A Sirius Matter -Plus-DOUBLE STAR TIPS -

[bigjoe (JOSEPH)]

Originally Posted by AG Hybrid

You don't need big aperture. It just makes it a cake walk. Well... as long as seeing isn't bad.

Too true Adrian; but let's see how low we can go with ease - 90mm perhaps?

bigjoe.

[MattT]

I should add that the Pup is defiantly there in the 70mm just not a clean split. Think it's called 'detection' for the real observers

[bigjoe (JOSEPH)]

Originally Posted by MattT

I should add that the Pup is defiantly there in the 70mm just not a clean split. Think it's called 'detection' for the real observers

Great that you got detection and were almost able to get a clean split with only 70mm Matt!

However Squashed, Figure Eights, and Kissing Doubles are not considered a clean split - at least we need a hairline split; some black between the stars.

This could still happen though, at that aperture, but the seeing would need to be extraordinary!

Maybe this could happen at 90mm, but it was difficult even in a TV 101!
And as usual; the more reports on this the better!

bigjoe.

[Tropo-Bob (Bob)]

Originally Posted by MattT

I should add that the Pup is defiantly there in the 70mm just not a clean split. Think it's called 'detection' for the real observers

Matt, can U tell us what magnification and EP were you using? Also, a little more about your 70mm scope (brand & focal length). Were U using a driven EQ mount to track Sirius?

[MattT]

Hi Bob,
The 70mm is a Skywatcher 70x900 so a focal length of f13 or close to. I think I stated earlier that there is no visible CA in this scope. Sirius did show up with the slightest purple haze out of focus all of which disappeared when in focus. Eyepiece for this is a UOVT 6mm which gives 150x (University Optics Volcano Top) I did try a 19mm Panoptic with a 3x ES focal extender
(Powermate)...there was no difference in the image.
I could see 2-3 diffraction rings around the Star which I think means that was too much mag for the conditions, as nice a sight as it was. Didn't think to try some other longer FL eyepieces, next time.
Used two mounts and EQ3 with tracking which is a great match for the 70mm and also my old pillow block EQ which also has tracking.

[AG Hybrid (Adrian)]

Well done Matt.

[Tropo-Bob (Bob)]

Matt, that's amazing that you saw the Pup with a 70mm scope. I am gobsmacked!!! I was pleased to finally find it in an 8" and thought I had done well.

Big Joe, maybe your list needs to state a minimum aperture for initial detection, and perhaps a minimum aperture that the Pup can be seen by experienced observers who are already familiar with the double.

[bigjoe (JOSEPH)]

Originally Posted by Tropo-Bob

Matt, that's amazing that you saw the Pup with a 70mm scope. I am gobsmacked!!! I was pleased to finally find it in an 8" and thought I had done well.

Big Joe, maybe your list needs to state a minimum aperture for initial detection, and perhaps a minimum aperture that the Pup can be seen by experienced observers who are already familiar with the double.

Amazingly so Bob !! As it was not seen in a TV85 in good conditions, with a very experienced observer !! So the long focal length with the steadier image it seems, and good optics, seeing, plus the observers visual acuity, have all helped here in this very modest aperture refractor; so well done Matt - those long focal length refractors are something else when it comes to doubles: I'm sure of it!

PS: And it seems no real need for an Apo!

bigjoe.

[bigjoe (JOSEPH)]

AMMENDED SUMMARY OF DOUBLE STAR OBSERVING TIPS SO FAR
- VIZ SIRIUS:

1: SEEING - Must be excellent.

2: ALTITUDE - Well above the horizon in
most instances.

3: APERTURE - 100mm+, Cooled and well collimated, though probably no more than 12" due to the affects of seeing on large obstructed scopes; though it now appears certain, that even a 70mm achromatic refractor of long focal length can result in DETECTION!

4: POWER - The use of it is necessary - Helps darken sky background, and with limiting magnitude ; 200x + may be needed.

5: USE A MASK - Hex , may be necessary.

6: ORIENTATION - Is your diagonal/scope displaying an upright E/W view; If not adjust accordingly.

7: PRACTISE on Rigel say - Bright, with similar separation. Know what a separation of 10" will look like in your go - to EP - VIZ - Know your field.

8: DRIFTING - Let Sirius A drift past the field stop , and disappear, as B will surely follow.

9: WARM CLOTHING , and stool if necessary.

10: PATIENCE - and lots of it - It could take many attempts!

11: LESS GLASS - Use of EP with fewer elements 4/5 max to increase contrast and detection, may be of help.

12:AVERTED AND DIRECT VISION - Go back and forth between direct and averted vision, until the companion is held in direct view.

13: ZOOM EP - Use of a good marked zoom EP, to find the optimum power for the seeing and filters if necessary.

14:HIGHLY ACCURATE FOCUS - TOGETHER WITH A NICE FLAT FIELD, FREE OF CURVATURE - this is a must also , and you may have to re-focus often.

15:VERY STABLE MOUNT - Absolutely no wobbles!

16:VIEWING AT TWILIGHT - Can reduce the glare of Sirius A - and this goes for other bright primary doubles as well!

17: HOOD or COWL; this WILL help if streetlights or other bright light sources are a nuisance -- I rarely observe without one in any case!


PS: If something has been overlooked, we would all welcome further additions!

bigjoe.

[The_bluester (Paul)]

A quick report from Snake Valley. Last night was not looking at all promising until near dark when the sky cleared up nicely.

In short, we got it! For about an hour, Sirius and the pup were clearly visible and separated in the C925 and a couple of other people snagged it as well both through my scope and their own (most of which were a lot bigger)

It took a few minutes to see and I resorted to moving Sirius just out of view but once spotted it was repeatable with Sirius centered in the FOV. After about an hour the seeing deteriorated and the airy disc of Sirius put an end to seeing the pup.

[bigjoe (JOSEPH)]

Originally Posted by The_bluester

A quick report from Snake Valley. Last night was not looking at all promising until near dark when the sky cleared up nicely.

In short, we got it! For about an hour, Sirius and the pup were clearly visible and separated in the C925 and a couple of other people snagged it as well both through my scope and their own (most of which were a lot bigger)

It took a few minutes to see and I resorted to moving Sirius just out of view but once spotted it was repeatable with Sirius centered in the FOV. After about an hour the seeing deteriorated and the airy disc of Sirius put an end to seeing the pup.

Glad you found it Paul.

bigjoe.

[The_bluester (Paul)]

Yeah, it was a very nice moment, very nice to grab a personal first for the weekend. I had another try the following night but the conditions were not as good leaving it just not quite there. Then it clouded over completely and it was a night for wine and talk rather than observing.

I thought a couple of times I could see it on the second night but was never quite sure so I am putting down to wishful thinking rather than an actual detection second time around, the first night there was no doubt once I detected it initially. I will hopefully have another try from home in the near future and see how I go there. The sky is not quite as dark as Snake Valley but pretty good and we often get pretty good seeing (I live about 6KM out of a smallish rural town and 60KM away from a major city)

Edit: to talk to a couple of the pointers in the list above.

1: SEEING - Must be excellent.

Yes, very good seeing in the early part of the night I was successful.

2: ALTITUDE - Well above the horizon in
most instances.

Sirius was near it's peak elevation above the horizon at the time.

3: APERTURE - 100mm+, Cooled and well collimated, though probably no more than 12" due to the affects of seeing on large obstructed scopes; though it now appears certain, that even a 70mm achromatic refractor of long focal length can result in DETECTION!

Detected in a CPC925 so about 235mm aperture. I tried with a 130mm refractor as well but did not manage detection, but I did not have a short enough EP to stack on the magnification.

4: POWER - The use of it is necessary - Helps darken sky background, and with limiting magnitude ; 200x + may be needed.

Detection was at 313 X mag in my case.

5: USE A MASK - Hex , may be necessary.

No mask used in my scope nor in the big dob where we also had success. The pup was nicely between diffraction spikes in the dob.

6: ORIENTATION - Is your diagonal/scope displaying an upright E/W view; If not adjust accordingly.

Caused a little bit of mental adjustment between scopes due to different orientation.

7: PRACTISE on Rigel say - Bright, with similar separation. Know what a separation of 10" will look like in your go - to EP - VIZ - Know your field.

That was the first step, a seeing check and mental check of the rough separation on Rigel first.

8: DRIFTING - Let Sirius A drift past the field stop , and disappear, as B will surely follow.

First detection made by this method, I used slow motion slew controls to move Sirius just outside the field stop.

9: WARM CLOTHING , and stool if necessary.

10: PATIENCE - and lots of it - It could take many attempts!

Thrilled to bag it on the first attempt. Failure on the second night I think an indication of the seeing conditions on the first.

11: LESS GLASS - Use of EP with fewer elements 4/5 max to increase contrast and detection, may be of help.

Possibly yes, EP in use was a Plossl in a 2X Barlow.

12:AVERTED AND DIRECT VISION - Go back and forth between direct and averted vision, until the companion is held in direct view.

Done, initial detection with Sirius out of view, later detection with averted vision, a bit more practice with direct vision in the C925. Easy with direct vision in the big dob.

13: ZOOM EP - Use of a good marked zoom EP, to find the optimum power for the seeing and filters if necessary.

14:HIGHLY ACCURATE FOCUS - TOGETHER WITH A NICE FLAT FIELD, FREE OF CURVATURE - this is a must also , and you may have to re-focus often.

A small focus change and it was gone.

15:VERY STABLE MOUNT - Absolutely no wobbles!

16:VIEWING AT TWILIGHT - Can reduce the glare of Sirius A - and this goes for other bright primary doubles as well!

First detection was in late twilight.

17: HOOD or COWL; this WILL help if streetlights or other bright light sources are a nuisance -- I rarely observe without one in any case!

[bigjoe (JOSEPH)]

Just goes to show Paul, it's not as easy as some might suggest.

A big scope you have really, 9 1/4 with its flatter field than most SCT's; would have been very good for this, but not the 130mm refractor that's interesting!

You did everything right as per list, so well done!

PS: A personal first too. Sirius B is something every Amateur should bag.

bigjoe.

[The_bluester (Paul)]

Originally Posted by bigjoe

Just goes to show Paul, it's not as easy as some might suggest.

A big scope you have really, 9 1/4 with its flatter field than most SCT's; would have been very good for this, but not the 130mm refractor that's interesting!

You did everything right as per list, so well done!

PS: A personal first too. Sirius B is something every Amateur should bag.

bigjoe.

I am probably not being entirely fair on the refractor which was very very nice to observe through and gave lovely low powered views of the same objects that we were observing at higher power through my SCT. Mainly M42 and Eta Carina.

In it's defence time ran out to stack on the power, with the EP we had handy for it we were limited to about 115X mag though it might still have been doable with more patience. Hopefully I get the chance to view through it visually again (It is chiefly used as an astrograph by its owner) and if it is still early enough in the season, have another crack splitting Sirius with it from home.

Something I found very interesting was the difference in the airy disc between my C925 and the big dob. The SCT at high power produced a disc looking pretty much exactly as the Celestron manual would lead you to expect when collimating, basically a small but sort of broken, fuzzy disc made up of lots of little concentric ring sections buzzing around the centroid of the image. The dob produced a noticeably tighter and cleaner star image which led to better apparent separation between the two with the obvious addition of diffraction spikes from the secondary spider vanes. The biggest issue was that Sirius was almost painfully bright, it was easy to project a clear image of the star on your hand a couple of feet away from the EP!

[MattT]

Have given it a go over the last couple of nights around 11:30pm. Sirius at that hour is about 40º above the horizon and descending into the western murky sky. Melbourne on both nights was pretty awful and all I saw with the 70mm f13 and 90mm f11 Achro's was a ball of glare and no sign of the pup at all. Finding a sharp focus was impossible....conditions are everything.

Will now wait for early Spring mornings for the next try.

Matt

[Tinderboxsky (Steve)]

Well, at last I can report in that I have been able to spot the Pup this viewing season.
Last night was the first clear night without the coastal cloud that has been a constant companion for many months. Seeing and transparency was excellent but with a near full moon approx 60 deg away.
The Pup popped out easily when holding Sirius just outside the field stop at 320X. Once seen, the Pup reminded visible when moving Sirious back into the FOV. I reduced magnification to 200X and was able to maintain seeing the Pup. scope was NA140SS with Baadar Fringe Killer filter on TRex mount. I did not have my ED103 on hand to try the Pup with that aperture.
Then got distracted by some magnificent views of Jupiter.

Steve

[Tropo-Bob (Bob)]

Well done Steve.
As for me, I have not had a clear night since I have seen the Pup!

[MattT]

Good one Steve

To prove to myself I wasn't seeing things I decided to throw my biggest scope at it and got out the 10" f4. 8 Newt. After a few minutes I was rewarded with the Pup...a dull slightly green star, further out from Sirius than I remembered it to be. Eyepiece an ES 8.8 82 giving roughly 133x with a 2mm Exit Pupil.

As the finder on the Newt is a 60mm f5.5 ED refractor I put the 8.8mm eyepiece in that scope and saw...nothing.

[Tinderboxsky (Steve)]

Thanks Bob and Matthew.

I have made up some simple aperture stops and if I get another good night I am going to experiment stopping down the aperture and see what happens. I will only bring them out and try on a night of excellent seeing and Sirius is still reasonable high.

Steve.

[goober (Doug)]

Tried from Melbourne last night with a 127mm APO and a variety of eyepieces. Seeing was quite good for Melbourne at 9pm. Spent an hour on it with no luck. Rigel was absolutely no problem with any eyepiece I threw at it, from a 13mm Ethos down to a 3-6mm Nagler zoom.

I could see the E star in the Trapezium with no difficulty, and the F star popped in and out.

The pup still eludes me.

Can anyone confirm the PA is similar to Rigel? I know the separation is at around 8-9". I was looking east of Sirius for the Pup, similar to Rigel, letting it drift into the FOV hoping to snag it before Sirius appeared.