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How To Reconcile Conflicting Information In SkySafari Star Database? Can I Trust The Data? (Answer: Read On!)

check out the information on Tau Scorpii - the text is correct, Tau Sco has no companion, but the parametric data on the side is for a different star, describing A and B components. I have tended to implicitly trust Sky Safari’s collation of the catalogs, but now I am uncomfortable doing that. This error isn’t the result of a disagreement between a couple of catalogs about just how luminous a star is or something like that - whatever function or algorithm was used to combine catalog data to create the SkySafari database has completely screwed up and put the wrong star’s data in for Tau Sco. What else has it borked? This probably isn’t a one-off screwup.

PS there is no forum in the huge list of forums for reporting problems/bugs. This is not a “feature request” - this is a FAULT that requires fixing to restore confidence in the product.

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    Bill Tschumy

    Tau Sco is listed in the Washington Double Star catalog as a double star.  The attached image shows the data.

    This may or may not be an error in the WDS but we can only report what is in the catalogs.  If you are confident the WDS is incorrect, you can report an error to them.

  • 0
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    Bill Tschumy

    Also, problems/bugs are reported in the forum for the platform you are reporting the problem in.  The SkySafari / iOS App forum is the correct place if you observed the problem on iOS.

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    TasmanSkies

    Thanks Bill, I'm glad to have a SkySafari person respond to this.

    Re: the right place to post something: bear in mind that the logical place for organising things for those intimately familiar with the forum structure may be very different from the first time arriver who has a bug to report who seemingly cannot find any place on the app or on the website to report this issue and who eventually finds that not only is the support submission thing not valid for the specific Simulation Curriculum product they have but they actually need to post it in a forum instead, only to find the forum has three dozen categories none of which are titled: Report Issues Here or similar. Reporters should not accidentally end up posting in the wrong place and have to be told "you should have actually posted over there" because it is annoying to be told you are standing in the wrong line when you are just trying to help. And I doubt this is iOS app specific, so why would I think that was the right place?

    Re: Tau Scorpii and whether there may or may not be an error: the info text in Sky Safari itself says:

    "Unlike many stars of its kind, Tau Sco seems distinctly single, with no evidence at all of any companion... Tau Sco is among the most-observed stars in the sky; in the past half-century, it has been mentioned in over 400 scientific papers." OK, this text could be completely wrong (it clearly isn't accidentally included text from a different star though) but a little bit of online searching shows that this descriptive text is accurate - and therefore the parametric data is incorrect, wherever SkySafari referenced it.

    So there shouldn't be any debate about this. Even the WDS catalog entry you clipped for me says: " Nature of this double is uncertain" which is overstating the case if anything. The data shown in your clip all seems to suit a single star, with only the entry for Mag pri 2.9 and Mag sec 5.8 suggesting a double. 

    Yes, you can only report what is in the catalogs, but clearly you need to pick catalogs to reference because the data in them is not all identical. Out of all the catalogs you collate, why is it that WDS wins in this instance? Why not SIMBAD? Does it make sense for SkySafari to be simply overriding the data from other catalogs if it finds an entry in WDS, even if the entry is reporting something that is inconclusive or uncertain? And yes there is something SkySafari can do even if there is strange data in catalogs you reference. Maybe you could go through all the WDS entries you import and if the entry in WDS says things like "Nature of this double is uncertain" you could include that text in SkySafari, and even maybe not override the data from SIMBAD (or whatever) but instead add an additional WDS entry after all the other stuff that reproduces the data you show above... you DO have options to deal with this! Please don't just shrug and say "computer says no..." and "what can we do? Our hands are tied!" 

    Now, yes, I potentially could, as an everyday Joe Bloggs, make a submission to WDS to tell them their catalog has an obvious error in it - if I could find yet another issue reporting form - but surely it would be (a) more notable and therefore more likely to be effective if the makers of a planetarium app were to report it and (b) a gracious thing to do in support of your product: "Hm, yes, that is strange, we'll send that into USNO so they can check their WDS catalog, thanks for reporting that!"

    Please take this a little bit seriously.

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    Bill Tschumy

    The star description is taken from Jim Kahler's STARS website (by permission).  He is an acknowledged expert on stars.  That description may differ somewhat from the data that comes from the catalogs.  It is not uncommon to see the description and the data to differ in distances or magnitudes by a slight amount.

    The WDS is the definitive source for data on double stars.  No other catalog even comes close.

    Looking at the raw data of the WDS, it looks like there was only one observation of this star that reported it as double and the separation was 0".  That is probably why it is displayed as "Nature of this double is uncertain".  There is no field in the raw data that explicitly indicates that.

    In suggesting that you report it, I'm just trying to spread the effort around.  I'm not a professional astronomer and I have no more weight that anyone else.  The professional catalogs are littered with errors (unfortunately).  We have set up a policy to not try to correct the catalogs ourselves.  Otherwise, there is no authority.

    I will look into reporting this, but maybe you should as well (double the impact).

    I don't think this means you cannot trust SkySafari's data.  You happen to have found a fairly rare case.  I scanned a chunk of the catalog and could only find a handful of entries where the separation is 0.  I have no idea why these are in the catalog but I assume they have their reasons.

     

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