David Geary

Orion Nebula sketch

M42, the Orion Nebula, sketched when high in the sky (and therefore out of the worst light pollution), from town on a moonless night.

Equipment used was a 16 inch Dobsonian and 26mm Meade Super Plossl giving me about 80x magnification.

M42 always looks like someone’s right hand holding a bow to me.  Ironic as its constellation is Orion the hunter.

(Coalville, 15th February 2018)

Moon Observations

I decided the best way to proceed with recording my observations of the moon was to make a special observing log just for the moon, and organise it according to the days of the month. This way I can keep a track of exactly what’s visible when. Before I carry on, I just wondered if anyone would like to suggest a few more features to try and find.  More specifically, what’s the best example of a ghost crater and lava dome?

(Day one is new moon)

Day 8 – exactly on first quarter
Got a good view of the Alpine Valley (the largest valley on the moon). It was quite close to the terminator and appeared as a dark wide line. Cloud prevented any more observations.

Day 9 – one day after first quarter
I have decided this is probably the best day of the month to view the moon. Moving from top to bottom, I got a good view of the Alpine Valley. Also a good view of Montes Apenninus, one of the best mountain ranges on the moon – the line of mountains ended just short of the terminator. Further down, the Straight wall (the largest fault line) was as clear as the nose on your face. Decided that 250x magnification definitely showed more detail than 155. The Alpine Valley has a serrated edge on the side furthest away from the terminator.

Day 10 Found the Straight Wall. It’s in the middle of a ghost crater, but it’s barely visible.

Day 11 Observing the moon with Harry. I couldn’t see the straight wall.

Day 12
I found two lava domes, Gamma and Delta, near the crater Gruithuisen. (Just a little down from the Bay of Rainbows.)  The 13mm eyepiece worked well, but the 8mm was even better, so maybe about 200x is best for these small features on the moon.  Close by I also found a lava channel on the Aristarchus Plateau. It was white with a few sharp turns. I’m not sure if this is classed as a sinuous rille.

Full moon
Can’t find the Cordillera Mountains, so this will not go on the list of good objects to find.

3 days after full moon and 3 days before first quarter
Found the alpine Valley, just above and to the right of the Sea of Rains. It’s in the middle of a narrow triangle formed by three prominent craters – Plato, Mitchell and Eudoxus. Even though the terminator was a considerable distance away, it was still visible, but only just. Must try when the terminator is closer for a better view.

 

Hubble’s variable nebula, and H-beta filter targets

Thursday 18th January  10.30 to 11.30pm    No moon   Observing from my back garden in Coalville

After several unsuccessful evenings, I finally found Hubble’s variable nebula. The trick is to wait until it’s at its highest point in the sky and therefore out of the worst light pollution, i.e. directly south.

I was concerned it would be so small it would be difficult to distinguish from a star in the low magnification wide angle eyepiece I was using to search for it – like Neptune and Uranus. However, when I actually found it I realised you’d never mistake it for a star – it’s too dim. The reason I’d had difficulty finding it was because it’s just very faint, even in my 16 inch Dob.

Hubble’s variable nebula looks a bit like a very small globular cluster – just a smudge at low magnification. At higher magnification of a 100 or 150x you can discern a triangular shape, with just a hint of a star at the tip. The best view was without a UHC or OIII filter.

Hubble’s variable nebula can be found by hopping from the star in the bottom of the drawing to a nearby double star, and then onto the Nebula.  It’s just above and to the left of Orion.

 

 

Had another go with the H-beta filter. I could see there was something there when I looked at the California Nebula, but I think I was using too small a FOV to make out any shape. I could see a bit of a fuzz surrounding one of the stars in the belt of Orion, but no Horsehead nebula. M43 wasn’t any better with the filter. The only significant extra detail I could see was a line behind the bow in the Orion nebula.  Not sure whether to keep the filter.

Orion Nebula Trapezium

Wednesday 12th December 2017
8.30 to 10pm Moon just past first quarter
A while ago at the club, someone suggested I try and see all six stars in the trapezium with my 16 inch Dobsonian.  Last night was really clear and I managed to see all six. I had a vague recollection I’d managed this before, but have only been able to see the four brighter stars the last few times I’ve tried. It must be something to do with seeing conditions/transparency.
All six stars were visible in my Vixen LVW 13mm eyepiece, which provides 155x magnification in my scope. The fainter two stars weren’t visible in my 8mm Televue Radian eyepiece, but I recall seeing them in an old Televue plossl eyepiece I used to own.
Comparing the two faint stars, the bottom one is slightly more inclined towards its neighbour, whereas the top one is pointing out more to open space. The bottom one is easier to see, but both stars were coming in and out of view, depending on atmospheric conditions.

David Geary

M17 The Swan Nebula (In Sagittarius)

Thursday 14th September   8.30 to 9.30pm   No moon

Found the Swan nebula. It’s not visible in the finder scope so I had to sweep the sky looking through the main scope to find it. I didn’t need a filter for this bit – the main body of the swan is visible without one. It could easily be mistaken for a galaxy. Once I’d found it I switched eyepieces giving me slightly higher magnification at 80x. A light pollution filter revealed the neck and part of the head. Not sure whether I prefer the UHC or OIII. It’s right what people say, there is a dark area in front of the swan’s neck – darker than the surrounding sky on all sides.  My star atlas calls M17 the Omega Nebula, which sent me off the trail for a bit. It also suggests the Swan Nebula has a star cluster right on top of it, but I didn’t see any noteworthy stars through the scope.

The Swan Nebula is impressive because of the unusual shape, whereas the Eagle and Lagoon Nebula are impressive because of the combination of a nice star cluster and nebulosity. I recon these three nebulae are about the best in this section of the Milky Way.  After scanning the surrounding sky quite thoroughly using a light pollution filter I couldn’t see anything else glowing, save perhaps a very slight smudge that I suspect was the Trifid Nebula.  Thanks to Nick in one of his posts for putting me on to the Swan Nebula, I may have overlooked it otherwise.

David Geary

The Lagoon Nebula

Saturday 9th September   9.30pm   Coalville   Streetlights nearby

No moon   Visibility clear but not brilliant

Another nebula that could easily be overlooked as you can’t observe it unless you have a clear horizon to the south.  I preferred the view with the UHC – the stars were brighter.  The OIII did however show a bit more nebulosity amidst the star cluster on the right.  This nebula is worth a look.  It’s visible from July to September so you’ll have to be quick if you want to see it this year.

David Geary

Globular star clusters close to the horizon plus the Eagle Nubula

Saturday 12th August 2017 10.30 to 11.30pm
Moon approaching last quarter and rose shortly after my observing session.
Observing with my f5 16 inch Dob.

I set my scope up in my Dad’s front garden this evening because it has a clear view to the south. The aim being to observe some new globular star clusters close to the horizon. To be honest, it was starting to get a bit boring observing the same stuff over and over again, and the only ways to observe new stuff are to go to a much darker site, go on holiday to Australia, or explore a lower patch of sky that’s previously been blocked by trees.

I soon discovered that nothing was visible in the finder scope this low down. The sky is lighter closer to the horizon and didn’t provide enough contrast. Instead, I used the Telrad to point the scope in roughly the right direction, then used my widest field eyepiece to scan for what I was looking for.

M22 proved reasonably easy to find, and reasonably impressive. It seemed to be quite spread out for a globular star cluster, lacking the usual concentrated core. It looked best in my Meade Super plossl, giving 80x magnification, rather than the 155x I normally use for globular clusters. I was denied a view of another globular cluster, M4, by a tree halfway down the street – which tells you how low it was.

I also managed to see M12 and M10 for the first time. (Also globular clusters.) They’d eluded me on previous occasions. Both were smaller and fainter, and needed 155x before I could see any individual stars.

A bonus was the Eagle Nebula. This looked best through an OIII filter at 60x. There are three bright stars at one end, and a cluster of about a dozen stars at the other end, with some cloudiness in-between. A UHC filter showed the nebulosity as well, but it wasn’t so pronounced. Without a filter, the cloudiness wasn’t visible at all. The fact that the Eagle Nebula is located by some prominent stars is handy, which should make it easy to point out to beginners. I can well imagine this nebula is a main attraction in more southern countries where it’s higher in the sky. If it’s clearly visible this low down it must be really impressive elsewhere.

I also showed my girlfriend Saturn, which she’d never seen before. It wasn’t a bad view for how low it was.  So there we are. It’s not every night I can say I’ve seen four new objects. Plus I saw the brightest meteor I’ve ever seen. If you want to see these globular clusters for yourself, and the Eagle Nebula, now is the right time of year.

David Geary

Sketches of Jupiter

 

Here are a couple of sketches of Jupiter I did last month.  I thought they might demonstrate the kind of views you can get of planets with a large Dob.  The first was made on Saturday 1st April at 2am, and the second was on Saturday 8th April at 11.30pm.  The scope was a 16 inch f 5 Dobsonian with a 1/10th wave primary mirror and a good quality unspecified secondary.  If I remember correctly, I worked out that the secondary mirror covers 21% of the area of the primary.  (Anything less than 20% is supposed to be good for planets.)  Teeters Telescopes in the US do a 16 inch f 5 Dob Planet Killer, so they must think it’s a good spec scope for planets.  I realise you’d get better views with a 6 inch apochromatic refractor.  I brought my scope for deep sky objects, but was pleasantly surprised by what I could see on Jupiter.

Half the trouble with observing planets with a Newtonian is tube currents.  This isn’t an issue with this scope – because it has no tube.  I usually pull up the shroud on the upper side just above the primary, to let out any warm air.

Obviously the main thing when observing planets is to wait until they’re high in the sky.  The light is then passing through the atmosphere at more of a right angle, meaning the light travels a shorter distance through the air.  This results in less blurring.  I also avoid looking over houses close by, as warm air rises from these too.

David Geary

Report on The Peak District Star Party

Peak District Star Party – Riverdale Campsite

Saturday 25th March 2017  

7pm to 11pm   No moon

M51 (The Whirlpool Galaxy) and NGC 5195  

It’s been my ambition for 20 years to see the spiral arms of a galaxy, and I finally got the opportunity to take my 16 inch Dob to a dark sky site last Saturday.  Shortly after arriving I asked a guy with a big Dob which galaxy is the best bet.  As I suspected, the answer he gave was M51.

I trained my scope on M51, and as usual, I could see this galaxy plus the fainter galaxy, NGC 5195 underneath.  Where I live, in town, I can see the bright core of M51, and the dimmer outer regions, but I can’t see any detail.  I was very much hoping things would be different in the Peak District.

By mid-evening I could see that the outer region definitely looked brighter in some places than in others.  I found that 150x magnification showed more detail than lower magnification.  As I moved away from the core, downwards and to the right, there was quite a dark area, then a brighter area as I moved further way from the core.  But I couldn’t piece the lighter and darker areas into a spiral.  By 10.30, however, I was confident I could see at least a little piece of a spiral.  The most obvious part started on the right of the core then swept down and round to the left underneath the core.  There was also a hint of one on the opposite side.  I decided that if I could work out from my own observations which way the spiral arms went round, then I would conclude I’d really seen them.  After finding some sketches on the internet when I got home I decided that this in fact was the case, so I’m counting the expedition as a success.

Other targets

As you might imagine, most other things looked a little more impressive, particularly M3, the globular star cluster just above Bootes in Canes Venatici.  The most noticeable difference was the Owl Nebula.  In the past I’ve only been able to see this using a light pollution filter, but it was clearly visible through the main scope without a filter in the darker sky.  I still couldn’t see the eyes though.  Unfortunately I could still only see the usual four galaxies in the Virgo Galaxy Cluster, M84, M86, NGC 4338 and 4435.  Maybe I’d have seen more on another night or if I’d stopped latter.

22 inch Dob and 13mm Ethos eyepiece

I had a look at M51 through an 18 inch Dob, and then a 22 inch Dob.  I could see a bit more detail in each, but not masses more.  It’s the same when moving from a 10 inch to a 16 inch.  There’s a worthwhile improvement in what you see, but not as much as you might expect.

Interestingly, both guys were using 13mm Ethos eyepieces, which would give them around 150x magnification.  The opportunity to look through a really big Dob and an Ethos eyepiece made the trip doubly worthwhile.  I have to say though, that I wasn’t sufficiently awed by the 100 degree apparent field of view that I’m going to buy one.  Nor would a larger telescope be practical given how I store and transport my scope.

The one thing missing

The one thing missing from this event was the car loads of locals who’d travelled up to see the wonders of the universe and take advantage of the clear sky and fabulous telescopes.  There weren’t any regular campers who wanted a look either.  I did, however, notice that the campsite bar and café were jam packed with people.  Shame.  At least some people benefitted from the experience.  I enjoyed myself.  Even my girlfriend said she enjoyed the evening.  Praise indeed!

David Geary