Tim

That's a passing plane, with its lights flashing right at the moment of capture

My rule of thumb is....If I am not the scariest thing out there, then I am not out there.....

11 hours ago, FLO said:

THANK YOU to everyone sharing images made using their StellaMira 90mm.

They are much appreciated 🤗

Steve

This was just a test image, 3h 40m with the StellaMira 90mm from light polluted Coventry. Lovely scope!

8 hours ago, ScouseSpaceCadet said:

Astronomy Now magazine is indeed very good, however my Sky at Night magazine subscription is a ridiculously cheap £16.50 p.a. and I'm a bit thick, so don't mind the 'dumbing down'.

 

Yes, very good value, especially considering the calibre of the contributors ( I'm not talking about me  )  and there are usually some good value packages available throughout the year, 3 issues for a fiver etc.  

Now that they have demonstrated that physically reading a book or magazine is better for the brain than passively watching things, a subscription to a magazine can make for a thoughtful gift.

On 23/08/2022 at 20:55, gorann said:

I fully agree. Sky at Night is also only giving out four or five stars to everything they "test",  so it is the net, including SGL and CN, that you need to turn to for objective evaluations.

Items reviewed by S@N magazine are loaned to the reviewers for a short term by the suppliers that advertise within the magazine. They are "First Light" reviews, an not intended as an in depth critique such as a purchaser of the item might be able to provide after an extended period of use.

In the same way that you are unlikely to send out just any selection of your photos for scrutiny willy-nilly, the suppliers are hardly likely to loan out equipment they think will get a roasting in the magazines. So the very fact that a supplier submits a certain telescope, mount, or other equipment for magazine review in the first place should give you confidence that the supplier is sufficiently impressed by that product to lay it out for review, and so you might rightly expect only 4 or 5 stars items to make it into the magazine.  That said, if there is an issue with the item, we will, and do point it out, and often our observations lead to subsequent editions of the item being improved.

For the sake of consistency and clarity the stars awarded by S@N reviewers are governed by a set of guidelines, and should only be taken as a basic indicator of how the item performed on its first light. In addition, the articles are limited to a set number of words for printing purposes, so we have to be quite specific and sparing with the text, but everything you need to know, from a first light test POV, will be there.

Hope that helps

19 minutes ago, vlaiv said:

Meteors usually look like that when their trajectory is viewed at shallow angle (almost parallel to trajectory).

You have faint part, then strong part as meteor hits thicker layers of atmosphere and then "fireball" - when it burns up in atmosphere.

Trajectory has that distinct shape of projectile in gravity field - parabola.

It just looks very curved because it is viewed at very shallow angle - it has much more delicate curve.

Ah yes, hadn't considered that, but makes perfect sense. Many thanks

Tim

While reviewing a few images from the other night I noticed an odd trail on a single star. Then saw that there is no star there, and then, after heavily stretching the life out of it, noticed that the tail of this thing has a curve in it.

It's a 10 minute exposure, and there is no trace on the frame before this one. It was the last frame too, so I don't know if it would have been on the next.  The apparent curve is throwing me, and the fact that it doesn't have the drag of the stars, which maybe indicates a short lasting but bright event?

Image taken on 8th May at 23:14.

I'd be grateful of any suggestions

It might not help you with the rig outside, but in my obsy i find that a fan blowing cool air over my mount and gear keeps the condensation off.

Tim

On 12/02/2022 at 09:57, cajen2 said:

And don't even get me started on marine reefkeeping, where even a modest 90cm tank plus equipment runs into several thousand....each fish or coral that you buy is £50-£100+ ..... and the electricity / maintenance costs a fortune too.

One of the things that convinced me to sell my reef tank was the loss of a Flame Angel who somehow got sucked into the intake for the trickle filter. Back in 1992 he was £55, dread to think what they cost now!

It isn't just that laser collimators may not point to dead centre, even if they are perfectly super collimated themselves, the focuser has to be perfectly aligned and centred and able to hold the collimator centred, and the secondary must be absolutely square to the optical axis, and in practice is is quite easy with a laser to get an apparently perfect result when in actual fact there is considerable misalignment or twist happening. A star test afterwards will demonstrate this, but doesn't really help solve the issue.

That doesn't happen with a chesire so easily, and even if the focuser, secondary and primary are all a little offset within the tube itself, you can still get perfect collimation.

For a much more detailed discussion of the above, check out New Perspectives on Newtonian Collimation by Vic Menard, it includes ray diagams to illustrate what can happen. It also recommends chesire eyepieces, specifically the Cats Eye system.

With practice just looking at a slightly defocused star will tell you if something is amiss, and good collimation makes the biggest difference when observing planets.

HTH

Tim

I'm very sorry to learn of your loss Peter and offer my sincere condolences to you and your family.

The image is beautiful.

Tim

OAG for sure, but then I use them for everything, who needs two scopes to muck about with

Tim

Also, you need to eliminate the coma corrector while you test if possible.

When you get an image with an extra spike, try moving the star around to the 4 corners of the image as well as the centre and see if the extra spike remains all over the field.

One more thing, it has been many years since I've used a Baader Steel track,  I don't suppose there is a bright or shiny edge or surface internally on it anywhere? I have very vague memories of blacking down the end of a focuser drawtube in the past, but can't remember which focuser it was now. 

Tim

Any sign of astigmatism when the scope is cooling by any chance? I'm assuming the mirror is properly cooled when it happens??

You can check this by rolling the focuser either side of focus, back and forth. Possible to see it with a camera but more visible with a high power simple eyepiece, or with a Ronchi eyepiece. Look for the out of focus star pattern flipping 90° as you move through focus.

Tim

The odd thing for my setup, was no moving parts. If it was warmer I would have assumed an insect was on the objective and moving around, but it was quite cold and I scanned the tube inside and out with a bright light to see if there was anything like that, a spider or something, but no, completely clean.

I'm still stumped by what did it

I've just seen something really odd while setting up an imaging run, an apparently moving large dust mote.

Before I explain more, has anybody else ever seen or had a dust move moving around on their screen?  

I've got pics, but this is one of the more bizarre things I have ever seen while doing this, and I cant come to a reasonable or even feasible explanation. Help!

Cheers

Tim

3 hours ago, wongataa said:

Dark frames need to be done at the same time as light frames so everything is at the same temperature as when you took the light frames.  Flat frames can be taken at any time provided the orientation of the camera in regards to the telescope is the same as when you took the light frames (theoretically it shouldn't matter but it could do in the real world) so it makes sense to also take them at the same time before packing up.

I hate to disagree a bit, but am going to 

Dark frames need to be at the same temperature and duration of the lights. Using cameras with set cooling you can do them at any time, and even have a library of them ready to go as suggested above.

It is my experience however that flat frames are best taken on the same night as the lights, at the end of the session. because they not only remove vignetting, but also dust bunny artifacts, and these might move, present differently if focus point changes due to varying ambient temperatures (affects the scope not the camera) and sometimes the dust motes actually turn out to be ice crystals on some cameras, and they won't be the same on a different evening. All things considered, the flat frames are going to be most likely to coincide with the issues for any particular light frame if you can take them with conditions as absolutely similar as possible. So as Wongataa suggests, take them as your session finishes.

20 to 30 flat frames should do, with 50 to 100 bias frames to calibrate them.

Have fun

Tim

Very nice Martin, has a soft, otherworldy feel to it

Sounds like you would enjoy a star party and the chance to see gear working.

There are so many different approaches to the same goal that I see amongst various imaging folks, you'll have to figure out where you want to be on the scale, from quick setup, smash and grab imaging to full on control every factor and analyse every last detail. There is no end to the amount of technical interference you can involve in astrophotography these days, and only you will know where you will feel comfortable with your results. 

For my part I like to take the shortest, easiest route to my destination, and would say that having a permanently set up, accurately polar aligned, good quality mount will drastically reduce the amount of time required to set up other things, thereby increasing your dark sky time.

Have fun learning, there's no rush

Tim

It didn't really clear last night, but there were odd patches. 

Did anybody notice the pillar of light coming from the direction of Holt? 

Arrived today, site quite busy, wind cold and it's raining.

Glad we're in a caravan!

On 27/10/2021 at 22:19, saac said:

 Second best quote " we will never know the name of the last star,   but we know that it will be a red dwarf".

In that case we might as well name it now,  but difficult to choose between Rimmer and Kryton........  

Not a bad attempt really, the stars are a little soft but that won't be helped by the slight off focus issue. When I look at the image you posted I wouldn't say that the large spikes are perfectly spaced, and as mentioned above, it is easier to see that at the base of the spikes.

I never normally like the starless images, but the galaxy really stands out in yours and it does it justice.

If it is any consolation, M31 is one of the trickier targets to get "right," the huge dynamic range between the core and the outer edges make it tricky, but you've got a nice balance here already. More data will give you better contrast in the dust lanes, more definition in the highlights like NGC206, and better colour depth and smoothness, especially in the few areas that show a bit of hydrogen emission nebulae.

Good stuff, keep 'em coming

Tim

See you all there then.  We've been a few times to Winterfest. You'll know its me by the big wide German caravan with the door on the wrong side, the pair of large dogs, and the grumbling about anyone whose lights are too bright

If the forecast is good I'll have my 18" Dob, happy to share views.

Never mind the Holkham laser show,  the Xmas train ride through the campsite will be lit up like a.......well, like a Xmas tree !

Actually, my Deep Sky atlas gives a filter recommendation for every nebula in the comprehensive maps, I just rarely think to look there before resorting to the usuals. In fact, i'm wondering if it was the atlas that put me on to the H beta for the NAN, it might have been.  It is also useful on the cocoon nebula, although not so much if you want to follow the dark cigar nebula away from it.