Extracts the latest astronomical information for a list of stellar objects, in particular double/multiple stellar systems.
These are a collection of python scripts to extract the latest astronomical information available for a list of stellar objects that is input either by HTML table, or a simple text file.
My purpose in writing them was to get the best, or better, information on interesting stars listed in amateur astromical articles (such as this article or this article). These articles often have lists of interesting objects, but the coordinates and/or names can be lacking sufficient information needed to use with computer-guided amateur telescopes, or to look up other information easily on the web.
Information is extracted from Simbad Astronomical Database and written to HTML and fits-format tables using astropy under the hood. Note that these scripts are written for Python 3 only! If you're still using Python 2 please upgrade!
The scripts available so far are only a start at getting the physical information I'm really interested in, i.e. true luminosity, mass, stellar radius, separation and distance of binary or multiple star systems. The code to do that will be added at a later date.
The basic work flow is:
- Get a text format or HTML table format list of interesting objects. The only required information is a column of names or identifiers that we can pass to Simbad. (Lets call this data "level 0".)
- Run
star_query.pyon that input to get first guess at recognized Simbad identifiers for those targets, in particular WDS (Washington Double Star) and HIP (Hipparcos Output Catalog) IDs. This will also get basic observable data such as positions, parallaxes, proper motions, spectral types and B and V-band magnitudes. We'll call the output fits table from this stage "level 1". If you're just running it to get information on some arbitrary stars without an interest in known double/multiple star systems then you can skip ahead to step 5. - Run
process_wds_ids.pyon the level 1 data to get Simbad ID's for the primary, secondary, etc, components of the multiple star systems. (Only needed when you're interested in double/multiple star systems.) - Re-run
star_query.pyon the outut of step #3, using the new, more specific, IDs to get the observable data for all selected multiple star components. We'll call this "level 2". (Only needed when you're interested in double/multiple star systems.) - (Not yet implemented) Process the level 2 data to derive physical properties of the stars, e.g. distance, instrinsic luminosity, temperature, radius, and maybe ZAMs mass and lifetime, along with the physical separation of the binary/multiple star components.
A short series of blog posts discuss running these tools on Bob King's "Colored Doubles":
- Colorful binary star systems for small telescopes: Part 1
- Colorful binary star systems for small telescopes: Part 2
The following subsections provide an overview of the scripts. More detailed usage information is provided in the EXAMPLES.md document.
Given an input HTML table, FITS table, or text file containing
a set of stellar names (either common names or catalog IDs),
star_query.py can be run to produce HTML and gzipped
fits-format
output tables that contain the following information:
| Name | In HTML? | unit | Description |
|---|---|---|---|
| Star | yes | User-supplied star object ID | |
| SimbadID | yes | Main ID used by Simbad | |
| WDS | yes | Washington Double Star Catalog ID | |
| SAO | yes | SAO Star Catalog ID | |
| HIP | yes | Hipparcos Output Catalog ID | |
| NAME | yes | Common name | |
| HD | yes | Henry Draper Catalog ID | |
| RA_icrs | yes | hrs:min:sec | Right ascension, HMS, ICRS at J2000 epoch |
| DEC_icrs | yes | deg:min:sec | Declination, DMS, ICRS at J2000 epoch |
| RA_icrs_deg | no | deg | Right ascension in decimal degrees |
| DEC_icrs_deg | no | deg | Declination in decimal degrees |
| RADEC_bibcode | no | Bibcode for coordinates | |
| magB | no | mag | V-band apparent magnitude |
| magB_err | no | Uncertainty in B-band apparent magnitude | |
| magB_bibcode | no | Bibcode for B-band apparent magnitude | |
| magV | yes | mag | V-band apparent magnitude |
| magV_err | no | Uncertainty in V-band apparent magnitude | |
| magV_bibcode | no | Bibcode for V-band apparent magnitude | |
| parallax | no | mas | parallax |
| parallax_err | no | mas | parallax_err |
| parallax_bibcode | no | Bibcode for parallax | |
| pm_RA | no | mas / yr | Proper motion in RA |
| pm_DEC | no | mas / yr | Proper motion in DEC |
| pm_err_maja | no | mas / yr | Proper motion error major axis |
| pm_err_mina | no | mas / yr | Proper motion error minor axis |
| pm_err_angle | no | deg | Proper motion error angle |
| pm_bibcode | no | Bibcode for proper motion | |
| spec_type | yes | Spectral type including luminosity class | |
| spec_qual | no | Spectral type quality | |
| spec_bibcode | no | Bibcode for spectral type | |
| Teff_(Fe_H) | yes | degK | Effective temperature in K |
| [Fe/H] | yes | Metal abundance relative to Sun in dex | |
| Fe_H_bibcode | no | Bibcode for metal abundance and Teff |
All data items are written thhe gzipped fits table. Although some items are
left out of the HTML output by default they can be included using the
--fullhtml command line flag.
Extracts a clean list of Washington Double Star (WDS) IDs from the initial FITS-dormat output of star_query.py. The script then combines that with the information on all listed (likely and unlikely) companions from the main WDS data file to generate a list of likely stellar companions using one of several different filtering methods.
The output table produced by process_wds_ids.py can then be fed back into
star_query.py as input along with the --stage2 command line flag.
A separate bash script, download_data.sh, should be used before running process_wds_ids.py.
The bash script will download the main WDS data table needed by process_wds_ids.pyfrom CDS. (It also usesfitsmodhead.py` to fix a FITS header keyword
problem in the WDS data table that would otherwise prevent astropy.io.fits from
reading the WDS data.)
Along with the code this project comes with four example input files:
bob_king_colored_double_stars.htmlfrom Colored Double Stars, Real and Imagined by Bob King, Sky & Telescope, December 14 2016.alan_adler_pretty_double_stars.htmlfrom Pretty Double Stars for Everyone, by Alan Adler, Sky & Telescope, July 26 2006.brightest_m_dwarfs.htmlfrom 14 Red Dwarf Stars to View from Backyard Telescopes, by David Dickinson, Universe Today, 13 May 2014.alternate_input.txtis an example of the simple text file input format.
However most users will want to use it will their own inputs. The simplest
way of doing this, for a small list of objects, is to create a simple
ascii (or utf-8) CSV file following the format shown in alternate_input.txt.
The CSV file column containing the object names/ID can be called anything
and in any position within the file. However if its not called Star then
you must pass the name to star_query.py using the -c or --col command
line argument.
If you wish to use a longer list of object that is already formatted as a HTML table within a web page then follow these steps.
- Open the web page containing the HTML table in your browser.
- Right click on the page and select "View page source".
- Scroll down in the new window that opens, select the HTML table containing the objects, and right click again to select "copy".
- Open a text editor and paste the HTML table into it, then select
"save as" and save it with
.htmlextension. - Make a note of the
table column name for the stars names/IDs, as you need to
use it with
--colif it isn't the defaultStarexpected bystar_query.py. - You will almost certainly need to hand edit the HTML formatting of
the table before
star_query.pywill sucessfully use it, because astropy expects the table to stritly follow the table syntax and to not be too complex. - In particular, there must be one table row of column headings, i.e.,
the first table row (
<tr> ... </tr>) must have columns that are in<th> ... </th>format. - Spanning multiple columns with
colspanconfuses astropy. You'll have to either remove columns or add new columns to get the table to work. - Rows with either multiple names (e.g. "AX Microscopii/Lacaille 8760") or no names (assumed to be continuations of the previous row?) will almost certainly not work. Use your judgement to deal with them, but you may have to comment them out or delete them.
Simbad may not recognize a user-supplied identifier. Identifiers used
in an amateur astronomical community may not correspond to the catalog
naming conventions used by Simbad (.e.g "h3945 CMa",
or they may be from a catalog/source not recognized by Simbad at all
(e.g. "Struve"). In some cases Simbad recognizes the identifier but
returns multiple possible matches, or in rare cases accepts the
identifier but returns no data. In any case, star_query.py will tell
you which identifiers it had trouble with when it runs.
There are various ways to find identifiers that Simbad will recognize:
- Perform an object ID query at Simbad youself and see what it returns. If it returns two or more possible matches you can select which one best matches your intended target (based on position and magnitude, for example).
- If the basic query returns nothing then you may be forced to perform a Simbad coordinate query, if you have some idea of the Right Ascension (RA) and Declination (Dec) of the target. Note that amateur astronomical articles often only provide RA as hours and minutes, and Dec as degrees and arcminutes, leaving out the seconds and arcseconds and rounding off to the minutes/arcminutes. So to get a match so you will have to search all targets within a radius of your input. Simbad does this by default for coordinate queries, but the default search radius of 2 arcminutes may be a bit small and probably should be increased to 10 arcmin.
Once you have the "correct" IDs you can add them to
simbad_star_alias.csv, following the format of the entries already
present in that file. Or create your own alias file and pass that
into star_query.py with the --aliases command line option.
This code is made available under the GNU General Public License, version 3. See LICENSE for details.
This code has been developed on Linux, specifically Fedora versions 27 to 31, but has also been run successfully on Mac OS X 10.11 El Capitan using macports.
On Fedora you will need to have the following packages installed:
python3 python3-astropy python3-astroquery python3-numpy
The specific versions I'm using are:
python3.x86_64 3.6.4-7.fc27 @updates
python3-astropy.x86_64 2.0.2-1.fc27 @fedora
python3-astroquery.noarch 0.3.6-2.fc27 @fedora
python3-numpy.x86_64 1:1.13.3-4.fc27 @updates
Installing these packages, or having them already installed, should satisfy any other dependencies.
On a different Linux distribution, or on OSX using macports, installing a similar set of dependencies should get it working.
Each of the command line python programs use argparse, so you can the
--help command line option to get a full list of the arguments
each accepts.
A set of examples with commentary is provided in examples/EXAMPLES.md.
- Various sites, including babelstone, can be used to identify mysterious unicode characters in input HTML tables that Simbad may not be able to resolve.
- Divtable's table styler can be used to generate alternate CSS styles for the HTML tables.
- fv can be used to view and edit fits files. (Note that it refuses to modify gzipped fits files even though it reads them, so gunzip them if you want to edit a gzipped fits file.)
- The reference Bibcodes can be looked up using NASA ADS, which in many cases can get you access to a free scanned version of the article or a freely accessible PDF or HTML version of it (at least for articles from major journals that are over a year old).