Nebula Add-ons/Distance of galaxies

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HB M
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Nebula Add-ons/Distance of galaxies

Post #1by HB » 28.11.2005, 11:51

When you just only want to go to a Nebula like the Eagle or one of the Orion nebulas on arrival the view can be very dissapointing. The view you get depends on where you a coming from previously. To avoid this kind of behaviour I use the gotolonlat-command in a scriptfile.
Ive made a script file for UGC10214 and as usually by other nebulas is a lon or lat of 0 or 90 (or viceversa)enough to get the view I want.
Celestia brings me to that place when I start this script but unfortunatly nothing will be showing. It seems that it is caused by the use of these values. In need to tilt the approach a little bit to see the UGC10214. Instead of 90 I need to use a value <80. The same effect is with the mouse or with the arrowkeys.

Maybe not a bug: In the deepsky.dsc database from Herr doctor Fridger Schremp is the distance in Lightyears. The screen,however, display the distance in (K)Parsec. When I convert the Lightyears from the database into parsec I get a different result then the value showing on the screen.
I use 3.26167 for converting LY into pc. Is there another factor involved by this simple conversion??
Such as earth to object or sun to object?
HB

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t00fri
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Re: Nebula Add-ons/Distance of galaxies

Post #2by t00fri » 28.11.2005, 21:00

HB wrote:When you just only want to go to a Nebula like the Eagle or one of the Orion nebulas on arrival the view can be very dissapointing. The view you get depends on where you a coming from previously. To avoid this kind of behaviour I use the gotolonlat-command in a scriptfile.
Ive made a script file for UGC10214 and as usually by other nebulas is a lon or lat of 0 or 90 (or viceversa)enough to get the view I want.
Celestia brings me to that place when I start this script but unfortunatly nothing will be showing. It seems that it is caused by the use of these values. In need to tilt the approach a little bit to see the UGC10214. Instead of 90 I need to use a value <80. The same effect is with the mouse or with the arrowkeys.

Maybe not a bug: In the deepsky.dsc database from Herr doctor Fridger Schremp is the distance in Lightyears. The screen,however, display the distance in (K)Parsec. When I convert the Lightyears from the database into parsec I get a different result then the value showing on the screen.
I use 3.26167 for converting LY into pc. Is there another factor involved by this simple conversion??
Such as earth to object or sun to object?


First proposal: skip the 'doctor' but write my name correctly instead ;-): Schrempp.

No there is no other factor to convert ly to parsec. But since you did NOT specify what deepsky.dsc version you used, I cannot help you further.

The point is that in 1.4.0pre7 and FT1.0 strongly outdated versions are used, since meanwhile I merged in further catalogs with lots of additional distance data. Some also changed substantially, since galaxy distances still exhibit large /systematic/ uncertainties!

But don't forget the displayed values in parsecs were directly calculated from the input distances in ly.
But did you make sure that your observer position was at Earth when reading off the displayed galaxy distance??
Bye Fridger

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HB M
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Post #3by HB » 29.11.2005, 07:26

Fridger,

Sorry, for misspelling your name.

I'm using the large deepsky.dsc version with the 10610 galaxies which came with the Celestia FT 1.2 version.
HB

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HB M
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distance of galaxies

Post #4by HB » 30.11.2005, 11:33

Fridger,

To give you an example:
I've found in the large deepsky.dsc for the M33/NGC 598 the following information:
distance: 3.262e+6 (ly)
radius: 3.259e+4 (ly)

The information on the display gives:
distance: 989.58 Kpc
radius: 9.9918 Kpc

This is seen from "earth" about 1AU from the sun which is in the center of the screen.

On an approach to the M33 only the distance will change but the radius should remain the same.
HB

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HB M
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Post #5by HB » 13.12.2005, 09:42

HB wrote:

Fridger,

To give you an example:
I've found in the large deepsky.dsc for the M33/NGC 598 the following information:
distance: 3.262e+6 (ly)
radius: 3.259e+4 (ly)

The information on the display gives:
distance: 989.58 Kpc
radius: 9.9918 Kpc

This is seen from "earth" about 1AU from the sun which is in the center of the screen.

On an approach to the M33 only the distance will change but the radius should remain the same.


I've checked the latest release from CVS(2005-12-12) and have noticed that nothing has changed in the displayed distance and radius of galaxies.
It's a pitty to see that all the good work from Fridger and Toti to assemble 10610 records for the DSO database and with high precision positioning becomes more or less useless if the distance and radius maybe displayed accurate enough but to my humble opinion wrong.
Is there's any relation with the given Axis coordinates and/or Angle?
HB


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