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sedm.py documentation

ztfquery.sedm.py is module to access sedm data from pharos. If you do not have an account yet and are ZTF member, send an email to Richard Walters ([email protected]) to create one.

Requirements

  • You need an account on pharos.

Getting SEDM data

For example, if you want to download the cube(s) assocated to "ZTF18abqlpgq", simply do:

from ztfquery import sedm
squery = sedm.SEDMQuery()
squery.download_target_data("ZTF18abqlpgq")

The data will be stored under $ZTFDATA+/SEDM/ and each file is under their corresponding observation date ($ZTFDATA+/SEDM/YYYYMMDD).

You can then get the full path of the data on your computer.

squery.get_local_data("ZTF18abqlpgq")

When downloading_target_data or get_local_data you can specify which data you want using the which argument. (which='cube' by default)

For instance if you want the sedm spectra in 'txt' format (as in the marshal):

from ztfquery import sedm
squery = sedm.SEDMQuery()
squery.download_target_data("ZTF18abqlpgq", which='spec', extension='txt')
spec_fullpath = squery.get_local_data("ZTF18abqlpgq", which='spec', extension='txt')

Reading cube and spectra

To read cube and spectra you are invited to use pysedm (https://github.com/MickaelRigault/pysedm).

import pysedm
from ztfquery import sedm
squery = sedm.SEDMQuery()
cube = pysedm.get_sedmcube( squery.get_local_data("ZTF18abqlpgq", which='cube')[0] )
cube.show(interactive=True)

See details on pysedm documentation.

Structure

What Files

The information about which data has been acquired by SEDM every day are "what files". ztfquery is downloading the what files and store them inside $ZTFDATA+/SEDM/whatfiles.json. Every time you are requesting for data, if the dates is unknown, it is downloaded and whatfiles.json is updated. This is made automatically, don't worry.

The first time you are using the sedm module, the first query will be a bit slow because you will need to download all the what files. Then, it will only download the missing dates, most likely the latest nights depending how often you are using the module.

Citation

If you are using a SEDM spectrum obtained since July 2018 (incl.) please cite the pysedm paper