The Core Programme consists of three elements, which are in priority

(1) A Deep exposure of the Galactic Central Radian (GCDE): 4.30 x 10⁶ sec
(2) Regular scans of the Galactic Plane (GPS): 2.30 x 10⁶ sec
(3) Pointed observations of selected sources: 2.72 x 10⁶ sec

(2) Regular scans of the Galactic Plane (GPS):  The baseline set of parameters describing the GPS scans are the result of an optimization process taking spacecraft and ground segment elements, instrument characteristics and scientific objectives into account. Basically the scans will be performed once a week by executing a "slew and stare" manoeuvre of the spacecraft across the visible (accessible) part of the Galactic plane with an extent in latitude up to +/-10 deg. The angular distance between two "staring points" along the scan path is 6 deg, the extremes in latitude of the pointings are at b = +/- 6.45 deg. The scans will be performed in a sawtooth pattern with an inclination of 21 deg with respect to the Galactic plane, each subsequent scan being shifted by 27.5 deg in galactic longitude. A schematic view of two consecutive scans is shown in the Figure below. The sum of all GPS scans during a year provides a set of grid points ("dither pattern") which facilitates the imaging with SPI. The accessible part of the Galactic plane depends on viewing constraints, including the solar aspect angle, and on the season of the year.

(3) Core Programme Pointed Observations (sorted with target RA in ascending order):
 

For year 1 (AO-1) the CP guaranteed time for pointed observations (total for year 1 = 2.72 x10^6 s, see above) is split up as follows:

• 1.7 x 10^6 s (max) for unknown and known transient sources,
• 1.0 x 10^6 s (max) for the persistent Vela observation,  (see below for details).

Strategy for the selection of unknown and known transient sources:
These events can be triggered from INTEGRAL detections of  a "high state" during the GPS and/or GCDE observations or from observations external to INTEGRAL (e.g. ground-based optical telescopes) and are considered as TOO follow-up observations.
The following strategy will be applied: the allocation of 1.7 x 10^6 s for year one shall be used for either the following unknown transient sources of the following type:

• local group SN II, SN Ia, classical novae, previously unknown X-/gamma-transients
• and/or the known transient sources (GRS 1915+105, GROJ1655-40,1E740.7-2942,Cyg X-1, Cyg X-3, GX 339-4, Mrk 501)

Note on TOO follow-up observations:
It is expected that most TOO events will be detected during the Core Programme elements GPS and GCDE: this is one of the main reasons to perform the GPS and GCDE during the entire mission. TOO follow-up observations are scientifically important for INTEGRAL and a situation should be avoided where they cannot be scheduled because a specific time allocation (e.g. CP pointed observations for TOO follow-up observations) has been formally exhausted. Therefore, if at any time during an observation period of one year -- corresponding to one INTEGRAL AO cycle -- a TOO follow-up observation triggered by a detection in GPS and/or GCDE data is scheduled and executed and if the CP allocated time for TOO follow-up observations is already exhausted, then the data of the entire field-of-view of that follow-up observation will be made publicly available immediately, unless a AO-1 accepted proposal exists (see "General Programme", above). See also AO-1 documentation on "Science Data Rights" for full details.

It is understood that some flexibility should be kept by the ISWT in case a major ("once in a lifetime") TOO event (e.g. close-by SN) occurs and no or insufficient CP time for follow up observations is available anymore because the ceiling has been already reached. In this case the ISWT could review the priority assigned for the GCDE and GPS and, if available, probably re-assign remaining time from these CP elements. This would be an exception to the routine case where the execution of TOO follow-up observations will be decided by the Project Scientist. See also AO-1 documentation on "Guaranteed Time" for full details.

The General Programme (open time) observations, which complete the INTEGRAL observing programme, can be found here.