Clear. Then another question. In your database has all HIP/TYC stars?ajtribick wrote:It would also require changing Celestia's identifier handling: currently the HIP/encoded TYC identifier (which incidentally originated with the Pascal Hartmann catalogue) is treated as fundamental but that's not going to work with the larger catalogue as the additional stars will not be HIP/TYC stars.
Updated stars.dat including Gaia EDR3 data (update 2022-03-03)
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Art Blos
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Founder and head of the project "Celestia Origin"
TY for your returns. 
@ArtBlos: It would be correct if we knew exactly the number of celestia's users.
In this number, how do they use :
1 - stars.dat (original 1.6.1 2011 ?)
2 - stars_ext v 2.1c (GrantHutchinson's catalog - updt 2009 with 2,072,867 stars)
3 - stars_gaia v 0.1.2-alpha (fev 2020).
Because, they have several impacts to use one of the three catalogs...
@ajtribick : again Bravo for your work.
Do you know when your catalog will be given in v 1.0 ?
I understand (and I hope too all other users) the problem to update old celestia 1.6.1 32 bits to accept gaia 64 bits.
One day, it will be perhaps for celestia 1.8 !?!
@ArtBlos: It would be correct if we knew exactly the number of celestia's users.
In this number, how do they use :
1 - stars.dat (original 1.6.1 2011 ?)
2 - stars_ext v 2.1c (GrantHutchinson's catalog - updt 2009 with 2,072,867 stars)
3 - stars_gaia v 0.1.2-alpha (fev 2020).
Because, they have several impacts to use one of the three catalogs...
@ajtribick : again Bravo for your work.
Do you know when your catalog will be given in v 1.0 ?
I understand (and I hope too all other users) the problem to update old celestia 1.6.1 32 bits to accept gaia 64 bits.
One day, it will be perhaps for celestia 1.8 !?!
Soft: Celestia 1.6.2
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I lost my old user, so with us: since more 12 years
=> It is by doubting everything that everybody approaches the truth !
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I lost my old user, so with us: since more 12 years
=> It is by doubting everything that everybody approaches the truth !
Unfortunately not. The main reason for this are that the cross-matches to Gaia DR2 are incomplete. In the case of HIP2 stars I can fall back to XHIP for distance information but this is not possible for TYC2. There are also some stars in Gaia DR2 that do not have parallax information.Art Blos wrote:In your database has all HIP/TYC stars?
The stars.dat file contains all 117955 XHIP (HIP2) stars, but there are 118218 entries in the original HIP catalogue. Of the stars missing in HIP2, three are brighter than V=6:LukeCEL wrote:Is this stars.dat missing any bright stars? I know in previous versions all the bright stars have made it onto revised.stc.
HIP 55203 (ξ UMa), V=3.79
HIP 78727 (ξ Sco), V=4.16
HIP 115125 (94 Aqr B), V=5.19
These are multiple star systems which likely resulted in confusion in the data processing. Taking a quick look in SIMBAD for these three, they do have Gaia DR2 entries (in the case of the first two, the A and B components have their own separate entries) but since they are not HIP2 stars they are not present in the cross-match and therefore not in the stars.dat file.
The cross-match issues are the main reason I'm treating this as an alpha. It may well be possible to use SIMBAD's query interface to resolve this, but when it comes to dealing with multiple stars this gets messy.Art Blos wrote:Do you know when your catalog will be given in v 1.0 ?
Last edited by ajtribick on 19.02.2020, 21:04, edited 1 time in total.
@ajtribick : Few errors in the datas. 
Example : Gliese 86 A (HD 13445 A) , a 'nearstar' at 35 LY given in your file at 3.0659 KPc !!!
NB : SIMBAD (2018) gives 10.787 pc or 35.18 LY.
=> Perhaps another anomalies like this ???
Example : Gliese 86 A (HD 13445 A) , a 'nearstar' at 35 LY given in your file at 3.0659 KPc !!!
NB : SIMBAD (2018) gives 10.787 pc or 35.18 LY.
=> Perhaps another anomalies like this ???
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I lost my old user, so with us: since more 12 years
=> It is by doubting everything that everybody approaches the truth !
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I lost my old user, so with us: since more 12 years
=> It is by doubting everything that everybody approaches the truth !
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SevenSpheres
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OK, TY for your return.SevenSpheres wrote:jujuapapa, ajtribick's star database puts Gliese 86 at the correct distance of 35.172 light-years.
Perhaps, I have to look after a forgotten stc file in any subdirectory...
Soft: Celestia 1.6.2
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I lost my old user, so with us: since more 12 years
=> It is by doubting everything that everybody approaches the truth !
PC : Intel Core i9-9900K (4 GHz) , Chipset Z390 Exp, RAM 32 Go DDR4 3000 Mhz, SSD M.2 512 Go + HDD 3 To, MSI GeForce RTX 2080 8Go - W10 64b
I lost my old user, so with us: since more 12 years
=> It is by doubting everything that everybody approaches the truth !
While looking through the star browser, I came across two examples of potentially spurious stars: HIP 114110 and HIP 114176. Both are within a distance of 25 ly of the Sun.
SIMBAD, for both objects, notes them as:
There might be other such cases that I haven't spotted.
However, in my opinion, that issue doesn't detract too much from the overall quality of the data files so far.
Thank you in advance!
SIMBAD, for both objects, notes them as:
Non-existing star (scattered light from a nearby bright star).
There might be other such cases that I haven't spotted.
However, in my opinion, that issue doesn't detract too much from the overall quality of the data files so far.
Thank you in advance!
Good find. I'm not making individual corrections to the various entries as this would be a lot of work. Presumably these "stars" are missing in Gaia DR2 but because the cross-match is incomplete (even beyond just missing the brightest stars that are too bright for Gaia) I can't rely on the lack of a match being a non-existent object.
Given the date of the correction (1998 according to the list of errata), I'm slightly surprised this didn't get taken into account when compiling HIP2 (2007) or XHIP (2012).
Given the date of the correction (1998 according to the list of errata), I'm slightly surprised this didn't get taken into account when compiling HIP2 (2007) or XHIP (2012).
@Art Blos - I don't have any plans to do any updates on this unless someone finds a sufficiently severe bug, i.e. that something's gone wrong with correctness with respect to the input data. (Correctness with regards to external reality is another matter, which should probably be handled in revised.stc or an equivalent mechanism)
I don't think that spending time on things like trying to obtain a better DR2-HIP2 or DR2-TYC2 cross-match makes much sense given that the release of EDR3 is expected later this year, which would likely mean having to do it all over again.
I don't think that spending time on things like trying to obtain a better DR2-HIP2 or DR2-TYC2 cross-match makes much sense given that the release of EDR3 is expected later this year, which would likely mean having to do it all over again.
Post #35by ajtribick » 4 minutes ago
@Art Blos - I don't have any plans to do any updates on this unless someone finds a sufficiently severe bug, i.e. that something's gone wrong with correctness with respect to the input data. (Correctness with regards to external reality is another matter, which should probably be handled in revised.stc or an equivalent mechanism)
I don't think that spending time on things like trying to obtain a better DR2-HIP2 or DR2-TYC2 cross-match makes much sense given that the release of EDR3 is expected later this year, which would likely mean having to do it all over again.
Logical : in his time, Oppenheimer didn't ensure the after sales service of his invention...
Soft: Celestia 1.6.2
PC : Intel Core i9-9900K (4 GHz) , Chipset Z390 Exp, RAM 32 Go DDR4 3000 Mhz, SSD M.2 512 Go + HDD 3 To, MSI GeForce RTX 2080 8Go - W10 64b
I lost my old user, so with us: since more 12 years
=> It is by doubting everything that everybody approaches the truth !
PC : Intel Core i9-9900K (4 GHz) , Chipset Z390 Exp, RAM 32 Go DDR4 3000 Mhz, SSD M.2 512 Go + HDD 3 To, MSI GeForce RTX 2080 8Go - W10 64b
I lost my old user, so with us: since more 12 years
=> It is by doubting everything that everybody approaches the truth !
Interesting observation! I think you're probably right.
As an example, the LMC B[e] supergiant R126 (TYC 9167-518-1, HD 37974) is assigned a distance of 10.5 kpc in the Gaia geometric distance catalogue, versus a ~50 kpc distance to the LMC. I don't have a Celestia installation to hand as I'm writing this but it wouldn't surprise me if it were part of the "spike".
The measured parallax for R126 in Gaia DR2 is -0.074±0.028 mas. As the paper on which the geometric distances catalogue is based notes, it is possible to make inferences about distance from a negative parallax (even though the straightforward 1/parallax approach obviously fails). However the model used assumes that the star is part of our Galaxy, which is obviously untrue for a star that's in the LMC. Hence the nonsense distances.
So from what I can tell, this is correct with respect to the input catalogues, but not external reality
Judging by the picture, it looks like there might also be a similar "spike" towards the SMC. Querying Gaia again for the SMC Wolf-Rayet system HD 5980 (TYC 9138-1929-1), this is assigned a distance of 5.85 kpc based on a parallax of 0.061±0.041 mas, versus the distance to the SMC of ~60 kpc. Again the large error bars mean the assumption that the star is a member of our Galaxy becomes a factor.
If there's a catalogue listing extragalactic members of the TYC2 catalogue it'll probably be worth excluding such objects. If not, I guess it's a case of waiting to see what EDR3 looks like.
As an example, the LMC B[e] supergiant R126 (TYC 9167-518-1, HD 37974) is assigned a distance of 10.5 kpc in the Gaia geometric distance catalogue, versus a ~50 kpc distance to the LMC. I don't have a Celestia installation to hand as I'm writing this but it wouldn't surprise me if it were part of the "spike".
The measured parallax for R126 in Gaia DR2 is -0.074±0.028 mas. As the paper on which the geometric distances catalogue is based notes, it is possible to make inferences about distance from a negative parallax (even though the straightforward 1/parallax approach obviously fails). However the model used assumes that the star is part of our Galaxy, which is obviously untrue for a star that's in the LMC. Hence the nonsense distances.
So from what I can tell, this is correct with respect to the input catalogues, but not external reality
Judging by the picture, it looks like there might also be a similar "spike" towards the SMC. Querying Gaia again for the SMC Wolf-Rayet system HD 5980 (TYC 9138-1929-1), this is assigned a distance of 5.85 kpc based on a parallax of 0.061±0.041 mas, versus the distance to the SMC of ~60 kpc. Again the large error bars mean the assumption that the star is a member of our Galaxy becomes a factor.
If there's a catalogue listing extragalactic members of the TYC2 catalogue it'll probably be worth excluding such objects. If not, I guess it's a case of waiting to see what EDR3 looks like.