lunator

2 minutes ago, John said:

Many thanks for reminding me of Epsilon Arietis, close to Uranus. A lovely tight pair of stars that I have not observed for a long time. My seeing seems to be still good with this pair cleanly split from 225x upwards.

Thanks again 👍

Hi John 

One of my favourite doubles. It's on the front of my book :).

It is closing now. I calculated a minimum orbital period of 600 years but the current estimate is around 1200 years. One curious point is as far as I am aware Herschel never noted this pair. He may have missed it in his observing programme but a 5th star in a well placed constellation would be a target to observe I think. My preference is the pair were too close for Him to resolve around the 1780s.

Cheers

Ian

I thought I would look at Albireo and Almach in the ST80 tonight. I just used the 25 and 5mm orthoscopic eyepieces. I had started the session with the Moon and Jupiter. The ST gave a very warm hue to Jupiter. I looked at Albireo next at x25 mag. The secondary appeared pale blue (similar to my other scopes but the primary appeared yellow orange rather than yellow that I see in my othe scopes. I moved onto Almach and at x80 magnification the secondary was blue ( I thought I might see a greenish tint.)the primary was again a yellow but had an orange tint as well. 

Not this proves or disproves anything but certainly the apparent colours in the ST80 are different to the OMC250 and the Newt. 

Cheers

Ian

7 hours ago, ollypenrice said:

Last night I went outside again had exactly the same experience, with the same star. This has set me pondering about whether the effect might not be directly caused by the cloud, but by some process going on in the brain. I don't get the effect when I go out into a clear sky but perhaps something needs to settle in the brain when it observes a single star isolated by cloud. Something to do with orientation? I will try to find out whether I still get the effect if I'm dark adapted before looking up.

Olly

Hi Olly

I have been out tonight with the ST80. Some patchy cloud was moving South at a fairly high speed. I found when I looked directly at the Moon the cloud was clearly moving. When I looked directly between the Moon and Jupiter I could see both of them 'moving' in parallel due North 😁.

Cheers

Ian

I have experienced the 'migratory Star syndrome' (I've just made that up 😁) . It always occurs then there is a fair amount of cloud around and it is moving at a fairly quick pace but also some decent sized gaps. It does seem to be the brain decides the clouds are either not moving or moving more slowly than they actually are so the star HAS to moving to compensate. The illusion disappears quick if you just stare at the star for a few seconds.

On 22/11/2023 at 22:46, Ags said:

Not that I have a large dob, but my ZS66 can show nice colors in Albireo while the big dob will  'overexpose' them, but surely there are hundreds of faint doubles that are indetectable or colorless in my ZS66 but should show as moderately bright, richly colored doubles in the big dob?

Hi Agnes

In my 8" and 10" scopes colour is clearly visible down to mag 9.5 ang then the Purkinje effect becomes noticeable between Mag 10-11 where the fainter star in particular shows a blue tint. Below mag 11 I couldn't see any colour. These observations were predominantly from bortle 5-8 skies.

I have moved to a decent bortle 4 sky now so once everything is set up I might revisit some of these pairs to see if that makes a difference. I think it will but probably only 0.5-1 magnitudes.

cheers

Ian

Hi tico, refractors are excellent double star scopes. Their only real drawback is for tight doubles where you need resolution they tend to get e bit expensive.

If we take the Raleigh Criteria and use 5500nm as the wave length of the star then to achieve a clear. Split the equation equals 138/Aperture in mm. So a 120mm scope will cleanly split a 1.15" pair ( assuming roughly equal magnitudes 🙂)  Once you get up to 150mm scope or larger refractors get very heavy and expensive. My 200 F6 next will perform pretty well against a refractor and can split pairs down to 0.7" The conditions don't often allow this but when they co-operate it can be great fun to split them. 

A 120mm  refractor could get somewhere close to my newt at the Dawes or sparrow limit but the view show elongation of the pair rather than a clear split. 

If you want a refractor go for it as you won't be disappointed. If you want to chase very tight doubles you will have to consider a different design.

Cheers

Ian

Hi Jeremy I'm not totally convinced by this view. 

From personal experience the most vivid  (& false) colours I have seen was in my ST120 but it was more to do with it being an F5 scope. I have seen some nice colours in the 70 & 80mm scopes I have but the best views have been in my 200mm newt with orthoscopic eyepieces. The colours are more realistic the view of Almach, Cor. Caroli or Albireo are stunning.

Cheers

Ian

I can't help with the SS6 and sketches. I do use SS6 to record observations sometimes. Usually I draw sketches into an artist sketchpad and add notes. I then transfer the information into an Excel spreadsheet. My books are on my bookshelf in chronological order. 

Cheers

Ian

I have the celestron eyepiece and have used it for measuring doubles. The Bob Argyle books says you need a focal length of 2-4m for this to be useable for measurement. I use a 2x Barlow on my scope which gives a focal length of 4.5m (x360 mag).

I have measured wider doubles by using the ring micrometer and chronometric methods. Both covered in Bob's book and possible with a phone stopwatch -Ring micrometer method and. Stopwatch/illuminated eyepiece for the chronometric method. 

The best 2 periods of clear skies were lockdown 1 and the Iceland volcano back in 2011 (I think 🤔)

Aircraft contrails do cause a lot of cloud. More than just the contrails themselves.

It was an enjoyable show although the radio edit on BBC sounds is nearly 1 hour long. For some reason on BBC4 the show is only usually allowed 30mins.

The best view I had of the crab was in a friend's back garden in East Devon. We used their 10" Mak Newt. It was really bright. It looked like a thumbprint with some very obvious detail. A few days later I returned home to London and decided to look at it with my OMC250. I could just about make something out. It really made me understand how Light polluted my skies were and how envious of dark skies I was 😁.

Cheers

Ian

I saw it Monday in my 15x70s. It was tricky but definitely visible.

Peter, like DaveS I can provide provide some anecdotal evidence.

In the early to mid-80's. M31 was clearly visible naked eye. 

My Garden was in SW London it overlooked Fulwell Golf cours so may have been darker than expected.for the location.

Cheers

Ian

Great photos, 😁. You have really caught the colours 

Cheers

Ian

Hi Nik, generally a 5"scope will be good for most UK nights but when the seeing co-operates a well collimated 8" newt will split those doubles below 1" easily. It s just a rare occasion 🙂

Cheers

Ian

Had a short session out tonight before the clouds rolled in. My step-son and his girlfriend were around so as the scope had been out all afternoon so was well acclimatised.

His girlfriend had never looked through a telescope before so I thought I would start with Saturn. I got a very satisfying 'Oh Wow' a well known response to a first view of Saturn. 😁

The next stop was Jupiter. Showing some lovely detail at x150 and I did get a glimpse of the Io transit. The verdict was it was a good as Saturn.

I thought something different would be good so swung the scope round to  M57. At x100 it showed a clear doughnut shape. They were both pleased to see their first grey smudge 🙂

I couldn't help myself and had to show them a double Gamma Aries. They were intrigued to think that they were a pair of stars in orbit. I also explained they were discovered by Robert Hooke whilst he as following a comet.

The final target was Neptune. Apparently it is a favourite planet. It took some finding in the conditions but we finally managed to track down a tiny blue-grey disc. 

The clouds had rolled in some called it a night.

Cheers

Ian

Jack, I have to agree with Cosmic Geoff. I have an 8" dob it is a great scope for visual but it would be almost impossible to take images of deep sky objects with it. 

The general rule of thumb is a central obstruction of 20% or less will have virtually no impact on the appearance of the doubles compared to a refractor. 

My OMC250 has an obstruction around 30% and this will have a effect but the aperture means that I can resolve pairs much closer than any refractor I have owned. (All in the 70-120mm range)

If you are happy with a sub-150mm aperture I am sure a refractor will give super images but if you want to chase closer pairs then a mak of 150mm+ might suit you better.

Cheers

Ian 

Very nice report. Sounds like a decent location even with some LP on the horizon. 🙂

21 hours ago, Ags said:

Glimpsed outside my office in broad daylight around 8am this morning: Venus right next to the Moon!

I saw that as I left for work at 6.30. it was a lovely sight. 🙂

I've looked at a lot of doubles through a variety of scopes from small refractors like the ETX70/ST80 Upto my 8"reflector and 250mm OMC.

They have all given me good views of doubles. 

Generally I can see doubles down to about 1~1.5" on a decent but not perfect night. This equates to an aperture of around 120mm..

I do own an ST120 which on paper is ideal but as it is an F5 the colours can be a little strange.

It does come down to the age old question what telescope would get the most use...

I guess you need to decide what most important out of resolution, portability or purity of the image.

Cheers

Ian

Observing report 07/11/2023

Telescope 200mm F6 Seeing II/V Transparency II/V

I managed to get a couple of hours observing. Despite an early start the next morning I could still get some observing time.

Mr Dobbie had been out on a tarpaulin cooling down. I checked the collimation and it all looked good.

My first target was Saturn. It is still quite low but once I had clipped the vegetation I had a fairly good view. Titan was easily visible with Rhea visible occasionally. The Cassini division was also fairly clear.

The first new target I had was STF2567 in Aquila. A wide pair of stars with a noticeable difference in magnitude. Easily split at x50. The primary is yellow, the secondary is orange. The best view was at x100.

My next target was STF2563AB,C in Sagitta, a fairly close pair with a wide ‘C’ component. All components looked white. The primary is bright and the secondary and tertiary are of similar magnitude. Part of a kite shape asterism. Easily split at x50, the best view was at x75.

I moved onto STF2569 in Sagitta. A close pair of white stars with a moderate difference in magnitude. Part of a right angled triangle.

My final new double was STF2570 in Aquila. A close pair with a moderate difference in magnitude. The primary is white, the secondary is pale blue. Shares the field with a Sagitta shaped asterism.

Whilst I was in Aquila I thought I would check on my double CSR3. So I dropped down to STF2636 which shares a low powered field with CSR3.I am still amazed Struve observed STF2636 but ignore a wider but brighter pair.

Jupiter had cleared the trees and using the baader zoom I had a look at x50-x150. The detail on the belts was very good. I decided to get the 6mm ortho out giving me x200. This really brightened the image. I am assuming this is due to fewer elements in this eyepiece. The extra magnification helped to draw out detail in the belts and I could see Ganymede as a disk not just a dot.

After some time I decided that as the transparency was good I would have a look at Andromeda and it’s satellite galaxies. M31 & M32 are easy to spot but M110 needs very transparent skies to observe. When I looked at the galaxies in the 24mm giving me ~1.4°. I was very pleased that I could see a grey smudge exactly where I was expecting M110 to be.

I did have a quick look for M33 but I didn’t really see anything obvious.

I did get visited by 2 hedgehogs one walked right past the telescope 😄

The conditions are pretty good tonight. The transparency is very good. I got a decent view of M110 which isn't a frequent occurrence. Jupiter also showed great detail and I am sure Ganymede appeared as a disk. I hadn't really seen this before. I'll write up a full report tomorrow.

Cheers

Ian

1 hour ago, wesdon1 said:

@lunator I was trying to get some 90 sec videos of Saturn and Jupiter last night but the damn fireworks locally by my home, combined with a lot of smoke/haze, made it too difficult to get decent video data. I don't want to be a kill-joy but those damn fireworks get on my nerves! Thanks goodness it only happens for a few days once a year! 🤨

Unfortunately round here it s full crash bang wallop from the end of October to Christmas. Hopefully once I have moved it will be better. How you do get a chance to video Saturn and Jupiter 😄