View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0000763 | SkyChart | 1-Software | public | 10-12-20 19:40 | 13-05-06 14:34 |
| Reporter | testcy | Assigned To | Patrick Chevalley | ||
| Priority | normal | Severity | minor | Reproducibility | always |
| Status | closed | Resolution | unable to reproduce | ||
| Platform | X86 | OS | Windows | OS Version | 7 |
| Product Version | 3.3 SVN | ||||
| Summary | 0000763: Artificial Satellites Predictions | ||||
| Description | How accurate are the artificial satellites predictions calculated in SkyChart? I made a comparison with predictions available under http://www.heavens-above.com/ and they do not agree. I also tried observing some idirium flares calculated in SkyChart without any luck. | ||||
| Tags | No tags attached. | ||||
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The precision is very good due to the use of two of the reference software in the domain, Quicksat and Iridflar. The agreement with heavens-above is generally within the same second for Iridium flare and a few seconds for satellite culmination, probably because the two software do not use the exact same definition for transit or culmination. Read quicksat.txt in Ciel\data\quicksat\ for more information. But to obtain this result you must pay attention to a few point. - Compare with the middle column time in heavens-above page. - The TLE files that come with the program are just for example, they are way outdated. - Always update the TLE files before an observation, if possible daily, from space-track.org (the "download tle" button) or celestrak.com - Also update the quicksat.mag file one or two time a year from qsmag.zip on http://www.io.com/~mmccants/programs/index.html - Use precise coordinate for your location (and the same on heavens-above). - If a satellite pass is not show in skychart this is probably because this satellite is not include with the TLE file you are using. Or because it as no magnitude estimate in quicksat.mag so it is wrongly rejected as too faint. - For satellite pass the +/- column show the estimated error in second. If this column is not blank, you are using outdated elements. - For Iridium flare the +/- column show the distance and direction to the maximum flare. - I need to put this information in the documentation :-) |
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I am using the latest TLE files and the same coordinates as in heavens-above. But still the satellites predictions do not match or even come close. The +/- column for satellite pass is not blank. Any idea what the problem might be? |
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It probably still use an old file. Are you sure you put the new TLE file in the folder that show on the message when you click the "download tle" button ? This must be in the satellites folder under the "User settings" directory as describe here http://www.ap-i.net/skychart/en/documentation/directories_and_files Also be sure you select your new the in the calendar page instead of the default visual.tle. |
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Can I have several TLE files in that folder (downloaded from http://celestrak.com) and which one should I select? What is the visible.tle that is automatically created and always selected? The calendar window disappears after the iridflar window closes and I have to minimize the skychart window and maximize it to make it appear again. Also after minimizing the calendar window again it disappears and I need to press the calendar button to make it appear. |
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To download fro Celestrack go to http://celestrak.com/NORAD/elements/ Under "Special-Interest Satellites" click "100 (or so) Brightest" and save the file as visible.tle Under "Communications Satellites" click "Iridium" and save as irifium.tle You can also download any other file you are interested with. But I generally prefer to download from http://www.space-track.org because they include a convenient full catalog in a single file: "Bulk Catalog Data Downloads", "Full Satellite Catalog", "Three-Line Format (includes object names)" Put the files at the location indicated in note 1491 and launch skychart. The list of .tle files are listed in the calendar page and you can select them in this list. Your selection is saved if you save the program options. We will look at the window focus problem after this point is solved. |
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I followed the above steps, but I still get different results. For the same brighter satellites the times do not agree and there is always a difference of several minutes. Additionally, skychart shows more passes for the same brighter satellites and different iridium flares. Am I the only one that has these problems? |
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qsmag.zip has been moved to http://www.prismnet.com/~mmccants/ |
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I update the documentation with a few more information. http://www.ap-i.net/skychart/en/documentation/artificial_satellites I compare again the result from skychart with heavens-above for a few satellites pass and Iridium flare. All the event correspond within a few seconds. If you still have the problem and want to reopen please upload a zip file containing: - your skychart.ini file - all the .tle files you use (from userdata\satellites folder) - a screen shot of heavens-above iridium result - a screen shot of heavens-above ISS result |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 10-12-20 19:40 | testcy | New Issue | |
| 10-12-21 08:58 | Patrick Chevalley | Note Added: 0001488 | |
| 10-12-21 08:58 | Patrick Chevalley | Assigned To | => Patrick Chevalley |
| 10-12-21 08:58 | Patrick Chevalley | Status | new => resolved |
| 10-12-21 08:58 | Patrick Chevalley | Resolution | open => no change required |
| 10-12-21 19:21 | testcy | Note Added: 0001490 | |
| 10-12-21 19:21 | testcy | Status | resolved => feedback |
| 10-12-21 19:21 | testcy | Resolution | no change required => reopened |
| 10-12-22 08:59 | Patrick Chevalley | Note Added: 0001491 | |
| 10-12-23 15:15 | testcy | Note Added: 0001494 | |
| 10-12-23 15:15 | testcy | Status | feedback => assigned |
| 10-12-23 15:16 | testcy | Note Edited: 0001494 | |
| 10-12-23 15:19 | testcy | Note Edited: 0001494 | |
| 10-12-23 15:28 | testcy | Note Edited: 0001494 | |
| 10-12-23 16:18 | testcy | Note Edited: 0001494 | |
| 10-12-23 16:19 | testcy | Note Edited: 0001494 | |
| 10-12-24 09:16 | testcy | Note Edited: 0001494 | |
| 10-12-24 17:18 | testcy | Note Edited: 0001494 | |
| 10-12-28 10:20 | testcy | Note Edited: 0001494 | |
| 10-12-28 11:01 | Patrick Chevalley | Note Added: 0001500 | |
| 10-12-28 11:35 | testcy | Note Added: 0001502 | |
| 10-12-28 12:00 | testcy | Note Edited: 0001502 | |
| 10-12-28 12:03 | testcy | Note Edited: 0001502 | |
| 10-12-30 13:37 | testcy | Note Edited: 0001502 | |
| 12-05-17 06:43 | Brice | Note Added: 0002063 | |
| 12-06-02 11:30 | Patrick Chevalley | Note Added: 0002095 | |
| 12-06-02 11:30 | Patrick Chevalley | Status | assigned => resolved |
| 12-06-02 11:30 | Patrick Chevalley | Resolution | reopened => unable to reproduce |
| 13-05-06 14:34 | Patrick Chevalley | Status | resolved => closed |
