Dear Paddy,
Quote:
Originally Posted by Paddy
Here is report no. 2. for anyone patient enough to wade though it.
|
I certainly am ...
Quote:
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.
Quote:
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.
Quote:
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.
Quote:
Originally Posted by Paddy
And now following Les Dalrymple’s lead ...
|
oh no ...
Quote:
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 ...
Quote:
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?
Quote:
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