strangways sky report 22/10/09

[Paddy (Patrick)]

Dear all,

Here is report no. 2. for anyone patient enough to wade though it. Another aspect of this process is how much more I learn by checking my obs against books, internet and images. Very interesting.

Telescope 400mm f4.9 tri-dob relfector
Eyepieces 28mm UWAN, 17,13,9 mm Naglers, Paracorr
Skies clear, good seeing. Waxing crescent moon setting at 2300

This observing session was first light for my new 17mm T4 nagler, so involves some notes comparing it to observing with 24 mm Panoptic and 17mm LVW. And I am a happy chap.

Planets
Jupiter
The evening starts with Jupiter, the crescent moon still half an hour off setting. Musical accompaniment tonight is provided by numerous crickets. 132x Two moons are close together to the West of the planet (Io closest to Jupiter, then Callisto) and two further out and further apart to the East (Europa, then Ganymede). The Northern Equatorial Belt is well-defined and dark brown with a distinct notch about a third of the way across the disc form the western limb. I also note a thickening of the belt about the same distance form the eastern limb. Another fainter band to the North (the Northern Temperate Belt) is also visible and I can see further russet bands to the North of this. The Southern Equatorial Belt is also clear, paler and sandwiching a pale strip down the centre. The GRS is not apparent. The Southern Temperate Belt is also clear and has a very dark mark just to the west of the axis of the planet. Seeing affected by proximity to a tree. 175x shows little difference, the notch on the Nth Eq band is clearer as are some of the cloud bands closer to the poles.

Neptune at 175x shows as a pale blues disc, paler in the centre and bluer around the edges. I seek and fail to find Triton

Uranus appears as a pale blue-green disc, again paler in the centre and more coloured at the edges. Again no sign of a moon at 175x

47 Tucanae GC in Tucana. As there is still a little moonlight about, I visit 47 Tucanae, which I anticipate will be bright enough to allow a good comparison between my new 17mm Nagler and the Vixen LVW 17 and 24mm Panoptic that it will replace. I’m impressed by how similar the AFOV is to that of the 24mm Pan, yet how much better the contrast is. This confirms to my eye what I’ve heard others say – that magnification is what enhances contrast, not a narrower FOV. The contrast is similar for the Nagler and LVW, but AFOV strikingly different. I am indeed happy. As always, my eye is drawn to the little curved formation of stars near the core of the cluster, which surrounds a small area devoid of resolvable stars and slightly dark. There is a little parallel arc outside it and a hint of a counter curve making a fragment of a heart shape. Many stars are resolvable in front of the haze of the cluster. I note a strand of stars appearing to be pulled out of the cluster towards the North and another to the East.

I have always loved my LVW and Pan and am shocked at the ease and speed with which they are now consigned to their boxes.

NGC 7314 GX in Pisces Austrinus. 175x Partly edge-on spiral with bright but not sharply distinct nucleus. I have the impression of a dust land to the east of the nucleus.

NGC7285 GX in Aquarius . 175x I had forgotten that I looked at his lovely little pair of galaxies a few weeks ago until I saw their bright pair of nulcei staring out of their surrounding halo, which seem to have a prominence to the South-West.

NGC7582/90/99 GX in Grus 132x Hadn’t put the Grus trio on the list, but I couldn’t resist trying the new ep on these beauties. NGC7582 appears as an edge-on spiral with bright nucleus, central thickening and visible dust lanes. I estimate it as about 4’ long. NGC 7590 another edge-on spiral is about 2/3 as long and somewhat brighter with a foreground star at one end. 7599 is fainter than the other two, again about 4’ long, but wider than 7582 with less distinct nucleus. It seems wider at the Northern end.

NGC 7552 GX in Grus 135x Edge on spiral with bright nucleus. To the West of the nucleus is a dark dust lane. There is a foreground star at the Eastern end of the galaxy and another to the South.

NGC7213 GX in Grus 175x Very round halo around bright nucleus with no signs of spiral structure. I estimate halo is about 3’ across. I think that I’m looking at an elliptical galaxy, but the internet informs me that it’s a type a spiral and a Seyfert galaxy to boot.

And now following Les Dalrymple’s lead from the current AS&T I move into Horologium. He calls its stars “shy”. How polite. How sweet. They are little *******s to trace out a constellation from even in my dark sky. And how could anyone see a clock in this? But I eventually succeed as a koala roars and grunts obscenely.

NGC 1261 GC in Horologium 135x Some faintly resolvable stars, with impression of core using averted vision. I have a sense of a dark ring around the core, but this disappears with direct vision Small strands of stars to the both north and south. A fairly concentrated globular. 175x still gives impression of ring around the centre and some resolvable stars amidst a gC that’s mostly a haze.

NGC1433 GX in Horologium 135x Very distinct bar and nucleus. Halo very clear, but its hard to see the spirals. Appears about twice as long as it is wide. 175x spiral arms quite clear with averted vision and dark areas alongside the bar. A pair of Boobook owls serenade each other through the woodland.

M74 GX in Pisces 132x Face on spiral with distinct nucleus and dark areas throughout the disc, but I’m unable to discern spirals. I estimate about 7’ across. 175x I have an impression of spirals and some foreground stars riding on the tails of the spirals. Boobook owls joined by koala and neighbours barking dog.

NGC1365 GX in Fornax 132x Very distinct bar and 2 wide spiral arms. Dust lanes clear in both arms, but more so in the more curved of the 2. 175x shows more distinct texture along the arms with a dark patch at the base of the straighter arm near a foreground star. The other one appears to fan out somewhat as it passes a faint star about 2/3 the way along. Popplebonk frogs are now providing the chorus as I reluctantly pack up, tired and happy.

[ngcles]

Dear Paddy,

Originally Posted by Paddy

Here is report no. 2. for anyone patient enough to wade though it.

I certainly am ...

Originally Posted by Paddy

This confirms to my eye what I’ve heard others say – that magnification is what enhances contrast, not a narrower FOV. The contrast is similar for the Nagler and LVW, but AFOV strikingly different. I am indeed happy.

Glad you're happy. Its not so much magnification per se so much as exit pupil. I hate to keep on harping on about it (but I will anyway) but a telescope produces its maximum visual contrast on small low-contrast objects (like galaxies) when the exit pupil is getting down to about the 2mm mark. This is not new lore. It is not my lore. You can read this advice in the first edition of Hartung over 40 years old and in Lughunbul & Skiff's Observing Handbook -- and elsewhere. What's more, from what I've seen, it's correct.

Originally Posted by Paddy

I have always loved my LVW and Pan and am shocked at the ease and speed with which they are now consigned to their boxes.

I've had this phenomenon happen to me and seen it in many others. I remember my first truly premium ep was a 9mm T1 Nagler (I've still got it). It was hard to use anything else in my ep box -- everything looked better in that ep.

Originally Posted by Paddy

NGC7213 GX in Grus 175x Very round halo around bright nucleus with no signs of spiral structure. I estimate halo is about 3’ across. I think that I’m looking at an elliptical galaxy, but the internet informs me that it’s a type a spiral and a Seyfert galaxy to boot.

This galaxy is only about 15-odd arcminutes from Al Nair (Alpha Piscis Austrini) and is therefore very easy to find and has very high surface brightness. It is one of only four I know of that can be seen in telescopes in the Sydney CBD (at Sydney Observatory) and I use it there from time to time.

The classification is Sa ( an ordinary spiral with very tightly wound arms and large bulge). These can often look like an elliptical or lenticular type in the ep of large 'scopes. If you look at a DSS image like the one at NGC/IC project, you can see a few very thin, weak spiral arms within a halo and even an absorbtion lane dominated by a huge core and very bright nucleus -- justifying the classification. Like a lot of the galaxies in this part of the sky, it is about 70-80 mly away.

Originally Posted by Paddy

And now following Les Dalrymple’s lead ...

oh no ...

Originally Posted by Paddy

NGC1433 GX in Horologium 135x Very distinct bar and nucleus. Halo very clear, but its hard to see the spirals. Appears about twice as long as it is wide. 175x spiral arms quite clear with averted vision and dark areas alongside the bar. A pair of Boobook owls serenade each other through the woodland.

Good observation. Let me see now, x175 in a 40cm 'scope -- that would be about a 2mm exit ...

Originally Posted by Paddy

M74 GX in Pisces 132x Face on spiral with distinct nucleus and dark areas throughout the disc, but I’m unable to discern spirals. I estimate about 7’ across. 175x I have an impression of spirals and some foreground stars riding on the tails of the spirals.

Yep, that's very much the way I see it. True definite traceable "arms" are not easy to see in M74. I find NGC 2997 easier in this respect. Is it because it's higher in the sky? Is is because NGC 2997's arms are thinner and have more darks space between them?

Originally Posted by Paddy

NGC1365 GX in Fornax 132x Very distinct bar and 2 wide spiral arms. Dust lanes clear in both arms, but more so in the more curved of the 2. 175x shows more distinct texture along the arms with a dark patch at the base of the straighter arm near a foreground star. The other one appears to fan out somewhat as it passes a faint star about 2/3 the way along.

Beautiful detail that paints a real picture -- to me anyway. In really good conditions with 46 and 50cm, you can also see small dust-lanes within the bar either side of the nucleus as per the photos. NGC 1365 is just a stunner isn't it!

Thanks very much for taking the time to write this up for use all. Cloudy tonight in Sydney!


Best,

Les D

[pgc hunter]

Excellent report! Your galaxy observations are impressive, I think I need to drive a few hours to get some of the detail you're getting I observed NGC 1365 a few times in my 12" from outer suburban Melbourne, and really only can see the core. However those observations were made with a filthy mirror [/light scatter]

I have seen its spiral arms however with an 18" from a darker site. It's a fantastic object.

Originally Posted by Paddy

Here is report no. 2. for anyone patient enough to wade though it. Another aspect of this process is how much more I learn by checking my obs against books, internet and images. Very interesting.

That's one aspect of doing obs reports I greatly enjoy aswell, I find it fun comparing images to my obs/sketches and it's always gratifying to discover I wasn't imagining those details

[DavidU (Dave)]

Great report ! Good to read about the eye pieces as well.

[Paddy (Patrick)]

Les, Sab and David - thanks for your supportive responses. This is such a good process to go through. I'm learning so much more in so many ways. I'm afraid, Les, that I've got an idea of what exit pupil means, but actually getting my head around its implications is another matter. I will have to do some more reading to really understand how an exit pupil of 2mm gives the best contrast. I reckon it's about time I really learned the Hubble fork as well. Sab, it sounds like a trip to the Little Desert in November wouldn't be a bad move...

[barx1963 (Malcolm)]

Nice report Paddy. Glad you are getting so much use out of the Nagler. I enjoyed Les's column about Horologium, haven't had a chance to look for the galaxies in it yet, nice that you were able to.

Malcolm

[Lismore Bloke (Paul)]

Truly excellent report Patrick, very well detailed and nicely written. I am envious of your extra aperture, dark skies and your wildlife companions!!

Making notes in some form or other does bear out Les's experience that you tend to slow down, don't rush from one object to another trying to see as many as possible. Well done!!

[Paddy (Patrick)]

Thanks Paul.