<p>I am completely new to astrophysics and currently writing a paper on Cepheid variables for high school physics.</p>
<p>I would like to filter out all Cepheid variables in the local system which I would ideally query in python using astroquery. I find the Cepheid variables using <code>otype</code> and wanted to ask what the most efficient (in terms of putting minimum strain on the database) way to specify the local group would be.</p>
<p>Also, what are the coordinates for the local group I can use for a query in this style: <code>'region(circle, gal, 123.5 -17.8, 0.5d)'</code>?</p>

CC BY-SA 4.0
2021-05-31T18:06:26.180Z
Welcome to Astronomy SE! Please note that Stack Exchange is not a forum, it is a Q&A site. Also, please provide more details regarding what you have tried.
WarpPrime
CC BY-SA 4.0
2021-05-31T22:24:44.820Z
I've slightly adjusted your question's wording to make it a better fit to the site. Are you using astroquery? Have you checked the documentation and confirmed that you need further clarification? 
In Stack Exchange it's generally important to address "What have you tried so far?" *especially for software questions.* Is there any help here for example?  https://astroquery.readthedocs.io/en/latest/simbad/simbad.html What does "most efficient way" mean? Shortest search time? "most organized" results? The more you can explain exactly what you need what you've tried so far, the better.
uhoh
CC BY-SA 4.0
2021-05-31T22:26:36.320Z
https://learn.astropy.org/rst-tutorials/conesearch.html?highlight=filtertutorials
uhoh
CC BY-SA 4.0
2021-06-02T08:50:55.010Z
Thank you for your answers! I have updated and clarified the question with the things mentioned. Yes, I am using astroquery. As for what I have tried so far, I am able to filter certain regions of the sky. However, I am unable to filter out the local group because I don't know its "coordinates". Could you tell me what to put in `region(shape,frame,epoch,equinox,coordinates,dimension)` or `region(shape,identifier,dimension)` to only get results within the local group? (I could also do the conesearch you linked, but would still need to define an area, which I don't know)
Matthias G.
<coordinate><python><software><star-catalogues><local-group>
Filtering local region in SIMBAD
Matthias G.
# Filtering local region in SIMBAD

(Asked by: username_0 on 2021-05-31)

I am completely new to astrophysics and currently writing a paper on Cepheid variables for high school physics.

I would like to filter out all Cepheid variables in the local system which I would ideally query in python using astroquery. I find the Cepheid variables using `otype` and wanted to ask what the most efficient (in terms of putting minimum strain on the database) way to specify the local group would be.

Also, what are the coordinates for the local group I can use for a query in this style: `'region(circle, gal, 123.5 -17.8, 0.5d)'`?

**Tags:** coordinate, python, software, star-catalogues, local-group
> **Comments:**
> **username_1**: Welcome to Astronomy SE! Please note that Stack Exchange is not a forum, it is a Q&A site. Also, please provide more details regarding what you have tried.  
> **username_2**: I've slightly adjusted your question's wording to make it a better fit to the site. Are you using astroquery? Have you checked the documentation and confirmed that you need further clarification?  In Stack Exchange it's generally important to address "What have you tried so far?" *especially for software questions.* Is there any help here for example?  https://astroquery.readthedocs.io/en/latest/simbad/simbad.html What does "most efficient way" mean? Shortest search time? "most organized" results? The more you can explain exactly what you need what you've tried so far, the better.  
> **username_2**: https://learn.astropy.org/rst-tutorials/conesearch.html?highlight=filtertutorials  
> **username_0**: Thank you for your answers! I have updated and clarified the question with the things mentioned. Yes, I am using astroquery. As for what I have tried so far, I am able to filter certain regions of the sky. However, I am unable to filter out the local group because I don't know its "coordinates". Could you tell me what to put in `region(shape,frame,epoch,equinox,coordinates,dimension)` or `region(shape,identifier,dimension)` to only get results within the local group? (I could also do the conesearch you linked, but would still need to define an area, which I don't know)  

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## 0 answers

