Return to the Cloudy Nights Telescope Reviews home page


Observing >> Double Star Observing

Pages: 1 | 2 | (show all)
R Botero
Pooh-Bah


Reged: 01/02/09

Loc: Kent, England
Re: Some double lists for SkySafari Pro new [Re: inZet]
      #6056536 - 08/31/13 06:55 PM

Apparently later this year or in the new year (for v4). But the inclusion of the WDS catalog is not certain.
Roberto


Post Extras: Print Post   Remind Me!   Notify Moderator  
btschumy
Vendor - Simulation Curriculum
*****

Reged: 04/13/04

Loc: Longmont, CO, USA
Re: Some double lists for SkySafari Pro new [Re: WRAK]
      #6057652 - 09/01/13 01:04 PM

Quote:

With all due respect - SkySafari is a nice program (I use it myself on my Android phone) but it is no tool for serious double star observing: too many doubles missing, too many errors in the advertised data. The use of known orbits as goodie does not help much here - there are simply too few doubles with orbits compared with the vast rest without.
Wilfried



I would appreciate it if you would point out any inaccuracies in the SkySafari database. The only issue I know of is that we show the data for the AB pair (the first pair listed) and this is often not the one amateurs are interested in. We are hoping to address this and show information on *all* pairs in SkySafari 4.

With respect to it not having many doubles, are you aware that there are several orders of magnitude more doubles than are in the Double Star list? That list is just some of the best doubles. We really do have most stars in the WDS. The ones we don't have are those that could not be matched up with stars in the Tycho catalog.

We should have orbits for every star in the 6th Orbit Catalog so I don't know what else we can do.

Bill


Post Extras: Print Post   Remind Me!   Notify Moderator  
WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Some double lists for SkySafari Pro new [Re: btschumy]
      #6057801 - 09/01/13 02:41 PM

Bill, as non native speaker I may have been not clear enough: The use of orbits is a plus for SkySafari I appreciate but there are too few stars with known orbits compared with the whole WDS catalog to compensate for the many binaries not included in SkySafari. I detected this by chance when exporting an observation plan from AstroPlanner to SkySafari. Surprisingly about 25% of the selected doubles were missing.
If you want examples see simply the list of David Cotterell in this thread.
Next point is that rather often than not the advertised data in SkySafari does not match the data in WDS - see for example BU363 with SkySafari listing 11.8" separation from the Burnham catalog but slightly different magnitudes (6.21 for the primary instead of 6.18) and WDS listing 6.6" separation with 6.18. The different magnitude value may make sense as Hipparco gives 6.21 and Tycho 6.22 but the separation 11.8" is clearly wrong and is listed in the WDS neglected doubles catalog.

It may be difficult with all these catalogs with different data but I think there is a simple solution: All WDS doubles should be in SkySafari, known orbits should be used, known magnitude errors should be corrected, but Tycho is already outdated. Better source would be AAVSO or UCAC4.
Wilfried


Post Extras: Print Post   Remind Me!   Notify Moderator  
btschumy
Vendor - Simulation Curriculum
*****

Reged: 04/13/04

Loc: Longmont, CO, USA
Re: Some double lists for SkySafari Pro new [Re: WRAK]
      #6057860 - 09/01/13 03:11 PM

Quote:

I detected this by chance when exporting an observation plan from AstroPlanner to SkySafari. Surprisingly about 25% of the selected doubles were missing.
If you want examples see simply the list of David Cotterell in this thread.



Can you please provide the link to this thread?

AstroPlanner has a lot of problems exporting to SkySafari. It often uses the wrong designations of doesn't fill in the information in a way we can locate the object. Just because something exported from AstroPlanner can't be found doesn't mean we don't have it.

Quote:

Next point is that rather often than not the advertised data in SkySafari does not match the data in WDS - see for example BU363



I'm not sure what to make of this. We grabbed the data directly from WDS. It was several years ago since we last built that database and it is possible it has been updated in the meantime. I will look into this discrepancy. Do you have other examples?

We are doing a new build for SkySafari 4 so hopefully that will address any obsolete data. I really do want to have an excellent double star database in the app.


Post Extras: Print Post   Remind Me!   Notify Moderator  
WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Some double lists for SkySafari Pro new [Re: Cotts]
      #6057932 - 09/01/13 03:58 PM

Quote:

OK. I did a quick survey. I found ten WDS entries very near to RA18h 00m, DEC +25 00. At random. Sky Safari (SS) had every one of them! I suspected as much since SS has the entire TYC and GSC catalogs down to 14th mag or fainter. The WDS doesn't stray much beyond mag 13 for primaries so it is safe to assume that ALL the WDS primaries are in SS.

I'm pasting the list and results below. CN doesn't format this sort of stuff very well.....



18000+2544BRT 32 1897 2002 7 172 173 4.8 5.4 11.2 12.7 180002.57+254249.5
in SkySafari as TYC 2095-1032-1 no other desig. not listed as double

18000+2535HJ 1310AB 1828 2011 10 25 43 6.0 10.3 10.24 11.01 175955.47+253440.7
in SkySafari as TYC 2094-0062-1 no other desig. not listed as double

18000+2449COU 115 1966 2008 20 115 117 0.3 0.3 8.8 8.8 175959.33+244839.0
in SkySafari as TYC 2094-2151-1 no other desig. not listed as double

18009+2646TDT 635 1991 1991 1 229 229 0.6 0.6 11.22 11.71 180055.14+264547.3
in SkySafari as TYC 2099-2668-1 no other desig. not listed as double

18009+2633STF2263 1825 2004 34 162 160 7.5 7.4 8.73 9.93 180055.43+263257.2
in sky Safari with several desig. and as double star.

18009+2432TDT 636 1991 1991 1 195 195 0.5 0.5 10.82 11.00 180051.17+243150.5
in Sky Safari as TYC 2095-1383-1 no other desig. not listed as double

18010+2617BU 1461 1905 2002 3 185 185 23.2 22.9 8.6 11.8 180100.15+261715.8
in Sky Safari with several desig. and as double star
18010+2411POU3339 1905 2002 4 255 259 8.9 8.2 11.6 13.0 180102.38+241045.3
in sky Safari as TYC 2091-1047-1 no other desig. not listed as double

18011+2341POU3340 1905 2001 3 123 129 13.7 15.6 11.27 13.9 180108.31+234028.7
in SkySafari as TYC 2091-1329-1 no other desig. not listed as double

18016+2454POU3341 1905 2002 3 91 81 5.5 5.6 12.7 12.8 180135.99+245335.8
in SkySafari as GSC 2095-0703 no other desig. not listed as double

So my claim may be humorous but it is substantially correct.

Dave

edit: It would be instructive if someone looked up the same 10 WDS doubles in other Planetarium programs like Stellarium etc. to see how they do... Anyone???

DC



Bill, I simply quote this post - 10 random doubles from WDS, only one listed in SkySafari as double.
Another example for wrong data is Gam Equ - you might be interested in the thread http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5777010/page... on this topic including contacting SkySafari support.
Other examples are BU11, BU578, A567, HO389 ... I did not search for these examples, this are simply binaries on one of my lists in exactly this order as I searched for doubles with similar data as 90 Her - this gives the impression that data different from WDS is standard and not exception.
Wilfried


Post Extras: Print Post   Remind Me!   Notify Moderator  
inZet
member


Reged: 02/12/09

Loc: Milan, Italy
Re: Some double lists for SkySafari Pro new [Re: WRAK]
      #6058663 - 09/02/13 03:20 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


Post Extras: Print Post   Remind Me!   Notify Moderator  
azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Some double lists for SkySafari Pro new [Re: inZet]
      #6058797 - 09/02/13 08:09 AM

I think omitting close doubles makes it objectionably poor.

Pete


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cotts
Just Wondering
*****

Reged: 10/10/05

Loc: Toronto, Ontario
Re: Some double lists for SkySafari Pro new [Re: azure1961p]
      #6058975 - 09/02/13 10:28 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


Post Extras: Print Post   Remind Me!   Notify Moderator  
WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Some double lists for SkySafari Pro new [Re: Cotts]
      #6059595 - 09/02/13 04:13 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


Post Extras: Print Post   Remind Me!   Notify Moderator  
inZet
member


Reged: 02/12/09

Loc: Milan, Italy
Re: Some double lists for SkySafari Pro new [Re: WRAK]
      #6063127 - 09/04/13 05:51 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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
inZet
member


Reged: 02/12/09

Loc: Milan, Italy
Re: Some double lists for SkySafari Pro new [Re: inZet]
      #6073023 - 09/10/13 11:16 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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
R Botero
Pooh-Bah


Reged: 01/02/09

Loc: Kent, England
Re: Some double lists for SkySafari Pro new [Re: inZet]
      #6073485 - 09/10/13 04:01 PM

Thanks for the effort Gianluca!
Roberto


Post Extras: Print Post   Remind Me!   Notify Moderator  
inZet
member


Reged: 02/12/09

Loc: Milan, Italy
Re: Some double lists for SkySafari Pro [Re: R Botero]
      #6074509 - 09/11/13 07:30 AM Attachment (9 downloads)

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:
Code:
+--------------+------------+------+----------+--------+------+------------------------+--------------+

| 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 :
Code:
+--------------+------------+------+----------+------+------+-------------------+--------------+

| 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


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | (show all)


Extra information
1 registered and 2 anonymous users are browsing this forum.

Moderator:  PJ Anway, Rich (RLTYS), rflinn68 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 1405

Jump to

CN Forums Home




Cloudy Nights Sponsor: Astronomics