What was I seeing?

[gidion]

Hi,

I was out last night around 9pm (Jan 1st) and was getting some alright views of the moon.

I was using Skywatcher 130 Supertrak with a 2x Barlow and 10mm EP.

As the moon was so bright I went to use my moon filter (this one: Moon & Neutral Density Filters - Variable Polarizing Moon Filter)

How is this filter meant to be attached?

I dropped the Barlow into the scope first, I then screwed the filter onto the end of the 10mm EP before dropping that into the barlow. Is this the correct way? As I assumed the filter would be on the outside of the casings so that it could be altered (darker/brighter) as I am viewing.

After watching the moon for a while I aimed for Mars. (again same setup as above minus the filter).

When I got mars into focus it was not much bigger than what you could see with the naked eye, just looked like a star.

Then came the puzzeling part.

When I changed the focus to either side of optimum the star became a donut....... When I continued to focus in it looked as if the centre of the donut had 4 lines stretching out from it (at 2o'clock, 5 o'clock, 7 o'clock and 11 o'clock). This looked much like the view you get when you look into the scope from the top and see the bottom mirror with the 4 wires holding it in place.

Just curious as to what was going on. Why was mars so small and then acting so strange when i zoomed in?

Thanks in advance,

Luke

[Bizibilder]

You were seeing an out of focus image of the planet, the "lines" being caused by the supports for the secondary mirror.

Mars does look very small but you should be able to see that it has a definate disc, unlike a star that will always appear as a point of light no matter what the magnification used.

[part timer]

Okay, what you are describing inside and outside of focus is the diffraction rings (doughnut). On a refractor you would have a disc of light but your reflector has a central obstruction which causes the central black part. It the design of the scope and has no effect on the views you will get.

The spikes you describe are caused by the four vanes holding the secondary mirror and are also normal.

Mars is a small planet a very long way away so it only shows a small salmon pink coloured disk. At the highest powers of magnification on a good night you can start to see dark and light patches but Mars is never easy. You will get more immediately pleasing views of Jupiter and Saturn when these are well placed.

I should add that if you only saw a star then it was not Mars you were aiming at. It should be a definite disc you see when in focus.

The filter does screw into the eyepiece as you describe but I'm not sure of how that particular type is adjusted

When observing always use the lowest magnification that gives a good view. If you just use a high power then the atmosphere will often be too hazy or turbulent to get a good view.

[gidion]

Thanks for the quick replies.

Glad that the strange donut(ness) is no major problem. The image I was seeing was definitely circular, just with the size of it I wasn't sure how you could make out polar regions etc.

I see people on here talking of viewing the polar regions with 70mm refractors so assumed my 130mm would cope.

Would I see more if I used a yellow/red filter? Waited for the moon to vanish, and waited until midnight+ for it to climb even higher?

[Bizibilder]

Wait for Mars to climb higher - less mucky atmosphere for the light to pass through. Make sure the scope is solidly mounted and use a medium eyepiece, say the 10mm, spend some time looking at Mars - you will see more after a while but don't expect to see the same as an image in a book!!! You may see some dusky smudges on the surface, maybe a lighter polar cap. Go to the higher power (use the Barlow) and you should get a better view of the details.

You have to LEARN to observe - get accustomed to Mars over a few nights and you will start to see more and more details

Hope this helps.

[scotastro]

A variable filter can be separated with one part attached to the bottom of the barlow (assuming it has a threaded end) and the other on the EP. Rotating the EP will alter the brightness.

A 130P has a 650mm focal length which with the 10mm EP and barlow will only give 130x which will make the planet seem small.

To view planets well you need a telescope with a long focal length rather than one with a large aperture.

Mike

[Saturnalia]

Go with part timer's advice and have a gander at Jupiter - low in the South West at the moment...visible tonight until around 8pm.

[gidion]

Thanks for the advice, I will give Jupiter a go.

So with my focal length would that make this scope more suitable for DSO? Or am I in the middle ground where I'm not carrying enough Aperture for DSO?

[John]

Thanks for the advice, I will give Jupiter a go.

So with my focal length would that make this scope more suitable for DSO? Or am I in the middle ground where I'm not carrying enough Aperture for DSO?

A 130mm scope will show you quite a lot of deep sky objects - M42, the Orion Nebula should look nice for example.

Many DSO's are very faint so will appear as nothing more than faint smudges but it's still a thrill to see them with your own eyes.

Keep at it - with the exception of the moon, astronomy is not a hobby of "quick wins" - you need to work at it, observe often and learn to pick out the faint and barely discernable details.

The observing conditions vary widely in the UK - I've seen details on Mars with a 60mm scope on a good night when Mars is close to Earth, other times even a 12" scope will barely show it as a disk.

[pvaz]

Under 200x I find it very hard for surface detail on Mars, even at that mag the planet is tiny and needs good seeing conditions to reveal the darker features. On good seeing nights I can make out the white polar cap at 133x and some hints of the darker features but thats it.

If you are willing to wake up an hour before sunrise, and the seeing is good, you can experience a great sight on Saturn with anything around 100x. Mars should be good too and you can see the (tiny) polar cap. Let your eyes adapt and observe it for 10 min at least to adapt your eyes and see more detail.

PS-> If the stars twinkle too much when you look at the sky then the conditions aren't good. The steadier the stars appear the better.

[brantuk]

Actually you have accidentally hit on a good way of checking your collimation. If you were zooming slowly in and out of focus on a star, and the donut is made up of perfectly concentric circles, then you can be sure your scope has good (or near to perfect) collimation