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As of April 13, the archive is now using the STScI Single Sign-On (SSO) identity manager. To check on your account click here. For more information about how accounts were transitioned click here.

Retrieval Options

Once observations of interest are found, registered and anonymous users can retrieve the data. We describe here the various retrieval options for HST data and explain the various terms involved, which you will encounter on the retrieval page.

Retrieving Public Data Anonymously
You can retrieve public data using the username "anonymous" and your email address as your password .

Archive Username
MAST no longer registers their own set of archive users as was done in the past. As of April 2015, users may log into the Archive using an STScI Single Sign-On (SSO) Portal identity.

All STScI employees by default already have this SSO identity set up and can use these credentials for any requested login information requested by the Archive.

Non-STScI users either had their Archive username and password migrated to SSO credentials and were notified via email, or they need to register for an STScI SSO external account. If you want an archive account, you can register for one on the web. See our page for more information. If you register, you should receive your username and password via email in a few minutes.

Archive Password
This is the password that was given to you when you registered (See Archive Username, above). As of April 2015, the username and password are no longer specific to MAST and are referred to as the STScI SSO portal identity which will allow access to other STScI services without requiring additional usernames/passwords.

Delivery Options
How you want the data sent to you. You may chose either an electronic delivery option or a hard-media delivery option.

FTP: FTP the data to the destination shown
The data will be FTPed to the given destination.

SFTP: sftp the data to the destination shown
The data will be FTPed to the given destination using OpenSSH v2.

STAGE: Put the data onto the Archive staging disk.
The data will be written to the Archive staging disk. You will be able to pull from the staging disk using FTP and logging in with your archive username and password. Only non-proprietary data may be retrieved. You can delete your data when you are done.

DVD: Send the data to me on DVD.
The data will be written to a DVD and delivered to the mailing address you provide.

DISK or Hard Drive: Send the data to me on a Hard Drive
You may request data to be delivered on an external hard drive if you anticipate many GB of data retrieval. Currently the hard drive must be returned to STScI after the data are read onto your local drive. We have a limited number of drives for use and you MUST contact the Archive Hotseat (410-338-4547 or to coordinate your requests and use of the hard-drive option.

Verify Your Mailing Address
If you select one of the hard media options, we will ask you to provide a mailing address. If you need to make changes to your mailing address, simply make the changes in the form before clicking the Send retrieval request to ST-DADS button. Your request will not be sent until you click on this button.

You currently cannot have two hard-media requests in process at the same time with two different mailing addresses.

Destination (if you selected FTP or SFTP)
This is where you would like the data sent. These fields are required if you select the FTP retrieval option. The data will be delivered to this destination via FTP.

The hostname of the destination.

The name of the directory to which the data will be written. Please make sure that this directory exists, is writeable, and has enough space. The retrieval will fail otherwise. (Unfortunately, for technical reasons, we can't reliably estimate the size of your retrieval until the files are read from the optical platters, so we can't tell you whether there is enough space there, but generally, retrievals are rarely more than a gigabyte in total size.)

The username to be used when FTPing the data.

The password for the destination username.

Invalid Password Characters
There are five characters which, if present in a password, will cause the retrieval to fail: (, ), *, ", and /.

Retrieval Security
All the information you enter in this form will be sent to ST ScI through an SSL (encrypted) web connection using a Verisign certificate. The password remains encrypted until it is needed to transfer the data to you. The password is not retained after the data are transferred.

If your local system disallows FTP access or sftp (OpenSSH v2), and you are requesting only public data, you can use the STAGE option. If you are requesting proprietary data, you may select a hard-media option (Disk, DVD).

Science Files Requested
The type of science files (as opposed to reference files) that you would like.

On-The-Fly Reprocessing
ST ScI's On-the-fly Reprocessing (OTFR) system for WFPC2 and STIS was opened to external users in December of 1999. As of June 2000, ST ScI stopped archiving calibrated data for WFPC2 and STIS. In the first week of April 2001, we released the On The Fly Reprocessing System for STIS and WFPC2 data. On-the-fly Reprocessing for NICMOS data was implemented on Septmeber 26, 2001. ACS data uses the OTFR system.

Archived version of calibrated science data for non-OTFR instruments and OTFR data for OTFR instruments.

Raw science data. For OTFR, the "raw" FITS files are generated from telemetry.

Data Quality
Reports describing science data quality.

Observation Log Files
Jitter and pointing data files.

Waivered Fits
Now that most WFPC2 data have been reprocessed, MAST has discontinued on-the-fly reprocessing and supplies calibrated images directly from the static archive. By default, these files are delivered in multi-extension FITS (MEF) format. If you would prefer to receive the wFITS format previously used for WFPC2 data, check the box below. For details, see the WFPC2 Reprocessing page

Reference Files
Files used for calibration. You may select either the files that were used when the data was originally calibrated just before archiving, or the calibration files that should be used if you plan to recalibrate the data for non-OTFR instruments. Only the best files are available for data from OTFR instruments.

Used Reference Files
Files used for original calibration.

Best Reference Files
Files to use for recalibration.

File Extensions Requested

Entering specific file extensions
Enter the specific three-letter file extension if it is not listed in the scrolling listbox. Remember that science data is archived in FITS format (not GEIS), so for example, the .c0h and .c0d files will be combined into a single extension: c0f.

For common questions about retrievals see our FAQ page.