plot-constellations vs limited number HD objects

[László Heller]

Hi!

Can somehow the plot-constellations utility also limit the number of tagged HD catalog objects on the output image?

For me, it apparently can't. Displays everything detected, so the final output image becomes weird, see the below screenshot:


When I run
plot-constellations -B -b 5 ...

It only tags the 5 brightest well known stars on the output.

But when I run

plot-constellations -D -d <Path_to_hd.fits> -b 5 ...

In this case, it tags all the detected HD objects, no matter, how the -b parameter was set.

BR,

Ladislav

[László Heller]

Hi Dustin!

Any comments on the above question?

BR,

Ladislav

[Dustin Lang]

Hi,

Unfortunately, the HD catalog we've had floating around forever doesn't include magnitudes, so there's not an easy way to cut to the N brightest...

One could of course go back to the catalog source (eg http://vizier.u-strasbg.fr/cgi-bin/VizieR?-source=III/135A/catalog) and re-grab that catalog.  I would prefer to add that functionality to plotann.py (Python) rather than plot-constellations (C).

cheers,

dustin

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[László Heller]

Hi!

OK, I understand. Anyway could be possible to simply cut the HD list before plotting but not to the N brightest, rather only simply N whatever star? In other words to plot only N of HD stars with plot-constellations utility.

BR,

Ladislav

[Dustin Lang]

Sure -- you probably want to draw a random sample of N, otherwise if you take the first N they'll be in some order (maybe all in one part of the image).

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[László Heller]

Yup. BTW is there any tool to create a new HD.fits file also with magnitudes from the Henry Draper catalog source ?

[Dustin Lang]

https://github.com/dstndstn/astrometry.net/blob/main/catalogs/build-hd-tree.c

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[Dustin Lang]

but one would probably be better to just grab a FITS table from Vizier and add Python code to plotann.py to read it.

[László Heller]

OK, I see that HD catalog has also magnitude fields, Ptm and Ptg, see here:
http://tapvizier.cds.unistra.fr/TAPVizieR/tap/sync?request=doQuery&lang=adql&query=select%20*%20from%20%22III/135A/catalog%22%20order%20by%20%22recno%22&format=text

So grab the catalog via &format=csv and try to fix the related line in build-hd-tree-c.

I also checked the C code for plot-constellations and saw lines for filtering out N brightest stars (using -b N switch) here.

Later in that code, there is HD catalog processing, where I would put the following based on the previous code:

        // keep only the Nbright brightest?

        if (Nbright && (bl_size(hdlist) > Nbright)) {

            bl_sort(hdlist, sort_by_mag);

            bl_remove_index_range(hdlist, Nbright, bl_size(hdlist)-Nbright);

        }

I am not sure whether it'll work but will let you know.

[László Heller]

* I'll grab and I'll try to fix, of course. But maybe you can help me with C plot-constellations even when apparently you prefer plotann.py and the python language :)

[László Heller]

Hi Dustin

A comment in lines 35-37 in file build-hd-tree.c says:

http://trac.astrometry.net/browser/binary/henry-draper/henry-draper.tsv

(note, the Tycho-2 cross-ref file is also there, as are hd.fits and hd2.fits (with bounding-boxes))

The above link is invalid and there is no link to that cross-ref file. Can U please give me a working link to cross-ref file?

I created my own input CSV also with magnitudes, fixed the build-hd-tree utility (build-hd-tree.c, line 363) and now I would like to create my own HD.fits file.
Command line would be then something like:
build-hd-tree -b -T ./tycho2.kd -X ./cross-ref-file ./HD.csv ./HD.fits

BR,

Ladislav

[Dustin Lang]

Hi,

Sorry, but that's from 9-15 years ago, I don't have those files any more.  You can get them from

https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=IV/25

http://cdsarc.u-strasbg.fr/viz-bin/VizieR?-meta.foot&-source=III/135A

cheers,

dustin

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