astroquery.alma provides the astroquery interface to the ALMA archive. It supports object and region based querying and data staging and retrieval.
You can get interactive help to find out what keywords to query for:
>>> from astroquery.alma import Alma
>>> Alma.help()
Valid ALMA keywords:
Position
Source name (Resolver) : source_name_resolver
Source name (ALMA) : source_name_alma
RA Dec : ra_dec
Energy
Frequency : frequency
Bandwidth : bandwidth
Spectral resolution : spectral_resolution
Band : 3(84-116 GHz) = 3 , 4(125-163 GHz) = 4 , 6(211-275 GHz) = 6 , 7(275-373 GHz) = 7 , 8(385-500 GHz) = 8 , 9(602-720 GHz) = 9 , 10(787-950 GHz) = 10
Time
Observation date : start_date
Integration time : integration_time
Polarisation
Polarisation type : Stokes I = 0 , Single = 1 , Dual = 2 , Full = =3|4
Observation
Water vapour : water_vapour
Project
Project code : project_code
Project title : project_title
PI name : pi_name
Options
(I) View: : result_view = raw
( ) View: : result_view = project
[x] public data only : public_data = public
[x] science observations only : science_observations = =%TARGET%
Users can log in to acquire proprietary data products. Login is performed via the ALMA CAS (central authentication server).
>>> from astroquery.alma import Alma
>>> alma = Alma()
>>> # First example: TEST is not a valid username, it will fail
>>> alma.login("TEST")
TEST, enter your ALMA password:
Authenticating TEST on asa.alma.cl...
Authentication failed!
>>> # Second example: pretend ICONDOR is a valid username
>>> alma.login("ICONDOR", store_password=True)
ICONDOR, enter your ALMA password:
Authenticating ICONDOR on asa.alma.cl...
Authentication successful!
>>> # After the first login, your password has been stored
>>> alma.login("ICONDOR")
Authenticating ICONDOR on asa.alma.cl...
Authentication successful!
Your password will be stored by the keyring module. You can choose not to store your password by passing the argument store_password=False to Alma.login. You can delete your password later with the command keyring.delete_password('astroquery:asa.alma.cl', 'username').
You can query by object name or by circular region:
>>> from astroquery.alma import Alma
>>> m83_data = Alma.query_object('M83')
>>> print(len(m83_data))
225
>>> m83_data.colnames
['Project_code', 'Source_name', 'RA', 'Dec', 'Band',
'Frequency_resolution', 'Integration', 'Release_date', 'Frequency_support',
'Velocity_resolution', 'Pol_products', 'Observation_date', 'PI_name',
'PWV', 'Member_ous_id', 'Asdm_uid', 'Project_title', 'Project_type',
'Scan_intent']
Region queries are just like any other in astroquery:
>>> from astropy import coordinates
>>> from astropy import units as u
>>> galactic_center = coordinates.SkyCoord(0*u.deg, 0*u.deg,
... frame='galactic')
>>> gc_data = Alma.query_region(galactic_center, 1*u.deg)
>>> print(len(gc_data))
82
You can download ALMA data with astroquery, but be forewarned, cycle 0 and cycle 1 data sets tend to be >100 GB!
>>> import numpy as np
>>> uids = np.unique(m83_data['Member_ous_id'])
>>> print(uids)
Member_ous_id
----------------------
uid://A002/X3216af/X31
You can then stage the data and see how big it is (you can ask for one or more UIDs):
>>> link_list = Alma.stage_data(uids)
INFO: Staging files... [astroquery.alma.core]
>>> link_list['size'].sum()
159.26999999999998
You can then go on to download that data. The download will be cached so that repeat queries of the same file will not re-download the data. The default cache directory is ~/.astropy/cache/astroquery/Alma/, but this can be changed by changing the cache_location variable:
>>> myAlma = Alma()
>>> myAlma.cache_location = '/big/external/drive/'
>>> myAlma.download_files(link_list, cache=True)
You can also do the downloading all in one step:
>>> myAlma.retrieve_data_from_uid(uids[0])
If you want just the QA2-produced FITS files, you can download the tarball, extract the FITS file, then delete the tarball:
>>> from astroquery.alma.core import Alma
>>> from astropy import coordinates
>>> from astropy import units as u
>>> orionkl = coordinates.SkyCoord('5:35:14.461 -5:21:54.41', frame='fk5',
... unit=(u.hour, u.deg))
>>> result = Alma.query_region(orionkl, radius=0.034*u.deg)
>>> uid_url_table = Alma.stage_data(result['Member_ous_id'], cache=False)
>>> # Extract the data with tarball file size < 1GB
>>> small_uid_url_table = uid_url_table[uid_url_table['size'] < 1]
>>> # get the first 10 files...
>>> filelist = Alma.download_and_extract_files(small_uid_url_table[:10]['URL'])
You might want to look at the READMEs from a bunch of files so you know what kind of S/N to expect:
>>> filelist = Alma.download_and_extract_files(uid_url_table['URL'], regex='.*README$')
ALMA Archive service.
AlmaClass() | |
Conf | Configuration parameters for astroquery.alma. |