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Old 08-25-2018, 08:32 AM   #31
Keysh
 
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Default Re: Stellar Mapping

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Originally Posted by acrosome View Post
Yes, I'm pretty sure that's the CTIOPI list, so I can get it in spreadsheet form. Deconflicting that with Hipparcos will take a while...
I'd check to make sure. The new parallaxes reported in the Henry et al. 2018 paper are indeed from that group's observations with CTIO (Cerro Tololo Inter-American Observatory) telescopes in Chile, but the second part of Table 4 of that paper lists about 27 red dwarfs (in addition to those from Hipparcos) from other, non-RECONS studies, which may or may not be in a "CTIOPI spreadsheet", wherever you're getting that from...
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Old 08-26-2018, 09:47 AM   #32
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Default Re: Stellar Mapping

It' from here, on the RECONS website. It is supposedly up to date as of 01Aug2018, and lists Henry et al 2018 AJ 155 265 as one of the sources.
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Old 08-26-2018, 10:19 AM   #33
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Default Re: Stellar Mapping

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It' from here, on the RECONS website. It is supposedly up to date as of 01Aug2018, and lists Henry et al 2018 AJ 155 265 as one of the sources.
OK, well spotted!

In that case, you are still missing the non-RECONS stars from the second part of Henry et al.'s Table 4. E.g., a quick check shows that the stars LHS2597 and LHS5264--from the last row of Table 4--are not in the table you found.
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Old 08-26-2018, 12:50 PM   #34
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Default Re: Stellar Mapping

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OK, well spotted!

In that case, you are still missing the non-RECONS stars from the second part of Henry et al.'s Table 4. E.g., a quick check shows that the stars LHS2597 and LHS5264--from the last row of Table 4--are not in the table you found.
Hell. More hand editing. I still haven't gotten through the RECONS 100 list....
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Old 08-28-2018, 11:43 AM   #35
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Default Re: Stellar Mapping

Huh. Okay, I tried to reconcile the XHIP and RECONS100 datasets, and I've hit a snag. The galactic longitudes and latitudes don't match for objects that are in both sets. Dramatically. However, the conversions from HMS/DMS into decimal degrees for RA and DEC in the RECONS dataset do match. It's just the derived galactic latitudes and longitudes that don't.

The XHIP values for galactic latitude and longitude were in the dataset directly, whereas the RECONS ones were calculated using EvilDrGanymede's spreadsheet, so I'm inclined to believe the XHIP ones. But I'd really like to know why, since I'm going to make maps and this will result in the Astrosynthesis XYZ coming out different for the two sets. I could just derive the XYZ coordinates from RA and DEC, but then I loose the neat genre convention of defining directions as "coreward" or "spinward", "trailing", etc.

Are there different systems for calculating galactic longitude and latitude? It seems unlikely, but I had better ask.

EDIT-- Duh. I figured it out. The XHIP GLon is always a positive number up to 359.99999, whereas EDG's runs to positive 180 or negative 179.99999. To use EDG's spreadsheets to generate an XYZ I'll have to use his version, and derive the XHIP values.

Back to the salt mines.

Last edited by acrosome; 08-28-2018 at 02:13 PM.
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Old 09-06-2018, 05:18 PM   #36
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OK, after all of that effort I have now discovered SIMBAD. Wikipedia seems to imply that it's kept up to date regularly.

Anyone know just how trustworthy and up to date it is?

I ask because I searched for objects within parallax of 66 mas (about 14 parsecs) on SIMBAD and got 1313 objects. But when I went through XHIP, RECONS, and CTIOPI for the same radius and removed redundant entries I only ended up with 677 objects. Granted some of them are multiple systems that weren't split out, but not enough to account for that much of a difference.

Should I trust SIMBAD more? Some of it's entries are described as odd things like "Infrared source".

EDIT-- Wow. There are 207 HABCAT stars within 14pc of Sol. I'll end up shaving a lot of those off, though, since I plan on making cube-shaped sectors each about 10pc on a side. (Thus from vertex to vertex is about 14pc, which is why I'm searching that far.)

Last edited by acrosome; 09-07-2018 at 01:16 PM.
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Old 09-13-2018, 03:56 PM   #37
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Default Re: Stellar Mapping

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Originally Posted by acrosome View Post
OK, after all of that effort I have now discovered SIMBAD. Wikipedia seems to imply that it's kept up to date regularly.

Anyone know just how trustworthy and up to date it is?

I ask because I searched for objects within parallax of 66 mas (about 14 parsecs) on SIMBAD and got 1313 objects. But when I went through XHIP, RECONS, and CTIOPI for the same radius and removed redundant entries I only ended up with 677 objects. Granted some of them are multiple systems that weren't split out, but not enough to account for that much of a difference.

Should I trust SIMBAD more? Some of it's entries are described as odd things like "Infrared source".

EDIT-- Wow. There are 207 HABCAT stars within 14pc of Sol. I'll end up shaving a lot of those off, though, since I plan on making cube-shaped sectors each about 10pc on a side. (Thus from vertex to vertex is about 14pc, which is why I'm searching that far.)
CTIOPI and RECONS, at least, are specifically focused on things within a radius of 10 pc, so they're not trying to be complete at larger distances. They're naturally going to be missing stars further out.

SIMBAD is one of the main astronomical databases, specifically for stars. (It has coordinates for lots of galaxies, too, but the NASA Extragalactic Database is a better resource for galaxies.) It's very heterogeneous and not trying to be complete for individual parameters (like parallax).
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Old 09-20-2018, 12:23 PM   #38
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Default Re: Stellar Mapping

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CTIOPI and RECONS, at least, are specifically focused on things within a radius of 10 pc, so they're not trying to be complete at larger distances. They're naturally going to be missing stars further out.
CTIOPI and RECONS re-missioned themselves out to 25pc, once they thought that they had 10pc covered.
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