groberts

Thanks for the comments so far. Steve - the background measure for an L sub is 65 but given the right skew of data originally posted above this is to be expected, though it is obviouslly not correct; R = 16 and Ha = 0.014. After applying a basic Histogram Transformation to the L sub the value is 16, with normal data distribution now shifted towards the y-axis. There has been some increased light pollution this year from new neighbours but I now use a screen to shield the scope + when they've gone to bed and the lights are out it's fully dark but the problem still persists i.e. has to be a settings problem? Graham

No same as usual + including the gain and offset which is shown in the attached FITS header. Graham

I've been using a ZWO ASI1600MM-Cool camera + ZWO filters with Astro Photography Tool (APT) successfully for some years but recently, usually when capturing Luminance, the resulting sub seems to be blown out as if overexposed.; APT shows each sub as very bright if not completely blown out. I've played with the histogram settings without success and when I look at the subs in more detail in PixInsight it's clear that the basic raw sub data is heavily shifted to the right. Manual stretching after stacking sorts out the problem, by moving the black and mid-tones to the right to obtain a 'normal' stretch but I'm wondering if there's something I've got wrong in the capture set-up? I should point out this does not usually happen with other filters, especially narrowband. Attached is a basic 180 sec L sub straight out of the camera showing the skew to the right - even before manually correcting this once stacked the subs look a bit better in PixInsight. Graham

Two months past the summer solstice in late August, I was drawn to the constellation of Vulpecula (Latin for “little fox) and an interesting area of reflection and dark nebulae that provide good imaging possibilities, in particular LDN 768 / VdB 126 etc. At the centre, strung out from east to west (left to right), several dark nebulae seem to coalesce (visually) to create the form of a black cat or an alternative interpretation is that of the Loch Ness Montser. Moreover, above the cat’s head area of dark nebula forms what I’d describe as a furled umbrella (LDN 781, 782, 783 & 779), whilst towards the lower right edge of the image (below the cat’s rear leg) is the open star cluster of NGC 6793. Apart from its obvious beauty, the inspiration for this image was my four-year old granddaughter who just loves cats – especially her own one-eyed black cat! Graham Image Information: 21st 22nd & 23rd August @ Redhill, Surrey WO GT81 + ZWO ASI294MM Total Integration = 5hr 44m L 52 x 120 sec R 29 x 180 sec G 25 x 180 sec B 26 x 180 sec

It also explains why 80% of my imaging subs were messed up last night🤬

Doh!!! Sorry - in mitigation I was rushing to get to my grandaughter's birthday party - of course it should be in the Imaging / Deep Sky section. I can't see how to do this so have reported it to the moderators who hopefully can help.

Thanks Carole, much appreciated.

There’s much to see in this busy image which marks my return to astrophotgraphy after a summer break. Cygnus has such a great targets to image - I struggled with this (it's a long story) but happy with the outcome and looking forwards to darker + clear nights hereon 🫰 Graham X 7 nights from 6th to 22nd August, Redhill, Surrey William Optics GT81 + ASI294MM Pro Total Intergation 10 hr 50m Ha 45 x 300s OIII 42 x 300s SII 43 x 300s

Thanks Alan, I'll give it a try. Graham

If it even exists, can anyone point me towards a Wolf-Rayet catalogue that can be downloaded and used with Cartes Du Ciel? Graham

Fabulous image Rodd, thanks for sharing. Graham

I have a problem with some DSO nicknames, the problem is that they often absolutely do look like the object they’re meant to depict but, like an earworm is to music, once seen they are difficult to view any other way. So back in late February / early March I set out to produce an image of NGC 2174 (the Monkey Head Nebula) that was less 'monkey-like'! I'm rather pleased with the outcome, that has been processed in a dynamic SHO palette and, to my eye, is a lot less monkey and more emission nebula. Graham Imaging Details: William Optics GT81 + ZWO ASI294MM Pro camera + Chroma RGB and 3nm narrowband filters. Taken over 3-nights between 26th February & 2nd March SHO dynamic palette processed in PixInsight Ha 36x 300s OIII 30 x 300s SII 32 x 300s Total integration = 8hr 10min

Thanks Ian. The unusual blue / purple aurora was near Jökulsárlόn, at a place called Gerdi and was quite faint to the naked eye. The more typical green curtain aurora was further west, just south of Kirkjubaejarkklaustur and was much clearer to the eye, though as you may appreciate their majesty only really becomes apparent with a camera. Graham

A few images from southern Iceland, taken on 23rd & 24th March at different locations. The variety in colour and form was amazing and a lot of fun to see. Graham Camera: Canon 700D Lens: Sigma FL 10mm at f3.5 ISO 3200 Exposure: 10sec

An HII star forming region of dust and gases, sculpted by the radiation and interstellar winds emanating from the young (3 – 4 million years) open star cluster Dolidze 25 located near its centre. Along the inner edge of the main ring structure are numerous dark dust pillars and Bok Globules, not unlike those of the Elephant’s Trunk nebula. Despite its resemblance to the Elephant’s Trunk and the nearby Rosette nebula, it’s apparent size is smaller and much fainter in nature but still forms an excellent late winter image target which I really enjoyed imaging and processing. Graham Imaging Details: William Optics GT81 + ZWO ASI294MM Pro camera + Chroma RGB and 3nm narrowband filters. Taken over 5-nights between 6th and 13th February SHO Hubble palette processed in PixInsight Ha 53 x 300s OIII 36 x 300s SII 36 x 300s RGB 104 x 60s Total integration = 13hr 14min

There’s a lot going on in and around the Auriga constellation and this winter I’ve been mainly imaging in this region, almost exclusively using the Samyang 135 widefield rig. Here with the whopping 7.50o x 5.67o FOV this set-up provides, it easily incorporates both emission nebulae IC405, AKA the Flaming Star Nebula and it’s nearby (visually) neighbour IC410, the Tadpoles Nebula, as well as much more. Here is a dynamic PI processed SHO image + a cropped Ha starless close-up of the IC410 which shows the Tadpoles in good detail. Graham Imaging Details: Samyang 135 @ f2.8 + ASI 1600MM-Cool camera & ZWO 7nm HOS filters Ha 24 x 300s OIII 24 x 300s SII 18 x 300s Total Integration: 5hr 30min wo SHO versions of the Hubble Palette: (i) a basic mix and (ii) using a dynamic mix (the main image). Once more I have been impressed by the ability of this small camera lens to produce exceptional details and colour, but especially here with the Ha version of IC410, where the signature features of the so-called tadpoles have been captured to great effect.

Thanks Jody, much appreciated. I struggled with this for some time but eventually found a route to unlocking the OIII + achieving detail and good Ha colour in the rest + the Samyang 135 really does a great job with this type of object. Graham

I’ve long admired the spectacular SNR Simeis-147 AKA Spaghetti Nebula, which I first imaged with my standard William Optics GT81 scope in January 2022. The outcome was pleasing but with the limited FOV it had to be just a nibble of this very faint and large cosmic delight – something of an appetiser you might say. Therefore, ever since putting my Samyang rig together last summer I’ve had only one object in mind with this widefield set-up, which this time had to be the full menu version of Simeis-147! Apart from its size, Simeis-147 is very faint, making long exposure time essential, which is always difficult in the UK. Notwithstanding, an unusual spell of cold, clear nights this January provided sufficient opportunity over five nights to obtain just over 20-hours and a full image of this truly magnificent SNR. Graham Samyang 135 f2.8 + ZWO ASI1600MM-Cool Ha 60 x 5 min OIII 62 x 5 min Total iintegration 20 h 20 m

I have long admired other images of this exciting object but ruled it out as unsuitable for my equipment, then eventually found its allure too compelling and just had to give it a try at the end of last year. Whilst the reflection nebula NGC1333 is clearly the main feature, numerous exciting objects abound throughout this complex region, including many other reflection nebulae and Herbig-Haro stars. However, I’m most pleased that for the first time I’ve been able to capture the extensive interstellar dust / gas that is part of the larger Perseus Molecular Could, which I think really brings the entire image to life. Graham 25th Nov + 15th Dec + 16th Dec WO GT81 + focal reducer & ZWO ASI294MM Pro L x50 R x41 G x43 B x43 x180sec Total integration 8h 51m

Thanks for the feedback, much appreciated; my wife also said no.1 but I thought I'd ask the experts! Not sure about globular clusters but I do really enjoy the FOV from this lens. Graham

Andromeda fits perfectly in the FOV of my William Optics GT81, producing something of an 'up-close-and-personal' image of our close neighbour. This year, armed instead with my Samyang 135 + ASI1600MM-Cool set-up, in-between the clouds over the second-half of November I mangaged to capture 6.5 hours of M31 and really like the wider perspective of the alternative widefield format, which in some ways seems to provide a more powerful image? Before putting this to bed would appreciate any thoughts on which of the images is preferred - the first is standard processing and the second with the stars reduced? Thanks. Graham

Thanks Carole

As the Cygnus season draws to a close – in my case disappearing northwards behind my house – I was ready to snap one final Cygnus object using my William Optics GT81 but then looked closer and realised that with careful framing using my Samyang 135 rig there was another more ambitious possibility. The original object in question was SH2-119 AKA the Clamshell emission nebula. But by using the much wider field-of-view of the Samyang 135 it was possible to include the North America and Pelican nebulae as well, just! With some difficulty (weather) I finally managed to obtain 13-hours integration time over 6-nights, which has resulted in a pleasing SHO image. Graham Samyang 135 @ f2.8 + ASI1600MM-Cool Ha 61 x 300 sec OIII 54 x 300 sec SII 41 x 300 sec Total Integration: 13h 0m

Thanks, much appreciated. 😀 Graham

It had been a little while since imaging this object and it seemed a good time to return in late August armed with a new ASI29MM camera. It's not officially "First Light" which was back in late March but having then taken a break over the summer, it's the first time I been able to properly use the camera on a decent object and it does not disappoint, hope you enjoy it as much as I do? Graham WO GT81 + ASI294MM Ha 41 x 300sec OIII 82 x 300sec Total intergration: 10 hr 15min