NuSTAR Target of Opportunity (ToO) or Directors Discretionary Time (DDT) observation request

Submit requests to NuSTAR operations team for review

Fast ToOs (turnaround <= 48 hours) will only be approved for exceptional scientific opportunities

Active ToO/DDT observations
SAX J1808.4-365840 ksPI Sanna
Cyg X-13x20 ks coordinated with NICER for NuSTAR GO cycle-5 proposal 05284PI Steiner
EXO 1846-0314x25 ks coordinated with Chandra-HETG and VLA for joint NuSTAR / Chandra cycle-20 proposal 20400577PI Neilsen
NGC 5907 ULX175 ks coordinated with XMM-NewtonPI Walton
SN2019esa2x50 ks coordinated with XMM-Newton for NuSTAR GO program 04085PI Margutti
XTE J1810-19750 ks coordinated with XMM in 2019 Sept-Oct for joint NuSTAR / XMM cycle-15 program 078430
(3x40 ks completed)
PI Rea
SGR 1806-203 x 30 ks coordinated with NICER for NuSTAR GO program 04147PI Enoto

Please review the NuSTAR schedules for details of upcoming observations and the table of approved ToO programs from the NuSTAR GO program and joint GO programs with Chandra, XMM-Newton, INTEGRAL, and the Neil Gehrels Swift Observatory.

Principal requester
Best way to reach me:
24 hr Contact info:
Scientific Justification
Object type:
Triggering an approved GO program: If yes, then give mission and GO proposal number:
Scientific Justification:
Relevant URLs
Justification for this particular target:
Likelihood of detection, duration,
and recurrence of transient behavior:
Response time requested: Examples: < 24 hours , < 48 hours , within 1 week , at directors discretion (DDT)

Note that the majority of approved ToOs have response times within 1 week
Justification for requested response time:
Target details
Target Name
RA (J2000 decimal degrees from 0.0 to 360.0)
Dec (J2000 decimal degrees from -90.0 to 90.0)
from until
Date/time format options are described here. Default is UTC, unless you specify another time zone.
Observing time (kiloseconds)
Justification for observing time
(Give details of any source modeling, particularly for exposure time requests above 50 ks)
Expected NuSTAR count rate
(predicted instrument count rate for both modules using 50% PSF extraction with no dead time)

HEASARC WebPIMMS (set "Into:" field to 'NUSTAR') here.
Maximum expected NuSTAR count rate
(in case of flaring, bursts, etc)
Approximate expected spectrum
Source morphology
Coordination with other observatories?:

Clicking the Submit button sends emails and text messages to the NuSTAR operations team. A confirmation email will be sent to the 'Email:' field at the time of submission.

The request will be reviewed by the NuSTAR PI and the operations team and you will be contacted with a decision to approve or decline the request.

NuSTAR data associated with ToO or DDT requests submitted outside of approved GO programs will have no exclusive use period and, when completed, will be available via the public NuSTAR archive. See for more information.

A minimal set of data products for ToO/DDT observations performed within the last 14 days is also available as each observation progresses via the NuSTAR quicklook products webpage. Please carefully read the caveats on the use of this data detailed on the quicklook webpage.

Please contact   nustar-help at   if you have any questions.