Last night's 'Grand Tour'

[RobertI]

Given the low number of transparent, still and moonless nights of recent months, I decided to make use of last night’s clear skies to grab as many interesting DSOs as I could, so I could research and enjoy them over the coming few days.

So first from last night’s grand tour was NGC2537 or Arp 6, the Bear Paw galaxy. The 'paw' was easy to see and the field contained a number of fainter galaxies. Apparently this a Blue Compact Dwarf (BCD) galaxy containing knots of young, hot, blue stars giving it a  blue colour.  The knots are easy to see in the image.

The edge on spiral IC2233 was nearby and I didn’t realise I had caught both in the FOV, would have framed the pair nicely if I had realised.

Given the fairly good transparency I had another crack at Jones Emberson 1, and I think I could make out more structure and shape than my last outing, posted a few weeks ago. A faint but intriguing object.

Next was NGC2864 the Helix galaxy. I think a much longer exposure is required to get the outer envelope, I have only managed the core, but I think I may have captured some of the ‘hoops’ at about the 11 o’clock position (you might have to zoom in) – what do people think?

This field contains numerous galaxies and is, I believe, part of the Abell 1185 galaxy cluster. In the centre is Arp 105, aka Ambartsumian’s Knot, comprising NGC3561A and B (about 4 o’clock from centre). A tidal stream stretches to the left of this pair but sadly I could not pick this up, longer exposures needed as always.

I thought I’d have a bash at the Leo A dwarf galaxy. It needed 60 second exposures but something was starting to appear. Quite pleased I got anything.

The Silver Needle galaxy NGC4244 was next. A very thin galaxy, a central dust lane was just visible and a stellar like core. Some brighter clumps also visible. I also tried stacking 63x30 seconds whilst I had a break for tea, and more details was definitely visible, but not sure it was worth the wait, and I have not included this.

 

NGC 4490, the Cocoon galaxy, and NGC 4485 are also known as Arp 269. Some lovely detail visible including dust lanes, Ha clouds and interacting arms. One of my favourites of the night.

 

M63 the Sunflower galaxy, what can I say, just spectacular, with the numerous knots and dust lanes clearly visible.

 

‘The Box’ galaxies Hickson 61, so named because the four galaxies form a rectangular box shape. From what I could find out longest, faintest of the four is not part of the group and happens to lie in the line of sight.

 

Probably the highlight of the evening NGC4631 or Caldwell 32, the Whale galaxy, a beautiful side on barred spiral with its elliptical dwarf companion NGC4627. Many nice dust lanes are visible and this is a good candidate for Ha which I may try some time.

Thanks for sticking with me, hope you enjoyed!

[Stu]

Cracking stuff Robert, an enjoyable read!

Sunflower and Whale are favourites for me. Lovely!  

[RobertI]

3 minutes ago, Stu said:

Cracking stuff Robert, an enjoyable read!

Sunflower and Whale are favourites for me. Lovely!  

Thanks Stu, it was a great evening.

[MarsG76]

Great set, and from one night.... good work....

 

[AKB]

8 hours ago, RobertI said:

hope you enjoyed!

Absolutely!  I like the Silver Needle, Sunflower, Whale, .... er, well, most of of them, really 

[Martin Meredith]

A marvellous collection Rob! My favourite (hard to pick) is Ambartsumian's Knot. I'm fortunate in being able to make out the jet from my location (but only with a longish run of subs).

I see you're using median throughout. Is this to avoid taking darks?

Martin

[RobertI]

7 hours ago, MarsG76 said:

Great set, and from one night.... good work....

 

Thanks! With so many wonderful DSOs to choose from at this time of year I was like a kid in a sweet shop!

22 minutes ago, AKB said:

Absolutely!  I like the Silver Needle, Sunflower, Whale, .... er, well, most of of them, really 

Glad you enjoyed, half the fun for me is sharing with others, makes it worth the effort, wish I could do more.

2 minutes ago, Martin Meredith said:

A marvellous collection Rob! My favourite (hard to pick) is Ambartsumian's Knot. I'm fortunate in being able to make out the jet from my location (but only with a longish run of subs).

I see you're using median throughout. Is this to avoid taking darks?

Martin

Thanks Martin, I want to try and speed up my system a bit with a Lodestar X2 and possibly faster F ratio, but will need to fiddle with the alignment of the optical train (its not quite right) to achieve the latter so will wait for the summer.

I haven't been using darks, the hot pixel removal feature of SL seems to work well, although the images are noisier than I like. I am not using Median for any particular reason, would I be better off with Mean? Towards the end I did take 10 darks but it didn't seem to make a huge difference. I Can't seem to get the 'smoothness' I used to get, any idea what I could do to improve this?

[Martin Meredith]

Theoretically mean will deliver the best SNR and if you're using darks or hot pixel removal there is little benefit of median unless to get rid of transients like satellite trails. The difference is not so great but it might explain any lack of smoothness. Do you save FITs by any chance? If so, I'd be interested to have a play...

Martin

[RobertI]

Thanks  Martin, I’ll change this for next time. I do save the FITS, shall I post one (or do you need more?). 

[Martin Meredith]

If you happen to have the complete set (for the Ambartsumian, say, simply because its a great grouping, but any DSO would be fine) I'd be very happy to have a go at restacking with my new tool (ulterior motive!) and checking whether median vs mean makes much of a difference ...

Martin

[RobertI]

Thanks for the offer to do that Martin, zip file below with the 11 fits files (files are named 'helix' but they're not!).

Ambartsumain.zip

Inspired by your suggestion, I quickly used Deep Sky Stacker to stack the FITs files using median and average (assume this is the same as mean?), both images were a lot smoother than my SL version, but couldn't see any obvious difference between the two stacking methods. Will be interested to see how you get on.

 

[Martin Meredith]

Thanks Rob. After playing around a bit I can simulate the grainy look by setting the black point just a little too high combined with a fairly aggressive stretch. But the raw data is fine and it is possible (as you also found with DSS) to get smooth results.

Here are a couple of attempts using 9 of the 11 subs (you had a satellite or plane fly thru one, and another had eggy stars, although they had remarkably little effect on the stacking). I used median as I don't yet have hot pixel removal. 

I was hoping to get some hint of the 'loop' from the inverse image but no joy. It really is exceedingly faint.

[edit] Just to add. Something I hadn't realised before (though probably obvious ...) is that the black point setting is absolutely critical. I've implemented a fine control that allows shifting the black point by as little as 1 part in 2**16 and it reveals that the difference between a setting at say (arbitrarily chosen ADU number) 2000 and 2010 is remarkable. 

Martin

[Chris]

What a productive night Rob, got to be very pleased with such a big haul of interesting objects. The Jones Emberson 1 object looks faint but very intriguing, I'll be looking that one up to see if there's a Hubble pic of it? The Sunflower galaxy is my second favourite galaxy after M51, and the detail you've caught is lovely, really like that one! 

The box group of galaxies is great too, first time I've heard of this group! 

Inspiring stuff Rob  

[RobertI]

1 hour ago, Martin Meredith said:

Thanks Rob. After playing around a bit I can simulate the grainy look by setting the black point just a little too high combined with a fairly aggressive stretch. But the raw data is fine and it is possible (as you also found with DSS) to get smooth results.

Here are a couple of attempts using 9 of the 11 subs (you had a satellite or plane fly thru one, and another had eggy stars, although they had remarkably little effect on the stacking). I used median as I don't yet have hot pixel removal. 

Many thanks for doing this Martin, looks like it is a simple case of "over stretching" myself (sorry). I was using an ipad to remote control the whole thing, and the screen does not show the same level of detail as my laptop, so that might have had something to do with it. I shall try altering the black point and less agressive stretch next time, as I don't think my version shows any more detail than your smooth version.

I haven't thought about inverse images, I don't think SL allows this live, but I will try this in future for really faint stuff.

Thanks again.

[RobertI]

1 hour ago, Lockie said:

What a productive night Rob, got to be very pleased with such a big haul of interesting objects. The Jones Emberson 1 object looks faint but very intriguing, I'll be looking that one up to see if there's a Hubble pic of it? The Sunflower galaxy is my second favourite galaxy after M51, and the detail you've caught is lovely, really like that one! 

The box group of galaxies is great too, first time I've heard of this group! 

Inspiring stuff Rob  

Thanks Chris. This is a wonderful learning experience for me, so many of these objects I have never seen or heard of, and I am learning so much,it's very addicitive seeing one fantastic object after another. Glad you like the results!

[Chris]

Found an APOD for Jones Emberson 1

https://apod.nasa.gov/apod/ap121030.html

Beautiful PN!

[RobertI]

48 minutes ago, Lockie said:

Found an APOD for Jones Emberson 1

https://apod.nasa.gov/apod/ap121030.html

Beautiful PN!

That's Really nice Chris, it’s amazing how you can see galaxies through the middle of the nebula! I think @ollypenrice recently imaged it too, from memory this is what inspired me to have a go.

[MarsG76]

11 hours ago, RobertI said:

this time of year I was like a kid in a sweet shop

Yeah, I bet you were

 

[Chris]

1 hour ago, RobertI said:

That's Really nice Chris, it’s amazing how you can see galaxies through the middle of the nebula! I think @ollypenrice recently imaged it too, from memory this is what inspired me to have a go.

I know, pretty crazy being able to see galaxies through it like a looking glass. Some nice galaxies surrounding too. I'll have a quick look for the Olly P version, cheers.

[RobertI]

47 minutes ago, Lockie said:

I know, pretty crazy being able to see galaxies through it like a looking glass. Some nice galaxies surrounding too. I'll have a quick look for the Olly P version, cheers.

I just had a quick search of SGL trying to find the image that inspired me, there are several amazing images which I recall seeing before (none from Olly that I could find) but I'm now not sure! Either way I take my hat off to anyone that can produce quality images of this faint object.

[Chris]

10 hours ago, RobertI said:

I just had a quick search of SGL trying to find the image that inspired me, there are several amazing images which I recall seeing before (none from Olly that I could find) but I'm now not sure! Either way I take my hat off to anyone that can produce quality images of this faint object.

Me too, found one by another Rob which looked excellent, but these are conventionally imaged with long exposures not EAA. There can't be that many EAA images around of this object, great job    

[GavStar]

Cracking images Robert, thank you. Gives me some ideas for objects to try - particularly whale and sunflower.