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Some double lists for SkySafari Pro

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#26 inZet

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Posted 02 September 2013 - 02:20 AM

Bill, thank you for answering. WDS is a "live" catalog, you can't import it and forgot it. Data changes often. New doubles are discovered. You should provide an update every 6 months, at least.
For example, take GMC1, discovered two years ago by my friend Giuseppe. It is not listed in SkySafari, but I could easily split it.
I can understand if you don't include close doubles (<0.5") but all others should be listed.

Gianluca

#27 azure1961p

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Posted 02 September 2013 - 07:09 AM

I think omitting close doubles makes it objectionably poor.

Pete

#28 Cotts

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Posted 02 September 2013 - 09:28 AM

Several things: My point with my list of ten random WDS pairs was that EVERY WDS pair is shown as a (at least) a single star in Sky Safari. If you know the accurate RA and DEC (given in the WDS) then you can find the star, enter it into an observing list and have your scope GoTo that star. However, it seems from my admittedly small sample, that not very many of the WDS pairs are listed as double when you go to the 'Info" for these stars. I suspect one would find the same result with some other Planetarium programs but not for less than 50 bucks!

Regarding putting the WDS data in the 'info' part of Sky Safari, it is quite true that the WDS is a 'live' database and the data, a snapshot of the WDS at the time SS was written, will slowly go out of date. There is nothing SS can do about that except to continually produce new versions annually or so with the updated WDS. How expensive this would be to do is an exercise left to the student... I will guess that the cost would be prohibitive.

I think the inclusion of the sixth catalog of orbits is wonderful - I have had instructive fun watching Porrima go around its orbit etc. That the data for 6th Cat. pairs is date-accurate in both the planetarium screen and the 'info' screen is a fantastic feature (and what first attracted me to SS when Bill was showing it at OkieTex a few years ago). There must certainly be more pairs for which orbits have been published and that are not in the 6th catalog but, again, how expensive would it be to get them and enter them? And, it must be pointed out, the 6th catalog is a 'live' database and SS has a snapshot. These orbits are always being updated. and any particular version of SS will lack the updates. And, as stated earlier, the 6th catalog is a VERY small subset of the entire WDS and there's no solution to that situation. Again, not SS's fault.

What some people here seem to want is a full double-star planetarium program which is constantly linked via the internet to the WDS so that all data in the 'info' section is perfectly up-to-date and the actual positions of the stars in their orbits are perfectly shown if you zoom in fully. Plus all the other stuff in SS -galaxies, clusters nebulae, planets and moons and graphics and, and, and... I'd like to see that too, but I bet you'd be shelling out hundreds of dollars for such a program.. if it could be done at all...

Dave

#29 WRAK

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Posted 02 September 2013 - 03:13 PM

Dave, sorry for using your post for pointing out the shortcomings of SkySafari although I understood very well your intention to demonstrate that SkySafari is an excellent tool (especially for scope control it seems, but I don't use this feature) if you tweak it a little. But may be we can agree that it would be better to have no need to tweak.
Wilfried

#30 inZet

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Posted 04 September 2013 - 04:51 PM

Ok, all Tycho-2 is imported in StelleDoppie -test site- but matching with WDS needs to be checked and until next weekend I'll have no time to work on it.
Dave, I'll take your list (thank you!) as reference. I don't know where you took the data but a quick check with Simbad matches them all.

#31 inZet

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Posted 10 September 2013 - 10:16 AM

I have some problems checking Tycho-2 data because VizieR is under maintanance these days.
I can't even load the catalog in Aladin v7.5 software!

I tried to explore an alternative way not using Fabricious' "Tycho Double Star Catalog" (too old) data but imported the entire Tycho-2 file and tried to match the WDS based on coordinates and a proximity algorithm. Well, 1 of 5 does not match Fabricious'. Oh no! Including Dave's list. Including VizieR (when not offline).
Still investigating why. Can be my fault. Or... maybe, not, because all these results come from a single source.

#32 R Botero

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Posted 10 September 2013 - 03:01 PM

Thanks for the effort Gianluca!
Roberto

#33 inZet

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Posted 11 September 2013 - 06:30 AM

I fear what I'm going to say.
I hope to be wrong, but I think some Tycho-2 / WDS matches based on Fabricius' studies are not referred to primary star, but secondary.
Take 13126+5827 STF1732AB

In my not-matching list I can read:
+--------------+------------+------+----------+--------+------+------------------------+--------------+
| tycho2       | wds        | note | HIP_CCDM | HD     | Rcmp | chiave1                | w_tycho2     |
+--------------+------------+------+----------+--------+------+------------------------+--------------+
| 3849-00082-1 | 13126+5827 |      |  64454B  |   NULL | A    | 13126+5827STF1732AB    | 3849-00578-1 |
+--------------+------------+------+----------+--------+------+------------------------+--------------+


3849-00082-1 is the secondary, Fabricius gives it for primary star.

Simbad agrees with my analysis. See screenshot.

At times my algorithm fails. For example, on Dave's list 18000+2544 BRT 32 :
+--------------+------------+------+----------+------+------+-------------------+--------------+
| tycho2       | wds        | note | HIP_CCDM | HD   | Rcmp | chiave1           | w_tycho2     |
+--------------+------------+------+----------+------+------+-------------------+--------------+
| 2095-01032-1 | 18000+2544 |      |          | NULL |      | 18000+2544BRT  32 | 2110-01487-1 |
+--------------+------------+------+----------+------+------+-------------------+--------------+


which is dead wrong, because there's no 2110-01487 in this area. Still investigating.
Sorry I realized the subject doesn't conform this thread, I'll open a new one if interested.
I just wanted to demostrate to trust not a single source of data, including SkySafari, when they'll eventually import the WDS; including my site, of course.

Gianluca

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