Observing after RAG meeting at Rosliston Forestry Centre 28-29/6/19

A group of us stayed to observe after the RAG meeting last night. Starting at about 23:30 we continued until approx. 01:00 – at least I had to leave then although some folks continued!

A very big thank you to Rob Leonard for bringing along his 8 inch and 14 inch Dobsonian telescopes. Unfortunately I now find it very difficult to bring my own scopes to RAG meetings although that might change in the near future (hopefully!) Rob’s 14 inch Orion USA Dobsonian telescope gives incredible views – it seems to be much better than my 16″ Meade Lightbridge Dobsonian telescope although may hr it is just better collimated! Certainly the difference in weight between 14″ and 16″ is quite remarkable.

The evening started with a view of very faint noctilucent clouds just about the Belt of Venus in the northeast. These were little more than a fluorescence of the sky at this point between the darker Belt of Venus and higher sky and not as good as those I photographed on Thursday evening and certainly nothing like the spectacular display I saw last year when Damian woke me up at 3:30am one day and said, “Look out of the window!”

The highlights off the evening were some excellent views of Jupiter and Saturn through the two Dobs – Jupiter was so bright in the 14″ that it blew my night vision when I looked at it! The Gallilean Moons were definite discs rather than points and detail was visible in the belts of Jupiter although I could not see the Great Red Spot.

Rob was able to swap between a single eyepiece and a binoviewer on 3.2x Barlow with 20mm eyepieces (Barlow needed to give enough back focus in the Dobs = ca. 6mm). I was able to fuse the images off Jupiter easily but when we looked at a single star I saw two of them! I have noted before that I tend to get problems fusing images with binoculars and Rob’s binoviewer probably has given me one of my best views through such devices in terms of allowing me to easily fuse images that I have ever experienced. Saturn also seen as single image – definitely no issues with the binoviewer itself. Perhaps because I have some difficulties fusing images in these devices I personally prefer a single eyepiece but of course many people (including Rob himself) feel otherwise.

Rob had a go at trying to find Pluto but I think it was asking too much of a misty sky that never got properly dark so we did not get to observe the minor planet…..

M31 and M57 gave spectacular views in the 14 inch. The sky was misty with lot of moisture which limited visibility but it was quite still and M31 showed some of the best detail in the tendrils of stars coming out of its heart that I have ever seen – in a view that occupied a large part of the field off view in this 14″ Dobsonian telescope.

The misty sky affected the view of the Dumbell Nebula which, although visible, was surprisingly faint leading some observers present to say they needed to use averted vision.

The object that really made an impact on me was my first ever view of NGC 6287. This is a compact globular cluster that looked like a bright slight out of focus star that none of us could quite focus to a point in a field where Sky Safari Pro 6 planetarium software told us there were no bright stars. The listed magnitude is 9+ = however being so small we could see that all of this light was focused into little more than a star like point and so the object was a lot brighter than the listed magnitude would have suggested. With extended objected the listed magnitude gives you the integrated light across the object. For galaxies such as M33 and M101 this means that the light is spread out over wide area as these objects are large in the eyepiece and so the brightness at any one point is low. However we could see last night how for NGC 6287 the effect is reversed giving a high brightness level at any given point. I have seen a similar effect in the past with planetary nebulae which are often small and bright as well.

Andy

3 Responses

  1. Great evening folks – still don’t know exactly why my guidescope was crocked.
    Irony is my manual PA appears to have been spot on…

    I’ll pop my NAN image in another thread.

    Neil

  2. Cheers Andy- it was a really nice evening. We packed up pretty much straight after you left. When I was unloading the car this morning everything was soaking- to the point that I couldn’t see my face in the primary mirror of the 14″ because of the condensation. I’m sure that’s why M27 was a bit pants and probably why Neil was struggling a bit as well.

    The binoviewers are a funny one- I’ve had some incredible views in them this year- and when they’re working well they’re more comfortable for me than a single eyepiece. At the same time they seem far more prone to stray reflections and misting up and sometimes I just can’t get them working at all and don’t know why. I suspect that like all these things it’s a skill, and part of that skill is knowing when they’re not going to work and not wasting time on them…

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