davhei

2 hours ago, Ruud said:

Wonderful sketches. Making them must help to really know these star fields.

Thank you Ruud. Yes indeed, it really adds a dimension to observing.

I see some people add a touch of colour to their sketches as part of the finishing at home. Have to try that at some point, probably fairly simplistic on a phone app, me not being into photoshop and the like. Looks great for colorful stars.

Thanks Rob, a toothpick really helps to get the thin lines. I believe someone on this forum provided the inspiration, can’t recall who it was though. Anyway it works well and I will thank that person if I run into the post again.

Made an attempt to sketch a few of the brighter stars, seeing as the full moon was out and the sky wasn’t suitable for deep sky observing.

Experimented with diffraction spikes on Vega, Capella and Arcturus to get a nice bright look to imitate the view through the reflector scope. Overall very enjoyable!

43 minutes ago, Littleguy80 said:

Wonderful report. You’ve inspired me to give this a go in my 10” dob. Excellent observing skills  

Brilliant! I recall that you inspired me to observe quasar PG 1634+706 in draco. If you could see that then Mayall II should be a breeze. 😀

12 hours ago, Rob Sellent said:

Aye, 254 would be the mirror size: 254mm or around 10". The 1200 number is the scopes focal length: 1200mm.

Clearly lacking the skills of Davhei, I think I'd struggle to find Mayall II with a 10" under dark skies With an apparent magnitude of around 14, even under dark skies, I reckon Mayall II is a tad beyond what a 90mm could pick out

Not wanting to speak for Davhei but I imagine it is a pencil sketch of Mayall II (not M31) and the smudge could have been produced with a blending stump.

Thank you for your kind words! Not sure I deserve all that much praise on the observation skills, it mostly boils down to aperture and dark skies I think. 90 mm does seem a tad on the small side for this object though. As a side note, the deepest I've gone with my scope setup is in the range of mag 14.4 +/- 0.2 for a quasar and thereabout I think is the limit for my location.

You are spot on, 254 mm or 10 inches is the mirror size and 1200 mm is the focal length. The technique is also just like you guessed, a blending stump to create the diffuse effect and a soft pencil to get the graphite for the stump.

That is a beautiful sketch, very inspiring! Thanks Jack.

Welcome from a fellow swede. Enjoy stargazing in the coming dark season during the precious few clear and cold nights.

Oh, northern europe certainly presents challenges for the aspiring astronomer. 😂

To begin this year’s dark season I wanted to try something faint in order to really get the feeling of dark skies again. Have had the andromeda galaxy globular clusters on my list for a while and decided to give G1 or Mayall II, the brightest one, a go.

Finding M31 wasn’t difficult and even though G1 was surprisingly far from the core regions it was still a fairly easy star hop. Had prepared detailed charts beforehand and that certainly helped. The difficult part was identifying the triangle asterism with two stars in one corner, a faint star of similar magnitude in the second and G1 with a magnitude of 13.8 in the third.

Once dark adapted it was a distinct but faint averted vision asterism but I found that at higher magnifications I lost it a couple of times and had to start over with wider field EPs.

Mayall II appeared starlike at first, and after a while I thought it took on a slightly diffuse appearence. Either from the two faint stars close to G1 or from that it had an angular diameter greater than a pinpoint star. Could never separate the glob from the two stars for certain even though I may have glimpsed it at times. Or not. Could have been tricks of the mind.

Spent some time on this object and found it really enjoyable. First in a session a few days ago and then again yesterday when I made a sketch as a keepsake. Had major dew problems on the secondary mirror though that made sketching more difficult.

Shall have to try the fainter M31 globulars as well, maybe doable but would certainly stretch the limits of the scope and myself.

Brilliant Robin, thank you!

After reading up a bit more, it seems that after the core collapse in the progenitor star, matter can be expelled at velocites close to 0.1 times the speed of light. After hundreds or thousands of years it gradually slows down to the speeds initially mentioned, such as the 40 km/s that purportedly had been measured in the Veil today.

So the changing speed is key, meaning the shockwave covered a lot of distance in the beginning and the slower remainder of it energizes the nebula today, some 50 ly from where it started. Fascinating stuff.

Again, just trying to piece things together in an amateurish way. Please set me right if I’ve gone way off the mark.

Yesterday I was observing the Veil, a glorious sight. Amazing when it appears out of nowhere, distinct as can be, when putting a OIII filter in.

I started thinking about the physics behind the light from the supernova remnant and was hoping for some input from people with more knowledge.

Various sources seem to indicate that the progenitor star towards the end of its life blew away matter in a sort of bubble around itself with strong solar wind. When the star went supernova 8000 years ago the shockwave expanded outward and eventually hit the matter outside the bubble and energized the particles, causing them to emit light. In effect meaning the nebula glows because of the shockwave, expanding into the interstellar medium even today, 8000 years later.

The nebula is approximately 100 ly across however and I did a bit of calculating on the required velocity for the shockwave to reach 50 ly in 8000 years, concluding it would be close to 1900 km/s. Could very well have messed up the numbers though.

Now this seems very high. The sources I found mentioned shockwave speeds of between 40 km/s and 170 km/s. Scientists measuring the speed of the shockwave from supernova remnant W44 came up with 12.9 km/s. 1900 km/s is a far cry from any of these.

So I can’t understand how the shockwave could have an impact over the distances involved. Radiation from the explosion must have reached 8000 ly by now and couldn’t actively reshape the nebula as we see it now could it?

Would really appreciate some input on the mechanisms that make supernova remnants glow. Would add another dimension to the observing for me.

Many thanks in advance!

Welcome Dark Lane. I’m observing from similar latitudes in Sweden, a few degrees more south probably. I’ve been surprised at how much I’ve enjoyed observing under summer evening skies. Jupiter, Saturn and the moon have offered pleasing views and the occasional bright double star added a bit of deep sky to the mix. Give it a go if you get the chance. Perhaps the planets are too low in the sky for you this year but it gets better in years to come.

Summer evenings added the fun aspect of public outreach to the experience as well. Lots of curious people stopping to ask about the scope and take a peek at the moon. Not as much interest from the public on bitterly cold and dark winter nights let me tell you. 

Wish I had been able to observe that event. Remember following what happened in the news but I didn’t have access to a scope back then. What an sight that must have been, not least for an active amateur astronomer.

On 04/07/2019 at 11:34, Helen said:

Universe by Freedman and Kaufman is excellent.  It is very readable, with lots of examples.  There are myriad versions of it though.  I'd suggest looking for maybe 2 editions before the current one (much cheaper and all the fundamentals are the same).  It is a University first year text book, so also comes up secondhand regularly 🙂

Helen

Got this one used just now based on your recommendation. Content wise it is great, just what I was hoping for! My 10th edition seems to have some problems with plus and minus signs being replaced by 1:s and 2:s in a number of places though, poor proof reading I suppose. Issue has been discussed in another topic on SGL apparently. Still, really a great book that I am sure I will keep coming back to for a long time. Thanks for suggesting.

Welcome! Very nice images, keep them coming. Enjoy your scope!

Excellent sketch! So immersive. Thank you so much for sharing!

33 minutes ago, wxsatuser said:

Cambridge double star atlas has e1 as northern most.

I suppose with Interstellarum having so many stars it is unavoidable to have a few mistakes. Still, it is a pretty famous object at that.

By the way. I got confused when I set out to determine which pair is e1 and which is e2. Looking in my copy of Interstellarum e2 is noted as the northernmost pair.

Other sources and the angle measurements of the component stars firmly indicate e1 as the northernmost pair.

Is this an error in the Interstellarum atlas?

53 minutes ago, wxsatuser said:

Nice sketch.

Think north and west could come round a tad clockwise.

Thanks! You are probably right. I forgot to mark it at the eyepiece and had to add it at home. Was pretty tired at that point 😴

Welcome Simon! Have fun!

Kind regards from Sweden

Epsilon Lyrae is a favourite system of mine and one I’m fond of observing. I was again out to view Jupiter and ended the session by sketching the ”double double”-system.

I believe part of the fascination lies in its ability to aid in visualising astronomical distances. According to my understanding e1 and e2 mains are separated by 0.16 ly and the components of each main by 140 AU. The whole system being 162 ly distant. It bridges interstellar distances and solar system distance scales. Very cool.

Bright summer nights here in the north so few background stars were visible, only one in fact, but it helps determine orientation in the drawing I think.

Pretty happy with the separation, angles and brightness of the component stars. Seemed fairly true to the scope view I felt. Not entirely sure about the west/north notation though, but as a rough indication it works.

Yesterday evening I took advantage of the clear weather and trained my scope on Jupiter. In my latitudes it reaches a maximum altitude of eight degrees at best so especially in the beginning of the session it was very low on the horizon.

Still, having never observed Jupiter through a telescope it was an amazing sight. The two cloud belts around the equatorial zone could be seen intermittently during holes in the seeing and eventually as it gained altitude they got very clear.

Observed for around three hours and during that time Io moved from one side, disappeared from view and reappeared on the other edge of the gas giant. Fascinating to see orbital dynamics before my eyes in real time!

Finished off with views of Saturn that was rising. Beautiful.

First time planetary sketching as well, more difficult than I thought. Really enjoy having as a memento of a pleasant observation session though. Here it is:

Welcome! Enjoy the journey ahead.

Clear skies

You inspired me that’s for sure, brilliant sketch. More so as you describe it as quickly drawn. I have sketched a few deep sky objects but never lunars. Think I will give it a go next time I’m observing. Well done!

Welcome Dave! I started with binocular stargazing from a reclining lawn chair before venturing into telescopic viewing. Nice way to move forward.

Clear skies