Martin Meredith

I like the look of these and will certainly give them a go. I'm guessing you weren't using an Halpha filter? Abell 24 looks too diffuse for me to pick up much based on previous attempts -- will be a good test for the new cam though. Martin

I use a Bresser portable power supply (100W) for powering my AZ-EQ6 mount. It isn't cheap, but it is really light compared to my old car starter battery. The AC output is also useful for charging the laptop on journeys too. https://www.bresser.de/en/Astronomy/Accessories/Power-Supply/BRESSER-Portable-Power-Supply-100-Watt.html Martin

I expressed myself badly: I don't mean this is 'as good as' an eyepiece view (clearly it isn't!) -- I mean that on an equivalent poor night of seeing this feels equivalently 'live'

As my first foray into CMOS (inveterate late adopter here), this is a live animated gif of the Trapezium stars from last night in pretty unsteady seeing. This is a sequence of 30 frames of 50 ms exposure, gamma-stretched, with no alignment. The 'E' star and perhaps 'F' (see https://www.maas.museum/observations/2010/02/23/harry-zooms-in-on-the-trapezium-the-heart-of-the-great-nebula-in-orion/ for details) might just be popping in and out occasionally. It will be interesting to repeat this on nights with less atmospheric disturbance. Ths is perhaps the closest I've got to an eyepiece view using EEVA techniques. ASI 290MM, gain 110, bin 2 Martin

I have to agree that most of the time galaxy fields look best and are as informative as they're going to be in monochrome. Quasars too! In addition to bright and reflection nebulae (admittedly not my normal viewing), I'd argue that any fields involving stars (OCs, globs, multiple stars, carbon stars) also benefit from colour, not just aesthetically but in inspiring a closer look at the underlying astrophysics. Some months ago I came across a planetary nebula with an exceedingly blue central star that motivated me to see what was known about it (turned out to be extremely hot). Martin

Agreed, brilliant results for a first (or even nth) attempt. Martin

Thanks for reminding me about this. Surely one of the most interesting fields for small sensors? Here's my slightly wider view from 2020 which also incorporates a near integral-sign galaxy (top right). This is PGC 16507, type SBc(bar). Actually, there are quite a few fainter galaxies in the image, mainly edge-on. A highly-stretched close up of NGC 1723 (at the base in the above shot but oriented correctly below) suggests very unusual outer arms that are straight and tangent to the galaxy itself. I wasn't sure whether these were artefactual (no time to investigate further as yet) but I can see them on your shot too. [ignore the pesky tooltip -- I'm still working on them] Martin

Beautiful! We are lucky to have so many in reach concurrently. Martin

What an excellent first light! Looking forward to seeing more from this setup. I don't know if you're interested in galaxy clusters but that FOV and sensitivity looks ideal. Martin

That's really marvellous, Mike. I'd like to do this myself if it ever clears over here... Did you try making a GIF of the subs (as opposed to the evolving stack)? The movement ought to appear smoother. Martin

Nice work. Are you up above the light pollution on Tenerife? BTW I don't know CPWI but perhaps you can find the HH using its Barnard designation (B33)? Martin

... And even a 3rd 'ring' in Lyra. It is hard to be sure in this case but the DSS image shows the annular form well. This is K 3-27, a small grey smudge about 16 arcsec across, with a mag 18.3 central star (visible here outshining the nebula). The PN is challenging to spot in the full image. In the zoom there is a hint of a split (or two) in the ring. Try as I might I couldn't squeeze more than a slight tint of purple/blue out of this one. There are a couple of other (known) PNs in Lyra including SP 4-1 -- a tiny blue dot -- and Abell 46 which is very faint (though shows up as a dense crescent in H-alpha) and has a beautiful bright blue central star. Martin

This one is surely the other ring nebula in Lyra! I always look for M57 by pointing towards the midpoint of the 'lower' (southern) side of the parallelogram of 4 stars making up part of Lyra. If instead you were to look at midpoint of the 'right' (eastern) side of the parallelogram, you'd find M1-64, another member of the Minkowski catalogue (use "pn M 1-64" to find it on Simbad/Aladin), easily spotted with a mag 14.9 stellar 'jewel' set in the ring to the N. This has a surface brightness of 18.8, sufficiently bright to everexpose the DSS image wash out all trace of colour. As a comparison, at just 18 arcsecs across this is about one fifth the apparent size of M57 (whose surface brightness however is 20.3).

Here's another from that last session. This is NGC 6765, also known as M 1-68 from the Minkowski catalogue. This one is conical and blue with a mauve base. The SDSS image is fascinating and shows 3 whorls surrounding the base. Two of them are visible in my image (faint greyish disks below and to the left of the base of the PN; the third is just about there if you know where to look to the right). There is a discussion of this PN here: https://www.cloudynights.com/topic/500597-the-other-pne-in-lyra-ngc-6765/ In fact, there are several more PNs in Lyra besides this and M57. I'll post a couple below. Martin

Its very interesting to see such differences in timing. I've not used any of these pieces of software myself but it would be useful to know how much time they spend on each stage of processing (might be in the logs). In my own experience coding this stuff it is the star extraction that is most compute-intensive. Registration can be pretty fast. Another issue might be whether the app needs access to all subs simultaneously (e.g. for sigma clipped stack combination) or not. Knowing some of these things will point to an optimisation strategy. E.g. if star extraction is the hold-up it won't be worth processing in batches of subs and then processing the resulting stacks, but if all subs needed to be loaded at once then the batch strategy could work. Martin

Sorry to be posting Cygnus observations in late December -- a long wait for the next opportunity! Here's another one from the same session. Outside the Messier/NGC/IC catalogues one might expect to see relatively faint PNs, but M 1-79, discovered by Minkowski in 1946 (aka ARO 365/VV 268) is an exception, with a published surface brightness of 20.6. It is also a very colourful object just over half an arcmin across, and categorised as an 'elliptical PN with internal structure'. It sits in a relatively dense region of Cygnus in the Lacerta direction. Annotations (not shown) of some of the brighter stars suggests that it lies (visually) within with the very large open cluster NGC 7092 (which is over 2 degrees across and cannot be appreciated in this image). Paper [1] gives a distance to the PN of 2.7 +/- 0.9 kpc which is about 10 times further out than the open cluster. I mention distances because they are notoriously hard to obtain for PNs -- table 3 of [1] gives an indication of the wide spread of estimates for M 1-79 (one of which is sufficiently low to place it within the open cluster). I haven't observed many from the Minkoswki catalogue(s) but I'm running out of NGC/IC PNs and since the Abells are so faint I imagine I'll be seeking out more 'M' PNs in the future. Martin [1]

Hi Vin I think all those ideas sound feasible but I imagine the simplest would be to use a solid state drive if the disc is being used as working memory. But first it would be worth monitoring exactly what it is doing (in terms of disc/cpu) while processing your data, which is something you can do using Activity Monitor on the Mac. Martin

Here's one from my last session (in October). At first I thought I was looking at a double star rather than a planetary nebula: but as stacking progressed I could see that this appeared non-stellar, but at the same time not like any other PN I'd observed. This is in fact a proto-planetary nebula known as the Egg Nebula. Although it appears to be made up of two starlike entities, the object is a single F5 type star that is surrounded by a dense layer of dust/gas; the two bright spots are actually unresolved (in my case) beams of light that have penetrated the thinner regions of the dust (see https://en.wikipedia.org/wiki/Egg_Nebula for more on this). You can just make out these narrowly-divergent beams at the ends of the PPN in my shot but someone with a higher resolution setup ought to be able to get a better view -- I am right at the pixel limit here. Martin

We haven't had a post for a while so here's the last object I observed -- way back in October (sigh). Abell 2319 is the only Abell galaxy cluster in Cygnus. It sits near the border with Lyra. There are no NGC nor IC galaxies here. The 3 brightest galaxies have CGCG designations from Zwicky's Catalogue of Galaxies and Clusters of Galaxies. It is quite fun spotting the bits of fuzz amongst the stars -- there are quite a few more than a quick glance would suggest. I imagine there are no more Abell clusters in Cygnus due to the difficulty of spotting clusters in the rich starfields of the plane of the galaxy. It was the prospect of finding such a cluster in such a starry location that drew me to observe this field and then to add a touch of colour to the observation. There are quite a range of temperatures on view, ranging from blue to deep red. I particularly like the different shades of orange in the triplet at around 2 oclock. cheers Martin

Interesting thread. I'm convinced. Presumably you have to be careful about dead pixels (which a non-synthetic bias/flat dark would take care of, but which potentially leave you dividing by negative values once you subtract your constant)? Martin

Good to see the WBLs in a wider field context. Only another 731 WBLs to go 😉 . NGC 2290 is quite special isn't it? Martin

Kudos for braving 4.30am! We are fortunate to have 3 decent comets to choose from at the moment. Nice work catching a galaxy in the shot of NGC 4914. Martin

Just compared this to a 7m (21 x 20s) capture I made a year ago. Yours (and Mike's) is just so much deeper! I see that I noted some high cloud so maybe that accounts for a small part of it. You're getting about 80% more FOV than me too which makes a big difference. Great to have these comparison shots.

Interesting about the extra stars. Too much to hope they captured a nova? Maybe a variable star flare up or an asteroid? Odd though that there are 2 of them, so perhaps some kind of artefact. Martin

Fabulous images. That scope/hyperstar/camera combination is really singing. The wider field increases the chances of capturing some fascinating combinations as the IC 289 field shows. I imagine there was lots to talk about during the meeting. Martin