I'm doing a project that requires raw .fits images that contain a certain galaxy from the HST (F814W filter).

I've been able to find the calibrated images of the WFC view using the MAST data portal. However, there is no raw data listed. I would also like to find any of the corresponding HRC data as well if possible.

If anyone out there knows where to find the data, please let me know!

  • $\begingroup$ For my curiosity: what kind of projects require uncalibrated data with all the instrument artefacts? $\endgroup$ Commented Nov 19, 2021 at 12:01
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    $\begingroup$ Using it to generate a noise map for strong lensing ray tracing simulations. Will probably be unnecessary in the long run, but it may be useful to compare it to previous results that have been computed from a raw data pipeline. $\endgroup$ Commented Nov 19, 2021 at 23:42

1 Answer 1


You can get these data from MAST but it's not terribly obvious. Once you have filtered down to the data you want, selecting the data for download will produce a box that allows Uncalibrated file types to be returned. Searching the MAST archive for Hubble Space Telescope(HST) data from the Advanced Camera for Surveys (ACS; which contains the Wide Field Camera (WFC) and High Resolution Camera (HRC) you seek) in the specified filter (F814W; a Wide Filter, centered at 814 nm) for galaxy data (MAST query URL) should produce a display that looks like: Result of query on the MAST archive

Selecting data that you want to download (tick boxes on the left side; note this search was for public data so data that is still within its proprietary period after being taken and therefore only available to members of the proposal should not appear in the results) will produce a 'Download Data' button: MAST archive showing selected datasets and download data button

Clicking the 'Download Data' button will (might take a while if you have lots of datasets selected) bring up a dialog box which allows you to select 'Uncalibrated' and/or 'Reference' to see those file types along with the pipeline processed calibrated images (note the _raw and _spt FITS files options that have now appeared):

MAST archive screenshot showing Uncalibrated data

Selecting these will result in those datafiles being added to your downloadable dataset. HST documentation and the Instrument and Data Handbooks for all the current and past instruments can be found here. In particular the ACS Data Handbook has a Section 2.1 (Types of ACS files) which explains what the many suffixes mean. There are a lot of processing steps that occur to the raw data before pipeline products are delivered to the archive which are outlined in the later chapters of the ACS Data Handbook - it is strongly recommended to read these to understand the processing that was done and the calibration files needed if you are trying to replicate it, particularly for HST data (which has a lot of cosmic rays) and ACS data (which has significant geometric distortion). There is a section on manual recalibration of ACS data which makes use of Python.


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