco ball you see at lower elevation. I must have stared at it for several hours. I tried all my best eps from the 20mm through my medium power orthos to my Nagler 4.8. Even tried barlowing the orthos to get 3mm for max 500x. Still no joy 😞. I reckon if I was going to see it tonight was the night. It must be too faint for an 8” scope under Bortle 9 skies I guess. Still it was a really great night and an enjoyable if frustrating challenge. 

Weird how we see different field stars @John! With my Nagler which should give a similar magnification and fov I think, the dominant field stars formed a W rotated to the nw of Sirius in the ep view 🤷‍♂️

Edited January 21, 2020 by markse68