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Old 01-03-2011, 06:12 PM
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Paddy (Patrick)
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Another few good hours

Sunday night gave us denizens Strangways some more clear skies and I had some unfinished business in my chart 5 of the LMC. I spent quite a bit of time in the rich field around NGCs 2011-2040 before browsing some objects to the west of the chart. I think I now have notes for every object in chart 5 that's visible in my scope and feel quite a sense of achievement. Here are my notes for the evening. Except for the usual suspects visited at the end of the session - Omega Cent, M104, Saturn etc.

Telescope 410mm (16”) f4.9 tri-dob reflector
Eyepieces 28mm UWAN, 17,13,9 mm Naglers, Paracorr
Navigation: My charts of LMC Chart (#5 in particular) available at http://www.cloudsofmagellan.net.au

2250

Seeing excellent 1/5
Transparency good 6/7

NGC 2011/2040/2020/2021/2029/2032/2035/2040 Open clusters and emission nebulae in LMC

135x This is a stunning and complex area of sky, spanning the 37’ FOV of this eyepiece. Myriad stars against background haze through the western part of this complex and a broad area of luminosity with few stars to the east. 175X The eastern area of emission nebula is NGC 2040 (em neb) is a large 3’ area of diffuse glow with a few resolvable stars, roughly circular with a dark lane and further 2’ patch of nebulosity to the south. With averted vision several brighter clumps within the nebula become clearer. NGC 2040 is separated from the western part of this complex by a 4’ wide dark lane. The western part is very complex with a number of bright patches and dark lanes. Has about half a dozen resolvable stars. The western section is larger than 2040 and has a long, fainter extension to the NW. A pair of large bright patches in the southern part of the western section have extensions to the NE. NGC 2035 (em neb) is the southerly of these two patches, NGC 2032 (em neb) is to the north of 2035 and is larger and has a longer NE extension. 2032 appears 2.5’x1.5’ and 2035 is about 3’x4’. The wide NW extension of this western section arcs to the east and contains a 1’x.5’ brightening just to the NW of 2032 and this is NGC 2029(em neb). All of these objects brighten significantly with UHC filter and the dark lanes become more pronounced. A fine tracery of narrow lanes also appears especially in 2032 & 2035. The southern parts of 2032 & 2035 brighten very strongly and look a bit like a pair of kidneys. 2040 also appears more textured with an arc of brightness (convex west) emerging within its broader halo.

7’ to the NW of 2029 is NGC 2021 (OC)- a small, bright, fuzzy and slightly grainy knot against a wide N-S 12’ swathe of haze and stars. Dulls with UHC, but the background swathe of haze brightens. 8’ to the west of the southern tip of the swathe is a very bright knot of stars with a very bright stellar core, NGC 2011 (OC). With direct vision it looks small, about 30”, but averted vision reveals a larger faint halo and a diameter of 1’. Dims with UHC filter. To the south of 2011 is 2014 – a 3’x2’ rhomboid clump of bright stars at the southern tip of a broad 10’ wedge of scattered bright stars and nebulosity. 2014 stands out more distinctly from the wedges of haze and stars with UHC filter. The haze becomes brighter around the perimeter of 2014 and a dark lane to its north is accentuated. A 3’ dark gap separates it from NGC 2020 to the east which is a 2’ circle of smooth haze with one bright star in the centre, surrounded by a small dark inner ring. NGC 2020 lights up with UHC filter but the inner dark ring becomes more pronounced and less regular, with small branches of darkness reminiscent of the Trifid nebula.

A line through 2040 from 2020 leads east to NGC 2095, just to the east of a 25’ N-S line between 2 bright stars.

NGC 2095 Open Cluster in LMC

175X A sprinkling of faint stars against a long 4’x2’E-W rhomboid of haze with a long, thin, graceful arc of haze from its SW corner, heading NW. The whole thing is faint and easy to miss but very interesting on close inspection. The rhomboid looks thinner with UHC filter but the arc becomes more distinct and more contiguous with the rhomboid.

Tried without luck to find N70.

Henize N74 (Lucke/Hodge association116) Emission nebula in LMC

135X Large faint kite-shaped area of nebulosity and stars, tail to the east,
with a bright star, not very distinct against the background glow. To the north is a small flattened triangle asterism. 175X Looks about 12’x5’ and more detailed and distinct at 175x with a small bright knot at the western point, some wide dark lanes and more stars resolved. UHC filter enhances the kite shape and dark lanes. A SE-NW line of haze to the east also becomes more apparent.

NGC 2105 Open Cluster in LMC

175X Soft roughly circular 1’ glow with some grainy central concentration. Dims with UHC filter. 6’ to the SE is another smaller and fainter cluster which I’ve not marked on my charts.

At the western end of chart 5,

NGC 1846 Open Cluster in LMC

175X A bright, distinct and smooth 2’ circle of light with no central concentration. Fades to a soft edge. Not enhanced by UHC.

NGC 1844 Open Cluster in LMC

175X Smaller and brighter than1846 which is 7’ to the SE. Not enhanced by UHC.


NGC 1852 Open Cluster in LMC

175x A very regular round glow, but about half the size and brightness of nearby 1846. Not enhanced by UHC.

NGC 2669 Open Cluster in Vela

135X Very beautiful arch of delicate stars (convex east) and haze within rhomboid of brighter stars. The arch thins at both ends and has a stump of stars emerging from the concave side to give a mushroom shape. Bright outliers to north and south. The rhomboid looks about 15’ across and the mushroom about 10’.
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Old 01-03-2011, 06:30 PM
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orestis
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Way to go paddy great stuff,

Still cloudy here waiting for a clearing but having difficulty collimating dob.I'll ask you this question cause i know you'll know is the three large screws with the springs the adjustment screws.I didn't have these on my smaller scope.I'm a little confused and not sure if the laser is collimated itself.

Thanks in advance and great to see you making the most of your clear skies.

cheers Orestis
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Old 01-03-2011, 07:11 PM
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Nice report again Paddy and it's great you can make use of these perpetually clear Sunday nights! I swear it's the night with the highest frequency of clear skies. Conversly Sat night is the worst

Orestis, to check collimation of the laser, put it in a V-block, turn it on and aim at a wall. Turn the laser, if the dot's motion is circular/arcing as you turn the unit, then it's not collimated but if it stays in one spot it's okay.

However, the laser is really only useful for tilting the secondary so that the beam hits the centre of the primary. For initial centering of the secondary under the focuser, a cheshire is recommended, as is for completing primary alignment after you centered and aligned the secondary.
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Old 01-03-2011, 09:02 PM
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Paddy (Patrick)
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Thanks Orestis and Sab! Having Mondays off is great that way Sab, but I notice tonight that I also need Wednesdays off. In fact, astronomers shouldn't have to work - our appreciation of the universe should be enough!

Orestis, as Sab says I use a V jig to hold both ends of the collimator steady while I rotate it and mark out the path of the spot on a piece of paper ideally about 5 m away. Then tweak the screws to make the circle it makes as small as possible.

You will need to check the position of the secondary under the focuser before using a laser and I agree with Sab that a cheshire eyepiece is the best way to do this. I suspect that you won't want to wait til you can get your paws on one of these and you may find that using a plastic cap in with a small hole it the centre might do a passable job in the meantime. Some people use a 35mm film container. I used one of these from. But a cheshire is the way to go for good results. $59 at Bintel. Once the secondary is centred, you can adjust its tilt. Put the collimator in the focuser and turn it on. Make sure that the beam is not bouncing out of the end of the scope by passing a piece of paper over the end of the scope. If the mirrors are way out, the beam reflected off the primary may miss the secondary and come out of the scope. If it does, make sure you know where it is doing that so you can keep out of the way. Once you're sure that you're safe, get in front of the scope and look at the spot on the primary. The secondary holder has 3 screws on it which tilt the mirror against a spring. adjust these until the spot is in the middle of the primary. This means the secondary is properly aligned. Then go to the back of the scope. the Collimator will have a little 45 degree screen on it with a spot in the centre. The beam reflected off the primary and secondary back into the focuser will hit this screen. Adjust the screws at the back of the scope to get this to hit the little hole in the middle of the screen. When it does this, it will disappear like a little eclipse and you're collimated. The collimating screws are the ones with the springs. The 3 without springs are locking screws and a lot of people find they just muck up the collimation so leave them loose. You might find them helpful though. Use the springed screws to set the collimation then very carefully tighten the others just a tad and make sure the dot stays over the hole in the screen. Over time this will get much easier and once your secondary is in the right spot you only need to use the laser to adjust the inclination of the mirrors. You might Bob's knobs are good as you can adjust all the screws with your fingers. Putting stronger springs in (Bob's knobs provide them, but you might pick up good ones at a hardware store - I did for my 12" GSO) makes the whole thing more reliable.

Like a lot of people, I found this web site video very helpful

http://www.andysshotglass.com/Collimating.html

Hope this helps.
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Old 02-03-2011, 04:12 PM
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Thanks Paddy and sab for info,though the dot on the laser is playing up now when i turn it on its bright and then immediately fades so i can't see it far away.Maybe its the battery.

Anyways i had a look yesterday without it being collimated and will post a qucik report soon.

cheers orestis
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Old 02-03-2011, 05:10 PM
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Paddy (Patrick)
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Sounds like the battery.
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