Supergalactic plane incilination

What is the longitude of the ascending node of the supergalactic plane
and it's incilnation relative to the celestial equator. I understand
generally that the supergalactic coordinate system is rotated about 90
degrees from the galactic coordinate system. - Canopus56

In article .com,
canopus56 wrote:
What is the longitude of the ascending node of the supergalactic plane
and it's incilnation relative to the celestial equator. I understand
generally that the supergalactic coordinate system is rotated about 90
degrees from the galactic coordinate system. - Canopus56

The galactic coordinates of the pole and origin of supergalactic
coordinates are as follows:

supergalactic galactic

sgl sgb l2 b2

+90 47.37 +6.32 deg
0 0 * 0

Galactic to supergalactic rotation matrix:

-0.735742574804 0.677261296414 0.0,
-0.074553778365 -0.080991471307 0.993922590400,
0.673145302109 0.731271165817 0.110081262225

References:

De Vaucouleurs, De Vaucouleurs, & Corwin, Second Reference
Catalogue of Bright Galaxies, U. Texas, p8.

Systems & Applied Sciences Corp., Documentation for the
machine-readable version of the above catalogue,
contract NAS 5-26490.

* These two references give different values for the galactic
longitude of the supergalactic origin, and both disagree with
the above matrix, which gives l2 = 137.37 deg.

Patrick Wallace
__________________________________________________ _________________

Pat Wallace wrote:

In article .com,
canopus56 wrote:
What is the longitude of the ascending node of the supergalactic plane
and it's incilnation relative to the celestial equator. I understand
generally that the supergalactic coordinate system is rotated about 90
degrees from the galactic coordinate system. - Canopus56

The galactic coordinates of the pole and origin of supergalactic
coordinates are as follows:

supergalactic galactic

sgl sgb l2 b2

+90 47.37 +6.32 deg
0 0 * 0

Galactic to supergalactic rotation matrix:

-0.735742574804 0.677261296414 0.0,
-0.074553778365 -0.080991471307 0.993922590400,
0.673145302109 0.731271165817 0.110081262225

References:

De Vaucouleurs, De Vaucouleurs, & Corwin, Second Reference
Catalogue of Bright Galaxies, U. Texas, p8.

Systems & Applied Sciences Corp., Documentation for the
machine-readable version of the above catalogue,
contract NAS 5-26490.

* These two references give different values for the galactic
longitude of the supergalactic origin, and both disagree with
the above matrix, which gives l2 = 137.37 deg.

Patrick Wallace
__________________________________________________ _________________

Cripes you guys leave me in the dust with this stuff. I think i understood
the question "what is the angle of the plane of our galaxy as compared to
the plane of the enclosing galactic supercluster"? Did i get that right?
But I'm totally lost as to what the numbers in the answer mean. My best
interpretation is that if i were to hold my arm out and call that the
galactic plane and then rotate it 137 degrees up?down?left?right? that
would be the supergalactic plane?
Thanks - forgive my ignorance
Eric

In article ,
Cripes you guys leave me in the dust with this stuff. I think i understood
the question "what is the angle of the plane of our galaxy as compared to
the plane of the enclosing galactic supercluster"? Did i get that right?
But I'm totally lost as to what the numbers in the answer mean. My best
interpretation is that if i were to hold my arm out and call that the
galactic plane and then rotate it 137 degrees up?down?left?right? that
would be the supergalactic plane?
Thanks - forgive my ignorance
Eric

This...

supergalactic galactic

sgl sgb l2 b2

+90 47.37 +6.32 deg
0 0 * 0

...means (i) that the supergalactic north pole is at galactic
latitude 6.32 deg and galactic longitude 46.37 deg and (ii) that
the zero point of supergalactic longitude is at galactic latitude
zero. So the angle between the two equators is 83.68 deg.

Patrick Wallace
__________________________________________________ _________________

In article ,
Pat Wallace wrote:
latitude 6.32 deg and galactic longitude 46.37 deg and (ii) that
^
I meant 47.37. Sorry.

Patrick Wallace
__________________________________________________ _________________

Pat Wallace wrote:
In article ,
This...

supergalactic galactic

sgl sgb l2 b2

+90 47.37 +6.32 deg
0 0 * 0

..means (i) that the supergalactic north pole is at galactic
latitude 6.32 deg and galactic longitude 46.37 deg and (ii) that
the zero point of supergalactic longitude is at galactic latitude
zero. So the angle between the two equators is 83.68 deg.


Thanks, Patrick. I was trying to relate the angle of inclination of
the supergalactic plane to the celestial equator. 83.68 degrees sounds
about right for the angle between the supergalactic and galactic
equators.

When I plug supergalactic 0,0 into the NED Coordinate & Extinction
Calculator, it gives in equatorial -
http://nedwww.ipac.caltech.edu/forms/calculator.html

it returns -

Input: SuperGalactic
RA or Longitude DEC or Latitude PA(East of North)
0.00000000 0.00000000 0.000000

Output: Equatorial J2000.0
42.30997710 59.52821263 302.269517
02h49m14.39450s +59d31m41.5655s

vs. the angle of incidence of the galactic plane is:

NED Coordinate & Extinction Calculator Results
Input: Galactic
RA or Longitude DEC or Latitude PA(East of North)
0.00000000 0.00000000 0.000000

Output: Equatorial J2000.0
266.40506655 -28.93616241 301.401280
17h45m37.21597s -28d56m10.1847s

or 62.5 degrees for the galactic plane.

So the angle of the incidence of the supergalactic to equatorial plane
would be?

- Canopus56

Eric wrote:
Pat Wallace wrote:
In article .com,
Cripes you guys leave me in the dust with this stuff. I think i understood
the question "what is the angle of the plane of our galaxy as compared to
the plane of the enclosing galactic supercluster"? Did i get that right?

It's not a big deal. The supergalactic plane is simply the mean of the
"flattened pancake" of large galaxy clouds and the Virgo cluster
within, let's say, 100 million light years. Here's some graphs showing
the known universe in the supergalactic coordinate system -

Atlas of the Universe Plot 1B light years
http://www.anzwers.org/free/universe/superc.html

Atlas of the Universe Plot 100 M light years
http://anzwers.org/free/universe/virgo.html

When you look up at the night sky at the Virgo-Coma "Realm of the
Galaxies" -

- http://www.anzwers.org/free/universe/leda.gif (right-side)

notice that the Virgo Coma superclusters form in a line. This is the
"flattened pancake" of the nearby Virgo supercluster and nearby galaxy
clouds.

Fortunately, this "supergalactic plane" is almost at a right-angle to
the Milky Way galactic plane. If it wasn't, we would see little of the
galaxies in this nearby supercluster.

Try to vizualize how you would create a coordinate system if you
stripped away all the nearby bright-stars in the Milky Way and the
Milky Way DSOs and all that you would see are distant galaxy DSOs.
That's what the supergalactic plane and coordinate system does.

It is, however, confusing to mentally rotate and translate galaxy and
clusters between the three systems - the supergalactic, the galactic
and the equatorial.

- Canopus56

See also -

de Vaucouleurs, G. 1975. Supergalactic Studies.IV. Systematic
Orientation of Galaxy Clouds Relative to the Supergalactic Plane.
1975ApJ...202..616D
http://adsabs.harvard.edu/cgi-bin/np...pJ...202..616D

canopus56 wrote:

Eric wrote:
Pat Wallace wrote:
In article .com,
Cripes you guys leave me in the dust with this stuff. I think i
understood the question "what is the angle of the plane of our galaxy as
compared to the plane of the enclosing galactic supercluster"? Did i get
that right?

It's not a big deal. The supergalactic plane is simply the mean of the
"flattened pancake" of large galaxy clouds and the Virgo cluster
within, let's say, 100 million light years. Here's some graphs showing
the known universe in the supergalactic coordinate system -

Atlas of the Universe Plot 1B light years
http://www.anzwers.org/free/universe/superc.html

Atlas of the Universe Plot 100 M light years
http://anzwers.org/free/universe/virgo.html

When you look up at the night sky at the Virgo-Coma "Realm of the
Galaxies" -

- http://www.anzwers.org/free/universe/leda.gif (right-side)

notice that the Virgo Coma superclusters form in a line. This is the
"flattened pancake" of the nearby Virgo supercluster and nearby galaxy
clouds.

Fortunately, this "supergalactic plane" is almost at a right-angle to
the Milky Way galactic plane. If it wasn't, we would see little of the
galaxies in this nearby supercluster.

Try to vizualize how you would create a coordinate system if you
stripped away all the nearby bright-stars in the Milky Way and the
Milky Way DSOs and all that you would see are distant galaxy DSOs.
That's what the supergalactic plane and coordinate system does.

It is, however, confusing to mentally rotate and translate galaxy and
clusters between the three systems - the supergalactic, the galactic
and the equatorial.

- Canopus56

See also -

de Vaucouleurs, G. 1975. Supergalactic Studies.IV. Systematic
Orientation of Galaxy Clouds Relative to the Supergalactic Plane.
1975ApJ...202..616D

http://adsabs.harvard.edu/cgi-bin/np...pJ...202..616D

ok, i see now what your talking about, the pics made the difference
Thanks
Eric

In article . com,
canopus56 wrote:
:
When I plug supergalactic 0,0 into the NED Coordinate & Extinction
Calculator,...
:
So the angle of the incidence of the supergalactic to equatorial plane
would be?

Instead of 0,0, plug in the supergalactic pole: 0,90. This gives
equatorial coordinates 283.75,15.71, so the two poles are separated
by 74.29 deg. This is the same as the angle between the two equators.

Patrick Wallace
__________________________________________________ _______________________

Eric wrote:
ok, i see now what your talking about, the pics made the difference
Thanks Eric

Although we have pretty much wraped up this thread, the following are
my notes on visualizing the supergalactic plane for the DSO hunter.
This was what I was asking the top thread question for.

From the observing perspective of DSO hunters, the supergalactic plane
has meaning in terms of understanding the location of major groups of
bright galaxies and their positional relationships.

For example, in galactic plane, where we are embedded inside the
structure of the Milky Way, galactic DSOs are grouped around the
structure of the Milky Way plane. The following figure is a plot made
with Cartes de Ciel and shows a consolidated, non-duplicative catalogue
of approximately 340 Milky Way DSOs in Clark's, Messier's and
Caldwell's lists, as seen from the North Galactic Pole -
http://members.csolutions.net/fisher...ucture/GP1.jpg

In this diagram, the circle is the galactic plane projected onto the
celestial sphere. The FOV is about 270 degrees. The organization of
the galactic DSOs around the Milky Way plane is apparent.

Extragalactic bright galaxy DSOs are similarly organized around the
"flattened pancake" supergalactic structure of de Vaucouleurs. The
following figure is a plot made with Cartes de Ciel and shows a
consolidated, non-duplicative catalogue of approximately 820 galaxy
objects in Clark's, Messier's, Caldwell's and Arp's Peculiar Galaxy
lists, as seen from the North Galactic Pole -
http://members.csolutions.net/fisher...cture/SGP1.jpg

In this figure, the white circle is the galactic plane. I have drawn in
the supergalactic plane, using equatorial coordinates converted from
the supergalactic by the Nasa/Ipac Extragalactic Database Coordinate
Conversion Calculator.
http://nedwww.ipac.caltech.edu/forms/calculator.html

In the figure (SGP1.jpg), you are looking at the edge of the
supergalactic plane straight-on. As you can see, the supergalactic
plane is rotated about 90 degrees away from the galactic plane. Most of
the extragalactic DSOs plot like a scattergram, distributed on either
side of the supergalactic plane line. The spring "Realm of the
Galaxies" constellations - Leo, CVn and Coma B - can be seen near the
center of the figure and the supergalactic plane. Some major galaxy
superclusters are apparent, e.g. - the Virgo, the Coma, the Hercules,
and the Leo superclusters.

A similar grouping of extragalactic DSOs - the Perseus-Pisces and
Pisces-Cetus Superclusters - can be seen in another galactic plane view
- this time looking at the celestial sphere from the viewpoint of the
south galactic pole in the constellation Sculptor -
http://members.csolutions.net/fisher...cture/SGP2.jpg

That the Milky Way is embedded inside the "flattened pancake", the
supergalactic structure, like the galactic DSO figure shown above, is
more apparent when the celestial sphere is viewed from the
supergalactic north pole, as shown in the following figure -
http://members.csolutions.net/fisher...cture/SGP3.jpg

In this figure, the supergalactic plane is seen projected onto the
celestial sphere "face-on," as opposed to "edge-on" in a prior figure.
The white vertical line is the Milky Way galactic plane.

It is apparent that the bright DSO galaxies are grouped in some kind of
structure along the supergalactic plane - just as Milky Way
intra-galactic DSOs were groups around the Milky Way's galactic plane.

By comparing this figure (SGP3.jpg) with the more detailed plots at
Powell's Atlas of the Universe site - some of the supercluster regions
shown in Powell's 3-D images can be associated with the equatorial
celestial sphere projections shown in the above figure.
http://www.anzwers.org/free/universe/superc.html
- containing -
http://www.anzwers.org/free/universe/leda.gif

Prof. R.B. Tully, in his classic book - the Nearby Galaxies Atlas -
color codes these DSO galaxies by their supercluster association. If
you have the time to look at this Atlas at your local university
library, it is worth the trip to get some grasp of how the major spring
galaxy DSOs are related in 3-D. (I have left preparing an analogous set
of Cartes de Ciel plots for a future project.)

The final figure, part of the spring equatorial celestial sphere
covering the "Realm of the Galaxies" seen at an observing point at 41
deg N latitude, is shown with the supergalactic plane drawn in -
http://members.csolutions.net/fisher...re/MNight1.jpg

This is the portion of the equatorial celestial sphere seen about the
time of the Messier Marathon from 41N.

- Enjoy Canopus56

Tully, R.B. 1987: Nearby Galaxies Atlas. Cambridge Univ. Press.
http://adsabs.harvard.edu/cgi-bin/np...ga..book.....T