Alvin Huey
Carpal Tunnel
Reged: 10/18/05
Posts: 1831
Loc: NorCal
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Hi,
Where could I find such a catalog that is compatible with MegaStar? I''m working on many lists, including varaible galaxies. I want to better estimate the magnitude of the galaxy by using the USNO catalogue as it goes way down to mag 20+. The current catalog goes down to mag 15. Most of the galaxies I observed are fainter than 15.
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Clear Skies,
Alvin #26
22" f/4.0 reflector and 30" f/4.3 StarMaster
FaintFuzzies | TAC | TAC-Sac
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JakeSaloranta
sage
Reged: 09/18/08
Posts: 237
Loc: Sisu, Sauna, Sibelius...
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Google.com
Seach time: 0,06 seconds
ftp://ftp.nofs.navy.mil/pub/outgoing/usnoa/
I think that's it  Good luck trying to estimate magnitudes with USNO though, the magnitudes are often way off.
/Jake
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Jeff Young
Post Laureate
Reged: 08/04/05
Posts: 4122
Loc: Ireland
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Jake --
Do you know if MegaStar can consume those directly?
I know a program has to be run on them to convert them to AstroPlanner's format, but maybe MegaStar does a direct import. 
-- Jeff.
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Nikon 18x70s / UA Millennium Colorado:
Solarscope SF70 / TV Pronto / AP400QMD Coronado SolarMax40 DS / Bogen 055+3130
APM MC1610 / Tak FC-100 / AP1200GTO Tak Mewlon 250 / AP600EGTO
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Alvin Huey
Carpal Tunnel
Reged: 10/18/05
Posts: 1831
Loc: NorCal
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Thanks Jake,
I googled them a month or so ago and didn't get those.
Did anyone try these in Megastar?
Or is there a more accurate stellar catalog?
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Clear Skies,
Alvin #26
22" f/4.0 reflector and 30" f/4.3 StarMaster
FaintFuzzies | TAC | TAC-Sac
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BillFerris
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I'm sure you're already doing this, Alvin, but for newer observers following the thread: another option is to download and print a Digitized Sky Survey (DSS) image of the field around a target. The DSS goes to something like magnitude 20-21 so, there will be no shortage of stars for any visual observer. The Skyview Advanced Form is my portal of choice.
The SIMBAD Astronomical Database is another useful tool. The Aladin applet allows you to view a DSS image with an overlay indicating cataloged objects, including field stars. Clicking on an object will display basic information such as ID (a clickable link to more info), object type, celestial coordinates, magnitude, etc.
These may not be as convenient as a really deep stellar catalog loaded into MegaStar (or your other favorite deep sky atlas) but they are readily available. The SIMBAD site also has a link to VizieR, which is a repository for data from a boat load of professional stellar catalogs.
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Grand Canyon Adventure
Lowering the Threshold
18" Obsession
4.5" Meade 4500
10x50 Swift Audubon
Cosmic Voyage
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JakeSaloranta
sage
Reged: 09/18/08
Posts: 237
Loc: Sisu, Sauna, Sibelius...
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Quote:
Did anyone try these in Megastar?
Yes, it works fine. Make sure you download the *.acc files as well as the *.cat files.
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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Yea... Megastar doesn't plot galaxies anyhwere near faint enough if you are truely on the edge of the capabilities of a 16" scope or larger. With my 18", I commonly observed galaxies that were not plotted on Megastar. With my 25" scope, it's not uncommon for me to observe 4 or even more galaxies in a galaxy cluster that Megastar doesn't plot even a SINGLE member in. I'll second Bill Ferris' suggestion: the POSS DSS images are what I use rather than Megastar because, well, even Megastar isn't deep enough for a big scope. I access the POSS DSS images through the SIMBAD Astronomical Database. Also note that very faint galaxies are sometimes confused with stars in the default Megastar star catalog, and I would assume this would be true for other star catalogs as well. This is yet another reason to go with actual images over artificial graphics.
Edited by tatarjj (10/22/09 11:02 AM)
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Alvin Huey
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Reged: 10/18/05
Posts: 1831
Loc: NorCal
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Thanks, I downloaded them and it works in MegaStar.
Thanks Bill, I knew of what you listed, but didn't know that one can overlay the data over a DSS image. What I'm trying to do is estimate the brightness of the variable galaxy I observed.
Thanks John, I regularly use the actual DSS or Sloan images when observing...but what I'm trying to do is estimate the magnitude of the variable galaxies using known mags of nearby stars. When I make the observation, I note that it is a little brighter than "a", same as "b", a little fainter han "c", etc. Then go home and look up the mags of a, b and c and can reasonable estimate the actual mag of the galaxy when observed. The mags of the variable glaaxies vary as much as 5 mags.
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Clear Skies,
Alvin #26
22" f/4.0 reflector and 30" f/4.3 StarMaster
FaintFuzzies | TAC | TAC-Sac
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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Variable galaxies? I assume you mean quasars/blazars/BL Lac objects?
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
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Alvin Huey
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Reged: 10/18/05
Posts: 1831
Loc: NorCal
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Yes John, Blazars and BL objects. And yes, I'm aware that MegaStar doesn't go as deep as threshold objects in my scope or your scope, especially in galaxy clusters. We saw that in Abell 2065.
I'm a deep sky nut, but don't really care for much of stars or stellar catalogues. How does on interpret the mags if the red and blue is listed. They differ by as much as a mag and half. Visually is one or the other more accurate or average? I would think closer to the blue mag.
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Clear Skies,
Alvin #26
22" f/4.0 reflector and 30" f/4.3 StarMaster
FaintFuzzies | TAC | TAC-Sac
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obrazell
member
Reged: 04/03/05
Posts: 56
Loc: United Kingdom
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I think you best bet would be to post on amastro and let Brian Skiff answer as he knows most about these things.
Owen
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davidpitre
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Reged: 05/10/05
Posts: 1825
Loc: Central Texas
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Doesn't Megastar have the ability to overlay POSS images from Real Sky ?
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David
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David Knisely
Postmaster
Reged: 04/19/04
Posts: 8285
Loc: Beatrice, Nebraska
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Quote:
Doesn't Megastar have the ability to overlay POSS images from Real Sky ?
Yes, it does (along with the ability to import the USNO A2.0 catalog containing 526,208,881 stars down to magnitude +19). Clear skies to you.
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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org
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Alvin Huey
Carpal Tunnel
Reged: 10/18/05
Posts: 1831
Loc: NorCal
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I got Real Sky and now just imported the USNO A2.0 catalog. Works very well together and is very useful on the field. I wish I had the uncompressed version of the Real Sky (aka POSS) on my laptop.
Since John and a couple others that the mags may be be a bit off. The red and blue mags are listed, I'm trying to determine the visual mags based on these two numbers, if there is one. I remember that the listed blue mags of glaaxies is about 0.5 to 1 mag fainter than the visual mag.
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Clear Skies,
Alvin #26
22" f/4.0 reflector and 30" f/4.3 StarMaster
FaintFuzzies | TAC | TAC-Sac
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