John

14 year old thread revival !

The original topic was on refractors I see.

Integrated Flux Nebulae is a new term to me Gerry but its always nice to learn about new stuff

Thanks for the link as well

I think the best advice that I can give is to be adaptable. Roll with the conditions that are presented and select targets accordingly

35 minutes ago, cotterless45 said:

...Rather similar to light buckets letting in lots of light pollution. There was another gem , air turbulence bubbles are said (!) to be 4" diameter . Using a 4" aparture frac will optimise this ! I'll put that idea next to my cloud busting gun....

 

To be fair, I have read this theory of atmospheric cell sizes enabling smaller apertures to make the best of the seeing conditions a few times before. Refractors do seem to "punch above their weight" sometimes.

Filters of this type work on nebulae. For better views of clusters and galaxies dark skies are the answer.

I use good quality O-III and UHC (mostly the former). Best start a new topic in the eyepiece section for more info

Don't worry too much about the optimal magnficiation for disks or Uranus and Neptune - it's the moons that you are trying to pull out of the darkness around them. Using very high magnifications helps pull faint point sources out. I've used these techniques for supernovae and quasar spotting as well.

Here is a link to Cartes du Ciel. It's quite not as pretty as Stellarium or Sky Safari but it is free and seems to be pretty accurate for planetary, comet, asteroid etc positions:

https://www.ap-i.net/skychart/en/start

The wide, ultra and hyper wide field eyepieces enable you to see a good size chunk of sky while delivering an effective exit pupil and enough magnification to darken the background sky if there is some light pollution around.

I think that is what the article is saying though perhaps the way it is expressed could be better ?

10 minutes ago, Barry-W-Fenner said:

On the subject of FOV - I have been viewing open clusters and enjoy using my 48 mag - 25mm BST to view most of the larger clusters. What would be a good low power eye piece in my 200p to view targets such as the double and M45 in full? I would like to achieve what the full object looks like in the finderscope but a bit more detailed.

Thank you

 

Barry

If you can go for a 2 inch eyepiece you will get a larger true field of view. 30mm - 35mm would be an effective focal length. The skys the limit with regard to budget really - the 32mm or 38mm Skywatcher Panaview are around £80, the Aero ED's a little more but a bit better corrected as well. Other 2 inch wide fields such as Explore Scientific etc go upwards in price and quality from there.

Used you might get something for around £50 if you keep your eye out.

Then you have the question of filters, when you come to those - 1.25 inch or 2 inch ??? - it never ends does it !

Excellent report Neil - congratulations on seeing the HH

I've not yet managed it again this winter. 

Your report reminded me of my first sighting of this enigmatic target. I've said this before but do think Jeremy Perez's description is one of the best that I have come across for this one:

".... Really, it's like trying to see a little bit of nothing with a little bit of less than nothing resting over it...."

I agree with you on the 40mm Aero ED - the best of that range and much better than I expected even in my F/5.3 12 inch dob.

Its good enough that I can't see me being tempted by a Panoptic 41 or the newly re-released Pentax XW 40 given the frequency with which I use a 40mm focal length eyepiece with the dob (not all that often).

We seem to have some consistency in the sketches. Mine has the smallest true field because of the longer focal length scope and higher magnification but mark my approx field on Wiu-Wiu's friends image and rotate it and you get a reasonable correlation:

Spotting the moons of Uranus is that much harder than seeing Neptune's moon Triton. They are around 1 magnitude fainter and Triton is pretty dim to start with.

Keep at it though

I have similar pads on my dob bearings but what bears agaist them is a smooth black laminate rather than metal sheet. I don't get the dust issue. The laminate surfaces used on my dob ar similar to those on top of kitchen worksurfaces I think.

Hmmm - clear all day, now clouds

Yes, the 2 inch steel tubed tripod is a lot sturdier and taller as well. The AVX tripod is sturdy but I think the top fitting might be different from the EQ5 / HEQ5 / Skytee II fitting ?

This is my 130 on the Skytee II / Berlebach Uni 28:

Which 130mm refractor ?

I use a 130mm F/9.2 triplet refractor on the Skytee II but the mount is on a Berlebach Uni 28 tripod which adds a lot of height and stability to the mount.

I'm not sure that the 1.75" tripod would a) be tall enough or b) sturdy enough ?

Just now, Adam Barnsley said:

Thank you for your help. As always, your opinions are invaluable. I wonder how John's test came out.

Regards

I didn't use the 7mm XW much last night I'm afraid plus I was using a long refractor rather than my dobsonian.

I'll try again another time.

The TMB/LZOS 130 refractor is amazing in dewey conditions - it simply does not dew up. This seems to be due to the use of Kruppax 50 as a tube material. Last night the outside of the tube, the focuser and finder were running with dew but the objective stayed completely clear for over 4 hours. I have to use a dew shield with my ED120 under those conditions.

Its been very clear for most of the day today despite Clear Outside predicting 95-99% cloud cover all day. Hope it stays clear through the evening into darkness

The way that I observe for moons around Neptune and Uranus is:

- To use high magnifications, eg: 300x or more.

- To examine carefully the area of sky that surrounds the planetary disk, noting any possible point sources of light, their position relative to the planetary disk and an approximation of distance away from the planetary disk in terms of disk diameters (Neptune is approx 2.2-2.4 arc seconds, Uranus 3.4-3.7 arc seconds.

- Triton at Neptune is easier to see than any of the Uranian moons but even then hardly a "piece of cake".

- For faint point sources of light I find that a kind of averted vision helps them to pop out. This technique involves defocussing my eye so I'm sort of staring past the planet. I guess "1000 mile stare" is another description of this !

- Make a sketch of the above "suspects" - rough is fine but orientation is important.

- I then use Cartes de Ciel to check to see if there is a moon at or close to the place where I've seen the faint point source. Cartes du Ciel is easy to flip to replicate the image that the scope sees.

Checking the software source last is important I feel because I don't want to take the risk of seeing something that I expect to be there, if you see what I mean

Hope that helps.

That would be good

The true field shown in my sketch is .22 of a degree and its newt orientated (obviously).

If it stays clear I'll have my 12 inch dob out later tonight and re-check my sketch, again.

This will sound odd but I don't find apps a reliable guide to what can actually be seen in the eyepiece. Those other stars are definitely not visible even with my 12 inch dob and that will go down to mag 14.7 point sources.

A couple of dabs of glue on the edges of lens retaining rings a quite commonly found feature in new optics. I guess the idea is to deter DIY dismantling.  Glue that strays onto the surface of the objective is rare thankfully and definitely a QC issue.

I've found this oberving sketch done by another observer in 2014 using a 10 inch scope at 280x. The observation location was Mobile, Alabama and therefore Sirius higher in the sky than it gets here but, allowing for the slightly larger field of view in this sketch, the field stars look recognisable although I have one in a slightly different position - I'm not a regular sketcher !

Here are the two sketches (mine is the cruder looking one and dated 2019 !):

This Sky & Telescope article was written a couple of years back but is relevant:

https://www.skyandtelescope.com/observing/sirius-b-a-new-pup-in-my-life/

The "Pup", Sirius B is magnitude 8.44. It's the huge brightness difference between it and Sirius A plus the relatively close separation (around 10 arc seconds) and it's low altitude from here in the UK that make it very challenging.

I have seen Sirius B with both my 12 inch dob (reasonably often) and my 130mm triplet refractor (less often) at around 250x - 300x magnification. It was not to be last night with the 130mm refractor though, although I may have had fleeting glimpses of the B star from time to time. Nothing certain enough the claim the split.

I did check the field stars with the 130mm refractor and they matched those that are in my sketch although N & S were reversed in the refractor of course.

If Sirius was higher in the sky, especially on these winter nights with all the central heating around, it would split somewhat easier. If your view of the star is across open fields, moorland etc rather than any housing that would help as well.

As Craig says, you just have to keep trying and one night things will come together.

18 minutes ago, Ice Cat said:

My daughter named a star for her sister for Christmas just because she wanted to give her something a little different, now when I have gone to look for it on a database, its not there. Tbh, I'm not surprised having read this thread, just feel like one daughter has been robbed of money and the other will now try to find a star that the chances are she will probably never actually find because it's so faint.

If you can let us know the ID of the star someone might be able to find it for you ?

There are quite a few star catalogues around which you might not be aware of.