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Re: APOD: The Large Cloud of Magellan (2015 Aug 27)

Posted: Fri Aug 28, 2015 4:27 pm
by neufer
BillT wrote:
Actually Gaia can resolve some stars in the LMC.

Gaia has just completed its' first year of normal operation and one of the things mentioned in the ESA's blog post is this:

"Gaia has delivered detailed light curves for dozens of RR Lyrae type variable stars in the LMC, and the fine details revealed in them testify to the very high quality of the data."

They also posted their first HR diagram of just 2 million stars. They are saying that they will have the first major data release after the second year of operation is completed next year. The link is http://sci.esa.int/gaia/56387-gaia-s-fi ... ervations/
Just to be clear:

Hubble's angular resolution is ~0.05 arcsecond or ~2,500 AU at LMC distances (~50,000 pc).

The largest known star is red hypergiant VY Canis Majoris (VY CMa) with a diameter of 13.2 AU.
Hubble's resolution of ~60 AU at VY CMa's distance of 1,170 pc
means that it can't really even resolve this Milky Way hypergiant.

However, what Hubble & Gaia can do is to isolate stars from their neighbors for
discrete analysis including locating the centers of their blurry light signatures to very high accuracy.

Re: APOD: The Large Cloud of Magellan (2015 Aug 27)

Posted: Sun Aug 30, 2015 12:58 pm
by Ironwood
I didn't realize the large magellanic cloud was so freaking big in the sky. I was trying to research what the farthest northern latitude it was visible from and read that it covers an area of sky that is 9 x 11 degrees. I had no idea it was that huge. I'd always pictured it as smaller than a full moon.

Re: APOD: The Large Cloud of Magellan (2015 Aug 27)

Posted: Sun Aug 30, 2015 2:08 pm
by Chris Peterson
Ironwood wrote:I didn't realize the large magellanic cloud was so freaking big in the sky. I was trying to research what the farthest northern latitude it was visible from and read that it covers an area of sky that is 9 x 11 degrees. I had no idea it was that huge. I'd always pictured it as smaller than a full moon.
The other side of that observation is that most people don't realize just how tiny the full Moon is.

Re: APOD: The Large Cloud of Magellan (2015 Aug 27)

Posted: Tue Sep 01, 2015 4:34 am
by Nitpicker
Chris Peterson wrote:
Ironwood wrote:I didn't realize the large magellanic cloud was so freaking big in the sky. I was trying to research what the farthest northern latitude it was visible from and read that it covers an area of sky that is 9 x 11 degrees. I had no idea it was that huge. I'd always pictured it as smaller than a full moon.
The other side of that observation is that most people don't realize just how tiny the full Moon is.
Another other side, is that the LMC is about the size of one's outstretched fist. If you find yourself at a sufficiently southern latitude, give the LMC a power salute on a clear night and you'll see what I mean.

(To see the whole LMC reasonably well, such that the lowest part culminates above an elevation of 20 degrees, one needs to be in the southern hemisphere, most ideally at a time around the December Solstice. Book your Xmas holiday now!)

Re: APOD: The Large Cloud of Magellan (2015 Aug 27)

Posted: Tue Sep 01, 2015 1:56 pm
by Chris Peterson
Nitpicker wrote:
Chris Peterson wrote:
Ironwood wrote:I didn't realize the large magellanic cloud was so freaking big in the sky. I was trying to research what the farthest northern latitude it was visible from and read that it covers an area of sky that is 9 x 11 degrees. I had no idea it was that huge. I'd always pictured it as smaller than a full moon.
The other side of that observation is that most people don't realize just how tiny the full Moon is.
Another other side, is that the LMC is about the size of one's outstretched fist. If you find yourself at a sufficiently southern latitude, give the LMC a power salute on a clear night and you'll see what I mean.

(To see the whole LMC reasonably well, such that the lowest part culminates above an elevation of 20 degrees, one needs to be in the southern hemisphere, most ideally at a time around the December Solstice. Book your Xmas holiday now!)
I've seen it well. It's rather boring (although the experience is improved if you have a good sense of what you're actually looking at). It just looks like a clump of the Milky Way- a faint gray patch. Our eyes simply didn't evolve to recover much information from astronomical objects. Thank goodness for cameras and other instruments!

Re: APOD: The Large Cloud of Magellan (2015 Aug 27)

Posted: Wed Sep 02, 2015 12:35 am
by Nitpicker
Chris Peterson wrote:
Nitpicker wrote: Another other side, is that the LMC is about the size of one's outstretched fist. If you find yourself at a sufficiently southern latitude, give the LMC a power salute on a clear night and you'll see what I mean.

(To see the whole LMC reasonably well, such that the lowest part culminates above an elevation of 20 degrees, one needs to be in the southern hemisphere, most ideally at a time around the December Solstice. Book your Xmas holiday now!)
I've seen it well. It's rather boring (although the experience is improved if you have a good sense of what you're actually looking at). It just looks like a clump of the Milky Way- a faint gray patch. Our eyes simply didn't evolve to recover much information from astronomical objects. Thank goodness for cameras and other instruments!
Yeah, almost all deep sky objects look comparatively dull to me now, even through the eyepiece of my small 6" telescope. Once I started attaching a camera to my scope, I found I hardly ever used my eyepieces anymore, except perhaps occasionally, to show other people the view of the Moon and the bright planets. And even the Moon and the bright planets look more detailed in photographic images (after processing) than they do at the eyepiece.

But still, on a clear night (even under my suburban skies) it is nice to spot the LMC and SMC unaided, and to realise that they are not just fluffy little atmospheric clouds passing a few thousand feet overhead.

Re: APOD: The Large Cloud of Magellan (2015 Aug 27)

Posted: Wed Sep 02, 2015 2:50 am
by neufer
Nitpicker wrote:
Yeah, almost all deep sky objects look comparatively dull to me now, even through the eyepiece of my small 6" telescope. Once I started attaching a camera to my scope, I found I hardly ever used my eyepieces anymore, except perhaps occasionally, to show other people the view of the Moon and the bright planets. And even the Moon and the bright planets look more detailed in photographic images (after processing) than they do at the eyepiece. But still, on a clear night (even under my suburban skies) it is nice to spot the LMC and SMC unaided, and to realise that they are not just fluffy little atmospheric clouds passing a few thousand feet overhead.
And what was your experience with SN 1987A :?:

Re: APOD: The Large Cloud of Magellan (2015 Aug 27)

Posted: Wed Sep 02, 2015 6:00 am
by Nitpicker
neufer wrote: And what was your experience with SN 1987A :?:
I was 13 years old and perhaps still jaded from the fizzer that was Halley's Comet a year earlier. I don't recall seeing SN 1987A. I wasn't much into astronomy at that time and I didn't have ready access to a telescope (and certainly not a digital camera). I imagine that it would have looked much like any other magnitude +3 star.