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• Supported Instrument Modes
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Home > Information for Researchers > Applying for Observing Time

SOFIA Observing Program

• Applying for Observing Time
• Cycles 0 and 1
• Instruments
• Observing on SOFIA
• Observation Planning
• Data Cycle System
• Education and Public Outreach Activities
• Additional Information, References, and Publications

Applying for Observing Time

SOFIA Proposal Tool

Requesting observing time on SOFIA is a two-phase process. In Phase I, observers must submit a scientific proposal that outlines the purpose of the observations and provides a list of targets, instrument configurations, and estimates of the required exposure times. Phase I proposals must be prepared with, and submitted through, the SOFIA Proposal Tool (SPT). A Java-based application based on the HST proposal tool APT, SPT is available for downloading on the Data Cycle System (DCS) web page. It runs on a variety of computer platforms and operating systems. Because it is downloaded to the proposer's computer, the astronomer can prepare his/her proposal without requiring a connection to the SOFIA web site. An internet connection is required, however, in order to submit the proposal. SPT requires the proposer to specify the following information in a proposal:

• Proposer Information (name, affiliation, address, e-mail, co-I's, etc.)
• Target list and information (source name, RA, Dec, proper motion)
• Observational set-up (e.g., instrument, instrument mode, observing mode, exposure times, observing and scheduling constraints, water vapor constraints)
• Scientific Justification (fixed page limit; separate pdf file)
• Technical Justification
• Miscellaneous information (e.g., keywords, status of previous observations)

The proposer must generate a separate PDF file containing the text of the Scientific and Technical Justifications, which are then appended to the form generated by SPT itself. The completed proposal can be submitted simply by clicking a button in SPT. Detailed observing plans must be generated for successful proposals in Phase II.

Exposure times for observations with FLITECAM, FORCAST, and HAWC can be estimated from the SOFIA Instrument Time Estimator (SITE).

The effect of water vapor on proposed observations can be estimated by running ATRAN to compute the atmospheric transparency over the desired wavelength range.

Schedule

Except for Cycles 0 and 1, the SOFA observing cycle will last for a year, starting in October and ending the following Spetember. Proposals for an observing cycle are due at the SSMOC five months before the start of the cycle (i.e., 30 April, midnight PST). A Call for Proposals (CfP) for an observing cycle will be issued at least 90 days before the proposal deadline. The TAC will meet to review proposals and allocate time not more than TBD months after the proposal deadline. Announcement of observing time will be sent to proposers immediately after the TAC meeting, and not later than August for the cycle starting in October.

Time Allocation Policies

The SOFIA observatory is open to the entire international astronomical community. During the first few years (observing cycles) of the SOFIA program, observing time will be divided between General Investigator (GI) observations, engineering time, guaranteed time for the instrument teams, and Director's Discretionary Time (DDT). The GI time is divided between the US community, which receives 80% of the science observing time, and the German astronomical community, which is allocated 20%. Observing time for international investigators (i.e., neither US nor German) is available from both US and German time allocations. Some limited amount of GI time will be available for Target-of-Opportunity (ToO) and Service proposals. The latter consist of short (< 3 hour) observations carried out by the staff on behalf of a General Investigator.

GI observing time is awarded based on peer review by the SOFIA Time Allocation Committees (TACs). The US and Germany will have separate Calls for Proposals and STACs and proposals can be submitted to either the US or German TAC. Normally, astronomers at US institutions will submit their proposals to the US TAC and astronomers at German institutions will submit proposals to the German TAC. Proposals from international investigators will be submitted to both TACs. US astronomers, and international astronomers requesting time out of the US allocation, should submit their proposals electronically to the SOFIA Science and Mission Operations Center (SSMOC) at NASA Ames using the proposal tools provided by the SOFIA program (SOFIA Proposal Tool; see below). German astronomers should follow the proposal guidelines set forth by the Deutsches SOFIA Institut (DSI).

After the TACs have met and made their recommendations, and NASA has been informed, the Observatory Director, in consultation with the Deputy Director, will review the recommendations and grant final approval authority for observing time. Observing time granted to proposals will be charged against the total time allotted to the country whose TAC recommended the proposal.

It is important to note that

• All researchers will propose for, and be granted, observing time in units of hours (or fractions thereof), not full flights.
• There will be no "make-up" time for science observations lost due to weather, observatory problems, or instrument malfunctions.

Reserved Target List and Restricted Observations

The teams who have constructed the various SOFIA science instruments will have time to commission their instruments and, in some cases, guaranteed observing time. Objects that these teams plan to observe during commissioning and guaranteed time will be listed on the Reserved Target List and will be blocked from observations by GIs. No GI may request time to observe these sources using the same instrument and modes, and similar exposure times (within a factor of 3), as those selected by the SI teams. The Reserved Target List of blocked objects and the associated instrument modes will be available April 2008 for Cycle 0 and November 2008 for Cycle 1. Once the teams have exhausted their commissioning and guaranteed time, the remaining (i.e. unobserved) sources and their associated modes will be removed from the restricted list and released for observations by the general community.

Duplications Policy

Because SOFIA observing time is very limited, observations that duplicate those that have already been taken are to be avoided as much as possible. A duplication is an observation of a target that has been previously and successfully observed with SOFIA using the same instrument configuration (instrument, mode, filter, etc.) and an exposure time within a factor of 3. GIs should examine the SOFIA archives before submitting proposals in order to ensure that their proposed observations do not represent duplications. Duplications will be identified by the SSMOC staff before proposals are submitted to the TACs. Although in general the TAC will not allow proposals which represent duplications, the decision to allow such duplications of targets and observations lies ultimately with the Observatory Director and Associate Director. These decisions will be made on a case-by-case basis.

DDT and ToO

Approximately 10% of the total observing time available on SOFIA will be reserved for Director's Discretionary Time (DDT). This time will be awarded by the Director without peer review by the TAC. Targets of Opportunity (ToOs) come in two flavors: those that can be planned ahead of time and included in a normal observing program/proposal (e.g., a SN monitoring campaign) and those that arise during an observing cyle. Proposals to observe the first type of ToOs should be submitted in response to the normal Call for Proposals and will be reviewed by the TAC(s). Proposals to observe the second type of ToOs, by definition, cannot be submitted to the normal TAC in response to a Call for Proposals. These proposals will be reviewed by special peer review committee established by the Observatory Director. The time needed for observations of approved ToOs of this second type will be taken from the DDT. An investigator whose scheduled observing time is canceled as a result of ToO observations will be compensated in the following observing cycle. This is the only instance in which "make-up" time will be scheduled.

Cycles 0 and 1

Philosophy and Policies

During the first year of SOFIA operations, observing time available to General Investigators will be limited, primarily due to the need for time to carry out extensive engineering tests and commissioning of the aircraft, the telescope, and the instruments. These requirements will ultimately set the schedule during this first year. The Observatory Director is currently planning to reserve about 200 hours for GI observations in the first year. (Since SOFIA will fly only once a week during the first year, for about 8 hours each flight, this corresponds to about 6 months.) However, because this time is limited and subject to changes in the schedule necessary for engineering tests, it is being offered to the community on a ``shared-risk'' basis. Potential observers should keep in mind that the capabilities of both the instruments and the observatory may be somewhat uncertain at the time the first Call for Proposals is issued. We emphasize the ``shared-risk'' nature of this cycle by labelling it Cycle 0. Note, however, that proposals for Cycle 0 will not be due before SOFIA has been certified for science flight operations and observatory and instrument performance information are posted on the web. This is tentatively scheduled for January 2010, which is when proposals for Cycle 0 will be due. The current schedule is given below.

Any astonomer may submit a proposal in response to the Cycle 0 Call for Proposals. Proposals which best demonstrate and highlight SOFIA's capabilities and its complementarity to existing ground- and space-based observatories, while simultaneously setting forth scientifically-worthwhile projects, will be given preference. The time granted to any single proposal will be limited to about 8-10 hours. GIs will not be allowed to propose observations of objects on the Reserved Target List. There will be some funding available to the GIs of accepted Cycle 0 proposals.

Operations

SOFIA will offer access to two facility-class (FSI) and two principal-investigator-class (PSI/SSI) instruments during Cycle 0. (See the instrument section below for definitions of these terms.) The Facility Instruments will most likely be FLITECAM and FORCAST. The SSI will be HIPO; the PSI will be one of the German instruments (either GREAT or FIFI-LS). However, the final decision regarding instrument availability will be made at the time the Call for Proposals is issued. Because of the compressed schedule for the first observing cycle, observers will be given only short notice of the allocation and scheduling of their observing time. Therefore advanced preparation will be crucial for successful operations.

Astronomers requesting observations with FSIs during Cycle 0 are strongly encouraged (but are not required to) to contact the FSI team prior to submitting a proposal and consider collaborating with them. All investigators requesting observations with PSIs must collaborate with the PSIs teams during Cycle 0 and all subsequent observing cycles.

All observations in Cycle 0 will be taken in Visitor mode. Service mode observations will not be allowed during Cycle 0. GIs will not be allowed to submit ToO proposals in response to the Cycle 0 Call for Proposals.

Cycle 0 Schedule

The tentative schedule for Cycle 0 is given below.

Cycle 1 Schedule

The tentative schedule for Cycle 1 is given below.

Because the plan is to obtain approximately 200 science hours during Cycle 0, this cycle may extend beyond the dates given in the table above (depending on engineering needs). This implies that the start of Cycle 1 may be delayed. However, Cycle 1 will end on 30 Sept in order to move onto the normal cycle schedule for Cycle 2.

Instruments

The observatory has three classes of instruments: Facility Science Instruments (FSIs), Principal Investigator Science Instruments (PSIs), and Special Purpose Principal Investigator Science Instrument (SSI). The astronomical community may apply for observing time on any of instruments. However, proposers wishing to use a PSI/SSI must obtain prior approval from the PSI team and include the PSI team as part of the investigator team on the proposal. Support of observing with PSIs will be provided primarily by the PSI teams and therefore these proposals must be technically approved by the PSI teams before submission.The SOFIA staff will provide support for astronomers using the FSIs.

Except for one combination of instruments (HIPO + FLITECAM), only one science instrument will be flown at any given time. Science instruments will be changed at most only once every other week.

The characteristics of the various SOFIA instruments (e.g., sensitivity, resolution, etc.) can be found on the instrument web pages . Exposure times for observations can be estimated from the SOFIA Instrument Time Estimator (SITE) on the DCS web page. Currently, SITE works only for the FLITECAM, FORCAST, and HAWC instruments.

The various modes in which the instruments can acquire data can be found on the Supported Instrument Modes page.

In addition to these instruments, SOFIA will also carry on board a Water Vapor Monitor (WVM) for determining the water vapor overburden. Target acquisition and guiding/tracking is accomplished using the three optical imagers, the Wide Field Imager (WFI), Fine Field Imager (FFI), and Focal Plane Imager (FPI).

Observing on SOFIA

Observing Modes

Observations can be made in one of three modes: Visitor, Queue, and Service. Visitor observing mode entails observations made by a GI who is aboard the aircraft. Queue mode entails observations made by members of the SOFIA staff for an observer who is not present on the aircraft. Although the presence of the GI is the only formal difference between Visitor and Queue mode, in practice, an effort will be made to concentrate Visitor mode observations from a given proposal during a few adjacent or closely-spaced flights in order to make it practical for the GI observer to be present. Most, but not all, of a flight on which a GI is present will probably be dedicated to the observations proposed by that GI. Queue mode observations, on the other hand, will be scheduled whenever the conditions are appropriate for the observations and the observing schedule allows.

Observations made with PSIs are considered Visitor mode observations, as they require the PSI team to be present on the flights.

In addition to Queue and Visitor modes, investigators can also request observations with FSIs to be carried out in Service mode. Service mode observations are short duration (< 3 hours) observations made by the SOFIA staff on behalf of an investigator who is not present on the flight. Essentially, they are short Queue mode observations. Proposals for Service mode observations will not be part of the normal proposal cycle. That is, SPT is not required for their submission and they will not be reviewed by the normal TAC. A small internal TAC designated and convened by the Director will review Service mode proposals and make recommendations to the Director. Service mode observations may come out of the DDT.

Observation Planning

Phase II

Astronomers who are granted time on an FSI will have to submit an Observing Plan and Astronomical Observation Requests (AORs). AORs provide all of the details needed to carry out an observation, including instrument mode and configuration, filter, integration time, etc., and represent the smallest observation "unit". AORs are generated by the GI using the AOR Editor, provided by SOFIA, to modify the pre-defined Astronomical Observation Templates (AOT). Each AOT corresponds to a unique instrument operating mode. A GI will need to specify the following information in an AOR:

• Target position
• Guide star(s)
• Required observing conditions and restrictions
• Exposure time
• Instrument mode and set-up (e.g., filters, gratings)
• Telescope set-up (e.g. chop, nod, dither parameters
• Observing priority

Some of this information will already have been filled in based on the material in the accepted proposal. AORs are not required for observations with PSIs or SSIs. A summary of the various FSI observing modes and the AOTs that define them are given on the Supported Instrument Modes page.

The Observing Plan details the order in which various AORs for a program are carried out. The GI modifies the Observing Plan generated from his/her proposal, using the Observing Plan Editor provided by SOFIA., to specify any special requirements relevant to the observations. Such information may include special calibration requirements, observation order for targets, water vapor constraints, observation time constraints, etc. All observing plans will be reviewed by the SSMOC staff before being passed on to the flight planner.

Completed AORs and Observing Plans will be required to be submitted to the SSMOC (via the Internet) TBD weeks in advance of the scheduled flights.

Flight planning

During regular operations, the observatory will fly three times per week (Mon-Fri), for approximately eight hours each flight, and 44 weeks each year. Each flight will be broken into a number of flight legs, each lasting anywhere from 10 min to about 4 hours, during which an astronomical target is observed. Therefore, the number of targets observed on any given flight will range from 2 to about 20, with an average of about 7. Because SOFIA is a flying observatory, planning observations is far more difficult than on ground-based or space-based observatories. Flight restrictions (e.g., the fact that SOFIA will take off each evening and land typically 8-10 hours later at the same airfield) constrain the amount of time possible to spend observing any given object. Although the limit varies with declination, at a maximum, only about 5 hours can be spent on any given source in a single flight. (This would be the best case, for an object observed while SOFIA is flying west.) Moving to a new object requires turning the aircraft, which requires a few minutes, and embarking on a new flight path. Furthermore, observations are restricted to telescope elevations between +20 and +60 degrees.

Flight planning will be done by the SSMOC staff for GI observations using FSIs (taken in either Visitor or Queue mode). A flight plan is generated for a given flight using the set of targets and exposure times, the observing altitude and fuel consumption, models for the wind and water vapor, and any flight restrictions (e.g., restricted or special use airspaces). Because GI observations are requested and scheduled in units of hours, flights with an FSI will typically contain targets from more than one project and GI, independent of whether the observations are done in Queue or Visitor mode.

A representative SOFIA flight plan for a flight starting and ending at Moffett Field is shown below.

Flying on SOFIA

TBD

Data Cycle System

The SOFIA Data Cycle is illustrated below. For a proposing investigator, his/her research begins as a proposal, progresses through observation planning, and produces data upon the execution of the observation. These data are archived, and for FSIs, reduced into data products according to the instrument mode of the observation. Finally, the data subject to the original research proposal are retrieved, analyzed, and published. An investigator looking to simply make use of archived and reduced data enters the lifecycle at the retrieval step.

The set of software tools designed to manage the data archive and allow investigators to participate in the data cycle (for example, by writing proposals, or querying the archive) is known as the SOFIA Data Cycle System (DCS). The DCS integrates and automates the observing and data retrieval process. A suite of tools is provided to an investigator, the tools produce data, and the tools and data interact with DCS services 'behind the scenes'.

SOFIA Archives

A key component of the DCS is the Data Archive, which is the repository for all raw scientific and housekeeping data accumulated during SOFIA flights and any pipeline products produced thereafter (for example, pipeline reduced data for FSIs). Access to the SOFIA Data Archive is via the DCS Web pages. GIs are able to retrieve their data from the archive during the 1-year proprietary period using an assigned DCS login username and password. While any member of the astronomical community may browse the archive, retrieval of (non-proprietary) data requires a researcher to register with the DCS and obtain a username and password.

The process of searching for and retrieval of science data in the SOFIA archives is similar to that used in most astronomical archives. Specifically, a researcher will be able to search on:

• Project ID or observer name
• Target name or coordinates
• Instrument, wavelength, or observing mode
• Observations date

A search can also be done on a combination of parameters. Summary data are returned for all matching data products, with enough detail for the researcher to determine what datasets are relevant to his/her project. Once the researcher has identified the data products she or he would like to retrieve, the files are staged to a public FTP server and a direct link e-mailed to the user. The researcher can then download the files at his or her leisure using a standard FTP client. All science data products are available in their original (native) format (e.g. FITS).

GIs who wish to retrieve proprietary data need only specify the observation planning (proposal) ID for their program. As with general searches, a list of summary data is returned first; the GI can then request some or all of the actual data files.

Education and Public Outreach Activities

SOFIA is the first major observatory specifically designed to support education and public outreach (E/PO) activities as a significant component of research programs. In conjunction with defining specific observation sequences and AORs, successful proposers will also choose an E/PO program option. The selection of an E/PO option is not required until after a proposal has been awarded observing time. They will have three options:

1. To be matched by the E/PO office with a team of 2-4 educators who will be trained to understand the experiment and accompany the GI team on some of the SOFIA flights along with a Facilitator from the SOFIA E/PO office.
2. To be matched by the E/PO office with educators in the GI team's local area for classroom visits, curricular enrichment etc., assisted by the E/PO office;
3. To design their own E/PO effort connected with their SOFIA observing program, assisted and financially supported by the E/PO office.

The GI will also designate a member of his/her team to act as the E/PO liaison. This person will maintain contact with the E/PO office and the educators assigned to the observing team for a period of at least several months before and after the awarded observing time.

The SOFIA E/PO office will be responsible for organizational and clerical work associated withe the E/PO component of science flights, working with whomever the PI has designated as the team's E/PO liaison. Approved E/PO activities will be supported financially by the E/PO office and do not need to be included in the research program budget. When an educator team is partnered with the observing team for a flight series, the SOFIA E/PO office will take care of travel and lodging logistics for the educators and provide them their own space in the SSMOC, separate from the observing team. E/PO guests will receive substantial training before flights, will always be accompanied by escorts from the E/PO office, and will be under the authority of the on-board Mission Director. At all times during flights with E/PO guests, safety and the scientific observations will have highest priority.

Additional Information, References, and Publications

Additional information about the SOFIA program and instruments can be found on the Selected Publications page.