After observatory activation, and a calibration and a verification phase, the first NuSTAR data sets from the baseline mission phase became publicly available on August 29th, 2013 through NASA's High Energy Astrophysics Science Archive Research Center (HEASARC). The second NuSTAR data release (DR2) took place on November 25th, 2013, the third (DR3) on February 5th, 2014, the fourth (DR4) on May 7th, 2014, the fifth (DR5) on September 23rd, 2014, the sixth (DR6) on March 31st, 2015, and the most recent (DR7) on September 17th, 2015, when 334 data sets (ObsIDs) were made public.
As of the date of this last data release, 1750 (1106 excluding slews) NuSTAR data sets (ObsIDs) have become public. Notice that, in addition to these major data releases from the baseline mission phase, there are some NuSTAR data sets from targets of opportunity (ToOs), coordinated observations with other observatories, and from the NuSTAR Guest Observer program (observations for Cycle 1 started in Spring 2015) which have been and are being made public according to their individual public dates based on the duration of the limited-use periods for these datasets.NuSTAR data are most easily accessible via the usual HEASARC archive interfaces, i.e., Browse and Xamin, by querying the master table of NuSTAR data sets archived at the HEASARC, the NUMASTER table. Notice that NUMASTER contains all NuSTAR observations which have been processed and successfully validated by the NuSTAR Science Operation Center, and many of these data sets may not yet be public. Users should check the public_date parameter in NUMASTER in order to determine the public availability of observations. Proprietary data are indicated by having either a null value or a date in the future for the public_date parameter in the NUMASTER table. Users can query this table and download the data associated with the selected observation(s) using the usual Browse/Xamin procedures.
Expert users who already know the Observation IDs (ObsIDs) of the dataset(s) in which they are interested, can also directly access NuSTAR data via the HEASARC's ftp site. The public NuSTAR data are at http://heasarc.gsfc.nasa.gov/FTP/nustar/data/obs/00/ in subdirectories 0, 1, 2, 3, etc., determined by the first digit of their ObsID: thus, the data for ObsID = 80001001002 are in the directory http://heasarc.gsfc.nasa.gov/FTP/nustar/data/obs/00/8/80001001002/.
There are some known 'issues' or unusual features for a number of the released datasets. Potentially problematical issues are indicated by the parameter issue_flag in the NUMASTER table having a value set to 1. The issue_flag may indicate a value of data_gap > 0, nupsdout > 0, solar_activity is not NULL, or use of a non-standard instrument setting. The specific nature of the issue affecting the observation will be indicated in one or more non-blank or non-zero values of the following parameters in NUMASTER: data_gap, nupsdout or solar_activity, or may be indicated in the comments field for the dataset. In addition, the coordinated parameter in NUMASTER lists observatories for which coordinated observations were made with the specified NuSTAR observation. The comments parameter in NUMASTER contains a brief text synopsis of the major known issues and unusual features.
As of September 17th, 2015 the HEASARC's NuSTAR Archive has 'caught up' with all of the available NuSTAR data from the baseline mission phase. From October 31st, 2016 onwards the data from a NuSTAR observation
(1) as part of the NuSTAR Guest Observer Program should become public 12 months after their receipt of the completed observation by the proposals Principal Investigator;
(2) as part of an approved NuSTAR Guest Observer ToO Program should become public 6 months after their receipt of the completed observation by the proposal's Principal Investigator;
(3) as part of another mission's Guest Observer Program which could also award NuSTAR observing time should become public at the same time as the exclusive-use period for that other mission's data expires;
(4) as part of an unanticipated ToO or Directors Discretionary Time (DDT) observation will have no exclusive use period and will be placed in the public archive within two weeks of the completion of each observation;
(5) as part of the NuSTAR Legacy Survey program or from calibration observations of astrophysical sources will have no exclusive use period and will be placed in the public archive within two weeks of the completion of each observation;
Unanticipated ToO and DDT requests may be submitted through the NuSTAR SOC website. Note that the Principal Investigator of Guest Observer Programs may choose to waive the exclusive use period for their observations.