Jump to content

Banner.jpg.b83b14cd4142fe10848741bb2a14c66b.jpg

Spring!


Size9Hex

Recommended Posts

A superb night with the moon out of the way. The Dob was in its element hoovering up galaxies, but the evening was also unusually tranquil. There's normally a constant hum of traffic near me, but this time there was hardly a sound, until after midnight when an owl started calling.  

I caught the Fly in Auriga again. In my limited experience, it seems brighter and easier than the other Auriga nebulae, although I can only see a very small part of it resembling a fuzzy star. Raising the magnification (80x and up) was more help than any filter in revealing this section.

Before Auriga got too low, I also looked for the Spider, Flaming Star and IC410. Higher mag wasn't of much use, so I tried at 50x (a 5mm pupil, which is larger than I've used before on these targets) with and without UHC and Oiii. The view was very bright with no filter, but also uniform and flat. No nebulosity at all. Oiii seemed the best, plunging the scene into near blackness, but a lumpy kind of blackness. I tried comparing this against the scene off-target, but it all seemed a bit inconclusive and it may have been my brain playing tricks. Darker skies might be a very simple answer to this.

On to the galaxies. My brain always connects the dots in Leo into a New Forest pony rather than a lion. A tremendous scene of three galaxies in the eyepiece at once NGC 3608, 3607 and (faint at mag 12.3) 3605. Leo isn't short of triplets! Also caught NGC 3632 (Caldwell 40) just out of view alongside.

A nice time in Canes Venatici too, partly from the Caldwell list and partly from anything that looked interesting on the map.

The Cocoon pair, so close to the constellation star Chara that I always visit while in the area.
NGC 4369
NGC 4449 (Caldwell 21) looked a total mess.
NGC 4618 and (faint) 4625 in the view.
M94 was dazzlingly bright by the standards of the evening!
NGC 5005 (Caldwell 29) and 5033
Silver Needle Galaxy
Whale Galaxy

The Whale was surprisingly faint for the magnitude, and was maybe a touch too close to the lights from town. I failed to find NGC 4656 which I was expecting to be an easy and bright tick below it. Also failed to spot NGC 4236 (Caldwell 3 in Draco) which I thought would have been easy at mag 9. Writing this now, I can see it's a large and dispersed mag 9 compared the the other galaxies which are more compact. Maybe that's a factor in missing it.

I'm loving my first galaxy season and I feel like I've not even scratched the surfce. There's a surprising amount of variety even though they don't exactly gift any easy detail. The view of three galaxies at once is mind boggling to me though. Such incomprehensible scale! What a superb hobby that we can see such things.

I finished off with the Double Double in Lyra and M13 in Hercules. Old amigos from my very first session with binos last summer, and the first things I viewed in the scope in the autumn before they disappeared for the winter. Nice to welcome them back!

Link to comment
Share on other sites

Another excellent report Paul :) 

For galaxies (but also globular cluster and nebulae), you should also check the surface brightness, not just the magnitude. Well packed targets work like or almost like point sources. In the limit case we have stars of course. For these targets the visual magnitude is generally a good indicator. For extended targets, the visual magnitude is less and less important, sometimes almost useless, and instead the surface brightness is the main reference to consider. As you don't know a priori what to expect, I suggest you to have a look at both if you can. It can happen that an object is reported with a visual magnitude well within the limits of your telescope, but then you discover that its surface brightness is far beyond and the target is simply invisible.

 

A typical example is M33 (NGC 598):

- Magnitude: 5.70
- Surface brightness: 14.20
- Dimension: 68.7 x 41.6 '

Its visual magnitude is well within every telescope / binoculars, and actually even visible with naked eye. Although viewing M33 with naked eye is possible under very dark skies (and also used by some members here in SGL as initial checkpoint before attempting the Horse Head nebula), this target is enough extended that a modest amount of light pollution can be sufficient for making this target undetectable. As you can see, its surface brightness is quite low, and this is more correct indicator for the brightness of this target (one of the most difficult targets in the Messier Catalogue).

Link to comment
Share on other sites

1 hour ago, Saganite said:

Quite a haul of interesting targets Paul, pleased for you: thick cloud here tonight, so relaxing , perusing the Cambridge Double Star Atlas, glass of red in hand, and feeling quite mellow ! :happy11:

 

A great way to spend an evening. My glass was quaffed all too quickly tonight! :icon_biggrin:

Link to comment
Share on other sites

46 minutes ago, Piero said:

Another excellent report Paul :) 

For galaxies (but also globular cluster and nebulae), you should also check the surface brightness, not just the magnitude. Well packed targets work like or almost like point sources. In the limit case we have stars of course. For these targets the visual magnitude is generally a good indicator. For extended targets, the visual magnitude is less and less important, sometimes almost useless, and instead the surface brightness is the main reference to consider. As you don't know a priori what to expect, I suggest you to have a look at both if you can. It can happen that an object is reported with a visual magnitude well within the limits of your telescope, but then you discover that its surface brightness is far beyond and the target is simply invisible.

Thanks Piero! Useful tips (as always). It's interesting what you say about condensed targets that are almost point sources. I've recently wondered if the division between point/extended sources isn't clear cut, and whether it's magnitude or brightness that would come into play. I find this optical juggling an interesting part of star gazing, and also how our eyes and brain interpret the faint stimuli. I'm always happy to optimistically have a look for something regardless though! I guess part of it is that the numbers tell us the magnitude and (I guess?) the average surface brightness, but beyond what the numbers say, a target might have areas of higher than average brightness so you can grab at least a small part of it. The Fly is maybe a good example. I only saw a minute fraction of what's there!

Link to comment
Share on other sites

15 minutes ago, Size9Hex said:

Thanks Piero! Useful tips (as always). It's interesting what you say about condensed targets that are almost point sources. I've recently wondered if the division between point/extended sources isn't clear cut, and whether it's magnitude or brightness that would come into play. I find this optical juggling an interesting part of star gazing, and also how our eyes and brain interpret the faint stimuli. I'm always happy to optimistically have a look for something regardless though! I guess part of it is that the numbers tell us the magnitude and (I guess?) the average surface brightness, but beyond what the numbers say, a target might have areas of higher than average brightness so you can grab at least a small part of it. The Fly is maybe a good example. I only saw a minute fraction of what's there!

I don't know where exactly the shift is. In a crude way, one could use visual magnitude for proper point sources and surface brightness for DSO. I have to say that I am a bit like you. I have a look at the targets anyway as I believe there is a lot of fun in that. The concept comes up useful when you don't see the target and you realise what went wrong with that. I usually star hop with Stellarium Mobile on my tablet. There isn't any indication of target surface brightness. Said this, one can still have an idea by checking the target size and the visual magnitude. If the object is moderately large and the visual magnitude is almost at the limit of my telescope (in my case this limit is just 9-10 mag), I already know that that target is going to be a challenge. If so, I try anyway, but all possible techniques crossing my mind at the time are tried. :)

Link to comment
Share on other sites

As has aready been stated another very good report, there really have been some cracking write-ups on observations over the past few months making this a must visit area of the forum, well done.

On M33 I can see it naked eye from here on many nights but the dam horse has yet to be seen, I am beginning to wonder if it is even there.

Link to comment
Share on other sites

3 hours ago, alan potts said:

On M33 I can see it naked eye from here on many nights but the dam horse has yet to be seen, I am beginning to wonder if it is even there.

I don't have expertise to share on how to find it, otherwise I would.

What I can say though is that it took me a while to recognise how faint targets for my 60mm (some messier and NGC of average brightness) can look like. For months these were just confused with the background. Of course these targets would be detectable by many experienced members in here without much difficulty with my telescope. 

My point is that apart from the required sky conditions, a lot in the detection process has to do with the idea of 'what to expect'. This learnt patterns are also what makes an experienced user see features in Jupiter, while a new member just sees two equatorial belts and 4 moons. Now, Jupiter is a routine target, galaxies or glob clusters are still common targets, but that nebula seems quite different from most of the targets one usually observes. I guess it requires a specific training. If so, I would enquiry the members who spotted it to know exactly how it looked like, to know specific treats which were easier to recognise, the size of it at a certain magnification, glass used, how to place the field of view to keep bright stars out, which afov worked the best, whether specific eye dark adaptation were taken in the previous 30-40 minutes (e.g. no looking at bright globulars), angle of averted vision and what ever additional trick was employed.

Then I would try to spot these faint patterns only without care of spotting the 'head' itself, but just to find out where to look at. Once those references are there, observation after observation, a bit more should gradually appear. 

Thankfully there are some experienced members in here who spotted it, so part of this information to improve your pattern recognition, can be retrieved.

Just a comment of course,

Piero

Link to comment
Share on other sites

On 3 April 2016 at 05:57, cotterless45 said:

Super report , Canes Venatic is one of my favourite areas. Get up early and the whole of Cygnus and Aquila are up awaiting high summer,

clear skies !

Nick.

Thanks! It certainly packs a punch for a constellation with only two stars, and Cor Caroli is a stunning star from which to start hopping! Can't wait to see the summer constellations again - I only caught the briefest of uncollimated views with my new scope late last year.

Link to comment
Share on other sites

On 3 April 2016 at 06:02, alan potts said:

As has aready been stated another very good report, there really have been some cracking write-ups on observations over the past few months making this a must visit area of the forum, well done.

On M33 I can see it naked eye from here on many nights but the dam horse has yet to be seen, I am beginning to wonder if it is even there.

Thanks! :icon_biggrin:M33 is an enigma to me. My skies at home aren't great, but from the report you'll see they are by no means bad either. Nonetheless, 2 miles up the road into the countryside, my 10x50 binos consistently give me a better view of M33 than the 10 inch has ever delivered at home. I need to give it a proper go naked eye one day given its reputation as a Horsehead benchmark test.

My experience is really limited with the faint diffuse nebulae. All I know is that the only nights I've managed to see one, every galaxy I've looked out has absolutely jumped out of the finder scope, and the sky has been choc full of naked eye clusters to the point that they're actually distracting in the corner of my vision. These nebulae must be incredibly faint.

Link to comment
Share on other sites

@Piero sometimes all it takes is for someone to point it out. The other night I was out with a few other observers, I had the Leo triplet in my eyepiece, but could I see that third one!? Not until someone came over and showed me exactly where to look and what I was looking for.

Link to comment
Share on other sites

Excellent report, and a great thread of continuing ideas too. ;) Lovely list of galaxies there and that is just scratching the surface.

I agree what you expect to see has a huge bearing on what you do see and often the expectation has to change or be more educated by experience. I think I've started with 'nebula eye': having seen a few difficult ones, I'm getting better at finding the subtle differences in the skies where they hide. And size is the real kicker: knowing how large a target will be and then seeing it is a revelation!  Think about the first time you tried to hunt down Andromeda and how hard that might have been......was for me :) 

 

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.