Martin Meredith

More the prowess of the open source world! I think animation is also useful for anyone coming at EEVA afresh to see the kind of rubbishy subs we often have to deal with, and how the magic of stacking & sub deselection can still lead to useful observations. The distribution on the Jocular thread has been updated to include this feature. Martin

Good idea. I will work on it...

Great comet shots guys! No chance here at the moment. Is this one moving quite quickly? It seems to have moved from star-poor to star-rich and back to star-poor regions in just a few days. I do like the wide FOV in Orion. Certainly the core motion in 2 minutes looks quite substantial in Mike's last shot. Martin

Sounds like a great night's work. I love tracking down these objects too, though I haven't done much of that recently. You never know what awaits, and the likelihood that only a handful of observers have bothered to check out any of these individual groups adds to the excitement. Strangely, Abell 75 is one I visited last month, noting the ultra-compact PCG and the lovely chain of galaxies leading down from 55 Psc. Here it is in colour (doesn't add much!) Martin

With a filterwheel you can have your cake and eat it. I often take the decision on whether to use colour literally half-way through an observation of an object. Sure, this approach adds to the initial expense, but it isn't going to need upgrading ever unlike the camera (or at least, there is no temptation to upgrade). Other benefits of mono include being able to use it (more efficiently at least) with narrowband filters and spectral gratings, should your interests move in that direction. Martin

Jocular v0.3 is now available. Jocular does 3 interlinked things: (1) live EEVA capture/processing; (2) automatic organisation of captures to allow reloading/reprocessing of previous captures; and (3) simple but extensible DSO planning with export of observing lists etc. This is a substantive release with considerable simplications and quite a bit more functionality, including live LRGB processing and native support for the Lodestar and SX electronic filter wheel, arbitrary user DSO catalogues, interface customisation and easier calibration. Feel free to have an explore and do let me know (by PM or this thread) of any issues. Jocular is an open source distribution that works on OSX, Windows and Linux so long as you have a Python installation. Development has been done on a Mac with and without retina screens. Unlike in the past when I suggested using miniconda, I'm now recommending getting this directly from python.org and choosing a pre v 3.8 release (3.7.9 is fine). This is because the GUI toolkit I'm using (Kivy) does not support Python 3.8 at the moment. If you already have Python 3.8 or higher please PM me so I can advise on how to get the script to ignore 3.8 during installation. The attached zip contains the distribution. You can separately download a couple of example captures, one mono, one LRGB, to play around with. There is also a document describing how to import Vizier and other catalogues. I've provided a bash script for OSX and Linux users, and a batch script for Windows users. These install Jocular with a single command once you've got Python. Just download the zip, unzip it anywhere, open a command window, navigate to the directory where you unzipped it, and type ./joc in the command window (OSX/Linux) or run the joc.bat file (Windows). The first time round this will check that you have a Python system available, then it carries out the required dependency installations in a virtual environment (basically, this keeps the code hermetically-sealed from anything else you may have in the Python ecosystem), then starts Jocular (the whole things takes a minute or so). Subsequently, you will launch Jocular with the same command and it will be up and running in a second or two. There is a README that repeats this information. If you wish to use Jocular for native capture on Windows, you will need to ensure that you have libusb installed. This can be done most easily using a small executable from https://zadig.akeo.ie which is just used once to do the installation. Although I don't have access to a Windows machine in general, I did manage to install it on one and so have an existence proof that native capture will work, but I would be interested to hear of others' experiences as testers have had issues trying to get the USB side working. The main limitations are (1) very limited native support, but you can still dump FITs into a watched folder, and you can now dump master calibration files too; and (2) restricted to mono cameras, but there is support for mono + filtered colour using LAB space manipulations. There is a toolkit-related issue I'm aware of when using an auxilliary screen where the scaling doesn't work, but I believe this will be fixed in the Kivy release candidate, so is a temporary issue. I'm also going to produce a separate window that can be used for outreach pretty soon. I'd like to say particular thanks to SGL members Bill S, Mike JW, Callump, AKB, London David, Wormix and CatBurglar for testing, encouragement, suggestions, bits of code, ideas, and generally being patient while I sorted out various issues. Also thanks to Terry Platt from Starlight Xpress for some pointers on coding for the Lodestar & filterwheel. I'm sure there will be some teething problems, but nothing that can't be fixed. I will produce some additional resources (videos etc) in the coming weeks. Please check further down the thread for any updates to the distribution. Good luck! Martin Jocular (1M) Updated 26 Nov 2020: jocular.zip User manual (1.7M): manualv3.pdf Description of how to import external catalogues (1.9M) jocular_imports.pdf Example images (27.7M) (unzip and copy into captures directory and restart Jocular) examples.zip

These are two of my favourite Arps. Arp 145 is one of the few galaxies with a complete ring that is also large and bright enough for our scopes, and the field is enhanced tremendously by the stellar car headlights sitting just above it. The ring itself could easily be mistaken for a planetary nebula. It also has special memories as I spent many hours looking at Arp 145 as it was my test image while I was working on the live stacking algorithm.... Martin

Hi David While a few people have tried (and succeeded to a certain point) in using undriven mounts for EEVA, nobody that I know has actually continued past the point of initial experimentation. The lack of a driven mount is compounded with the long focal length of most large-ish Dobs. It just isn't a lot of fun trying to keep the object centred for long enough. So yes, you really need a driven mount. I suppose you could try your existing Dob with an equatorial platform but I don't see many people doing that either for EEVA. On the other hand, you don't need a large aperture in the same way you would with visual work. A 6" f5 reflector is quite easy to mount and will show a lot of stuff; an 8", preferably at f4 will show more than enough interesting objects for a lifetime while producing bright images quickly. Others use smaller refractors and still others use SCTs, which are a very adaptable scopes when paired with focal reducers. RASAs are fine but few seem to use them for EEVA (and there are downsides, like inability to use a filterwheel due to excessive occlusion of the light path since the camera is positioned at prime focus, but then again, use of filterwheels in EEVA is also a minority pursuit). The key is to ensure that any scope you choose is fast (which might require the use of a focal reducer), and to choose a sensor that is well matched, so you don't end up with blocky pixels due to excessive undersampling. And also to ensure that you can reach focus with the sensor, given the format of the camera body, and likewise that you clear the mount for those mountings/scopes where the camera is attached at the base. My own sweet spot is a very simple system consisting of a sensitive (big pixels) mono guide camera that weighs 50g and slips into the drawtube of my 8" f4 imaging Newtonian, which is mounted in alt-azimuth. I do use a filterwheel so with a mono camera I can also do colour or narrowband without swapping anything in or out -- its a very flexible approach. It also enables me to take darks quickly. Some people here do use NV devices, but most of the reports you mention that are accompanied by images come from people using CCD or CMOS cameras. I see PeterW has replied as I write this, so I imagine you will get some NV opinions too! All the best Martin

I think severe contrast stretching is definitely EEVA (at least potentially; I do it all the time). As for long exposures, I don't think anyone really minds here so long as the intent is observation/astrophysics rather than AP. I've gone nearly up to an hour trying (and failing) to spot z=6 quasars. I'm certainly interesting in hearing about your approach. Martin

This is WBL 086 from last night. As is often the way, I came across a group of galaxies with no clear designation and checked to see if they corresponded to a WBL group, and in this case they did... This small field contains 5 NGCs and a member of the Flat Galaxy Catalogue (FGC 337). The main galaxies are highly-contrastive. NGC 1067 is the face-on next to the FGC 337 and is an instance of a bulge-less spiral (SABc). These are really photogenic quite apart from anything else, and you might be interested in a recent dataset listing 200 of them: https://arxiv.org/pdf/1902.09892.pdf which argues for the face-ons being counterparts to the edge-ons of the FGC and revised FGC, so it is fascinating to find an 'orthogonal' pairing so close to each other. The third member of that grouping is a plain old elliptical, NGC 1066 and all that. The three are at 201-218 MLyrs, so presumably a physical group. The right hand side of the image is dominated by the type E-S0 NGC 1060 (which often appears in studies of early type massive galaxies in the local universe). Just above it is NGC 1061 which is an intriguing Sb type. The close up (below) shows a fat core with thick arms. The object at the tip of the S arm might well be a star. Further out to the R is type S0 NGC 1057. This grouping is a little more spread in terms of distance estimates (196-279 MLyrs) but it seems likely that all of these are linked. There are quite a few patches of fuzz in the field. I let this run for a bit as there was a lot to see (spending *only* 10m30s on this hardly does the galactic variety justice!) details of NGC 1061 cheers Martin

Here's a recent observation of Arp 282 to throw into the mix. I added about 1 minute in each of RGB to a 2 minute luminosity 'base' as I am starting to do when I see possibly interesting stars in the field. I just noticed that the bright star at the right is a double (you can make out the secondary in line with the spikes to the SW). It is known as HO 623 (not sure who HO was). The primary is spectral type K2III and mag 7.2 while the secondary is just over 9 arcsecs away and has a magnitude of 12.3. It is separated in all three of our shots. I love the delicate wound-up arms of the spiral NGC 160

Good to see some more of these rarely-observed(?) groups. Agreed, the last one presents a lovely spiral. Some of them are really wonderful groupings. I've just dug out my WBL 685 observation from last year and I see from my log that I wrote: "Very interesting field. Star-rich, and with 7 decent galaxies. Seeing looks bad. Upper edge on is NGC 7345 and to its right is mag 15.2 type SBa NGC 7342. The group at the base have mags 14.7-15.6. One of the upper edge ones (the one to the right) appears to have a slight curve to it, or perhaps another gx. There are a bunch of fainter and/or more compact galaxies in this field too." (these descriptions make more sense with my original orientation, but to match yours I've redone the orientation) Coincidentally, there was a striking WBL group amongst my observations last night -- will post in a moment. Martin PS Note I've added a choice of white or black frame to Jocular. I think I prefer the black frame -- less contrast and easier on the eyes!

Sounds very interesting. I think it is best to keep this thread for the peculiar galaxies/groups, but there is a thread dedicated to GCs started by Mike JW which would welcome observations of AM-4 and other GCs. Martin

When I observed this last December I too struggled to see much but with time a very interesting 'hook' shape (upside down question mark) emerged: There appears to be a galaxy being obscured by the brightish star to the S though nothing is listed on my charts. I certainly need smaller pixels to handle these horrible square stars! Martin

I wonder if it related to the issue with Nebulosity on Catalina as documented in this thread: https://www.cloudynights.com/topic/679560-nebulosity-4-not-running-on-macos-catalina/ What SLL and Nebulosity might conceivably have in common is the USB-handling library, libusb. It is possible that a Catalina update fixed that issue for you. I've been using OSX for some decades now and I must say that Catalina for me has definitely been the most troublesome variant to date. I hope it isn't indicative of lower standards at Apple otherwise its Linux here I come 🙂 Martin

Great to see some of the outer planets and their satellites. Funny you should have an owl too; I have what I think is a screech owl flying across my FOV round about the same time each night (11'ish)! Martin

I'm also using astropy for this FITs stuff too. It makes it very easy to handle headers/data at least for standard images (I've not looked at tabular data using astropy). I was also using astropy for coordinate conversion, transits, solar altitude and the like until recently but it does insist on connecting to NASA every few days to update the time to nearest picosecond or something -- so beware! In the end I recoded it using Meeus's Astronomical Algorithms (which I think is probably the basis for the astropy code anyway). In case it helps, there is a great resource on data science in python written by an astrophysicist, available as Jupyter notebooks here: https://github.com/jakevdp It isn't datascience for astrophysics though, but it might be useful when getting data into various formats using python. cheers Martin

Thanks Andrew. That's the list I was looking at too (its in the appendix of the pdf). I was hoping perhaps there would be some agreed conventions for simple stuff like what filter was used etc but apparently not.

The FITS standard https://fits.gsfc.nasa.gov/standard40/fits_standard40aa-le.pdf mandates and reserves a number of field names for the header of a FITS format file, but the keywords are quite limited and any software that writes FITS headers can extend them ad infinitum. Does anyone know if there are any conventions for field names in astronomy software? I've looked at a couple of well-known AP programs and find that there are different field names used to signify the same thing e.g. EXPOSURE and EXPTIME, CREATOR and SWCREATE, etc. So it seems the answer to my question is probably no. But I'd be interested to hear from people about this. My use case is in developing software that can process FITS coming from a variety of capture engines, and I'd prefer not to have to know about each capture engine's header conventions in advance. cheers Martin

Hi Tim Welcome to SGL! You might get better responses if you post in the imaging section but I'll have a go at a possible answer. Is it possible that DSS knows your that images were binned (this info may well be in the FITs header, depending on which capture software you used). If so, the FWHM estimate might already have taken binning into account. I guess I would expect FWHM values to be independent of binning so long as your arcsec/pixel resolution is well below FWHM in arcsec. Martin

The other thing to add regarding refocusing is the importance of acquiring a set of parfocal filters which include a clear (C) or a luminosity (L) filter. This way, there is no need to refocus when adding narrowband, at least for EEVA purposes. I have the Baader LRGBC set which includes both L and C. The difference is one of passband: L covers pretty much the same as RGB combined, while C is much wider and therefore better for making use of the near-IR sensitivity of modern cameras. The 3 members of the Baader narrowband set are parfocal with these too, so I just pack my 9-slot filterwheel with the lot of them, plus a piece of flocking for a dark filter, and a spectral grating (which almost certainly isn't parfocal!). https://www.baader-planetarium.com/en/blog/the-baader-l-rgb-c-ccd-filters/ In fact, all of my luminosity captures are taken through a C filter (so I guess I lose a tiny fraction of transmission). I do this so that if I'm observing something in mono that turns out to be potentially interesting enough to add a quick colorisation, I can simply add some RGB to the end. Or vice versa, if I'm doing an LRGB capture and want to improve spatial resolution and depth, I can add more L (actually C) without refocusing. Martin

Agreed, wonderful image and FOV in short exposures. I've used Ha in an EEVA setting, but not for a while. There are some objects with plenty of signal, but the best time I had was adding it to luminosity data 'live' (using SLL). This animation shows the effect of adding Ha to a L base can be quite informative. I'm planning to add a L+Ha mode to Jocular in addition to the LRGB and mono, using the saturation slider to modulate the effect of Ha. It helps of course to have an electronic filter wheel for multispectral work during a live session. Martin

That's a great image. This is my LRGB version stretched as far as I can go, oriented almost like Rick's. Seems a case where we need AP amounts of data to see this plume! There are several quite bright globs in here according to his image, inlcuding the pinky-red object at the upper-right.

By coincidence, I was also looking at Arp 168 a few nights back, wondering about its inclusion in the Arp catalogue. What I found striking were what I imagine must be dusty regions of M31 -- only visible when stretched a lot. There is something that could be described as a plume (on the NE side of the galaxy in this shot), but equally it could be part of the outer envelope of M31. Thanks for pointing out the globs of M31 (I now plan to add them as a catalogue). I can imagine how much fun it would be to track them all down. Martin