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

Submit GO requests to NuSTAR operations team for review

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

Active ToO/DDT observations
4U 1608-5260 ks for NuSTAR cycle-4 proposal 04161. PI Degenaar
AT2018cow2 x 30 ks, second observation coordinated with XMM on 2018-07-23PI Margutti
Mkn 33580 ks coordinated with HST and XMM-Newton for cycle-15 joint program 078050PI Schartel
MAXI J1820+0702 x 40 ksPI Fabian
SN2004dk2 x 50 ks for NuSTAR cycle-3 proposal 03054. Observation in 2018 August coordinated with XMMPI Margutti

Please review the NuSTAR schedules for details of upcoming observations and the table of approved ToO programs from the NuSTAR, Chandra, and XMM-Newton GO programs.

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 conformation 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 deny the request.

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