Thursday, 10 September 2015

Cornish Nights - Part 2

6th September 2015
Eeking out the last of the Summer after schools have started back, in the peace and quiet of our favourite campsite on the Roseland Peninsula, is beginning to become an enjoyable habit.  This is the third time we have been to this site and every time, we've been lucky with the weather and it has allowed some time for observing under clear skies.  But, this week in particular has been better than the rest.
Having been before and knowing what to expect, there was no question of wondering if the scope would fit in the car, but more of, what will I leave behind if anything to make sure the scope does fit.  I haven't been able to bring the SBT with me this week.  There had to be some compromise!  But, the 150p and the EQ mount stand in as a very capable travel/holiday scope for weeks just like this.  I set it up just outside the tent, checked collimation after the journey and settled down to watch the sun go down over the field next to the campsite.  Then, it was just a case of leaning back in the chair and spotting the first stars to come out.  Deneb put in an appearance almost directly over head, then Ursa Major started to emerge from the darkening sky.  I haven't made any sort of checklist or specific list of targets for the holiday, and was quite happy to just go with the flow.  Whilst waiting for the last of the daylight to disappear, I remembered that Saturn has been around throughout the Summer, and I wondered if it was still view-able.  I checked out its position on Stellarium, and sure enough, though relatively low, I could make it out with relative ease.  That was the first decision made.  I haven't seen Saturn for around 2 years because of my observing location at home means that there are various hills and buildings obscuring the view.  It was good to see it again, first at 25mm, and then at 8mm and finally 5mm.  8mm gave the better view of it in this case.  I found the 5mm EP wasn't quite sharp enough, and the seeing conditions out over the horizon towards the see meant that the planet wavered in and out of focus.  However, conditions did allow me to see some small specs of light dotted around the planet, which I later found to be some of the moons of Saturn.  However, as tricky as it was, I wasn't able to identify them individually.
This got me thinking.  If I could see Saturn from my position now, what else would I be able to see that I would otherwise struggle to observe from home?  I ran through my list of Messier objects that I still need to tick off the list.  By far, the single constellation that has the most within its borders is that of Sagittarius.  I started to check out the various charts and star atlas to compile a brief list, and then I got to work.
First up, M8.  This is an open cluster associated with some nebulosity.  This is also known as the Lagoon Nebula.  At mag. 6, it's within the capability of the 150p with some ease.  Although, I did often wonder what it would look like through the SBT.  The cluster itself was nicely visible, and I did see some nebulosity through the 25mm EP.  I decided to try the UHC filter in combination with the EP.  Did the filter make a difference?  Well, yes it did, but not much.  I felt the cluster lost some of its definition a little.  I think it was border line improvement/hindrance to be honest.  Nevertheless, the object could be marked down as seen.
M21 was next on my list.  Sagittarius is home to many open and globular clusters,  This cluster was well defined against the backdrop of darkening skies.  I could resolve approximately 30 stars in the cluster, although I don't doubt at all that the cluster itself contains many more stars than that.  Still, it's nice to see a cluster where you can resolve individual stars.  Many clusters appear more as smudges of light through the 150p as I was reminded throughout the session.
M22 was once such cluster, although it is defined as a globular cluster.  I had remained with the 25mm eyepiece throughout so far, not wanting to lose any light to the magnified field of view.  This time, the 25mm allowed be to see the cluster edges, quite large in comparison to the field of view.  Sagittarius is fairly low on the horizon at the moment, so I was also aware of all the extra thickness of atmosphere that I was observing through to pick these objects out.  A quote from the notebook.....

"The SBT would obviously help, but just having a first look about the teapot asterism is awesome."

M28 is among the easiest of targets to find in Sagittarius.  It can be found within a couple of degrees of the star Kaus Borealis, the top of the teapot if you like.  However, making it easy to find doesn't mean it will be the easiest to observe.  M28 is another globular cluster, but one that I struggled with.  At mag. 7, again, within the capabilities of the 150p, I found it hard to resolve, even with averted vision.
I decided to take a break from star hopping around Sagittarius and moved on to M9 in Ophiuchus.  This is yet another cluster, but at mag 8, was going to start testing the limits of my 150p.  Happy to work with what I had brought with me, and put some time and effort into searching these objects out, I tracked it down.  Star hopping to the area where it can be found was fairly straight forwards, but picking it out was incredibly tricky.  At first, I thought there was an problem with focus, but regardless how I tried, I couldn't get this one part of the field of view into a sharp focus.  However, I noticed the surrounding stars were coming in and out of focus accordingly.  This was the only way I could determine that what I was actually looking at was M9.
Remaining in Ophiuchus, I moved onto M10 and M12.  I've decided to pair these together in terms of observation notes for they appeared very similar to me.  Both clusters were quite intense at their cores. but faded quickly.  The backdrop to the cluster consisted of 10 or so individual stars that probably are not associated with the clusters.  I did find myself having to double check M10 when I first observed it as I thought I could start to make out some spiral structure to it.  I re-checked the charts and noted that it was a cluster and not a galaxy.  That will be my tired eyes playing tricks on me then!
Tired eyes indeed.  It was nearing time for me to turn in.  But first, there was just time to take in some other Summer favourites.  M27, the Dumbbell Nebula appeared grey and wispy set among hundreds of individual stars.  The Ring Nebula, M57 was just a short hop away.  I viewed it with the 25mm and the 15mm EPs.  The nebula is a brilliant target to observe, even with smaller magnifications.  Spending some time at the EP will help to resolve the ring structure of it, but I couldn't make out the central star with the 150p.  Another job for the SBT!
Just as I was about to start packing, I turned to the North East and could make out Cassiopeia easily.  I allowed my eyes to wander down towards the the constellation of Andromeda before settling on a patch in the sky.  The Milky Way had been visible all night, arching direct above my through Cygnus.  I refocused and stared for a while as this patch slowly come out to define itself against the darker backdrop.  What I was looking at was Andromeda, the spiral favourite of many an observer, and an easy 'wow' moment when introducing people to the world (or should that be universe?) of visual astronomy.  Moments later, the 25mm EP was in, the Telrad was pointing straight at it, and there it was.  An excellent way to end a first night under clear Cornish skies!

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