1st Field Trip - What to target 29th Dec 2019

[Fo_Cuss]

1st Field Trip - What to target 29th Dec 2019 42.83 2.95 - Twilight to Darkness

... It's all going to be last minute.com.

Er... Just accidently posted, before writing the post ... give me 15 minutes to complete

......................

Development Phase 1 will be completed

The Tripod is done ... totally re-engineered.

I have to 'bush' the focus tube tonight.
Tomorrow, I need to add photon baffles
... it has one; I'm going to add another four (Black 3.0 cannot deliver to scope requirements ... will post the details).

I also must black the objective lens doublet (how did that get left till the death ?)

... oh; and clean the 4mm Omni Plossl, because I have Pixies living with me.

I do believe 'that is it' for phase 1
IE. An upgraded 60/f700 refractor scope, with Omni Plossls 4, 12, 2x Barlow

Setup

My guess is that the main tent will be down, and we will just have a beach windbreaker in action.
Hopefully not needed, as the forecast is for 20 kph gusts, averaging at 8 kph.

We will have chairs, and a table, and we should be calm, having arrived early.

The concept is to gain a broad range of terrestrial observations, during the afternoon.
... meaning that we should be comfortable with the setup.

As the light begins to go, the camp will be dismantled, leaving us pret for the sky observations.
(Warm clothing and lots of food, is prepped.)

State of Mind and Body

My guess is that we will be back-endish; and consequently in need of 'getting on it'.

If we can successfully latch on to an objective, then we will get our second wind (and progress).
If we struggle ... the sea air, cold, and previous festivities will take their toll.

Prior Research

None at all until tonights look at in-the-sky.org

All the terrestrial stuff has been researched, because it doesn't move.
This date wasn't known until now - I guess it's normal, cos it all depends on viewing conditions, and festivities.

Anyway ... 29th looks very good.

So, what do you think re targets?

I've noted Uranus and Neptune ... and M81/2 seems isolated on the map (but may be wayyyyy beyond first viewing capabilities).

Maybe first lift the spirits with a planet, and have a crack at a distant object (accepting an honorable failure)

🌝

[Fo_Cuss]

Just found this page : http://www.jb.man.ac.uk/astronomy/nightsky/

Ian Morison suggests Uranus and M31/3 and he provides instructions on finding them (which is great)!

He makes no mention of Neptune, so perhaps it is not easy to view.

http://www.darkskytelescopehire.co.uk/viewing-m81-and-m82-galaxies-in-a-telescope/

... suggests that M81/2 can be found and viewed - they also provide instructions.

Therefore, I think that these will be the target objects 👍

Interestingly, both sources mention the use of binoculars, so I put those on my expedition list.

I'm thinking that it might be useful to discover what the brightest object will be in the sky ... the first object that will become visible as we enter the twilight zone 🌝

Edited December 28, 2019 by Fo_Cuss

[Fo_Cuss]

Inbetween preparing (what should have been prepared yesterday, if I'd had time)
... I've expanded and modded the target acquisition list.

The moon is now on the list, as I've read that it can be seen, though through atmospheric haze.

M33 is below M31, and has been added as an alt.
IC405 is purported to be visible, so it too is on the list.

I've saved the sky maps and gimped them to B&W to save ink.
Of course, having never done this before, there is a high possibility of 'failure to find anything specific'.

I'm banking on M81, as it is below Polaris.
Surely I can find Polaris 🌝

[wormix]

M42 needs to be on your list - easy to find and will keep you going all night long

[Stu]

Good luck with your mission!

Some thoughts....

With a 700mm focal length and a 12mm plossl as your longest focal length eyepiece, you will have a maximum field of view of under 1 degree. To find anything easily you will need an accurately aligned finder scope, do you have that sorted?

M33 could be challenging as it is very low surface brightness. M31 is big, 3 degrees along its length so you will only fit the core in.

M42 is a must, an amazing object. You could add the Double Cluster to your list too, although you may have to view each cluster separately. If feeling adventurous, the Auriga Clusters M36, 37 and 38 are lovely.

Good luck.

[Fo_Cuss]

It's all madness.
The workshop is a mess.
The scope final assembly was this morning ... but it collimated perfectly, and the focus tube is now effectively an interference fit.

Only got two extra baffles in last night - cleaning the lenses took forever.

Anyway, everything is piled up outside, awaiting my son.

I've cleaned up a 20mm Kellner for spotting, and the finder scope can be tuned at 10km during daylight.

It's not how I wanted it to be.
Realistically, it's a trial run.

Looking forward to getting there ... some calm at last.

Hahaha ... it's a beautiful day 🌝

[joe aguiar]

I would recommend a night watch book plainsphere or theres a map caledd deepsky 600

joejaguar

[Fo_Cuss]

Overall; a highly successful mini expedition; though it was always going to be successful, regardless of results, as it was all about learning and gaining experience.

Kit

The kit for one day, is pretty much the same as the kit for a week, except less food.
That caught me out, because normally, food planning is fairly detailed.
In this case, I had simply written food...

This resulted in our central heating 'microwaved jacket potatoes' remaining on their plinth, for later viewing on our return 
The moral being ... make your list detailed (the Devil is in the detail).

Thankfully, a belt & braces approach meant that there were no problems, and there was only a breeze (northerly), so adequate clothing and double socks, meant that we were not at all cold.

Journey

Followed the signs (stupidly, because we are in France), meaning that we lost 45 minutes down increasingly difficult tracks.
... consequently arriving at the site at 15:30hr.

However, we got a break, as ...

The site was perfect
A hard standing for both the car and setup together - no carting gear around.

Due to brain fade, and arriving late; annoyingly we didn't get an image of the site and setup.
Neither did we measure scope elevation; though it's flat, so a guesstimate is 1.4m above sea level.

There was a scrub hedge behind us to the South, but this didn't obstruct (what I believe to be) Venus @ 19 deg.
Therefore, we can say that this elevation offered unobstructed views, with...

The scope set to 1m
... as we were using the prism (which isn't a prism).

The prism seemed to give no problems, so we left it in and avoided procedural changes.

The mount, with it's new bearing design, was utterly perfect ... the difference between happiness and continual frustration.
So too, the newly bushed focus tube.

These two elements, combined with the re-engineered tripod, meant that panning was simply 'a pleasure', and focussing was almost straightforward in respect to vibration (though there is still room for improvement).

The 'tilt & lock' requires further work.
However, for the most part, it functioned well - the moon filling the FOV could be easily tracked, though there were the odd occasions when the friction failed, and reacquisition was required.

All these issues will be solved, during the major upgrade that will follow.

Focussing

With the vibrations minimised, there remained the issue of difficulty in finding 'absolute focus'.
There seems to be an arc of movement, where little happens, unless focussing on stars.

Perhaps this is down to 'contrast' and more work being required on flocking and baffles.
Also, a larger diameter rotary focus knob may help ... it is on the upgrade list.

Overall, I believe the limitation lies with the objective doublet lens.
When cleaning it, I discovered that its surface is produced from concentric bands, that are only visible when breathing on the lens.
Of course, this is being anyway replaced.

Terrestrial Viewing

We had used the scope 'as is' for the first time, back in early November.
This doesn't count as a field trip, as we knew nothing about scopes, and it was simply a fun day out.
However, we had witnessed a very strange phenomenon, where distant objects were mirrorred, presumably by a differing thermal layer.
As much as anything, it was this that kickstarted 'the telescope project'.

Would we see the same phenomenon again?

No ... not this time.
The atmospheric conditions were obviously different.
We could see everything ... even just making out balcony rails at 11km !!!
(what will it be like with a 90/f1000 setup?)

However, we did accidently stumble upon a refraction proof ... discovered when examining the images.
This was really exciting, when it dawned on me, what I was seeing.

Remember the simple experiment of 3 horizontal lines drawn on a card, and placed behind a body of water?
The middle line stays at the same height.
The top line is higher.
The bottom line is lower.

This means that everything above the viewing line of sight is stretched up
... and everything below, is stretched down.

We were always told that an aquarium amount of water would mimick a large volume of air.
Hahaha ... the terrestrial viewing experiment proved it, with the aid of google street views.

A wall painting of a tree was stretched, and on further investigation, I found the houses behind it were stretched
... and clearly, everything was stretched, regardless of the image position through the lens.

What a fantastic excuse for a school science field trip 😁

Celestial Viewing

Flushed with success, and a tuned finder scope, we entered the twilight zone.

The moon was clearly viewable, and we gained some good images (for the scope spec).
To the right and down, was a very bright object (I presume to be venus).
However, the image was dissapointing.
I think that it must be a failure on my part, to adjust the ISO setting ... a lesson learned (or to be learned)

Venus (perhaps)

Polaris
Ha!
I said that I would get Polaris

 

Capella (perhaps)

This was the first object to become visible in the East...

DK UMa

I am fairly confident with this ID...

Kite Cluster

My son assures me that the main cluster looked like a kite.
It was to the right and up from DK UMa.
We couldn't capture the full cluster with the 12mm Omni Plossl...

By this time (around 19:00hr)...

The 2nd battery was failing, and everything was completely wet through with dew.
It was as if we had been in a downpour.

On top of that, we could see that every image was of concentric circles.

We hadn't achieved our objectives, but that was always on the cards.

For ourselves, the trip was a huge success, as we had experienced the difficulties.
This will enable us to be much better prepared for the next time.

... which hopefully will not see a repeat of the incredible condensation drenching that we, and all our kit, recieved.

🌝

[Fo_Cuss]

48 minutes ago, joe aguiar said:

I would recommend a night watch book plainsphere or theres a map caledd deepsky 600

joejaguar

Yes, I do need an onsite map.

I was thinking that a laptop will be useful, with a sky map application.

But I also need to fit an angle disc to the central axis, and one to the horizontal axis.
In fact I need lots of things....

[Fo_Cuss]

Here is the moon at around 22 deg ... the gimped version & the original:

I am not an expert with Gimp.
The objective was to remove the central haze.

The moon was masked using paths, to create an inverted selection, enabling the background to be removed.
The hard edge was then healed.

At least it gives us something from our field trip.

I must now learn how to stack the images.

But I was wondering about the star images.
They show what we saw.

Can anybody inform me as to why we see concentric rings?

Is it down to the objective lens, and the banding that I saw when cleaning the lens?
Or maybe it's the dew?

The lens is going to be changed, but I'd appreciate some feedback on this.

Oh and does anyone understand how read the dew information on forecasts, because it really killed off the night viewing?

[Fo_Cuss]

Ahaaa!
The mystery of the rings of light, around stars, has been solved  🎓

Here is Polaris (the earlier image after denoising):

I was reading a paper by Roger Ceragioli, discussing how he observed Sirius B with a 145 mm refractor.

In it, he described using an aperture mask, as recommended by double-star observers such as W.R. Dawes.

"It alters the diffraction pattern of stars from the normal bull's-eye pattern to one in which a bright star shows the Airy disk, but with the diffraction rings mostly suppressed."

Boom!

Further research indicates that the diffraction rings (Airy Pattern), result from the telescope being perfectly focussed (with the Airy Disk in the centre).

That was such good news.
Not only because we gained confirmation of ideal focus, but it eliminated the confusion over whether this ring pattern was due to condensation dew.

For those who are interested; here is the aforementioned paper:

https://www.rasc.ca/sirius-b-observing-challenge-results

🌝

[JOC]

10 hours ago, Fo_Cuss said:

Further research indicates that the diffraction rings (Airy Pattern), result from the telescope being perfectly focussed (with the Airy Disk in the centre).

Just as an observation 😉 I thought that the Airy ring pattern arose when you had a perfectly COLLIMATED telescope and you DE-focussed the stars - the rings appearing concentric due to good collimation (the lining up of the mirrors in the scope's optical system) when the stars were deliberately NOT in focus.  Sirius is often a bit wobbly and 'disco like' due to the amount of atmosphere that we see it through being low on the horizon (so I am not altogether sure that a paper like Sirius is always going to be relevant to other stars - it does have specific issues not shared with other targets), but most other stars should appear as the same pinpoints of light as you see with the naked eye when viewed with the telescope IF you ARE in focus.  I am surprised you could not get the moon crisper than you did either.  Maybe you were plagued with dew - I've seen airy discs appear on mine when the dew is about.  All your pictures suggest to me a scope that was NOT in focus OR plagued with dew - I think you will find that you could improve on a different night.  

[Fo_Cuss]

1 hour ago, JOC said:

I thought that the Airy ring pattern arose when you had a perfectly COLLIMATED telescope and you DE-focussed the stars

You may be right.
Sadly ... I was quoting the Wiki opening paragraph, which annoyingly takes a different view to your own.

Quote

"... the Airy disk and Airy pattern are descriptions of the best-focused spot of light that a perfect lens with a circular aperture can make, limited by the diffraction of light."

https://en.wikipedia.org/wiki/Airy_disk

Let us not forget that Wiki has a long and proud history of being incorrect 🤓

Either way, delving a little deeper is never a bad idea.

1. R Nave - I would suggest starting here, because the subject is explained in an extremely simple manner, referring to a diagram:

He doesn't specifically state 'best focus', but rather :
"that is the best that can be done with that size aperture" ... (best focus?)

http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/cirapp2.html

2. Edmund Optics has their take on subject.
Personally, I would have liked a couple more sentences (or tighter punctuation) ... but a re-read brings clarity

https://www.edmundoptics.com/knowledge-center/application-notes/imaging/limitations-on-resolution-and-contrast-the-airy-disk/

3. Molecular Expressions goes to town on the long, unpunctuated sentences.
Here is their opener:

"The three-dimensional diffraction pattern formed by a circular aperture near the focal point in a well-corrected microscope is symmetrically periodic along the axis of the microscope as well as radially around the axis."

In legal documents, punctuation is frowned upon, as it can be used to elicit specific meaning from a sentence 🥳

https://micro.magnet.fsu.edu/primer/java/imageformation/airydiskbasics/index.html

 

[JOC]

If those images posted on 31 Dec above, starting 'venus I think' are the best you are seeing then there is something wrong, either with the scope (possibly dew) or your process. 

What sort of telescope is it? 

I am sure that even a cheap and cheerful scope should do better than you are seeing.  I have a small scope and it shows me things as crisp as my big telescope.  Those images just look way off focus to me.  You do mention that the kit was drenched by the time you had finished so I reckon you were swamped with dew which won't give you any pleasing images at all.  You definitely should NOT be viewing all those concentric rings.  People deliberately De-focus to get them in order to check their collimation, but then pull the focus to make things crisp spots of light which is what you should be seeing - it doesn't matter how you interpret those links if you are seeing those rings and can't get rid of them then something is wrong - either you have optics smoothered in dew, not in focus or a bit of both.  When you are viewing things in focus the stars should be entirely crisp spots of light, Venus should be a bright spot with clear edge - it might be going through phases like the moon and the brightness might be a little off-putting, but the image should be a clearly defined circle or part circle - not the wobbly edged blob in your photo - OK it might be a photographic flaw, but if you saw it visually like that it wasn't being viewed properly, the moon should also resolve to entirely crisp edge that you could slice your fingers with - just like you see it with the naked eye only bigger.  If you have sufficient magnification and a semi-useable scope the craters should also have sharp, crisp edges.

[Fo_Cuss]

The scope (generic refractor 60 f/700), at that time was in fairly original format, with a few minor improvements and Omni Plossl's ... but still not at all ideal (with a poorly ground crown).

I'm fairly sure that Venus was out of focus - ie. operator error.
It was our first stargazing attempt, and with such a wobbly scope ... gaining focus was problematic.

The moon ... it was classed by the astronomer sites as being 'unviewable', due to its proximity to the horizon (on that date and time).
We had a crack at it, because it was there in plain site.

Venus (if that's what it was) was even lower than the sun.

Focussing, as stated, was not at all easy, but I remember that this was the best that we could get for the moon.

We were happy with that, as it makes a nice enough image, even though it is lacking detail.
(Hahaha ... Gimp to the rescue) 😁

At that point in time, there was no dew.
We were in the twighlight zone, waiting for darkness to arrive, and for the first stars to appear.

My son took a stint on the scope, and it was he that announced that he had achieved focus on Polaris ... and that it was the best that he could get.
All the stars were showing diffraction rings or Airy Patterns (though we didn't know that terminology at the time).

It was around this time (shortly after) that the dew hit.
A remarkable drenching, on a scale that I have no recollection of experiencing before, when camping out.

My best guess, is that it was not condensation that caused the Airy Pattern ... particularly now, after reading up on the subject.

Overall ... this was effectively a trial run ... experiencing the madness of working in the dark, and struggling to know exactly what one is looking at (other than Polaris and the moon) 🥴

We learnt a lot, in terms of actual observing, rather than talking about observing.

Anyway, my scope is nearly completed - this subject will be revisited in hopefully better conditions, and certainly with ourselves benefitting from this first experience.

🌝

 

 

 

 

[JOC]

1 hour ago, Fo_Cuss said:

Anyway, my scope is nearly completed - this subject will be revisited in hopefully better conditions, and certainly with ourselves benefitting from this first experience.

Perhaps I can suggest that you wander outside the next time its reasonably clear with a pair of average every day binoculars and focus on the moon (even on one of those afternoons when he is out during the day (don't point a the sun though) and a few stars, maybe Pleiades, it should show crystal sharpness everywhere when in focus.  If you can't achieve the same or better with your telescope on a dew free night then I am going to suggest that you might soon get frustrated and perhaps need a better telescope?  Try clicking on my Avatar photo a couple of times and it should show you the photo it comes from which I took.  You should be looking at getting the same sort of amount of sharpness visually through your scope and should be able to match it with binoculars (and that's not even a brilliant photo).

[Fo_Cuss]

Yes, it is a good image of the moon 🙂

Expectations for my scope performance are very high.
It is now 90 f/1000, flocked, baffled, and damped at each interface.

Initial confirmation testing, produced very encouraging results - remarkable focus capability, with images now in full colour.

However, we will see what we will see...

🌝

[JOC]

3 minutes ago, Fo_Cuss said:

with images now in full colour.

That might be the case during the daytime, but I wouldn't hold out the same hope at night when things tend be B&W 😉

[Fo_Cuss]

I understand.

However, at a fundamental level, the best prospects have been achieved.

I would certainly modify my baffle assembly method, for a second attempt ... but that's normal when prototyping.
The most important aspect is that the scope epitomises 'the black abyss of nothingness'.

Consequently, I am of high hopes that, whatever colours are presented to the lens ... these will have the best chance of being recorded.

Hahaha ... probably too much blue (I'm led to believe).

Anyway, we will all see, soon enough.
For a project of this scale; there is no point in hiding failure, or negative outcomes.

Let's hope that there are none ... though, even 'post snagging' it would not be unusual for that hope to be forlorn 🥴

🌝