Martin Meredith

Jocular v0.2 Here is a minor update to Jocular along with a new 3-step minimalist installation procedure for MacOS, Windows or Linux. These steps only need to be followed the first time you install Jocular, so if you already have Jocular on your system, just pick up the jocv002.zip below, unzip it anywhere and you're ready to go. Main changes 1. Left and right arrow keys scroll through the subs 2. Up-arrow selects/deselects the current sub (so it doesn't contribute to the live stack) 3. Down-arrow toggles between sub view and stack view 4. There is now an automatic black point option that simplifies setting the background level Instructions Step 1. Install python. If you already have python3 and pip on your system, you can skip this step. Otherwise, visit https://docs.conda.io/en/latest/miniconda.html and install miniconda for your operating system (choose the Python 3.7 version). Follow the installation instructions given there (could take a few minutes). Once complete, check that all is fine by opening a terminal window (command window in Windows) and type the following to see the version number (3.7.6 in my case): python --version Step 2. Download the latest Jocular release here:jocv002.zip (210k, yes k!) and unzip it to anywhere you like. Navigate to that directory (jocv002) in the terminal window, then change to the jocular directory by typing cd jocular Step 3. Install the required packages Mac users pip install -r requirements.txt Windows users pip install -r requirements_windows.txt When that has finished (a few mins on a slow link) you can launch Jocular by typing python jocular.py There are instructions in the user guide for adding the DSO database and the example capture of Arp 145 to practise on. Please send me a direct message in case of any issues and I will update this thread. I am not aware of any Linux users to date, so it might be necessary to create a Linux-specific requirements file. I am still working on a LAB-colour version for later in the year. cheers Martin

This time we're in Crater at around -23 degrees looking at Arp-Madore 1100-224 (*). This is listed as "close pair, pair of spirals + comp'ns." It isn't very clear to me what the 'companions' part of the description refers to, but we certainly have a pair of quite distinctly-oriented but actually quite similar spirals with a lot of visible structure. The upper galaxy (N is up here) is NGC 3511, type SABc, quite bright at mag 11.5. This is a type intermediate between a barred (SB) and an unbarred (SA) spiral -- the c refers to how loose the spiral arms are -- in the case, quite loose. The lower galaxy is mag 11.9 NGC 3513, type SBc, face-on, displaying a bright clear bar and what to my eye looks like an interesting 'overlapping' arms structure although I think it is an artefact -- again, quite loose. You can imagine that if the two galaxies were oriented in the same way they might look quite similar. Both galaxies are approximately 50 million light-years distant. Maybe they are included in the 'peculiar' category as potential 'interactees' although I haven't yet been able to find any evidence for this online (admittedly I haven't looked very hard...). The DSS image of NGC 3513 is incredibly blue though, suggesting ongoing intense star formation, perhaps due to an encounter between the two in the past. There are a couple of star-like points in the upper arm that are really bright and I wonder if they are foreground stars in our own galaxy or bright knots in the galaxy itself. Looking at the DSS image I'm inclined to favour the latter. Martin (*) Due to the way the catalogue names are based on coordinates, sometimes things which are part of the same AM description appear to have separate AM designations. This is a case in point. Here NGC 3513 is listed as AM 1100-225, but it is clear that the description applies to the pair of galaxies.

Thank you Mike. Yes, there are many advantages to being a little further south from an astronomical point of view! Here's another AM object (actually, there are 2 AMs here: more on that in a moment). This is the central region of Abell 1060, better known as the Hydra Cluster, which in turn is part of the Hydra-Centaurus supercluster. The chain of galaxies snake their way between the two bright beacon stars. These stars are HR 4162, mag 4.9, M1 type with a high colour index (1.6) and therefore worth revisiting one day for a look in colour; and HD 91964, mag 6.7 type K4/5, again with a colour index of 1.5. It is a real challenge to control these stars and at the same time see the fainter parts of the galaxies. There are 6 NGC galaxies in this shot, labelled on the negative view, and one more just out of shot (and quite a few more in the Abell cluster itself). Hickson 48 is just over 0.5 degree north of the cluster (and Hickson 48 is the 7th most southerly member of that catalogue). What does the Arp-Madore atlas say about this cluster? One 'peculiarity' of the way the data is laid out is that the same AM designation can occur multiple times (in spreadsheet terms, the same identifier can be found on multiple rows). Each row corresponds to one of the objects within the entity (cluster, double, triple etc). In this case there are three entries for AM 1034-271, and they read cluster (core=dbl. e) dust; irregular/disturbed; cluster,"cluster (disturbed sp.,m82-type) peculiar disk; dust,large disturbed sp. w. pec. dust I find that it isn't always easy to determine which description applies to the cluster and which to the members. The first line obviously does concern the cluster, with two ellipticals at its core (although NGC 3311 is considered to be an intermediate stage E-S0). I initially thought that the second line corresponded to NGC 3312 (type Sb) although it doesn't look very m82-like to me. Looking more closely at the coordinates, I'm now inclined to believe the description applies to NGC 3307 (type S0-a). It seems that the 3rd description denotes the large spiral NGC 3312. Bonus Arp-Madore object! What about NGC 3314? Well, this innocuous-looking galaxy is not part of AM 1034-271 at all, but has its own AM designation of 1034-272 with the description "rare/distinctive,spindle galaxy = projection?". This is actually the most intriguing object in the entire image. It was discovered as recently as 1999 to be two overlapping galaxies with no physical relationship -- a very rare occurrence for relatively bright galaxies. Given that the Arp-Madore catalogue was compiled prior to 1977, the description seems prescient. The foreground galaxy is a face-on spiral, designated NGC 3314a (type SBab, mag 14.1), against a tilted background spiral, NGC 3314b (type Sc, mag 13.5). I would like to think that you can just about can make out a hint of the spiral in my shot (see this blowup too, where both the face-on circular structure and perhaps part of a spiral arm is visible): To appreciate how really remarkable the coincidental line-up of these galaxies is, I really recommend taking a look at the beautiful Hubble photo here https://apod.nasa.gov/apod/ap110715.html Thanks for looking Martin

This is AM 0831-224. (Note that the names are an abbreviation of the RA/Dec). This catalogue takes you into some strange places -- I think this is the first time I've observed in Pyxis. The entry reads: "companion,edge-on sb w. 5 app. comp's" i.e. type Sb with 5 apparent companion galaxies. One of the companions is the Sa type galaxy near the bright star at around 2 o'clock. Two of the other companions are visible but rather faint. What I like about the main galaxy (which is actually NGC 2613) is that it is embedded in a star-rich field, somewhat unusually for galaxies. Some hint of spiral arms is apparent along with quite an extended halo and very bright stellar-like core. This is a rather bright galaxy (mag 11.1) at an estimated 73 million light years distance. The galaxy is very similar in appearance to NGC 3771 in Pegasus if memory serves (next to the 'deer lick' group). It is a massive galaxy whose rotational properties have been studied for a while.

The Arp-Madore (AM) catalogue is less well-known than Arp's collection of peculiar galaxies and galaxy groups. It isn't too surprising why: most of the catalogue members are not so easy to see from mid-Northern latitudes (the most northerly member of the catalogue has a declination of a mere -21 degrees 43 minutes). The clue is in the full name of the accompanying book: A Catalogue of Southern Peculiar Galaxies and Associations (1987), Cambridge University Press, the full text of which is (legally!) available at this link in HTML format: http://ned.ipac.caltech.edu/level5/SPGA_Atlas/frames.html For Northern hemisphere observers, capturing more than a handful of AM catalogue members is going to be a challenge. From the UK for instance most Arp-Madore objects don't rise more than 16 degrees above the horizon at culmination. However, EEVA is made for exactly this kind of challenge! The full catalogue contains 5846 galaxies or groups of galaxies so the situation isn't so bad: there are 174 entries down to -23 degrees and as many as 1285 down to -30 degrees. Quite a few are members of the NGC and IC catalogies too. And there are some real beauties (as well as plenty of very faint/small objects!). One of the things I like about the AM catalogue is the existence of brief but tantalising notes, such as rare/distinctive,hi.s.br. linear object irregular/disturbed,chaotic spiral w. app. comp'n interacting; ring; close triple that make me just want to go out and observe them to see if I can spot these features. And from my experience so far it is sometimes really hard to to do, making it a seriously fun pursuit... I've set up this thread so that anyone can post their Arp-Madore observations (visual, night vision as well as EEVA) all in one place. Similarly, if anyone has any Arp-Madore resources, anecdotes, historical references, etc, please feel free to write about them too. And in case this all sounds very Northern-centric, of course it would be fabulous to hear from anyone who has access to the full Southern sky! You can find the full catalogue here https://vizier.u-strasbg.fr/viz-bin/VizieR-3 but I've spent a few hours mangling that into what I hope is a slightly more useful and augmented format as a comma-separated value format file that can be loaded into spreadsheets etc here: ArpMadoreReduced.csv In a while I'll start to post some of my recent observations of Arp-Madore objects. Is anyone up for the challenge? cheers Martin

I have to agree, there is a lot going on in this field -- as is often the case (I sometimes wonder why EEVA is seen as a 'brief' observing approach when it can take 10-20 minutes to track down and enjoy all that there is in a single field). The detail you're getting in the NGC galaxy is amazing. The bright inner ring seems to be split (is this the dust lane you're referring to?). I had to look it up in my Herschel Objects guide. Nothing much to add to your description except that it was discovered on 11th April 1785. Not bad at f6.3 in 10s subs either... Martin

They're impressive results especially given the light pollution. I also like the FOV you're getting with that scope/reducer/sensor combination. That looks like a nice comfortable setup. Whenever I can I try to find a way to trail the cables so I can setup just inside the door, although there's always a bit of draught... Anything to stave off the cold and lengthen the observing session! Martin

Thanks Mike and Paul. I was in that region again last night taking a look around the other parts of the cluster and will post some images in this thread over the coming days. This is the south east part (on the sky -- I prefer to think of it as SW on the chart). The wiggly line of galaxies a the top correspond to those on the left in the main image above. Again, lots of galaxies here, but I particularly wanted to look at the two face-on spirals. The one at the left edge is NGC 4921 which is type Sab (moderately loose-armed spiral). While listed at magnitude 13.5, it has quite low surface brightness at 23.7. It took me a long time to see any decent structure in the arms. Long exposure photos show a lot more going on that I have been able to capture. Just S of this galaxy and at around 2 o'clock with respect to the elliptical NGC 4923 which is on the edge of the shot is a bright (magnitude 17.9) quasar (redshift 0.24). The other galaxy to highlight is the face-on spiral at the base of the image. This is NGC 4911, magnitude 13.7 and with a higher surface brightness of 22.3. This is of type SABb which I believe corresponds to a loose spiral with a hint of a bar -- something I'm sure many of could do with right now -- but I need to revisit the galaxy classification system to be sure about that! I see a kind of 'poppy' petal structure here with the bright central nucleus and offset disks in the negative close up below. There are plenty of other interesting galaxies in the field, mainly ellipticals and S0 type galaxies (the type at the juncture of Hubble's tuning fork where ellipticals blend with spirals). The shot contains 6 NGCs and 3 ICs. One day I will count how many NGCs/ICs there are in the entire Coma Cluster but it must run into several dozens. Further out still to the SE is NGC 4926 and 4926A but I didn't stray out there on this occasion. Martin

There's a lot going on in the ear-brain system but just dealing with the ear part of it... if one were to unroll the cochlear so that frequencies are laid out in a line from low to high, we'd have about 35mm (of basilar membrane) running from 20 Hz at one end to 20 kHz at the other. Frequencies are mapped on to those 35mm approximately logarithmically, so 1000 Hz is about half way along. The fact that is is quasi-log and not linear in frequency is important because it means it is easier for the brain to normalise differences in fundamental frequency (just a linear shift in the pattern) amongst other things. The reason is that when the fundamental frequency f0 of a harmonic series f0, 2*f0, 3*f0 , ... changes, all of the harmonics shift by a multiplicative amount in linear frequency (e.g. 100, 200, 300 -> 150, 300, 450) whereas they shift by a constant amount in log frequency. This not only applies to harmonics when say the voice pitch changes; it also applies to the frequencies that correspond to resonances of the vocal tract, the things that define for example which vowel we are hearing. Differences in vocal tract length between talkers (especially between gender, and between adults/children) can amount to 20% or so, which gives rise to different resonant frequencies for identical vowel. Hence the brain has to solve a vowel normalisation problem, and this amounts to a simple linear shift in pattern when the spectrum is represented on a log scale. Not that the ear was designed for speech. But harmonic sounds (i.e. sounds driven by a repetitive waveform) are common in nature. MPEG compression exploits this (and other) properties of hearing.

The Fourier transform is certainly useful but mainly as an implementation device these days. The ear doesn't perform a Fourier transform. It might seem like a small distinction but is actually really important (music appreciation and speech perception most likely would be very different if the ear did do a Fourier transform!). BTW Did you know Fourier is credited with discovering the greenhouse effect? Martin

Chris, have you checked out SonicPi (https://sonic-pi.net)? Its not just for RPi (I have it on my Mac and use it to try to get my son and his friends into programming - it seems to work!). Its great for exploring chords etc. Speech synthesis has moved on a long way. Some forms of synthetic speech can be more intelligible than natural human speech when mixed in noise. But I know what you mean: once you know what is being said, it just pops out! Speech recognition too. In 2017 speech recognition reached parity with humans on some reasonably challenging types of speech.

I wasn't meaning to look at this yesterday evening but scanning the charts in the middle of a session the density of galaxies was too much to avoid having another look at Abell 1656, better known as the Coma Cluster. This is only the central part, with the two main supermassive ellipticals NGC 4884 (left) and NGC 4874 (right). Most of the objects on view here are galaxies! The cluster is part of the Coma-Virgo supercluster and is near the North galactic pole, so little own-galaxy dust to dim things in the intervening 320 million light years or so.. COM4937.pdf This screenshot of the relevant chart gives an idea of galaxy positions and orientations. I haven't checked thoroughly for faint galaxies in my image but I think there may be mag 20 and fainter lurking in there. However, to see the details it is better to look at the pdf (which is part of the Pretty Deep Maps set that can be downloaded from the link in my sig): COM4937.pdf NGC 4921 and 4911 look to be very photogenic galaxies just off to one edge that I hope to look at tonight. cheers Martin

Similar fundamental principles apply in terms of acoustic uncertainty. The longer the time window one uses to measure frequency, the better one can measure the frequency of a component and the better frequency resolution is obtained, but localising that frequency component in time is worsened. And vice versa. The spectrogram as used in sound analysis embodies a certain choice of the frequency/time resolution tradeoff, and what's more, the frequency resolution is the same at all frequencies. The ear (specifically, the cochlea) is different. It has very good frequency resolution (and hence poor time resolution) at low frequencies (sufficiently good to easily resolve the harmonics of the human voice, for instance), but poor frequency resolution (and good time resolution) at high frequencies (say 2 kHz and above). This is all accessible to the amateur. A good starting point for spectrograms is the excellent freeware praat (http://praat.org). I have a lot of Python code for going further e.g. producing cochleargrams. Martin

Hi Mike It would certainly be interesting to put together some shots of the Leo Arps. I think I have them all now. Just a matter of finding some time... Martin

And here's an updated shot of Hickson 57 which I visited under the name of Arp 320 😉 Exposure is actually 9 x 20s = 3 mins (exposure is estimated automatically at present...) Martin

Took a look at SHK 371 last night, oriented as in Mike's image. Doesn't add anything substantial to Mike's capture, but a lovely group to observe anyway!

Beautiful groups. I've added SHK 371 to my list for tonight. Here's a shot of Hickson 57 (Copeland's Septet) from a few year's back. And just for fun, here's a shot from the year I started out in EEVA when I was using the Lodestar colour camera and a StellarVue Nighthawk achromatic 80mm f6 refractor (horrible star bloat!)

Nice shots Bill -- always good to compare. I like how in the last image you've managed to preserve the bright central part of NGC 3115 while also showing the elliptical halo around it. It is currently clear and the scope is outside cooling, so I may have another go at q3 with 30s subs tonight, but later on when it gets to around 45 degrees above the horizon. Before that the plan is to look at the remaining Arps in Leo (which has 27 of which I've observed 11 so far). Martin

Thanks Mike. On NGC 3115, I'm always amazed when an NGC galaxy that looks innocuous on the charts turns out to be a real beauty. Nowadays I almost never look at observing guides in advance in order to enjoy the surprise when this happens. This is an object that responds well to the interactive observing style because the appearance changes dramatically with increasing stretch from a thin lens shape to showing the extensive elliptical-style halo, fitting with its classification as E-S0. Burnham devotes 2 pages to NGC 3115, noting that it is "somewhat difficult to locate in a blank portion of the sky". Marv, thanks for your kind words. I'm not sure about cutting edge but I think it shows that there is a lifetime's worth of interesting objects within reach even for modest equipment. I'm still using my Lodestar X2 mono which I think must be over 5 years old now and no plans to upgrade any time soon. Thanks Rob. We've had a lot of wind here recently (these shots were taken before that arrived). I would normally (on a good moonless night) be able to just about pull out a mag 20.6 point source. Looking again on Aladin at the DSS image it appears very blue (and that magnitude estimate is in the blue filter apparently) so perhaps I'm lacking some sensitivity in that part of the spectrum. Martin

Great report and congrats on making out Hickson 50 -- that is a seriously faint group. BTW have you checked out Reiner Vogel's Hickson guide? pdf here: http://www.reinervogel.net/index_e.html?/Hickson/hickson_e.html Martin

NGC 3115 is a mag 10.1 E-S0 type galaxy in Sextans. It is not only bright but has a high surface brightness of 19.5. This is one of several galaxies known as the 'Spindle Galaxy'. Just to its SW (in this image) -- but invisible in this image -- is UGCA 200, a mag 16.3 dwarf galaxy with a surface brightness of 24.5, about a 100 times less than NGC 3115. Both are at around 30 M light years so could conceivably be interacting. UGCA 200 is also incredibly faint on the DSS image. I reloaded into Jocular and in this negative, hugely-stretched, dusty image it is possible to make it out -- just about. This is what I love about astronomy, EEVA-style: the unexpected and the challenging, and UGCA 200 combined both of these. UGCA 200 is described in [1]. Another bright galaxy in Sextans is NGC 3044. This is type SBc (or SCd), mag 12.5 with a surface brightness of 22.2. In this relatively long exposure some of the structure of the galaxy can be seen: central condensations, some hints of higher densities towards the edge (presumably spiral arms), and a faint tilted lane at the right hand end (more clearly seen in the negative image). Reading [2] and [3] (if I'm interpreting things correctly) this is an 'extraplanar diffuse ionised gas halo' that has been blown out by supernovae (first detected in our own galaxy in 1963). Fascinating! The reason I took a longer exposure was to try to capture some of the faint galaxies and no fewer than 3 quasars in this small field. I've marked the faintest galaxy detected. Details for the quasars: q1: mag 19.3 (red filter), redshift 0.48 q2: mag 20.0, redshift 1.24 q3: mag 20.6 (photographic), redshift 1.53 As you can see, q3 escaped me on this occasion. Anyone fancy having a go? cheers Martin [1] https://arxiv.org/pdf/1003.0201.pdf [2] https://arxiv.org/pdf/astro-ph/0006301.pdf [3] https://arxiv.org/pdf/astro-ph/0510079.pdf

Nice captures Bill, and quite short overall exposure time too. I definitely want to look at these the next time out, maybe in colour too. Martin

Very nice sequence -- that's fast! I'll take a look when we next get a clear night. The skies have been milky for days here, with a fair amount of wind too. Your setup sounds a bit like mine: the windier it is, the nearer the house, with a fine estimate of whether the end of the scope will hit the door... Martin

You never really know what you are going to get when pointing the scope at an Arp peculiar galaxy. At least I don't, preferring not to look them up beforehand... Arp 253 presents a really strange field, not just because of the Arp, but because of the strange object to their south. The Arp galaxies (UGCA 173/174) are a well-matched pair with identical magnitudes of 15.0. The right hand of the two has a couple of knots at each end. Both galaxies have a distinct curve as if they are dancing around each other (which may well be true). The galaxy to the south has the appearance of a % symbol albeit with a curved central bar. I can find very little information about this except that it is mag 14.0 MCG-01-25-033 and is regarded as a 'galaxy in pair of galaxies'. The DSS image does show a lot of blue so there appears to be some interaction going on, but for the life of me I can't work out where the other galaxy is. I guess it could lie just behind it in the line of sight. Or perhaps the classification refers to it as somehow paired with the Arp? It would be interesting to find other galaxies with this kind of morphology. Total exposure is 4 minutes (16 x 15s)

Nice one. I have a shot of this (similar exposure) from a few year's back which confirms the presence of the strange sticking out bit! On the DSS2 image that part is quite blue suggesting recent star formation, presumably being the part most disrupted. Apparently class Sc spirals have loosely-wound spiral arms that give rise to an S shape https://space-facts.com/galaxies/types/ I hadn't noticed the ring in the neighbour until you pointed it out. Excuse the dust and the pattern noise... The integral sign reminds me that I must post Arp 253 from the other night which contains a 'percentage sign' galaxy in the field! Martin