ZTF Metadata
Quick Links
The tables describing the metadata for ZTF products are:- ZTF Science Exposures Metadata
- ZTF Calibration Metadata
- ZTF Raw Metadata
- ZTF Reference Image Metadata (same for deep reference images)
The ZTF data products themselves are available here, for browsing or for retrieving with an API:
How to locate a ZTF file from its metadata
The path of a ZTF data product file can be deduced from its metadata according to the following rules, where the + signs indicate concatenation and the bolded strings represent metadata columns or strings derived from metadata columns.
Below, year is the first four characters of filefracday, month is characters 5--6 of filefracday, day is characters 7--8 of filefracday, and fracday is characters 9--14 of filefracday.
- Science Exposures
-
File Path Pattern:
'https://irsa.ipac.caltech.edu/ibe/data/ztf/products/sci/'+year+'/'+month+day+'/'+fracday+'/ztf_'+filefracday+'_'+paddedfield+'_'+filtercode+'_c'+paddedccdid+'_'+imgtypecode+'_q'+qid+'_'+suffix
where paddedfield is the field padded with initial zeros to 6 characters, paddedccdid is the ccdid padded with an initial zero to 2 characters; suffix can be any of the following:
- sciimg.fits (primary science image)
- mskimg.fits (bit-mask image)
- psfcat.fits (PSF-fit photometry catalog)
- sexcat.fits (nested-aperture photometry catalog)
- sciimgdao.psf (spatially varying PSF estimate in DAOPhot's lookup table format)
- sciimgdaopsfcent.fits (PSF estimate at science image center as a FITS image)
- sciimlog.txt (log output from instrumental calibration pipeline)
- scimrefdiffimg.fits.fz (difference image: science minus reference; fpack-compressed)
- diffimgpsf.fits (PSF estimate for difference image as a FITS image)
- diffimlog.txt (log output from image subtraction and extraction pipeline)
- log.txt (overall system summary log from realtime pipeline)
Example search (for proprietary data, can add --user myemail.astronomy.edu:mypassword after curl):
curl -o out.tbl "https://irsa.ipac.caltech.edu/ibe/search/ztf/products/sci?POS=255.57691,12.28378"
For one entry in the output, the metadata contains:
- filefracday = '20180411467847'
- year = '2018'
- month = '04'
- day = '11'
- fracday = '467847'
- paddedfield = '000535'
- filtercode = 'zr'
- paddedccdid = '11'
- imgtypecode ='o'
- qid = '3'
Therefore, the URL to the science exposure is:
https://irsa.ipac.caltech.edu/ibe/data/ztf/products/sci/2018/0411/467847/ztf_20180411467847_000535_zr_c11_o_q3_sciimg.fits
- Calibration Bias
-
File Path Pattern:
'https://irsa.ipac.caltech.edu/ibe/data/ztf/products/cal/'+year+'/'+month+day+'/bias/'+filtercode+'ccd'+paddedccdid+'/q'+qid+'/ztf_'+filestartdate+'_'+filtercode+'_c'+paddedccdid+'_q'+qid+'_bias.fits'
Example:
Try the following search in your browser:
https://irsa.ipac.caltech.edu/ibe/search/ztf/products/cal?WHERE=ccdid=11+AND+caltype=%27bias%27&CT=html
The entry of interest has metadata:
- ccdid = '11'
- qid = '3'
- nightdate = '20180411'
- filtercode = '00'
Therefore, the URL to the bias frame is:
https://irsa.ipac.caltech.edu/ibe/data/ztf/products/cal/2018/0411/bias/00/ccd11/q3/ztf_20180411_00_c11_q3_bias.fits
- Calibration High Frequency Flat
-
File Path Pattern:
'https://irsa.ipac.caltech.edu/ibe/data/ztf/products/cal/'+year+'/'+month+day+'/hifreqflat/'+filtercode+'/ccd'+paddedccdid+'/q'+qid+'/ztf_'+filestartdate+'_'+filtercode+'_c'+paddedccdid+'_q'+qid+'_hifreqflat.fits'
Example:
Try the following search in your browser:https://irsa.ipac.caltech.edu/ibe/search/ztf/products/cal?WHERE=ccdid=11+AND+caltype=%27hifreqflat%27&CT=html
The entry of interest has metadata:
- ccdid = '11'
- qid = '3'
- nightdate = '20180411'
- filtercode = 'zr'
Therefore, the URL to the high frequency flat frame is:
https://irsa.ipac.caltech.edu/ibe/data/ztf/products/cal/2018/0411/hifreqflat/zr/ccd11/q3/ztf_20180411_zr_c11_q3_hifreqflat.fits
- Raw
-
File Path Pattern:
'https://irsa.ipac.caltech.edu/ibe/data/ztf/products/raw/'+year+'/'+month+day+fracdate+'/ztf_'+filefracday+'_'+paddedfield+filtercode+'_c'+paddedccdid+'_'+imgtypecode+'.fits.fz'
Example:
Try the following search in your browser:https://irsa.ipac.caltech.edu/ibe/search/ztf/products/raw?WHERE=ccdid=11+AND+imgtype='object'+AND+filefracday=20180411467847&CT=html
The first entry has metadata:
- filefracday = '20180411467847'
- filtercode = 'zr'
- paddedccdid = '11'
- paddedfield = '000535'
- imgtypecode = 'o'
Therefore, the URL to the raw frame is:
https://irsa.ipac.caltech.edu/ibe/data/ztf/products/raw/2018/0411/467847/ztf_20180411467847_000535_zr_c11_o.fits.fz
Currently, the possible values for "imgtypecode" pertaining to raw image data files are:
- o = science (on-sky); see example above.
- b = bias calibration image
- d = dark calibration image
- f = dome/screen flatfield calibration image
- Reference Images
-
File Path Pattern:
'https://irsa.ipac.caltech.edu/ibe/data/ztf/products/ref/'+fieldprefix+'/field'+paddedfield+'/'+filtercode+'/ccd'+paddedccdid+'/q'+qid+'/ztf_'+paddedfield+'_'+filtercode+'_c'+paddedccdid+'_q'+qid+'_refimg.fits'
Example:
Try the following search in your browser:https://irsa.ipac.caltech.edu/ibe/search/ztf/products/ref?WHERE=field=000535+AND+ccdid=11+AND+qid=3
The entry of interest has metadata:
- paddedfield = '000535' which has a field prefix of 000
- filtercode = 'zr'
- paddedccdid = '11'
- qid = '3'
Therefore, the URL to the primary reference image is:
https://irsa.ipac.caltech.edu/ibe/data/ztf/products/ref/000/field000535/zr/ccd11/q3/ztf_000535_zr_c11_q3_refimg.fits
- Deep Reference Images
-
File Path Pattern:
'https://irsa.ipac.caltech.edu/ibe/data/ztf/products/deep/'+fieldprefix+'/field'+paddedfield+'/'+filtercode+'/ccd'+paddedccdid+'/q'+qid+'/ztf_'+paddedfield+'_'+filtercode+'_c'+paddedccdid+'_q'+qid+'_refimg.fits'
Example:
Try the following search in your browser:https://irsa.ipac.caltech.edu/ibe/search/ztf/products/deep?WHERE=field=000535+AND+ccdid=11+AND+qid=3
The entry of interest has metadata:
- paddedfield = '000535' which has a field prefix of 000
- filtercode = 'zr'
- paddedccdid = '11'
- qid = '3'
Therefore, the URL to the primary deep reference image is:
https://irsa.ipac.caltech.edu/ibe/data/ztf/products/deep/000/field000535/zr/ccd11/q3/ztf_000535_zr_c11_q3_refimg.fits