Fermi Science Support Center

FAQ

  1. When was Fermi launched?

    Fermi was launched June 11, 2008.

  2. What was Fermi called before launch?

    GLAST--Gamma-ray Large Area Telescope.

  3. How do I get help with the Fermi data?

    Submit questions through the FSSC helpdesk: http://fermi.gsfc.nasa.gov/help/

  4. How will I learn that Fermi has detected a burst?

    Subscribe to the GCN (Gamma-ray burst Coordinates Network--see http://gcn.gsfc.nasa.gov). When either the LAT or the GBM detects a burst, a series of messages will be sent to the ground through TDRSS, resulting in GCN Notices that are fixed format messages disseminated by e-mail, page or internet socket. Additional Notices will be sent out as a result of ground processing. In addition, as a result of further ground processing, the instrument teams may send out GCN Circulars, free format messages relaying information such as burst durations, fluences, spectral parameters, etc. Finally, check the GRB page on the FSSC website for links to other sources of burst information.

  5. Why does running ROOT produce errors when I am using the Fermi Science Tools?

    The science tools use a specific version of ROOT for the GUI's and plotting. So in general it is not possible to run another version of ROOT in the same window that you setup for the Science Tools. One solution is to run the Science Tools and Root in separate windows so there is no conflict.

    Another solution would be to build the Science Tools from source and use the --without-root option in the configure step. This would disable the GUI's and plotting from the Fermi Science tools but allow you to use your version of Root in the same window.

  6. Why am I receiving an error about a missing library when I run certain Science Tools (e.g. gtexpmap)?

    If the tools complain of a missing library and you have it installed on your system you may need to let the Science Tools know the location of the library.

    For Linux systems you can set the LD_LIBRARY_PATH so that the tool can locate the library. We use libf2c as an example.

    For C Shell variants:

    > setenv LD_LIBRARY_PATH $FERMI_DIR/lib/libf2c.so

    or if you are using a version of the Bourne shell then:

    > export LD_LIBRARY_PATH=$FERMI_DIR/lib/libf2c.so

    MAC users running OSX may need to set an additional environment variable to run the science tools. This will mean that IDL cannot be run in the same window as the science tools.

    For C Shell variants:

    > setenv DYLD_INSERT_LIBRARIES $FERMI_DIR/lib/libf2c.so

    or if you are using a version of the Bourne shell then:

    > export DYLD_INSERT_LIBRARIES=$FERMI_DIR/lib/libf2c.so

    If it is not installed you will need to install it using your package manager or by hand. Contact your system administrator if you need help.

  7. Why does the Model Editor not show the menus at the top of the GUI?

    Unfortunately, the model editor has not been successfully implemented on OS X 10.5 (Leopard) for both Intel and PowerPC Macs (as noted on our release notes page). This is due to a conflict with Apple's Aqua GUI. We are working on the problem.

    The workaround is to just use a text editor to modify the xml files directly.

  8. How do I request a file containing only the spacecraft data?

    You may download the spacecraft data file directly from the LAT data server.

    Put any coordinates and radius (or leave them blank) and select the time range that you are interested in (for example: 2008-08-04T15:43:37 to 2009-09-04T08:41:20 (239557417 to 273746480 seconds Mission Elapsed Time)). You can also enter "start, end" for the times.

    Make sure that the box for "Spacecraft data file" is checked and the other are not checked. Then click on "Start Search". The spacecraft data file returned will be valid for the entire sky.

  9. How do I download the weekly spacecraft and data files without using a browser?

    You can use wget to download the weekly files. For the weekly photon files, use the following command:

    wget -m -P . -nH --cut-dirs=4 -np -e robots=off \
    ftp://legacy.gsfc.nasa.gov/fermi/data/lat/weekly/photon/

    and for the weekly spacecraft files, use:

    wget -m -P . -nH --cut-dirs=4 -np -e robots=off \
    ftp://legacy.gsfc.nasa.gov/fermi/data/lat/weekly/spacecraft/

    You may wish to update the mission-long spacecraft file instead.

  10. How do I download the spacecraft file for the entire mission?

    The mission-long spacecraft file is available at the FTP site:
    ftp://legacy.gsfc.nasa.gov/fermi/data/lat/mission/spacecraft/

  11. How do I retrieve a large number of GBM light curves?

    You can use wget to download the summary plots. Use the following command:

    wget -r -m -P . -nH --cut-dirs=3 -nd -np -e robots=off -A"*lc_all*.gif" --retr-symlinks
    ftp://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/

    to go through the archive and download all the gif files with lc_all in the filename. You can modify the string in -A"*lc_all*.gif" to select any of the plots that you might be interested in.

  12. Where do I find the current background files for LAT data analysis?

    You can download the background files from this page and they are under the Likelihood fitting (gtlike) section.

  13. How do I use multiple photon files in the LAT data analysis chain?

    The best way to use the multiple photon files is at the gtselect step. Input the files using the @filename format, where <filename> is simply a text listing of the multiple photon files. One way is to write the text file by using:

    ls -1 L09*_PH0?.fits > evt.txt

    then call gtselect using:

    gtselect infile=@evt.txt

    Remember, if you have multiple queries in your directory you'd need to be more selective with the ls command.

  14. How do I define an extended source for use in LAT data analysis?

    The syntax for using the Spatial Map model is

    <spatialModel type="SpatialMap" file="map.fits">
    <parameter scale="1" name="Prefactor" min="0.001" max="1000.0" value="1" free="0"/>
    </spatialModel>

    This goes in the xml in the

    <source>
    </source>

    definition along with the spectral parameters.

  15. I received the following runtime error: "There should be exactly one energy range cut, one acceptance cone cut, and at least one time range and/or GTI cut." How do I resolve this error?

    This error occurs when a tool such as gtexpmap finds duplicate DSS keywords in the FITS header. So you must delete one of the duplicated keywords. After that you must change the keyword NDSKEYS to reflect the surviving number of DSS keywords. You also must renumber the remaining keywords so that the numbering is consecutive and the max is the same as the total number, otherwise the tool will fail. You can use the FTOOL fv to accomplish this, but other FTOOLS such as fmodhead should also work.

    To avoid this error, when using gtselect be certain to match the following parameters to the exact values used when extracting the data from the LAT data server:
    • Minimum and maximum event energies
    • RA and DEC positions for the acceptance cone
    • Tmin and Tmax in MET

    Note: When using the python modules this can result in the error "Caught St13runtime_error at the top level: RoiCuts::sortCuts:"

  16. Why am I receiving the following runtime error in running gtbary, gtpphase, gtophase, gtpsearch, or gtpspec, even though there is no such event time XXXXX in the event file?
    "Cannot get Fermi spacecraft position for XXXXX Fermi MET (TT): the time is not covered by spacecraft file <your-event-file-name>"

    For the pulsar analysis tools to work properly, a spacecraft file needs to cover a slightly wider range of time than event data. Otherwise, the tools produce the error message. Depending on the functionality of the tools, those tools need to read not only the contents of "TIME" column of event files, but also other time values in an event file. For example, gtpphase, gtophase, gtpsearch, and gtpspec read the contents of START and STOP columns in GTI (Good Time Interval) extension. In addition to that, gtbary reads and writes back FITS header keywords TSTART, TSTOP, DATE-OBS, and DATE-END in every extension of a given event file. All of those time values must be within the time coverage of your spacecraft file.

    From an error message only, it is impossible to identify which time value in your event file produces the error, but most commonly it is the start time of the earliest GTI or the stop time of the latest GTI.

    To remove the error, you can either discard events outside the time span covered by your spacecraft file by sub-selecting events with gtselect, or use a spacecraft file that completely covers the time span of your event data. Note that, however, those header keywords that gtbary reads are left unchanged by gtselect. After time-filtering by gtselect to remove all events outside the time coverage of your spacecraft file, gtpphase, gtophase, gtpsearch, and gtpspec will successfully convert all event times left. However, gtbary will keep complaining about the time coverage if any of the above header keywords is out of bounds.

    The FSSC data server is designed to give you a spacecraft file that covers a slightly wider time range than requested, in order to accommodate the need explained above. In other words, as long as you use a spacecraft file that comes with an event file, you will not see the error.

  17. When calculating source maps in Binned Likelihood, I received the following runtime error: "File not found: Sourcename.fits". How do I resolve this error?

    This error occurs when your XML file includes an extended source. You will need to modify your XML in two ways:
    1. Change the SpatialModel attribute entry for the extended source to include map_based_integral="true"
    2. Modify the SpatialModel file attribute entry to include the proper path to the extended source template. You can download these templates from the Catalog page (look for "Extended Source template archive").

    An example of the proper XML format is available here.

  18. When calculating the diffuse response in Unbinned Likelihood, I received the following runtime error: "File not found: Sourcename.fits". How do I resolve this error?

    This error occurs when your XML file includes an extended source. You will need to modify your XML for the extended source. You should change the SpatialModel file attribute to include the proper path to the extended source template. You can download these templates from the Catalog page (look for "Extended Source template archive").

    An example of the proper XML format is available here. Be careful to not include the map_based_integral="true" modifier, as that should be used only for Binned Likelihood.

  19. Why am I receiving the runtime error "Unsupported timing extension" when running gtpphase, gtophase, gtpsearch, or gtpspec?

    These tools only accept Fermi event files that have NOT been processed by gtbary, or any other tools that perform barycentric corrections on the event files. Instead, they read uncorrected event files, and perform photon arrival time corrections on the fly. For more information, the following article explains the topic in greater detail.

    Pulsar Analysis: Handle With Care

  20. I received the following error when performing a likelihood fit: "Caught St12out_of_range at the top level: vector::_M_range_check".

    This error commonly occurs when there is an error in the inputted model file. Here are some troubleshooting steps:
    • Check for spelling errors.
    • Check that the diffuse and isotropic model files are where the model says they are and are named correctly.
    • Verify that the model file loads in modeleditor.
    • Also check that the energy ranges you are trying to fit match those in your event file (you can use gtvcut to check this).
    If you have checked all of these things and are still having issues, don't hesitate to contact the helpdesk.

  21. How can I improve performance of the pulsar analysis tools?

    LAT data retrieved from the data server and obtained in the weekly files is not guaranteed to contain time-ordered events. Since the pulsar tools rely on timing between events, one way to improve performance is to sort the events into time order. To do this, use the ftsort command:

    ftsort infilename.fits[events] outfilename.fits[events] time

  22. Does gtpphase follow the phase assignment convention that phase=0 is the peak of the radio flux? If not, what convention is followed?

    From a Science Tools' point of view, an origin of pulse phase is a part of a spin ephemeris. In other words, gtpphase does not assume any convention on the phase origin, but just computes pulse phases solely based on given parameters. The computation procedure is described in detail in section titled "Ephemeris computations with spin parameters" in Appendix A of the Pulsar Tools Anatomy.

    That means, technically speaking, that a phase origin for each ephemeris is arbitrarily chosen by a supplier of the ephemeris, and that gtpphase simply follows their convention. If you have a particular ephemeris of your interest, you probably would like to ask your questions to a contact person for the ephemeris.

  23. What will the Fermi GI program provide to successful proposers during this Cycle?

    During the first Fermi GI program cycle investigators may receive funding, pointed LAT observations or observing time on facilities available through the National Radio Astronomy Observatory (NRAO) and the National Optical Astronomy Observatory (NOAO).

    In this Cycle PIs can propose to:
    • Analyze all data released by the Fermi mission
    • Analyze correlated observations
    • Undertake Fermi-relevant theoretical research
    • Develop new data analysis techniques for the Fermi data
    • Perform observations relevant to Fermi on facilities available through NRAO and NOAO
    • Request high-end computing resources
    • Repoint the LAT

  24. What Fermi data will be available during this Cycle?

    All LAT and GBM science data will be publicly released in this Cycle. The LAT Point Source Catalog will also be released. Also, the LAT instrument team will continue to release fluxes, spectra and light curves for about sources of scientific interest and transients that exceed a threshold flux of 2x10-6 ph/s/cm2(E>100 MeV).

  25. What is the difference between regular and large Fermi GI program proposals?

    Regular proposals propose studies that can be carried out during a single one-year cycle and will be funded at an average level of $50-80K, with a maximum of $100K. A large proposal proposes a more expansive research program that may require a higher level of funding and up to three years to carry out; the average funding will be $100-200K per year, with a maximum of $200K per year. Progress reports will be evaluated in the peer review process for the second and third cycles of the large proposal's research program. Although not required for a large proposal, long term service to the Fermi mission, such as the development of a publicly-available capability that enhances Fermi's scientific return, will be favored. Approximately 8 new large proposals will be awarded in each GI cycle.

  26. Can I submit a theory proposal?

    Yes, the Fermi GI program will fund theory research programs that are relevant to Fermi. Note: a request for NASA-provided high-end computing resources can be submitted through the Fermi GI program.

  27. Can I submit a proposal to develop a new data analysis technique?

    Yes, the Fermi GI program will fund the development of new data analysis techniques that are relevant to Fermi. These techniques should be published for use by the scientific community, but need not be implemented in a publicly-available tool. The FSSC will host a library of user-supplied tools.

  28. What aspects of multi-wavelength research will the Fermi GI program support?

    The Fermi GI program will support all multi-wavelength research that is relevant to the Fermi mission. The GI program will fund the personnel costs of scientists engaged in analyzing data from Fermi and other astronomical facilities, including travel and page charges. Note that the Fermi GI program will also be awarding observing time on facilities available through NRAO and NOAO.

  29. Do I need to submit a budget and institutional signatures for the first phase (scientific justification) of my Fermi proposal?

    No, in the first phase proposal you only provide the maximum total budget (a single number) that you will request if your first phase proposal is successful. This budget can be no more than $100K for a regular proposal and $200K per year for a large proposal. You do not need to provide a detailed budget and signatures by your institution's administrators until you submit a second phase proposal if your first phase proposal is successful. Your total phase 2 budget cannot exceed the budget you provide in phase 1.

  30. How do I provide the maximum total budget in the first phase?

    Please enter the maximum total budget that you will request on the RPS proposal form only. This number should be entered as an integer in units of $1000; thus a maximum total budget of $52,000 should be entered as 52. Civil servant salaries should be included in this budget.

    In the scientific justification (the PDF text that you will upload through RPS) please describe briefly the level of effort that will be devoted to the research (e.g., 0.5 FTE of a postdoc); this cycle, you may include the actual dollar amount.

  31. What is the 'NASA FTE Commitment' that must be entered on the first phase RPS form?

    We must report the number of NASA civil servant FTEs for which support is requested by all proposals that are submitted, whether or not the proposals are successful. Thus, if your project (if successful) will fund one tenth of a NASA civil servant's position for one year, enter 0.1 in this field on the RPS form. Scientists who will be supported by this proposal but are not civil servants should not be included. The civil servant salaries that will be supported should be included in the total budget.

  32. Does the page limit include references?

    Yes, and also figures.

  33. If I am submitting a multiyear large proposal, which budget number do I enter on the RPS form?

    Enter the budget for the first year, not the total for all years. The budget for each subsequent year will be assumed to be the same. In the science justification please describe qualitatively the level-of-effort profile.

  34. Can there be separate science and budget PIs?

    Yes, the PI for the second (budget) phase may be a different person than the PI for the first (scientific justification) phase. Please state in the first phase proposal that the budget will be submitted with a different PI; similarly, in the second phase proposal please identify the proposal number of the first phase proposal. Both PIs are responsible for ensuring that the institution through which the budget proposal will be submitted is willing and able to accept a Fermi GI program grant and to disburse the funds as requested.

  35. Can investigators at foreign institutions receive Fermi GI program funding?

    No, to receive funding investigators must be based at US institutions that have registered with the NASA Solicitation and Proposal Integrated Review and Evaluation System (NSPIRES).

  36. Why would an investigator at a foreign institution submit a proposal?

    All investigators may request observing time on telescopes available through the Fermi-NRAO and Fermi-NOAO Cooperative Arrangements whether or not they are based at US institutions. Also, all investigators may request LAT pointed observations. However, an investigator at a foreign institution cannot receive funding from the Fermi GI program, but co-investigators at US institutions may request funding in proportion to their participation in the proposed research. Finally, an investigator at a foreign institution may use a positive evaluation of their proposal by the Fermi GI program peer review panel to secure funding by a foreign agency.

  37. Can GI Program funding be used to bring a collaborator at a foreign institution to the US for a meeting?

    No.

  38. What NRAO observing time is available through the NRAO-Fermi cooperative arrangement?

    NRAO is committing approximately 10% (or 450-650 hours per year) of the scientific observing time on the Very Long Baseline Array (VLBA), the Very Large Array (VLA), and the Robert C. Byrd Green Bank Telescope (GBT) to proposals submitted to the 'Joint Proposal Process,' which requires only a single proposal for both NRAO observing time and Fermi funding. In the future, observing time may be available on the Expanded VLA (EVLA) and the Atacama Large Millimeter/Submillimeter Array (ALMA--scheduled to be completed in 2012). Proposals to the 'Joint Proposal Process' are limited to less than 200 hours of observing time each.

    In addition, investigators may submit proposals through the 'Cooperative Proposal Process' for NRAO observations of 200 or more hours, or Target of Opportunity observations. In this process, proposals are submitted first to the regular NRAO proposal process and, if successful, to the Fermi GI program for funding.

    NRAO's commitment of observing time to this cooperative arrangement will depend on the number and quality of the proposals submitted.

  39. What NOAO observing time is available through the NOAO-Fermi cooperative arrangement?

    NOAO is committing time on a large number of different optical telescopes to proposals submitted to the 'Joint Proposal Process,' which requires only a single proposal for both NOAO observing time and Fermi funding. Proposals to the 'Joint Proposal Process' cannot include target-of-opportunity or survey program observations.

    In addition, investigators may submit proposals through the 'Cooperative Proposal Process' for NOAO target-of-opportunity and survey program observations. In this process, proposals are submitted first to the regular NOAO proposal process and, if successful, to the Fermi GI program for funding.

    NOAO's commitment of observing time to this cooperative arrangement will depend on the number and quality of the proposals submitted.

  40. What is the difference between the 'Joint Proposal Process' and the 'Cooperative Proposal Process' in the Fermi-NRAO and Fermi-NOAO cooperative agreements?

    The Joint Proposal Process awards both time on telescopes available through NRAO or NOAO and Fermi funding as a result of one proposal submitted to the Fermi GI program.

    In the Cooperative Proposal Process observing time is awarded as a result of a proposal submitted to NRAO or NOAO, and funding is awarded through a proposal to the Fermi GI program. The evaluation of your proposal to NRAO or NOAO, if successful, will be forwarded to the Fermi GI program. Please state in your proposals to the Fermi program and either the NRAO or NOAO programs that you are applying under the cooperative proposal process.

    See the NRAO and NOAO webpages for additional details

  41. Where do I provide the specifics of my proposed radio observation?

    If you are requesting radio observations through the 'Joint Proposal Process,' then click 'yes' for 'Joint Proposal' on the first phase RPS form and enter 'NRAO' as the observatory. Please provide summary information on the RPS webform, and then describe the observation in an additional page of your scientific justification (the PDF file you will upload through RPS). Also include the target in the RPS target form. There are no NRAO-specific webforms.

    The specific information you should include in the scientific justification can be found here.

  42. Where do I provide the specifics of my proposed optical observation?

    If you are requesting optical observations through the 'Joint Proposal Process,' then click 'yes' for 'Joint Proposal' on the first phase RPS form and enter 'NOAO' as the observatory. Please provide summary information on the RPS webform, and then describe the observation in the text of your scientific justification (the PDF file you will upload through RPS). Also include the target in the RPS target form. There are no NOAO-specific webforms.

    The specific information you should include in the scientific justification can be found here.

  43. Can I serve on a peer review panel if I submitted a GI proposal?

    Yes, we encourage members of the community to assist us evaluate the proposals. Besides providing a service to the community, serving on a panel provides insight into the peer review process (which will assist you in writing future proposals), a crash course in new research areas, and opportunities to meet new colleagues. You must have a PhD at the time of the review, which will be held in the Washington, DC, area. To ensure fairness, rigorous conflict-of-interest rules will apply. If you are interested, please send an e-mail to the HEASARC Peer Review mailbox.

  44. Can NASA grants be used to pay for travel by (but not salary for) non-U.S. co-investigators if it is related to the collaborative work proposed?

    No. NASA funds research to be conducted on a no-exchange-of-funds basis. Generally no-exchange-of-funds means that scientists who work for foreign institutions are not funded by NASA. We pay for the research conducted by researchers at US institutions, and foreign agencies pay for the research conducted by researchers at foreign institutions.

    Travel is a legitimate research expense and is a component of the funding required to support the research effort of a foreign researcher. It is not a "supply and/or service." Therefore it is not permissible to use NASA funding for this expense.

    These rules are found in the Guidebook for Proposers, Section 2.3.11(b)(vi):<

    (vi) Prohibition of the Use of NASA Funds for Non-U.S. Research. NASA's policy welcomes the opportunity to conduct research with non-U.S. organizations on a cooperative, no-exchange-of-funds basis. Although Co-Is or collaborators employed by non-U.S. organizations may be identified as part of a proposal submitted by a U.S. organization, NASA funding may not normally be used to support research efforts by non-U.S. organizations at any level; however, the direct purchase of supplies and/or services that do not constitute research from non-U.S. sources by U.S. award recipients is permitted. See also Section (l) of Appendix B.

    These rules flow directly from requirements in the NASA Federal Acquisition Regulations (FAR) Supplement, Part 1852.235-72.

  45. Can a collaborator on my proposal be funded directly by a separate sub-grant from NASA to avoid double-institutional overhead charges?

    No, this is not permissible. See below. The only exceptions are cases involving government instituions or mixes of government and non-government institutions. It is recommended that you contact us in those cases.

    Refer to sec 2.3.10 of the 2010 NASA Proposers Guidebook for details:<

    It is the responsibility of the Proposing Organization to place subawards for Co-Is at other organizations. Other than the special cases of collaborative arrangements involving government organizations, and unless specifically noted otherwise in the NRA, the proposing PI organization must subcontract the funding of all proposed Co-Is who reside at other non-government organizations, even though this may result in a higher proposal cost because of subcontracting fees.

  46. Do my Co-I's that are requesting funding need to provide signed letters of commitment, as was the case the past?

    No, They simply need to log in to NSPIRES and register as a statement of their commitment. However, a 1-2 page CV for all funded co-I's is still a requirement.

  47. Do unfunded Co-I's need to register?

    No. That is not necessary.

  48. Do I need to include a statement on the relevance of the proposed work to NASA in my proposal?

    No. It is assumed that any proposal relevant to Fermi is relevant to the astrophysics strategic goals and subgoals in NASA's Strategic Plan. Proposals that are relevant to the Fermi GI program are, by definition, relevant to NASA.