theastrodragon

So, finally a clear night in Didcot, even if everything frosted over!

M96 in Leo, no colour but it does show some nice detail around the core

250mm R/C @ F5.4, SXVR-814. 105x120s (210m)

I think the more blue looks a lot better. The stars and nebula in M45 are pretty blue/white

I'm thinking on getting the Riccardi 0.75 reducer/flattener (the M63 fit) for my 10" RC.

Problem is, there seem to be two recommended spacings on the sites selling it, one about 74mm, the other about 88mm - quite a big difference!

Also I have been unable to find any data on how precise the separation has to be for the best correction.

Does anyone have any actual experience, or some data that is less variant? I'd be grateful

Still no dark and a moon, so time for narrowband and fake colour.

NGC6960, the western part of the veil nebula complex (aka the Witches broom)

120mm Tak @ F5, SX 814. 75m H-alpha, 75m OIII.

Red channel H-alpha, Green and Blue OIII with a bit of emphasis on the blue.

This is a reasonably large (about 110 arc sec across ) and bright planetary in Aquila.

Mix of narrowband and broadband; 40min each R, G, B, and 60 min each H-alpha and O-III

Tak 120D @ F7.5, from Didcot over two nights

Could do with more photons (can't they all!), but its June and no dark to work with. The image is cropped to keep it at a sensible size

eep! wrong image file! should be the right one this time

I did this originally in RGBHa, but while it gave some good detail, it was too peach.

So thanks to the recent good weather, I got 90minutes of L data, which has made a big difference to the look and colour. Its a really low object from Didcot, but the clear nights made a big difference

45x120s L,  15x120s in R, G, B,  45x120s H-alpha

120mm Takahashi APO @ F7.5

This is a really hard target for me - its very low from Oxfordhire anyway, and trees and houses mean I only get about a 60 - 70min imaging window.  Even so its only 18 degrees above the horizon.

Normally I wouldn't really bother, when we get nice days in the summer the haze typical makes this object un-imageable due to the clag. But the recent fine spell has been different - lovely clear nights, clear down to the horizon. So while its still suffering from the altitude, and lighting made the gradients horrible, I took 4 nights to work on it.

1st night 30m RGB 20m each of RGB

2nd night RGB 20m each again

3rd night 70m L

4th night 70m H-alpha

A lot of fiddling around to process! Even with 4 nights of data, it was a lot more grainy in the outer parts than I was happy with, so in the end I binned it x1.5 in software - while you can still see the graining, its a lot less noticeable.

120mm Tak APO @ F7.5, Starlight Express Trius 814

M17 is a very difficult target for me - not only is it low, trees mean I have to image it when rising.

So this was taken at an altitude of 15 degrees, well into the murk. I also have a very limited window of about 90 minutes in time.

This was taken over two nights; first 30m each in R,G,B, then on the second night 90m in H-alpha. With the limited photons it was a compromise between the detail and colour - its a bit more salmon than I'm happy with, but given the circumstances I'm not too disappointed.

120mm Tak 120D @ F7.5, SX Trius-814

Getting light at night now, but it did seem a pity to waste the clear nights. This is Abell 1656, the Coma Galaxy Cluster, over two nights

Total of 300m luminosity (150x120s), 120mm Tak APO @ F7.5, SX 814, UV/IR filter

I imaged this in January, and while the initial processing was a nice smooth image, it lost some detail.

So I redid it to show more of the detail along the disk. Its more noisy than I'd prefer as a result, but it does show a lot more fine detail, it was a very good night (by the standard of Oxfordshire!)

83x120s L, R/C 250mm @ F5.5, SX-814

I only really started to pay attention when I went to unguided exposures!

For guided work, +/- 5' in el and az is fine, the only error you'll be left with is field rotation, and unless your doing a really long sequence that's rarely an issue.

Unguided work does need a lot more care to be taken with your setup, but there are benefits - for me, the benefits outweigh the care/time needed

I try and get down under 120", preferably closer to 60", but then I'm imaging unguided.

This may be of interest

I try and get the azimuth as close to zero as possible, but as you can see the ideal elevation depends a lot on what you want to minimise. I usually try and make that err on the minus side, usually around -60". But your mileage may vary.

I'm not sure at what point alignment is 'good enough' for your particular mount.

I'd say 6' (0.1 degrees) is a good alignment for normal use, that should give you good enough except for very long exposures..

Closer is better, but at about 2'/120" you get into which particular error are you trying to minimise. The correction is different for minimising different types of drift or field rotation.

Taken after the moon had got low in the west.

250mm R/C, SX-814. 87x120s L

Could probably have used a bit more time, getting the detail in the galaxy made the background a bit grainier than I'd like, but hopefully not too annoying

M65 in Leo, in glorious black and white.

250mm R/C, SX-814, 75x120s L, unguided.

More detail in the arms than I expected with this one

So, nearly 3 am and what to image for the last hour...? M3.

250mm R/C @ F5.4, SX-814. 20x60s in R,G,B. No real need for an L layer, M3 is pretty bright.

Thanks to cloud I only got 70m of luminosity - I was hoping for more like 150m - but the central detail still seems to have come out fairly well

250mm R/C, SX815, 35x120s L

Not a great night, but after this winter any night is usable!

250mm R/C @ F5.4,  SX 814, 80x120s L, unguided.

Hopefully once the current moon is out of the way I can get some colour.

I'm using 85mm on a GSO 10" RC, and its pretty much spot on at 0.67.

Using a SX-814, chip size 12.5x10mm and the corners are OK. I'm not sure how large a chip you can go to before aberrations become an issue

M78 from the last few nights. Lots of light pollution - I only have a hour window when its not so bad, and that means living with it if I want a decent exposure time.

250mm R/C, SX814, 45x120s L, 20x120s RGB, unguided

You've brought out some lovely detail of the dust clouds between the spiral arms there.

I had hoped to get a bit more detail in a messier object with 3 hours of exposure, but M109 is fainter than I thought.

Its also hard to get the detail out in the arms without blowing the core out too much, I need to do more fiddling with this. I'd hope to add colour, but found a major flare issue, I think from trying too early and a neighbour putting a light on. I'll probably try later in the year when its higher earlier.

250mm R/C, SX814, 90x120s Luminance (180m), unguided.

A rather pretty edge on spiral in Coma Berenisis. Frost over everything last night, but at least it was clear!

250mm R/C @ F5.35, SX814. 165m Luminance, unguided.

M74, 150m L, 10" R/C, MX-814 from Oxfordshire

Hopefully the next dark moon will let me add some colour, but it's coming along. Getting rid of the light pollution gradients was a hassle, its low enough for me not to be clear of the worst of it.

M74 isn't terribly bright, but it does show some nice structure