Mike JW

9 hours ago, Martin Meredith said:

Any idea whether the Ultrastar issue can be fixed? It looks like some kind of weird inverted bleeding of charge from the bright stars. I assume it is always horizontal, flowing along the rows. Does it also occur when you expose in unbinned mode for a sufficiently long time?

Martin 

It only happens in 2x2 binned mode. So to loose it, I have to go for a black background which then looses detail in the DSO. It does not happen in unbinned mode even after 5 minutes. Yes it is always horizontal. No idea why it happens or if it could be fixed. Extremely annoying. Mike

I too had another go at the Arp 104 bridge. Attached. In the original the bridge can be picked out amongst the noise. Below is a my attempt - what a mess!

Mike

Arp 268 in Ursa Major is a delight to view because the view is so unexpected. It is a dwarf galaxy, not far away, just a mere 10 million lyrs away. It is quite active with young blue stars. Arp classed it as a galaxy (not E or S) with irregular lumps.

I have also been trying out Jocular. First image is my normal SLL view. Second image is Jocular - zoomed in. The black lines coming out of the stars is a Ultrastar oddity when I use 2x2 bining mode - so annoying.

Bootes VV 223. A friend pointed out this faint pair, actually a triple. It is a triple with a tight pair.  Mag 16.5.

In contrast here is VV 678 in Coma. At first glance I thought two, then three, maybe four galaxies. Actually classified as NN in the VV catalogue = disrupted nest (group of three or more). I would suggest there are four galaxies - mag 15.7.

Hi Martin,

Superb write up and shots. So much going on in this area.

Mike

Martin in a previous post mentioned the interest in this area. It is also the Webb Society Galaxy of the Month. Owen has written a very informative piece re this galaxy and the interactive Aladin Map on the website shows many more galaxies. I picked up quite a few of them - mainly as faint grey fuzz spots.

https://www.webbdeepsky.com/galaxies/2020/galaxy/april

I had to extend the capture to see if I could pick up any of the tidal streams and to my delight I just got the one between IC 790 and PGC 40736. I have played with the image a little in photoshop to get rid of the noise but to leave the tidal stream. Far left of the shot and near the bottom is a cluster of galaxies. Aladin image would suggest they are galaxies. Pretty Deep Maps shows this galaxy group with the faintest being mag 19.4. In addition to the obvious bright galaxies I located 26 other galaxies in this shot.

Mike

Hi Alan, Your report gives such a "sense of excitement" - there is so much up there to be excited about and at times in awe.. Mike

Last night (15/4/20) I took another look at Y4. Obvious that the core has changed from a curve to a more rounded appearance. Closer inspection suggests three separate brighter chunks. Are there two more behind the bright front three? Comet appeared to be dimmer than a few nights ago. Mike

Noting the posting in Hickson Galaxies - Hickson 40, it seems appropriate to post here Arp 321 which is also Hickson 40.

It amazes me just how well we do with the EEVA technique. Below is the original plate (200 inch Palomar scope) and my image from back in February. I have marked the galaxy Leda 82490 as it is at a similar distance to the main galaxy group and high resolution images reveal some distortion to it. This would suggest that at some point is may have interacted with the Arp group. The bottom three galaxies show signs of interaction, especially in high resolution images.

Mike

and a SHK thread........cloud now drifted in so tonight not likely....

Thanks Bill, I had forgotten it was VV as well. Looking good for tonight - comets and then dive off to Virgo is my plan. Mike

I enjoy this group. Wins the award for prettiness. It is of course Arp 321 so we get two for the price of one and as you say 5 different galaxy types.

Below is a cropped image from awhile back with the galaxies labelled.

Mike

Hi Bill, Thanks for the extra information. I had not spotted the existence of NGC 5906. I have taken a closer look at my original image and below is a cropped view of the key area. It looks like their are two star forming regions at this point - presumably both form 5906?

In keeping with the idea of having separate threads to keep our observations together rather than get lost amongst the many other posts, here is the Hickson thread. 

If you have any more resources PM me and I can add them into this first post, whilst I am able to edit it.

If as the thread develops you can see improvements/different ideas then post your thoughts. Mike

Resources:

http://www.reinervogel.net/pdf/Hickson.pdf

https://ned.ipac.caltech.edu/level5/Sept01/Hickson/Hickson_contents.html

https://cseligman.com/text/hickson.htm

Hicksons sorted by constellation.xlsx

Hicksons sorted by number.xlsx

Impressed as always. Also very useful to post the extra detail for anyone wishing to pursue NV. Mike

Just enjoyed comparing the two images . Mike

Hi Mike, The reason your sketch works so well is that you have captured the low contrast/softness of view when we are viewing craters under intense lunar illumination. I struggle to capture the softness when sketching edge of moon landscapes.

I am assuming you blended the pencil on fairly smooth paper?

Mike

Thanks Martin, When I use the 15, its tracking is so poor that going beyond 5 second gives me elongated stars.. I have improved the tracking so I should probably have a go at 10 second stacks with the 15. See below an annotated version. Thanks for the link.

Always enjoy seeing what you achieve with your set up. Mike

Hi Dick, a decent result. Aperture doing the trick for you. I enjoy using my C11 (equatorial mounted) for EEVA and even more so if I use the 15" Dob (does not track so well).

Mike

In a recent post David did a shot of Arp 104 and noted that he had not picked up the bridge. Nor have I in the past so last night I decided to get the 15 and ultrastar on the case.

Ignore the C11 details on the image below. I used the 15 at f4.5, 83 x 5sec. There is a hint of the bridge but it could just be noise in the right place. What my efforts do show is that even with a large aperture scope and almost 7 minutes of stacking the bridge is not obvious.

Thanks Martin, Great idea to compare our two shots and the link to the video, adds more drama. Mike

Bill, Great to see your shots and the comparison. Enjoyed the BAA link but much of it way beyond my knowledge.

Comet Atlas 2019/Y4. (April 12th 2020)

I was given the heads up that Y4 is breaking up. As we know Y4 has been worth a look for awhile as the volatiles and dust were released; making it bright. Apparently in mid March the comet stopped (slowed down?) the release of volatiles and I assume this is the cause of it not getting any brighter. The stresses and strains on the comet (sun’s gravity) appears to have now caused fragmentation, dust pouring off to form the large dust coma. The core no longer has the normal spherical appearance. The fragmented rocky junks are ahead of the core giving it a curved, elongated appearance. Visible in the image are the different zones of brightness. What will happen next?

Following Martin’s lead with the Arp-Madore thread. This thread can be used to post our Arp observations, to help keep our observations all in one place. Do not feel you have to post your Arp observation here. It seems worth giving the idea a go. All observations are worth posting to give folk an idea what can and cannot be achieved.

A few resources:

Website: https://www.mantrapskies.com/  is a superb resource for images and information

https://cseligman.com/text/arpatlas.htm - always enjoy visiting this site which is regularly updated

http://arpgalaxy.com/

http://ned.ipac.caltech.edu/level5/Arp/frames.html - comprehensive material with original images

Arp.csv

Arp.Catalogue.xlsx

Arps by type.xlsx

Arps sorted by constellation.xlsx

If anyone else has suitable resources, send them to me and I will post them here, whilst I can still edit this post.

If as this thread develops, folk can see a better way of keeping the Arp posts together and better organised - please make suggestions.

Thanks to folk for their enthusiasm to give this approach a go.

Good hunting as you hunt out these targets.

Mike