SOFIA Science Data Archive: Overview

Note that there are also SOFIA Science Data Archive video tutorials, available at the IRSA YouTube channel . Look for the playlist collecting all the SOFIA videos in one place.

Contents of page/chapter:
+Background -- A little more about SOFIA
+Terminology, Hints, and Tips
+Instruments & Data Available, and Caveats
+Side Menu and Adding to the Tabs Menu
+Side Menu and Appearance
+User Login Overview
+Getting More Help

Background

More information about SOFIA and its instrument suite can be found at the SOFIA mission page at IRSA , specifically :

• the data page , which includes handbooks and the list of known issues with SOFIA data;
• the instruments page , which includes pages for each of the SOFIA instruments.

Terminology, Hints, and Tips

Telescope & Data Terminology

• Mission ID is a unique mission identifier. In the SOFIA framework, a mission is the same as a SOFIA flight. (List of all the SOFIA Mission IDs in the SOFIA Science Data Archive , retrieved via TAP .)

• Flight Series means a grouping of missions (flights) close in time where SOFIA originates from the same airfield and the same instrument is used.

• Plan ID is the identifier for the observing plan which contains all the observations (AORs). Each accepted observing program has a Plan ID; this can be thought of as basically a proposal ID. (List of all the SOFIA Plan IDs in the SOFIA Science Data Archive ,retrieved via TAP .)

• AOR is astronomical observation request, an individual SOFIA observation sequence. Each AOR involves many frames, and therefore multiple files.

• AOR ID is the AOR identifier. The AOR ID is assigned during the creation of the final version of an AOR to be used in flight. Multiple observations in one or more flights and/or instrument configurations can be associated with a single AOR.

• Observation ID is the combination of Mission ID and AOR ID, which together uniquely identifies each SOFIA observation. An observation will contain multiple data files. AOR ID by itself is not sufficient since some AORs are spread across multiple flights.

In practice, during a SOFIA mission (or flight), several Plan IDs (or programs) are executed, and each of these consist of one or more AORs.

The Mission ID, Plan ID, and AOR ID are metadata that can be found in the header of an AOR file.

Data levels

• Level 0: raw data in FITS format.
• Level 1: raw data in FITS format.
• Level 2: data corrected for instrument artifacts (e.g., flat-fielded, dark-subtracted, bad pixels removed).
• Level 3: flux calibrated and telluric corrected data (e.g., units of Jy/pix).
• Level 4: Any data product generated from the combination of Level 3 files (e.g., a mosaic) is a Level 4 product. For most instruments, Level 4 products could be generated from observations obtained across multiple flights, or even multiple flight series and observing cycles.

Note that not all instruments will have all data levels, and not every flight will have data from every level. The following are the expected data levels, at most, from each instrument:

• EXES: 0, 1, 2, 3
• FIFI-LS: 1, 2, 3, 4
• FLITECAM: 0, 1, 2, 3
• FORCAST: 1, 2, 3, 4
• FPI+: 1, 2, 3, 4
• GREAT: 1, 3, 4
• HAWC+: 0, 2, 3, 4

For much more information, see the SOFIA data processing page .

Tool Terminology

The words in blue rectangles at the top are 'tabs.'

This icon in the upper left pulls open a "drawer" from the left hand side which enables you to add or remove tabs from this top level (see below). Most of these tabs allow searching. The side drawer also can allow you to change the appearance (dark or light mode) (see below).

When you have results loaded into the SOFIA Archive, your browser window is divided into "panes", like "window panes." The contents of the panes depends on what you are doing with the tool, but could include an image pane, at least one table pane, and/or a plot pane. You can expand any of the window panes by clicking on the expand icon:

Each of the three main kinds of 'panes' in the display has its own toolbox in its upper right corner which operates on things in that pane, and the basic functionality for each of these panes is covered elsewhere in this document:

• The Tables section covers (among other things) the tables toolbox
• The Plots section covers (among other things) the plots toolbox
• The Visualization section covers (among other things) the images toolbox

In the SOFIA Archive, you can search by position or orbital parameters for moving targets, or any of a number of other SOFIA-specific searches. Searching is in its own section.

Instruments & Data Available, and Caveats

Data currently in the SOFIA Science Data Archive

Data from most instruments (EXES, FIFI-LS, FLITECAM, FORCAST, FPI+, GREAT, HAWC+), Cycles 1 through Cycle 9, are available in the SOFIA Science Data Archive.

Cycle dates and instruments: Which data are in the SOFIA archive?

Not all instruments, all cycles are in the SOFIA Science Data Archive. The table summarizes which data are in the Archive. (DNE means does not exist, e.g., data do not exist for this instrument in this cycle.) HIPO data are available here .

Cycle	Observation dates	EXES	FIFI-LS	FLITECAM	FORCAST	FPI+	GREAT	HAWC+	HIPO	Schedule/ Flight Plans link
Short Science	12/10 -04/11	DNE	DNE	DNE	No	DNE	Yes	DNE	DNE	...
Basic Science	05/11 - 12/11	DNE	DNE	DNE	No	DNE	Yes	DNE	DNE	...
Cycle 0	07/12 - 11/12	DNE	DNE	DNE	No	DNE	Yes	DNE	here	...
Cycle 1	04/13 - 02/14	DNE	DNE	Yes	Yes	DNE	Yes	DNE	here	here
Cycle 2	02/14 - 02/15	Yes	Yes	Yes	Yes	DNE	Yes	DNE	here	here
Cycle 3	03/15 - 12/15	Yes	Yes	Yes	Yes	Yes	Yes	DNE	here	here
Cycle 4	02/16 - 02/17	Yes	Yes	Yes	Yes	Yes	Yes	Yes	DNE	here
Cycle 5	02/17 - 11/17	Yes	Yes	Yes	Yes	Yes	Yes	Yes	here	here
Cycle 6	05/18 - 03/19	Yes	Yes	DNE	Yes	Yes	Yes	Yes	DNE	here
Cycle 7	04/19 - 03/20	Yes	Yes	DNE	Yes	Yes	Yes	Yes	DNE	here
Cycle 8	08/20 - 06/21	Yes	Yes	DNE	Yes	Yes	Yes	Yes	DNE	here
Cycle 9	07/21 - 09/22	Yes	Yes	DNE	Yes	Yes	Yes	Yes	DNE	here

• List of all the SOFIA Mission IDs in the SOFIA Science Data Archive (retrieved via TAP )
• List of all the SOFIA Plan IDs in the SOFIA Science Data Archive (retrieved via TAP )

All proprietary periods have expired. All the data in the archive are public.

Not in the archive:

Some early data through Cycle 0 are not in this archive.

• HIPO data are available here
• FORCAST commissioning data are available here
• Commissioning data for EXES, FIFI-LS, and HAWC+ are available here

More data?

Some teams may still plan to deliver reprocessed or high-level products to IRSA; with a few exceptions, those kinds of deliveries will, in general, be treated as Legacy deliveries and therefore be linked from the SOFIA mission page , and the data available through tools like the Data Collection Explorer .

Specific items, caveats, etc. to keep in mind

General information

• In an all-sky search, some columns in the result table have missing PLAN ID (i.e., PLAN ID= unknown). These are typically calibration observations.

• In an all-sky search, many rows of the result table have the Proposal PI column blank. These are typically calibration observations but may also be data products combining many different observations.

• Some observation dates are erroneously set to 1970.

• Data that are not public have release dates that are the actual, future release dates. Data that are aleady public may have the most recent processing date, as opposed to the date that the original observations actually went public.

• Some AOR ID and Plan ID are erroneously set to obviously incorrect values.

• Some positions, especially in the earliest data, have larger uncertainties. Recommend larger search radii to be sure you're catching all the relevant observations.

• The Preview tab in the results is only populated for (some) GREAT, FIFI-LS, and HAWC+ Level 4 products, and other instruments (or low level data for any instrument) will have a blank "No Preview Available." This is working as intended.

• When NAIF ID appears to conflict with Target Name, believe the NAIF ID. This is most common for some of the calibration AORs.

• Some data may only be available at Level 1 if they were never processed beyond that level.

• If the Observation Type is not OBJECT, do not not necessarily believe the Target or NAIF ID fields; it could be, e.g., flatfields at a completely different position (not the stated target).

• On searching for occultation observations: there are two choices. Easier: use the precovery search. Search for the occulter of interest, and look for results with target_moving = 0, which is equivalent to no NAIF_ID. Harder: do an all-sky query and filter the results by the object name of the occulter you're interested in (example: Titan). Results for that object but with no NAIF_ID are likely occultations, since the telescope was pointing at a sidereal target. You can confirm by looking at the proposal abstract in the AOR tab (example: 06_0160).

• The GUI filtering menu for Product Type considers blank fields to be "NULL" (for example, FLITECAM raw data), which seems a bit misleading but is working correctly (this is a feature not a bug).

EXES

• EXES started operations in 2015, so no data are available before that date.

• Level 1 raw files have no Product Type; Level 2 files have Product Type "raw".

• The EXES instrument does not have Level 4 data products, so an all-sky query for EXES Level 4 returns no results.

• Peculiar values for spectral resolution indicate calibration files.

FIFI-LS

• FIFI-LS started operations in 2014, so no data are available before that date.

• Peculiar values for spectral resolution are shown here as propagated from the FITS headers.

• Level 4 wxy_resampled, HDU 10, display shows pixels in units of Jy even though it's a coverage map.

FLITECAM

• FLITECAM was retired in 2018, so no data exist after that date for this instrument.

• The blank spectral resolution for FLT_A1_LM (energy bounds 4.4-5.53 microns) is working as intended; the Observer's Handbook doesn't list R for that combination of grism and order sorting filter.

• The FLITECAM instrument does not have Level 4 data products, so an all-sky query for FLITECAM Level 4 returns no results.

• OC1E FLITECAM data is only Level 1, so there is no Level 2/3.

• Some data products may be included in the download that according to the Data Handbook should not have been saved or archived.

FORCAST

• The FORCAST instrument only rarely has Level 4 data products, so an all-sky query for FORCAST Level 4 returns relatively few results.

• The cross-dispersed modes, X-, were not used in Cycle 4 and Cycle 5, so an all-sky query for FORCAST, GRISM, FOR_XG063 or FOR_XG111, returns 0 results.

• The FORCAST definition of SW and LW cameras is fluid so a few short wavelengths (such as 6.4 micron and 11.2 micron) fall under the LW category. This should not surprise the user. A complete definition of SW and LW cameras is provided in the Observer's Handbook, which can be found on the Proposal Documents page .

• Users should be aware that in the FORCAST query menu, the second number that appears on the Spectral Element menu is the filter width (in microns) of a given filter. This is not the same as the spectral resolution, which is the quantity provided in the FORCAST result tab under "Details". Most spectra are resolution (R)~100; cross-dispersed spectra (XG*) are R~1000. Medium and narrow-band imaging filters can also have a resolution (R~45-70).

• FORCAST footprints in the coverage tab may be larger than expected. NAXIS* and CDELT* are the same for different levels, yet Level 1 is shown with a much smaller footprint than Levels 2-3. The valid data really is a 256x256 square, but the Level 2 coadd has an actual fits header with NAXIS*=656, with the valid data embedded within a square of NaNs. The coverage software sees the 656 pixel dimensions in the actual FITS headers and draws the larger square.

• FORCAST FOR_F086 energy_bounds and spectral resolution may not be populated.

FPI+

• FPI+ started operations in 2015, so data is only available after that date.

• The FPI+ Instrument Team has not generated an instrument handbook, so this is not currently available.

GREAT

• The GREAT instrument does not have Level 2 data products, so an all-sky search for GREAT Level 2 returns 0 results.

• Not all the GREAT data are in FITS format. All the Level 1 data are FITS files, while Level 3 data are tarfiles consisting of CLASS files, and Level 4 can be either CLASS or FITS. (Level 2 data do not exist for this instrument.)

• GREAT Level 4: velocities derived by Firefly are wrong.

• GREAT previews may not exist for all data.

• For the GREAT instrument, a frequency channel is defined as a delta function, not as a Gaussian with a FWHM. This has to be kept in mind when performing a query by frequency. This is not the case for the other instruments.

• Some early GREAT observations have low spectral resolution (~1e3 instead of the usual ~1e7) from a rarely-used continuum mode.

• Some GREAT Line values seem unusual, like an observation of Jupiter with Line="L2_saturn", but those refer to continuum settings originally used on one calibrator but that may sometimes be used on others.

• GREAT files with INSTMODE=CAL have incorrect coordinates, target name, and NAIF ID. Unfortunately the INSTMODE keyword isn't visible to users without downloading the files

HAWC+

• HAWC+ started operations in 2016, so HAWC+ data is only available after that date.

• The raw data from HAWC+ correspond to Level 0 rather than Level 1. (Level 1 is raw for all the other instruments.)

• A few early HAWC+ observations used both band A and B in the same Observation, which results in the band B energy_bounds not being computed correctly since the ingest code sees a band A Observation and doesn't expect or allow for spectral elements to change within an Observation.

Side Menu and Adding to the Tabs Menu

The highlighted bar ("Results" in this example) is the tab you have in the foreground on your main window. You can use this side menu to add (or remove) blue tabs from the top of your SOFIA Archive interface. By default, Results, SOFIA Search, and Precovery are shown, along with the Job Monitor. Under "IRSA search tabs," Catalogs and VO TAP search IRSA holdings. Under "External archive search tabs," NED Objects and Multi-archive VO TAP (that is, a general TAP search) search other (non-IRSA) archives. Click on the "Hide Tab" button to remove that corresponding tab.

Side Menu and Appearance

This controls the appearance of the tool in your browser -- do you want it to run as light mode, dark mode, or respect whatever preferences you have set on your system? Try out the different modes; you may have a preference!

User Login

Getting More Help

You can submit questions to the IRSA Help Desk .

A set of frequently asked questions (FAQs) about the SOFIA Archive is here.

The IRSA YouTube channel has lots of short videos about IRSA tools.

Found a bug? The known bugs and issues in this version of the SOFIA Archive are listed here . If you think you have found a bug, before reporting it, please check this list, and read this online SOFIA Archive help. It may be a "feature" we already know about. If you have found a new, real bug, then please do contact us via the IRSA Help Desk . Please include your operating system version and your browser software and version. If you can, please also include any specific error message you may have gotten. (NB: In our testing, copying shortcuts worked on Windows and Linux; the command-C did not always work on Macs, but selecting and clicking the right mouse button often did when command-C did not.)