catburglar

It’s looking clear here for the early part of the night so I may get a chance to have another go at something between darkness and the anticipated arrival of clouds about midnight.🤞

Depends somewhat on the camera that you’re planning to use- but assuming the optics on the SCT are decent I think that’s likely to be better suited to planetary imaging- larger aperture than the mak and longer focal length than the newt, and easier to use with the adc…

I too couldn't let a clear night pass without snapping a shot of the M87 jet...When I first saw posts (probably 12 months ago) showing this I was amazed at how easy it was to capture...It was plainly visible in a single 10 second exposure. Apparently there's also a jet in the opposite direction, but this is more difficult to capture. I let my capture run for 5 minutes in the vain hope of being able to get a glimpse of it, but I guess it's not going to happen. Maybe next time 😉 .

Managed another session last night, first in a few weeks. I managed to get a couple of Arps in Leo (just after they transited the meridian which is a better part of my sky due to relatively lower levels of light pollution- but boy to I wish it was darker than it is... First up is Arp 263- at first glance this looks like a case of David vs Goliath- the small ring galaxy left of and just below centre appears to be shredding the prominent galaxy wrapped around the bright star. However, the narrative in the Cambridge Photographic Atlas of Galaxies suggests that none of the galaxies in the field are responsible for this disruption and suggests that the disrupting galaxy has been entirely "consumed". The images shows a number of bright spots representing regions of active star formation. Next up was Arp 316 (aka Gamma Leonis Group or Hickson 44)- or at least I managed to get 3 out of 4 members. The integral sign galaxy (NGC3187) clearly looks to be perturbed by the nearly edge on galaxy (NGC3190) close to centre (both are at circa 79Mly). The elliptical galaxy towards the edge of the field (NGC3193) seems to have distance estimates ranging between 65 Mly and 100+ Mly. This image (http://338arps.com/arp_316.htm) suggests that there is a bridge of material between 3190 and 3193, but it's not visible in my image or in the original Arp catalogue image (to my eyes at least).

I’m not sure that belongs in a “Long refractor” thread- it’s only F/9 after all…that should be in a “Big refractor “ thread- it certainly is a beast

True- I assumed the OP was referring to the package that’s offered at FLO with camera, uv/ir cut and CH4 filters…but you are correct it’s not clear

If the charts of FLO’s site are to be believed, the ZWO UV/IR cut filter has a band pass between 400-700nm (chart 1) and the CH4 band pass is 20nm centred around 890nm (chart 2) so if you use them together you’ll draw a blank because the band pass of the first filter will be blocked by the second filter…so I’d try them separately. Just adding to Vlaiv’s point- in general you could use the UV/IR cut with other filters e.g R G or B or OIII or Ha because the passbands for those fall within the passband of the UV/IR cut, but you may not need to because these filters will also often (but not always) cut the UV and IR regions. However, if you do stack filters, the focus will probably be shifted compared to using single filters- so in general I’d suggest using them singly.

The Baader 32mm and 18mm are my most used eyepieces for solar (also with a Daystar SS60). The 32mm is sharp contrasty an- with the eye guard extender- correct eye placement is easier than any other long FL plossl I’ve used. The 18mm still allows a full disk view, but the higher mag helps with seeing some of the smaller features. I only rarely use the 10mm BCO for solar- I find it seems to have a profound vignette that’s much less problematic for night time observing- it’s probably my most used eyepiece in my 10inch SCT…but that’s for a different thread.

I’d agree with Elp- that setup doesn’t need to be too much longer with a cooled camera.I only dabbled with a star tracker based imaging rig and found that polar alignment, finding/framing the target and getting sharp focus took longer than any other part of the setup. I suspect efficient use of your limited time is mostly down to practicing the setup process and becoming familiar with whatever software packages that you’d use. You can configure all of the acquisition parameters before hand and save as a sequence in APT or Ekos. And similarly guiding with phd (which would help extend your longest exposure time) only takes a few mins to get going with and you’ll be likely to loose fewer subs due of tracking errors so you might find you get more usable data from a cooled camera setup. From a weight perspective some of the newer LiFePO4 based power packs are not too heavy and should run the cooling and and camera for a good session. And if you’re worried about dew on your Surface, use a raspberry pi or compute stick and just VNC/rdp onto it to set the imaging run going and then put it away until you’re all done.

I suspect a modern cooled CMOS camera would produce better images than a modded DSLR even if your exposure times are limited to 30-60secs. The dedicated astro camera will probably have higher quantum efficiency and lower noise and therefore images will have better SNR than from the DSLR. But that doesn’t mean it’s a good thing for you because of your other requirements for light weight/quick set up. If you don’t want the ‘clonk’ of a laptop and additional power supplies I think sticking with the DSLR may be the better option-you could get it “Baader modified” rather than a conventional astromod because the Baader filter maintains daytime white balance but still gets you the improved h-alpha response for nighttime astro. But…a middle ground might be something like the Altair hyper cam 183c Pro…It’s fan cooled (but not TEC) so may have a bit less noise than your DSLR, it benefits from the higher QE that modern Astro cameras have but it would need some sort of device to control the acquisition. That could be raspberry pi or intel compute stick based device that can run off a small external battery for a few hours and would only add a couple of pounds to the overall weight of the package.

I’m not an expert imager, but I think I’d put the 1600 on the reflector… this way you maximise both the resolution of your luminance dataset and the ‘speed’ that you collect the signal. You can capture the colour data at lower resolution and tolerate a lower SNR in your colour data and this will (I think) have less impact on your final image… Although you will lose a bit of FoV (approx 1.8x1.2 degrees with this approach versus 2.0x1.8 if you put the ASI on the frac).

I think you’ve got a few different (almost ‘off the shelf’) options to get 1200mm FL: 8inch F10 SCT with 0.63 reducer 8inch F8 RC with 0.75 reducer 10inch F5 newt plus coma corrector 12inch F4 imaging newt plus coma corrector The latter will be the fastest of the bunch at any given image scale, but it might also take the most fettling to get it working well. If you’re happy collimating it the RC might be the easiest to live with.

I haven’t upgraded python in a while (my version is 3.9.9) running on Windows10. If I was setting up now I’d download the 64 bit installer…

I don’t have direct experience of this…my guess is that it can probably be made to work, but there are probably better options too. The specific issues with the scope arise because of the moving mirror focus mechanism- this can cause image shift when you change focus direction which makes focussing tricky, and also leaves you prone to mirror flop- where the mirror moves as the scope points to different areas of the sky (the nexstar OTA doesn’t have a mirror lock). An external focuser would help with the former and using an off axis guider rather than a separate guide scope might mitigate the latter. On the mount perspective- I guess it mostly comes down to guiding accuracy…if you’re imaging small dso’s e.g. if you want to get nice detail in smaller galaxies- I’m guessing you want to be imaging at about 1-1.2 arcsec per pixel. If you’ve got good enough seeing for that then you need your mounts total RMS guiding accuracy to be about 0.5-0.6 arcsec per pixel. If you’re getting figures around this with your current setup then the only way to know for sure is to give it a try…

This has been a useful illustration for me. Whilst I generally take the approach of adjusting the sliders until I’ve got something that looks half decent, I think I have a tendency to keep the stretch near to it’s maximum and the adjust the white point to make the image bright enough and then to reduce the background using the bg and nr sliders. Tony’s example with the asinh stretch shows a different approach- reducing the degree of stretch and leaving in a bit more bg. I’m guessing this is effective because the asinh stretch is more aggressive across the brightness range than say the gamma function, so any small tweak on the bg slider has a more significant effect on the resultant image. Reducing the degree of stretch mitigates this and provides a bit more latitude in which to work. I also note I’d left the config parameters at the default settings which I think were smaller than those Tony used. I’m guessing this has the effect sharpening ‘noise’ and reducing the impact of the noise reduction algorithm because the I was averaging over a smaller region…

The OP stated that they were expecting to use some sort of focal reduction and therefore this will most likely exacerbate the poor focus of IR wavelengths to which the lodestar is quite sensitive. Whilst we don’t see UV/IR cut filters listed in the equipment for images captured with SCT’s they do in fact include a UV/IR cut filter in the majority of cases -it’s called the Luminance filter in an L-RGB sequence. I don’t have the specifications for all manufacturers but many have cutoffs at around 400nm & 700nm- in the UV and IR ranges.

Couldn't agree more- there's always pip if I need to downgrade 😉 On a slightly more relevant note...I had a session with the dev version last night and had no issues. Here's a pre and post image showing the impact of the sharpening and noise reduction tools. I've posted a couple more from the same session in this thread. You need to be a bit careful sharpening data with lower SNR, and if you push it too far you'll see some ring artefacts and "blotchiness" in the sky background, but that's the same with any of these tools. Overall I think they're a really nice addition to the toolset, and on my low pixel count images it doesn't slow down the processing so I can still do it live- running the application on a cheap compute stick with a Celeron J4125 processor.

My observing site is "obstructed" to the North East by my house and to the South East by a dome of light pollution from a nearby industrial complex. As a result, I'm often observing things through the LP or when they're past transit and on their way down into the murk of the horizon. At about 10:30 last night a realised that Canes Venatici had cleared my roofline and wasn't yet in the light polluted skies of my south east perspective. I hadn't planned anything, so I went for a couple of showpiece Messiers- I've observed them visually before but these are my first EEVA observations of them. These are not really in the spirit of my previous EEVA observations, where I'm usually looking at stuff that's off the beaten track. But I have to say I am wowed by what these capture. In my skies I struggle to see spiral detail in these galaxies on all but the best of nights, and although it's not really visible in the cropped view of M94 because I've clipped the background a little, I actually captured the faint outer halo, which I've never seen in my 10 inch before. For info- I've taken advantage of the new sharpening and noise reduction tools- they work a treat, although if pushed too far they can generate ring artefacts around bright stars and take away a little too much of the faint background...but that's the same with all post processing- less is usually more. So a big thanks to @Martin Meredith for developing jocular- it's the interactivity and lossless nature of the application (I can always go back and reprocess a stack in near real time)- that got me interested in EEVA, and to the contributors to this EEVA observing thread, it generates lots of new and interesting objects to to add to my observing list on the next clear night- even from my suboptimal location.

Pat It looks like you had a good session. I think the issues with your start shapes are probably a combination of coma (exacerbated by too much distance between the reducer and the ccd chip) and tilt. I'm not sure if your using an 8 inch LX90, but this is the sort of field of view you should get if your using a 0.5x reducer at the correct spacing. Looking at your image of M51 compared to the one below, it looks to me that you're probably operating at a reduction of about 0.3- and that makes the coma and the vignetting around the edge of the image much worse. So if you can, I'd try to get the reducer a bit closer to the CCD - you'll probably still get some coma in the corner of the image, but if you can get the reduction factor to 0.5 or 0.6 I suspect you'll get better looking stars., and your images will be more evenly illuminated which makes manipulating the histogram a bit easier. The tilt is may be a bit more difficult to correct- are you using an eyepice clamp with just a single set screw...They can often introduce tilt. If you can get a compression fitting that has two or three screws and then tighten them up equally to hold the camera and that might help get your CCD plane parallel to the image plane. I'm afraid I've never used SLL, so I can't help much with that one- sorry.

I had a go at a couple of planetary nebulae last night...before the moon rose too high in the sky. I took a shot at Abell 21. I was surprised to get so much detail in this one given it's relatively large size and correspondingly low surface brightness. There are even fainter filaments in the area to the top right of this shot, but I couldn't capture them last night. I'd also like to try and get a bit of colour in this as well because the image by @Bill S shows both the red colour of the nebula and a couple of nice golden orange field stars which makes an attractive contrast. As Bill notes- this was thought to be a supernova remnant until recently (I tend to use the term recently for any new knowledge that's accrued in my lifetime, but I should probably rethink that definition since I'm mid-way through my 6th decade 😉 ) My second PN of the evening was M97 (NGC3587)- many of us will have observed this visually- surely there's nothing much new here? A bit of googling shows that all is not what it seems with the Owl- now the prototype for a new class of strigiform (owl like) planetary nebulae characterised by multipolar cavities in highly evolved planetary nebulae (https://academic.oup.com/mnras/article/479/3/3909/5037934?login=false ). I suspect many of us assumed that the owl eyes where the result of bipolar dynamics presented at a slightly oblique angle as seen in many "dumbell" style planetary nebula. But apparently that's not the case in M97. The dynamic modelling suggests a multipolar structure is required to create this visual appearance that includes both the "eyes" and some more complex structures at the periphery of the inner shell. The good news- there are other PN's that share similar features- Abell 33 and Abell 50 (although this might be a bit tricky due see any details because of it's small apparent diameter) and for the more southerly observers PN K 1-22 (ESO 378-1). Give them a shot on your next clear night- I'm sure it'll be a hoot.

I had another go at Arp 285 tonight to see if I could get any hint of the jet or tidal tail- but still no joy for me. It was a little less breezy than previous attempts, so I could get 20second exposures before field rotation became an issue. The moon, although nearly full, was still low and Arp 285 almost at the zenith for me, so not quite ideal, but pretty close. But...I still didn't get it...so maybe wait another week or so 'til the moon is well away.

I suspect the best advice might be to point as far away from the moon as possible. Because you’ve got some refractive elements with your set up (corrector plate and reducer) I think you’ll need the IR cut to get sharp focus ( a reflector can focus IR and visual wavelengths at the same point so can sometimes get away without one). I’d definitely leave the H-alpha out of the equation… Since galaxies emit across the range of visible wavelengths filters tend to be less effective- or at least that’s the conventional wisdom, but I’d be interested to see if the UHC does help at all.

I use a Telegizmos 365 cover with my SCT- it’s been outside for 12 months with no issues as yet… If there’s been a lot of dew on the OTA during an observing session I’ll try to lift the cover next day to make sure the scope dries…but otherwise it’s been trouble free- even through the recent storms…

When I first looked at these two galaxies in my capture I didn’t notice any sign of interaction- although they’re at the same distance and sure a common recession velocity, so I’d been hopeful of spotting something. I’m away for a few days so won’t get another chance to look at this for a while. Mike -your image seems to correspond with the bright patches shown in the 4.5micron band…And (this may be the eye of faith) Tony’s image seems to show the triangular knot that is the second of 4 regions within the jet. So there’s definitely a lot more than a first glance might suggest.

Mike Your image is a bit less noisy and the bridge is more clearly seen- I guess in part this is the benefit of greater aperture and large pixels leading to a "faster" system. How is your 15 inch mounted - is it an alt-az goto like Skywatcher or an equatorial platform? I seem to recall that the SW flextube tracking doesn't cut it for even 10 second exposures but if it could be fettled, then I might see a big dob in my future...although I do like the images that @AKBgets with his hyperstar and ultrastar camera... so that's also a consideration.