lunator

The frustrating thing about Sirius B is the ease with which Southern Hemisphere observers can split. I remember reading about someone spliting it in a 3" scope back in 2010. They had the luxury of a dark sky in Namibia.

I have the Baader Zoom, I use it quite a lot in the Dob. The field of view is a little tight at 24mm but I have never had an issue finding objects. From memory I think it give about 1° FOV in this scope/ eyepiece combination. 

I am an ortho eyepiece fan but the Zoom is very useful and as far as I am concerned I will be keeping it.

Cheers

Ian

Mayer and Herchel are slightly over looked with regards to double stars. The Struve catalogue did "hoover up" some of their discoveries.

The way I like to tell people about the potted History of Double star observing is Galileo wa first to see a visual double through a telescope. Mayer created the first  Catalogue. W. Herchel did the first systematic study of them and discovered Newtonian motion outside the solar system ( By accident tho' 😬).

Struve did the first large systematic study, although John Herschel should also be included in this for his work especially for the Southern Hemisphere. 

I generally stop at this point as Aiken et al are less well known. 😀

Cheers

Ian

I've come to this a bit late,  

I tend to try and keep descriptions simple. 

Pairs are Round, elongated, Notched or Split.

The last 3 descriptions are all  resolved as you can see there is more than one star. 

Amongst the pro's such as Paul Couteau and Bob Argyle it is generally accepted you can resolve a pair down to half the Raleigh Criteria. So for a 100mm/4inch scope pairs can be resolved down to 0.7". The disk will be very overlapped to no dark line but certainly you could see more than one star.

As a separate point. Paul Couteau said the resolving magnification started at twice the aperture diameter.

Cheers

Ian

I had another short but enjoyable session. Saw Pons-brook in the 15x70's. Clearly fuzzy (if that is not an oxymoron 😀 ). 

Had an hour or so looking at more doubles in Hydra. 

Tried to see a couple of galaxies but Leo hadn't come round enough to clear some trees. 

Cheers

Ian

Stu, very nice report. 

I do intend to do some galaxy hunting in the next few sessions. I will added theses to my list. Last night was a curious mix of conditions. Seeing varied from poor to very good. I managed spot the AB pair of Zeta Cnc in the 8" scope. 

The dew was very heavy to begin with but improved quite quickly. I only stopped observing as I was due to be up at 5am....

Cheers

Ian

Had a short session with the Dob.

Nice view of Zeta Cnc, managed to see all 3 components. Followed by M48 a nice open cluster.

Finished off with a few doubles in Hydra. 

Cheers

Ian

27 minutes ago, GasGiant said:

Cheers folks

Out of interest,  Why is there not such a thing as a  H a filter I can directly screw into my EPs ? 

I believe the main reason is the scope would concentrate the light from the Sun which would potentially cause the filter to fail with catastrophic consequences for the observer.

Hi Mark, 

Very nice report. I have the 15x70 and they are a very good pair of binoculars.

I will have to try for M65/66

Cheers 

Ian

I have seen it only once at an SGL star party.. back in 2011( from memory).

Now I have darker clearer skies I hope to have more chance soon.

Cheers

Ian

Got out last night for a quick session using my ultralight grab and go. 15*70 Binos on a monopod. 

There was some cloud about but in clear patches the transparency was excellent. I wanted to look a some southern targets.

M42, M48, M47, M46, IC418, Colinder 121

I was very pleased to spot IC418.

As a final target I had a look at Eta Cass and might have seen it elongated.

Cheers

Ian

You can use any mount which is sturdy and so stable but as Michael say's a driven mount makes it much more pleasant to observe close doubles. I have spent this winter using an undriven mount and whilst you can observe close doubles it is a bit of a faff... 😁

Do you have a budget in mind? What sort of scope are you hoping to use?

Cheers

Ian

I don't tend to drink whilst observing but if it is cold I will have a cup of Hot Chocolate when I come in 🙂

Cheers

Ian

It was only a binocular session for me last night. The Moon looked fantastic and I spent some time in Canis Major. In the 20x80 Sirius really sparkled. I always find that looking at Sirius and the fainter stars gives you a real sense of depth. You can 'see' the stars in 3D. 

I also spent some time looking at sigma Canis major. It is a K7Ib super giant star and it orange/red colour was very striking.

This is an observing challenge for anyone with a large telescope. There is s tight double In Casseiopeia STF216. It is 0.3" apart. There is a provisional orbit. It will probably take at least a 14" scope to split but anyone is free to try. 

Please post your observations both positive and negative

cheers

Ian

For me there are several reasons. 

First and foremost is the sense of enjoyment I get.

I also like challenges such as spliting doubles or teasing detail out of the planets. 

The other main reason is, I like solving celestial puzzles. My current pet project is STF216 a 0.3" pair is Casseiopeia.  ( A shout out to Robin_Astro for his help with this 😀)

Cheers

Ian

Just has a short session with binoculars tonight. After the rain the milky way really stood out. As the transparency was excellent. I was only using the 12x42s but all the winyer brighter clusters were visible. 

Out of all the Messier clusters I observed M35/36/37/38/44/45  the one I enjoyed viewing the most was M35. I think it was because it was just beginning to resolve into stars from a misty patch.

Cheers

Ian

I think both labels apply to me. Tonight I have been out with Binos to look at the the Milkyway and some clusters. I think of this as stargazers. At other times I am making in depth observations  and having conversations with other astronomers both amateur and professional I think of myself as an amateur astronomer.

cheers

Ian

There is a simple relationship in my experience..

The Dawes limit means you will not cleanly split the pair. If you want to cleanly split the pair the Raleigh criteria is more relevant. For white stars e.g 5500nm light it is 138/D.

From experience if you substitute the magnification M for D you will get a pretty close result.

So it becomes 138/18 ~ 7.5" 

Also from experience you can split pairs with a delta M of upto 2 magnitudes. 

I hope this helps.

Cheers

Ian

A very nice report 😀, as a fellow double star enthusiast I agree that on nights of exceptional seeing the stars really do look amazing.  

Even though I have moved to darker skies I still observes some doubles on every session.

Cheers

Ian

Hi Agnes

I think the website for star analyser can tell you if the scope/filter/camera are compatible. They say it works with a webcam so the 485 should be ok

It was good to catch up with some friends I haven't seen in a long time. The exhibition side and the retail side does need addressing. I didn't go to the talks as I baulked at £50 where I was only interested in 1 or 2 of them. 

I think FLO were there in conjunction with Pulsar, rather than I their own right. One thing that caught my attention was the OO scope on the FLO/Pulsar stand. 

Cheers

Ian

I think with Aladin desktop you have to load the catalogues in. From my quick look the best image is PANNSTARSDR1. The object looks like a spiral galaxy tilted at an angle to us a  bit like M31. 

Cheers

Ian

I think it is a galaxy, it is in GAIA DR3 and 2MASS.

Have a look at the desktop version of Aladin. That will hopefully give you more data.

Cheers

Ian

A classic case of the invisible double is STF1143. It has only been observed once but is still in the WDS. I have spent a few hours just scanning that area of sky to see if there might be something nearby. The current view is written up in the notes.

  Some error in position. See note in BDS II. Bu_1906.

 This may be STF1134AB with a larger error than is typical for a  FGW Struve measure.   Alternatively, this may be the same as STF1141