ACSZPT

Author: Nathan Miles

acstools.acszpt Module

This module contains a class, Query, that was implemented to provide users with means to programmatically query the ACS Zeropoints Calculator. The API works by submitting requests to the ACS Zeropoints Calculator referenced above and hence, it is only valid for ACS specific instruments (HRC, SBC, or WFC).

The API can be used in two ways by specifying either a (date, detector, filter) combination or just a (date, detector) combination. In the first case, the query will return the zeropoint information for the specific filter and detector at specified date. In the second case, the query will return the zeropoint information for all the filters for the desired detector at the specified date. In either case, the result will be an astropy.table.QTable where each column is an astropy.units.quantity.Quantity object with the appropriate units attached.

Examples

Retrieve the zeropoint information for all the filters on 2016-04-01 for WFC:

>>> from acstools import acszpt
>>> date = '2016-04-01'
>>> detector = 'WFC'
>>> q = acszpt.Query(date=date, detector=detector)
>>> zpt_table = q.fetch()
>>> print(zpt_table)
FILTER PHOTPLAM        PHOTFLAM         STmag  VEGAmag  ABmag
       Angstrom erg / (Angstrom cm2 s) mag(ST)   mag   mag(AB)
 str6  float64         float64         float64 float64 float64
------ -------- ---------------------- ------- ------- -------
 F435W   4329.2              3.148e-19  25.155  25.763  25.665
 F475W   4746.2              1.827e-19  25.746  26.149  26.056
 F502N   5023.0              5.259e-18  22.098  22.365  22.285
 F550M   5581.5               3.99e-19  24.898  24.825  24.856
 F555W   5360.9              1.963e-19  25.667  25.713  25.713
 F606W   5922.0              7.811e-20  26.668  26.405  26.498
 F625W   6312.0              1.188e-19  26.213  25.735  25.904
 F658N   6584.0               1.97e-18  23.164  22.381  22.763
 F660N   6599.4              5.156e-18  22.119  21.428  21.714
 F775W   7693.2              9.954e-20  26.405  25.272  25.667
 F814W   8045.0              7.046e-20   26.78  25.517  25.944
F850LP   9033.2               1.52e-19  25.945  24.332  24.858
 F892N   8914.8              1.502e-18  23.458  21.905    22.4

Retrieve the zeropoint information for the F435W filter on 2016-04-01 for WFC:

>>> from acstools import acszpt
>>> date = '2016-04-01'
>>> detector = 'WFC'
>>> filt = 'F435W'
>>> q = acszpt.Query(date=date, detector=detector, filter=filt)
>>> zpt_table = q.fetch()
>>> print(zpt_table)
FILTER PHOTPLAM        PHOTFLAM         STmag  VEGAmag  ABmag
       Angstrom erg / (Angstrom cm2 s) mag(ST)   mag   mag(AB)
------ -------- ---------------------- ------- ------- -------
 F435W   4329.2              3.148e-19  25.155  25.763  25.665

Retrieve the zeropoint information for the F435W filter for WFC at multiple dates:

>>> from acstools import acszpt
>>> dates = ['2004-10-13', '2011-04-01', '2014-01-17', '2018-05-23']
>>> queries = []
>>> for date in dates:
...     q = acszpt.Query(date=date, detector='WFC', filt='F435W')
...     zpt_table = q.fetch()
...     # Each object has a zpt_table attribute, so we save the instance
...     queries.append(q)
>>> for q in queries:
...     print(q.date, q.zpt_table['PHOTFLAM'][0], q.zpt_table['STmag'][0])
2004-10-13 3.074e-19 erg / (Angstrom cm2 s) 25.181 mag(ST)
2011-04-01 3.138e-19 erg / (Angstrom cm2 s) 25.158 mag(ST)
2014-01-17 3.144e-19 erg / (Angstrom cm2 s) 25.156 mag(ST)
2018-05-23 3.152e-19 erg / (Angstrom cm2 s) 25.154 mag(ST)
>>> type(queries[0].zpt_table['PHOTFLAM'])
astropy.units.quantity.Quantity

Classes

Query(date, detector[, filt]) Class used to interface with the ACS Zeropoints Calculator API.