Aperture Mask: Yes. Pluto: Not so much.

Got home from the trustees meeting last night to a glorious clear sky. On a Monday? Really?

I made an aperture mask for my dob over the weekend and was itching to try it out. The idea behind the mask is that on bright targets cutting out a bit of light and diffraction from the secondary struts should improve clarity, even though the aperture is reduced (350 to 160 in this instance).

And so after failing to resist temptation I was setup by 11:20:

Jupiter: Disappeared behind neighbors house. Need to catch it in the gap between house and apple tree 1.

Saturn: Seeing dreadful without mask: boiling away with no clarity at all. With the mask: same but dimmer. Hmmm.

Pluto: Spent ages looking for this. Definitely in the right place. Pluto formed a triangle asterism with two other faint stars. I upped the magnification to dim the sky glow and there was definitely something there. Wobbled the scope – that helped. Averted vision- didn’t make much difference. So- I’ve looked at Pluto but not seen it! Beginning to regret doing this on a work night…

Jupiter again. Behind apple tree 1. That moved quick! Damn!

Izar: At last- some success. Successively improved views moving from Baader zoom to binoviewers to adding aperture mask. In the final view the stars were pinpoint sharp and well separated with the companion showing a lovely blue.

Double double: the same experience. The 2 pairs were easily separated in all 3 configurations, but the binoviewers plus aperture mask gave the best view.

M13: Too dim for the mask, the best view was in the binoviewers- resolving all the way to the core and seemingly spherical, even though at that distance you don’t really have depth perception!

Jupiter again: Gotcha! Just before it snuck behind apple tree 2… Definitely a better view with the aperture mask- slightly dimmer but with much more clarity. 6 bands plus the GRS were clearly visible, with some detailing on the bands, plus the moons spread out as clear disks 3 to one side and one on the other.

Well worth the fatigue today!

Very pleased with the aperture mask- it’s not often an astro upgrade is almost free. It’s only really good for bright objects and with the binoviewers I had to velcro 4kgs onto the bottom of the tube to balance it- bit well worth the hassle!

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.


Fading Noctilucent Clouds

Popped out for a quick session on Friday night and there was a lovely Noctilucent Cloud formation to the North, so I popped my camera on a tripod and recorded it.

The video above was using a Canon SL1 at 22mm f4 taking 265 shots between 23:49 and 00:30. I used Pixinsight for a curves tweak and some unsharp masking and then Videopad to string it all together and add a bit of music.

The red light in the foreground for part of it is me setting up the dob. It doesn’t really add to the ambience- but it led a pretty good session despite needing to do a bit of cloud dodging. Finally got the Binoviewers dialled in for some good views of the Double Double, Izar, Albireo, M29 and M57. Really surprised that at similar magnification they outperformed my 7mm Celestorn X-Cel Eyepiece- the split on Izar was really clear, and the companion was a vivid blue, wheras the Celestron had them fuzzier and less colourful. Even Saturn came out to play- and despite hugging the horizon, the seeing gave me glimpses of the Cassini division plus Titan, Rhea, Dione and Enceladus. Best of all was M13- it resolved close to the core, but with tails everywhere- it looked like a ball of wool after a kitten’s been at it!

Now there’s a Surprise!

This week, we spent a couple of days in the Dark Peak, primarily to visit the RHS show at Chatsworth. We stayed at the Fox House Inn on the road from Sheffield into the Hope Valley. I spent my childhood and pre-university years in Rotherham, and this area was one of my hiking and cycling favourites in my youth.  I had quite forgotten how ruggedly beautiful this area is, and since it must be 50-odd years since I was here last, I took the opportunity to re-visit some old haunts. As the road from Sheffield to Hathersage rounds a bend on Millstone Edge, suddenly the whole of the Hope Valley opens up in front of you. This is known as the “Surprise View”. There is now a car park there so you can walk and enjoy the view. Surprisingly (!) I encountered this enlightened information sign.

It seemed a little curious, although informative, to choose M64 to expand on instead of the more usual culprits like M31.

I wonder if we should consider something similar at Rosliston? (If we could get someone else to sponsor it!)


Out of interest, and for comparison, Rob recently imaged M64 at https://roslistonastronomy.uk/catching-up-on-images.

Here is my own re-processed PD camera version from 4 years or so ago:


Observing Jupiter 28/5/19

Swadlincote. C6r refractor.

Some entertaining views waiting for Jupiter to rise . Amazing view of unfiltered M27. The Summer Triangle was high giving views of Cygnus. Serpens and Ophiuchus gave great views of open clusters , the “summer beehive ” IC 4665 and “Graff’s” , IC 4756, stood out as very fine. M5 is a gem to resolve.

After midnight a very bright Jupiter arrived. Opposition will be on the 10th of June. Although as quoted as being low in the south , it was nicely positioned to observe. Even low power showed Ganymede off the limb and the shadow of Io in transit. The size of the disc at x320 was amazing  at 47″. Best views were about x160. The south polar area being dark. The bands had dark edges with a lot of activity to the equator. Thin cloud acted as a good filter giving lots of contrast. Seeing soon deteriorated. Best just to keep focus and let the views come. A very interesting session , keep observing throughout the summer , under clear skies ! Nick.


A Year of Observing

“You’re writing a blog about a spreadsheet???” My wife has just discovered that not only have I adopted the habit over the last couple of years of sitting in the garden on clear dark nights and then making notes about it, but I’ve then been putting it into a spreadsheet and getting statistics about it. And now I’m sharing it in public. She’s giggling at me with what I hope is affection…

Last year I bought a 14 inch dob and after a few months enjoying the views and wandering through the skies I decided I wanted to be a bit more rigorous and start planning my sessions, so I started making notes on my phone of what I wanted to look at after reading observing reports on the web. I quickly moved onto recording the success or otherwise of these observations on a black notepad on my phone (to minimise disruption to my dark adjustment, although to be honest, in Bortle 5 skies it doesn’t make a huge difference), and it was a short step from there to Excel. I just spotted I’ve been doing this for around a year so I thought I’d share it, partly out of curiosity to see how it compares with others experiences…

Stating the obvious: we get quite a lot of cloud.

If it’s clear, I’m not doing family stuff and work’s not in the way then I’ll go out and observe. Altogether I’ve recorded 26 sessions. I’m pretty sure there have been more than that- if I’m observing in company I’m much less diligent about recording it. I also sometimes have quick sessions with my 8 inch for half an hour and I’m a bit rubbish about recording those too. So: 26 is roughly the number of ‘proper’ sessions where I’ve sat outside with a target list and written it down. From this I reckon twice a month is a good working average for how often I can do a ‘good’ session.


No of Objects 149
Messiers 65
No of Observations 280

If I was a bit disappointed to realise how infrequent observing sessions are, I was quite surprised by how many objects I’ve managed to record during that period- including quite a good chunk of the Messier catalogue. I suspect I’ve managed to get through most of the easier ones. From my location, although my southern horizon goes down to a few degrees in places, I’m looking directly over rooftops and at the dome of light pollution of Burton on Trent and often the orange haze makes finding reference stars to hop from very difficult, so I’ll probably need to make more effort to get to dark sites to grow this list a bit.


I wasn’t surprised to find that there are some objects I come back to again and again, but I was quite surprised to find the Leo triplet at the top of the list, although on 3 of those occasions I couldn’t find NGC3628. M13 is less of a surprise, I never get tired of looking at it and trying to resolve as far as possible into the core. I notice that over time I’ve been less inclined towards the higher magnifications. The Double Double is a favourite first port of call, both because it tells me how good the seeing is, and also whether my mirror has cooled. Plus, I love the idea of it as a vast interstellar executive toy- with six components that we can’t see. I’m sure M42 would have overtaken all of these if it were visible for more of the year and not so subject to winter weather.


Something I’ve not done much of is logging how often I can’t find or see things. The Horsehead is conspicuous by its absence (I picked up an H-Beta filter in March, but just missed out on the HH) and I really want to see Stephan’s Quintet visually- this will need darker skies! I suspect that if I was logging more diligently the times I’ve failed to find either of those targets they’d be quite high up on the list and I’m going to start doing that. I’m also going to record a bit more about where I observe (usually my back garden) and what equipment used.

I’ve attached the spreadsheet I’ve used in case anyone wants to re-use the format- it’s pretty basic and has just sort of grown organically as I’ve added bits and pieces to it. It’s a bit of effort to keep it up to date, but I’m glad I did it as it’s been interesting to look back over it and remind myself of what I’ve seen- It’s also a reminder of how great visual astronomy can be when you’re suffering the frustration of several weeks of cloud cover.

I’m going to brush over the slightly worrying and repeated experience, of reading about targets, thinking they sound great, then finding I’ve already seen them…

Log 18-19


Schroters Valley and the Gruithuisen Domes.

Looking at the Moon from the “window-sill observatory” last night, the lunar phase looked suitable to observe Mons Rumker. Unfortunately the exact phase and unfavourable libration precluded this, but as compensation there was a nice view of Schroters valley and the Gruithuisen domes. Better images of the domes than the last time I tried! (https://roslistonastronomy.uk/more-domes)

Hunting the Teapot

I have always wanted to see the Sagittarius “Teapot” from the UK, but never have done. You need a very dark sky and a very clear low southern horizon. Our recent Wales visit gave us the dark skies, but not the low horizon (too many hills!).

Anyway, last night, couldn’t sleep again. One palliative for this is to go for a walk. It was 03:30 AM and Sagittarius was just about culminating, so on with the dressing gown and boots for a trek to the bottom of the garden where you can see a low southern horizon. I also put my camera in my pocket, just in case. I knew where the “Teapot” was – between Jupiter and Saturn, but the Moon was up and it was just beginning to get light.

So, Jupiter and Saturn and Antares were obvious, but could only see the odd star where the “Teapot” was supposed to be – nothing resembling a teapot!

Out with the camera to see if a bit of image processing would show anything. After a bit of fiddling with the exposure, I got an image that might have potential.

So here is the processed image, and I am quite pleased with it. The elongated line near the teapot is a plane. Still haven’t seen the “teapot” visually though!