Stellarium not showing Comet Halley in its correct position?

stephenb (Stephen) · #1 10-07-2011, 09:15 PM

I'm trying to add Comet Halley data into the ssystem.ini file in Stellarium but when I open it in a text editor, then try to save it, I get an "Access Denied" message.

I am the administrator (and only user) of the PC, running Win 7, Stellarium 0.11.0. I've tried using Wordpad and Notepad with no success. And as far as I can establish I have full permissions to all folders.

Can anyone shed some light on what's going on?

mithrandir (Andrew) · #2 10-07-2011, 09:44 PM

Stephen,

There is a default ssystem.ini in the program install directory (usually %ProgramFiles%\Stellarium\data), and Vista or Win7 would only let an admin change it.

You can have a personal one in %APPDATA%\Stellarium\data. Copy the installed one to your dir. You might have to create the directory.

Andrew

BlackWidow (Mardy) · #3 10-07-2011, 10:46 PM

Have a look at the properties of the file. You may find it is set to read only. You need to change that setting to allow you to edit the file.

Regards
Mardy

stephenb (Stephen) · #4 11-07-2011, 11:22 AM

Thanks for the replies. Yep I tried everything suggested but wasn't able to successfully add the data. However I did find a feature in the configuration menu to download orbital elements from the Minor Planet Center. But I have found one interesting anomaly with 1p/Halley data...

Firstly what I'm am doing at the moment is entering in past dates and times to cross check all my photos and sketches of Comet Halley from 1985/86. I commenced this nearly 2 years ago and was able to pinpoint Halley's RA and DEC on my photos and sketches to the second. Every star on my photos/sketches matched Stellarium perfectly. I never got around to completing it however, so this week I decided to complete the project.

But now I'm finding the path of Halley is off track by several degrees. I am of course running a later version of Stellarium, and I can only assume that the orbital elements I have downloaded from the MPC are accurate.

It must be an issue with the data because I have the photographic proof of the comet's exact location.

Can anyone shed some light on to what could be happening? Should the data from the MPC be the most accurate?

mithrandir (Andrew) · #5 11-07-2011, 12:46 PM

Stephen,

ssystem.ini for 1P/Halley from MPC looks like this

Code:

[1phalley]
parent=Sun
orbit_Inclination=162.1905
coord_func=comet_orbit
orbit_Eccentricity=0.96715
orbit_ArgOfPericenter=112.293
absolute_magnitude=5.5
name=1P/Halley
orbit_Epoch=2455800.5
slope_parameter=3.2
lighting=false
tex_map=nomap.png
color=1.0, 1.0, 1.0
orbit_AscendingNode=59.3774
orbit_MeanMotion=0.0130342
orbit_MeanAnomaly=121.511
orbit_SemiMajorAxis=17.88185
albedo=0.04
radius=5
type=comet

This is taken from JPL/Horizons and Andreas' parser (mine seems to be broken), and has more significant digits in the values. There have been no observations added to the data since 1994, so the numbers will not have changed in Stellarium's lifetime.

Code:

[1PHalley]
# Data taken from JPL/HORIZONS
# correct for the specified time frame:
# Start Time : A.D. 2011-Jul-11 00:00:00.0000 CT 
# Stop Time  : A.D. 2011-Jul-11 00:00:00.0000 CT 
name                        = Comet 1P/Halley                       
parent                      = Sun
coord_func                  = comet_orbit
radius                      = 5.5
oblateness                  = 0.0
albedo                      = 1
lighting                    = true
halo                        = true
color                       = 1.0,1.0,1.0
tex_halo                    = star16x16.png
tex_map                     = nomap.png
orbit_Epoch                 = 2455753.500000000
orbit_TimeAtPericenter      = 2446477.4971088152
orbit_PericenterDistance    = 0.5884617797497997
orbit_Eccentricity          = 0.9670918775720379
orbit_ArgOfPericenter       = 112.2709434640211
orbit_AscendingNode         = 59.35052908354584
orbit_Inclination           = 162.1932522284531

# use M1 and k1 for the total magnitude of comets
#  absolute_magnitude = M1  brightness when 1 AU from sun and 1 AU from earth
#  slope_parameter = 0.4*k1 rate of brightening when approaching the sun
type                        = comet
absolute_magnitude          = 5.5
slope_parameter             = 3.2

Andrew

stephenb (Stephen) · #6 11-07-2011, 01:36 PM

Thanks Andrew,

I checked this data against my ssystem.ini and I amended every value to provide extra precision.

The ssystem.ini file is in %ProgramFiles%\Stellarium\data, as you said earlier, then ran Stellarium - no change.

I then changed the ssystem.ini in the Users%APPDATA%\Stellarium\data folder (I am the admin and only user anyway of this pc) and then ran Stellarium - and 1p/Halley is not found on the database at all

I am uninstalling and reinstalling the software and will try again.

Barrykgerdes · #7 11-07-2011, 04:55 PM

The release version of Stellarium does not have comet Halley in it. This file will be placed in the \stellarium\data folder by default. It will not overwrite anything in the user section. However if there is a ssystem.ini file in the user area it will take precedence when Stellarium loads.

I have an older large ssystem.ini file that does include coords for p/halley. The orbital parameters place Halley at 8h 28 52.8 and 2 08 26 (J2000).
The orbital parameters from this thread place Halley at 8h 30 59.9 and 1 58 35.0 (J2000) when inserted into the ssystem.ini file.

I don't know which is the closest. If you have some later sightings that agree better then use them. You could also feed the coords from 3 or more sightings over the last 20 years and generate a new set of orbital parameters yourself that should improve the overall accuracy. Don't forget to compensate for light speed.

Barry

Here is a large ssystem.ini file to try

stephenb (Stephen) · #8 11-07-2011, 05:15 PM

Thanks for the reply Barry. So, if I take the ssystem.ini provided and place it in the \stellarium\data, then delete the ssystem.ini in the user folder (so it doesn't take precedence), would that be the correct procedure in you opinion?

mithrandir (Andrew) · #9 11-07-2011, 05:19 PM

Stephen,

Quote:

Originally Posted by stephenb

The ssystem.ini file is in %ProgramFiles%\Stellarium\data, as you said earlier, then ran Stellarium - no change.

Don't change that one. Every time you upgrade Stellarium it gets overwritten.

Quote:

I then changed the ssystem.ini in the Users%APPDATA%\Stellarium\data folder (I am the admin and only user anyway of this pc) and then ran Stellarium - and 1p/Halley is not found on the database at all

Andreas' parser calls it "Comet 1P/Halley". That is what appears in the "name=" line.

If anything, I would expect positions to be more accurate for dates around 1994. These are the elements for 1994-Jul-11 and differ a little. See if they make any difference to your display.

Code:

[1PHalley]
# Data taken from JPL/HORIZONS
# correct for the specified time frame:
# Start Time : A.D. 1994-Jul-11 00:00:00.0000 CT 
# Stop Time  : A.D. 1994-Jul-11 00:00:00.0000 CT 
name                        = Comet 1P/Halley                       
parent                      = Sun
coord_func                  = comet_orbit
radius                      = 5.5
oblateness                  = 0.0
albedo                      = 1
lighting                    = true
halo                        = true
color                       = 1.0,1.0,1.0
tex_halo                    = star16x16.png
tex_map                     = nomap.png
orbit_Epoch                 = 2449544.500000000
orbit_TimeAtPericenter      = 2446466.9696176397
orbit_PericenterDistance    = 0.5876369748372741
orbit_Eccentricity          = 0.9670504573671932
orbit_ArgOfPericenter       = 111.3254544267585
orbit_AscendingNode         = 58.39231823706463
orbit_Inclination           = 162.2638347487183

# use M1 and k1 for the total magnitude of comets
#  absolute_magnitude = M1  brightness when 1 AU from sun and 1 AU from earth
#  slope_parameter = 0.4*k1 rate of brightening when approaching the sun
type                        = comet
absolute_magnitude          = 5.5
slope_parameter             = 3.2

Barrykgerdes · #10 11-07-2011, 06:51 PM

Quote:

Originally Posted by stephenb

Thanks for the reply Barry. So, if I take the ssystem.ini provided and place it in the \stellarium\data, then delete the ssystem.ini in the user folder (so it doesn't take precedence), would that be the correct procedure in you opinion?

That will work of course but if you update stellarium it will overwrite the ssystem.ini file in the\stellarium\data folder but not the version in your user area.

The best place to put you real working version is in the user area. If you don't like the version there remove it and put your new planned working ssystem.ini file in \users\your name\appdata\roaming\stellarium\dat a

I personally have no bother with permissions because I ran "take ownership" and re-set all the permissions to suit my requirements.

Incidently when doing a search you will need the exact name the comet is stored as. In Andrew's offered version it is "comet 1P/Halley". Halley or 1p/halley searches won't find it!

Barry

stephenb (Stephen) · #11 11-07-2011, 07:12 PM

Thanks Andrew and Barry, I will cross check these against the elements within the ssystem.ini that Barry provided in his last post.

edit: I've now installed Barry's file and Halley appears to be closer to its original path (my only frame of reference of its "original path" are my photos and sketches but they were done "on the spot" and are accurate), but they orbital elements make the dates out by exactly 6 days.

I'm assuming that with the minor variations in the decimal places in the values, that over time this will cause the error?

This is not a great issue for me as it is a consistent error (always 6 days), but the comet's path passed within a couple of minutes of some notable stars (iota Psc, omega Psc - in December 1985, and sigma Cap, HIP 100000 in March 1986) and in Stellarium does not show the comet getting as close as my photos.

I think this is as close as I can get, and I'm happy with the results. It's been a good learning curve with Stellarium (I still cannot get permission to edit/overwrite the ssystem.ini in the /data folder, irrespective of my Admin status

)

The reason I'm doing this is to compile all my information into a booklet to present to my family (and their families) in years to come.

Regards,
Stephen