Mike JW

ARP 212. (8/09/20) Arp 212 ( NGC 7625) is a great contrast to Arp 86. There are a variety of classifications - Ep, SApec, SO. Essentially it is 'a turbulent elliptical with dust'. There has been various studies of the dust content of this galaxy, which on reading I failed to understand. However these studies have led researchers to conclude that 7625 is the result of a merger, possibly of a similar sized companion. (There is no obvious nearby galaxy candidate for a fly by, thus the merger theory is favoured.) The companion would appear to have been well and truly 'eaten', such that little obvious remnants remain. The high level of dust could be obscuring the remains of the companion. However there is much 'indigestion' - dust appears to radiate out from the bright centre, with centres of star formation. There has been much starburst activity in the past but it has now passed its peak. However there are massive stars being formed within the dusty regions. There are more H alpha emissions to the north of the nucleus (up in my shots) - suggesting star forming activity? There is also a ring but it has a high dust content and low star density thus it is faint (not visible) in visible light. Below are two shots. The left hand wins the 'pretty view' award (I do love diffraction spikes) and the close up shows more detail. Mike PS cleaned the mirror yesterday - so no dust bunnies.

Great to have your input as well. Agree colour adds very little - to be honest I prefer the mono shots. Although the colour version picks up some of the companion detail in my second attempt. Mike

I was out there again last night and amongst other targets I re-visited Arp 86 and this time I used 11s subs and let it run whilst I was busy looking at info on other targets. A smoother shot maybe, but not significantly better.

Thanks Martin, As you know when I use the 15", I am limited to about 7 seconds because it drifts too much. However I do like using the 15 because of its large light gathering capacity. Your shot of Arp 86 complements mine as it gives the wider fov and hence the context of the galaxy pair hanging in space. Strip down of the 15" Dob today and mirror clean up time - hate cleaning the mirrors but it has to be done. Mike

06/09/20 - Here I am, one night later and this was serious desperation astronomy. I had time for just one target before it clouded up but well worth it. ARP 86 in Pegasus. Like Arp 46 this was classed by Dr Arp as " spiral with high surface brightness companion on arm". It is NGC 7753 the big spiral and 7752. This pair are about 272 million lyrs away and are gently interacting. Most likely 7752 has done a flyby and presumably will get pulled back towards 7753. This pairing are of the M51 type = grand design spiral with a small compact high surface brightness companion on an arm. These guys belong to the sub-class ; "close but still not perturbed". (The other sub class is where the pair have been seriously perturbed.) High resolution images show that the bridge to the companion has definite blue patches, implying star formation due to the companion stirring up and compressing the inter stella gas/dust. I picked up some of the star forming regions in 7753 and I was pleased to get the bridge across to 7752. 7753 is SAB(rs)bc. 7752 is IC (irregular compact and low mass). 7752 is very bright for its size . Studies suggest this is due to material being dragged from 7753 as it passed by. The main perturbation occurred about 600 million yrs ago as 7752 swung by and crossed the galactic plane of 7753 in a low eccentricity path . 50 million yrs ago it crossed back through the galactic plane. http://www.spitzer.caltech.edu/images/6566-ssc2019-03a-Galaxy-Merger-Arp86 - is well worth a look where we can see much star formation (blue). Also, take a look at the bridge - it has two distinct trails of stars. Also note just how bright and lumpy 7752 is - not a quiet place to live. (Also the details below the image labels 7753 as 7752.......) Despite the short session, it was well worth it to get the interesting shot and then to read up about it. That summarises why I enjoy the EEVA approach - use the camera to observe a target, then find out something about it, rather than spend the time and effort to get an image to then move onto the next image............... Mike

5/09/20. As well as Arp 46 (VV 314) I fancied a VV galaxy so I went for VV 400, (NGC 7698) It is a lovely elliptical but is classed as MMM = satellite lies on the bridge connecting the components. That classification defeats me - I see no companion or a bridge. However to compensate for this lack of companions note the galaxies at top right - several LEDA galaxies. Note also a small diamond shape of four fuzz spots approx 12 o clock from 7698 - another group of galaxies? Mike

5/09/20 - after a long run of cloudy nights I managed to grab an hour as the bright moon began to wreck the sky. I call this desperation astronomy. I know there will be poor images due to the moonlight and humidity........but in GB if you don't grab these chances then weeks of no observing become months....... ARP 46 in Pegasus. At first glance, I thought "this Arp is the galaxy pair" - wrong and right at the same time. The right hand spiral (actually a barred spiral - just got the bar and also a hint of a dark lane) is UGC 12667 and lies about 200 million lyrs away. Arp 46 is the left hand spiral - UGC 12265, (mag 15.1) and is classed by Arp as 'spiral with a high surface brightness galaxy on its arm'. High resolution images clearly indicate interaction between this galaxy pair. They are about 230 million lyrs away. UGC 12265 is classed as SB (rs)d pec,-loosely translated it is "all messed up" and to be more precise - barred spiral, with loosely wound arms, making a transition to being a ring galaxy and peculiar (messed up structure). Mike

Making progress. Looks like you have got lots of double stars - tracking issue I assume, but you picked up the central star with a small scope - impressive. Visually i have struggled in a 20" scope. Mike

Much going on in your shot. Must visit this area sometime. No clear spells recently or predicted. Mike

Here is my only reasonably successful attempt at a PN (other than M57). Used the 15" Dob and the ultrastar camera, back in May 2020. Abell 75, also known as NGC 7076, found in Cepheus. I could not find out much info on this emission PN. I came across two magnitude values: mag 13.4 and 14.5, two distance values: 6000 lyrs and 8000 lyrs away, two size values: 1.7 and 1.8 lyrs across. I thought I had picked up the CS (mag 17.4) but high resolution images show two and maybe three stars in the centre. Thus at best my unresolved fuzzy white dot is two stars. The PN is elongated- no idea why!! Must do some finding out. Quality images show the PN is slightly bi-polar - not picked up at all in my shot. Visually this PN would respond well to an O111 filter. I wonder if a smaller pixel camera would pick up more detail in this PN? Mike

Fascinating. I was not aware of the hour glass nebula. Those super clear nights are to be savoured. Mike

Hi Martin, Enjoyed seeing what can be achieved and making me think about camera/filter at some point in the future. Mike

Hi Martin, I too have tended to avoid PNs for the same reason as yourself. I end up being sure I have got it in the fov but then cannot locate it. I remain undecided as to whether it is better to go for short subs (5sec) or longer subs (10-15 secs). Owen has sent me various challenges which as a rule I cannot seem to get a shot. I have tried different stretches and still failed. Certainly colour would seem to be a helpful approach. Enjoyed the post with its info. Mike

Agree that summer is a lovely time to sketch clusters. Mike

I had not realised that globular clusters could be so far in toward the central bulge. Always something to learn. Well done for tracking this one down. Mike

Hi Martin, this second capture makes the point that cameras just like our eyes need good seeing/transparency to get the best results. Thanks for posting the comparison. Mike

Hi Martin, I agree re the challenge of finding a small target. It took me two sessions to find this one. Mike

Palomar Compact Galaxy Groups are distant, faint and compact groups of galaxies and present a difficult observational challenge but using the EEVA technique makes it somewhat easier to view. Resources: Alvin Huey - http://www.faintfuzzies.com/Files/Palomar Compact Galaxy v1.pdf, is a useful resource. Here is my list from VizieR Palomar Distant Compact Galaxies BIG LIST.xlsx My list contains the hyperlinks to take you to relevant data pages. Last night I attempted my first two Palomar Groups. It was a nightmare trying to be certain I was in the right area. One success and one failure. Palomar 2259+1329. This turned out to be reasonably easy to find. I went to UGC 12281 first (what a beauty it is) - bottom left and from there I edged the scope toward where the target should be. This galaxy points to the 'suspects' - not highlighted in the shot - take a guess as to what bits of fuzz they might be. Below is a close up of the group and to the right is the image from the Alvin Huey publication. See labelled image below for mag details Here is some data from NED. A=about 586 million lyrs away. B = about 400 million lyrs away. Assuming I have understood the data correctly (I had to convert redshift values) then this group is not a true group? No data for C and D. Galaxy -16.1 is about 400 million lyrs away. The area of extended fuzz has 5 data points in Aladin - galaxies, some with no data. Finally just below the label '19' there is a triangle of noise? coincides with three galaxies one of which is mag 19.8!!! Mike

Here is my recent observation of Pal 13. Not exactly a bright globular! I was uncertain whether I had located it at first as it is dim. Mike Notes: Palomar 13 is one of the least luminous globulars in the milky way. The gravitational behaviour of globulars clusters can be explained by the intense gravitational forces within such a cluster. It has been suggested that there may be dark matter associated with globulars but this is not needed to explain the globular dynamics. However, in the case of Pal 13 the star velocities are not quite as would be expected, suggesting that there could possibly be dark matter present in this rather extended globular. Some analysis suggests that 95% of the globular mass is not luminous, implying dark matter. However, if I have understood correctly the presence of unresolved binary stars and associated mass is yet to be fully determined and may have a bearing on the amount of proposed dark matter or whether dark matter is needed at all to explain the cluster dynamics. It also appears that this globular is at its peak of breaking apart (dispersion) as it orbits the milky way in a rather eccentric orbit. The stragglers ejected from the cluster are blue in colour. Pal 13 is also a low mass cluster.

I have just transferred my Pal 12 info from a separate post to keep this thread going with globulars. Palomar 12 at -21 DEC is too low for anything worthwhile but here is my attempt from last night (Aug 18th). It lies about 62,000 lyrs away and is about 52 lyrs across. It is a relatively young globular cluster. Its proper motion indicates that it may have been captured from the Sagittarius Dwarf Elliptical galaxy about 1.7 billion years ago. Below my poor shot is the Hubble image.

Hi Martin, great to see some more globulars being added to this thread, especially the palomar globulars. I had contemplated trying to get the numerous sagittarius globulars but anything below -20 Dec is tricky for me from GB.

Fun to try these sorts of captures. Mike

Hi Martin, this VV is one I shall never see. VizieR classifies it as M. Mike

Hi Martin, great to see the shots. Doing them in colour enhances the dark nebulae. It tempts me to head down the colour route at some point. Mike

Hi Martin, I so enjoy the patterns and the fact that these galaxies are at the edge of what we can achieve with EEVA. Imagine putting the camera on a 20" Dob in mag 6 skies.........dream on. Mike