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Magnitude problem
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Santiago Roland
Hi guys, i'm having an odd magnitude problem in XEphem. We own an
ordered copy of XEphem 3.7.1 (including the catalog CDs) and some faint asteroids show as 2 or 3-ish magnitude. I updated the version of XEphem packaged for Debian distros from this site () and the error remains unchanged. I attach a screenshot of my problem so you can help me out. I'm trying to compile now the version following this tutorial () P.S: I compiled RC 3.7.7 and i have the same... Any help would be great! Cheers, -- Santiago Roland.- --------------------------------- Jabber: santiago@... Diaspora*: Identi.ca: openPGP ID: 7BE512C5 openPGP key: --------------------------------- |
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Santiago Roland
I downloaded the latest files from MPC (the links are shown in the
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screenshot), maybe they were not updates properly? I also hit the download button for Lowell and AstMPC_dim... will try again... Best regards, Santiago Roland.- --------------------------------- Jabber: santiago@... Diaspora*: Identi.ca: openPGP ID: 7BE512C5 openPGP key: --------------------------------- El 12/11/14 a las 02:40, ecdowney@... [xephem] ±ð²õ³¦°ù¾±²ú¾±¨®:
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Santiago Roland
Ok, i downloaded the Lowell dim catalog, but i still have the mag 3
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asteroid thing using the Unusual from the MPC, maybe the address for download is bad? I tried to download it again with no luck Will appreciate any help. Santiago Roland.- --------------------------------- Jabber: santiago@... Diaspora*: Identi.ca: openPGP ID: 7BE512C5 openPGP key: --------------------------------- El 19/11/14 a las 19:46, Santiago Roland santiago@... [xephem] ±ð²õ³¦°ù¾±²ú¾±¨®:
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Santiago Roland
Yeah, i keep having the same problem. I downloaded the Lowell dim
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catalog and magnitudes are fine, The issue is with the MPC files. I downloaded them in the orbital elements page for planetarium programs, fetched the link and entered in the download links in XEphem, deleted all catalogs and reloaded them several times. I get for unusual, magnitudes around 3 or 4. Any other ideas? Logs that i can post? I deleted the .edb and generated them again. See object 2010 JT123, what magnitude do you have for this object? I compiled the lastest version and i'm running it on Debian, XEphem 3.7.6 Best Regards, Santiago Roland.- --------------------------------- Jabber: santiago@... Diaspora*: Identi.ca: openPGP ID: 7BE512C5 openPGP key: --------------------------------- El 21/11/14 a las 15:04, ecdowney@... [xephem] ±ð²õ³¦°ù¾±²ú¾±¨®:
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Santiago Roland
And also detected other problem that is maybe related to the magnitude
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problem. It is in the numbering of the asteroids, see in the screen i toggled high magnitude for a panorama view of bright asteroids and notices the asteroid 1 Irene and 2 Amphitrite, they are 14 and 29 numbered, so maybe this issue is related with the magnitude one. Is somebody having this problem? or just me? I compiled the latest version, and i'm running Debian Wheezy 7.0 with backports repository. See the screenshot. Best regards, Santiago Roland.- --------------------------------- Jabber: santiago@... Diaspora*: Identi.ca: openPGP ID: 7BE512C5 openPGP key: --------------------------------- El 21/11/14 a las 15:04, ecdowney@... [xephem] ±ð²õ³¦°ù¾±²ú¾±¨®:
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Hey, using xephem 3.7.7-RC3 they show an updated name of 2014 FD7. I don't find either name in the .edb files from Lowell or the MPC bright, or dim, even after update. MPC directly reports the mag as 23.2ish for now. JPL sez the object has a heliocentric distance ~1.52e8km (1AU). Can you send me the filename and line from your .edb file? grep? '2014.*FD7' ?? *edb and grep? '2010.*JT123'?? *edb I don't get any output for either query. check your install base (mine is /usr/local/xephem/catalogs) and from your ~/.xephem dir. During this chase, I deleted? files from /usr/share/xephem/catalogs... Reran the app. Found MPC files in my ~/.xephem directory! deleted those reloaded So, I asked the MPC for the single line for XEphem, and saved this into a file in ~/.xephem/ast.edb and I can find, load, query, and Sky Point the 2014*FD7 critter. The mag reports fine. # From MPO315289 (HACKED HERE, OK in ast.edb attached) 2014 FD7,e,15.4565,187.2564,138.8035 ,1.203030,0.7469466,0.048986,50.8130,12/09.0/2014,2000,H21.5,0.15 Attached is the hacked output from a JPL vector query with object data from JPL and the hacked table from the MPC direct query. I realize you are not looking for these data exactly, but trying to solve the XEphem .edb issue, but here is the 'truth' from my two main sources for a baseline for debugging. I don't have a lot of time to dig into the code, but hope this helps. Good first cup of coffee exercise for me this AM! --Wayne On Tue, Dec 9, 2014 at 5:37 AM, Santiago Roland santiago@... [xephem] <xephem@...> wrote:
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with a different primary name? On Tue, Dec 9, 2014 at 9:17 AM, Wayne Green <dxwayne@...> wrote:
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-- Wayne |
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Santiago Roland
So, is this page of any use?
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Cheers, Santiago Roland.- --------------------------------- Jabber: santiago@... Diaspora*: Identi.ca: openPGP ID: 7BE512C5 openPGP key: --------------------------------- El 10/12/14 a las 22:04, Wayne Green dxwayne@... [xephem] ±ð²õ³¦°ù¾±²ú¾±¨®:
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Hey, If you want to proceed, lets take this offline. dxwayne at . We can post summary results later. To quiesce this particular thread... I've just noticed some sort of disconnect between the XEphem built-in Ast...edb files and the 'daily' type of MPC orbit files. But!!! I am moving fast over this problem. I downloaded the MPCORB.DAT.gz file and found the asteroid you seek. However it would need to be converted to .edb file. The XEphem user doc describes the fields. The MPCORB.DAT file is? a 'FORTRAN' like fixed column deal. I deal with these types of files from Vizier all the time, using python/editor as my choice approach for the moment. There is a completely new technique embedded in astropy for example, that allows grabbing tabular data and converting to ds9 tsv files pretty easy. (as in I don't want to hand edit it!) and appears well formed. The MPC states "At present MPCORB is not available via anon-ftp on this site." Not sure what the ramifications for XEphem might be. I don't know the direct link between the XEphem download files and this master file.I took Ceres as an example, and could not match the fields up between XEphem doc, edb, and Ceres' This is about as far as I can go with this, short of writing a python script to convert the MPCORB to edb- several hours at best. I don't have that time in my schedule. I need to dig into the XEphem source code to understand the real process. Someone might make a hack that takes the file you get via the HTTP download and make the files you need. So, alas, this first cup of coffee exercise hit the bottom of the cup before the bottom of the problem. Do I get partial credit? This page lets you enter asteroids, and will return a .edb line for just your target(s) of interest. That is how I got my little ast.edb file hacked together for testing, and was able to spot the H issue. H is in MPCORB.dat. How well are your python skills?? I suggest to all to use the Anaconda python package from Continuum.io site. It is free, and well presented for general analytics use on all platforms. I've used it under Mac and Linux, astropy is there and completely integrated. There is a trick to managing the PYTHONPATH etc to make it sing. The 'Young Turks' of astronomy are migrating to iPython (Anaconda is supporting this well)? from IDL. For astronomy try to stick to the 2.7.6+, as the bulk of existing stuff is there. Python 3.3.x is OK, but 2.7 seems to be the one for astronomy for now, seems to be the base for os scripts too. --W On Wed, Dec 10, 2014 at 5:50 PM, Santiago Roland santiago@... [xephem] <xephem@...> wrote:
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Soft03Unusual contains a few objects of interest, but I don't want to see hundreds of those tiny small pebbles displayed as mag 3 objects when I've set the solar system mag. limit to 12 or 14.? As mentioned many (but not all) of the (newer?? e.g. 2010 ... ) entries have the letter H designation as the prefix flag for an absolute magnitude, but no numeric digits after the H, only the comma separator followed by the other "G" parameter.? So XEphem probably sets H=0 for these, and derives a current apparent mag. of 3 or so, just due to these being a few AU from Earth and/or the Sun. Earlier in the thread it's mentioned that 21.5 is the correct H value for the particular object being discussed.? Briefly scanning the list for entries that do have a number after the H, it looks like it's typically about 20ish.? So I just used vi in a terminal window to replace all occurrences of ",2000,H,"? with ",2000,H20.0,".? At least they don't fill the sky like locusts any more for any modest or auto. mag. limit.? |