Proposal Details - 1020003
Keeping watch over our Galaxy - the return of the GPS2 (Bazzano)

Proposal Abstract

For the first 5 years of INTEGRALs operational life, the scientific Core Programme included a keycomponent that was regular scans of the Galactic Plane. These led to a wealth of discoveries of new sources and source types, a large fraction of which were highly transient. These discoveries can certainly be considered one of the strongest results from, and legacies of, INTEGRAL. From AO-5 onwards, these regular scans were discontinued, and this resulted in a significant drop in the discovery rate of new systems in and around the plane of our Galaxy. In AO8, however, a multiyear proposal to reinstate the scans was approved and the programme is still on going in AO9. We propose here to continue the Galactic Plane Scans as a Key Programme throughout AO10 and AO11, to regularly monitor known systems as well as to dramatically enhance the chances of discovering new systems. This will allow a rapid response to bright events and a detailed study of faint transients and long term activity. Such a programme will be of high value to a very large fraction of the high-energy astronomy community, stimulating science immediately, and furthermore contributing greatly to the INTEGRAL legacy.To this aim, a total of 3 Msec (1 in AO101 and 2 in AO11) of observations is necessary to cover theplane with regular scans every orbit, excluding the central zone that will be covered by the GalacticBulge monitoring programme (should that programme be accepted), and any other region studieddeeply in other proposals. We suggest that in order to maximise the engagement of the scientificcommunity, the observations should be made public immediately. The team will make, as it is alreadydoing through AO8-9, the scw-resolution IBIS and JEM-X light curves (in two energy bands) and perrevolution mosaic images publicly available through the web as soon as possible. Any interesting source behaviour that emerges from our observations will be announced promptly, so that rapid follow-up is possible

Observation Strategy (Recommended by TAC)

Total of 1 Ms along the Galactic plane, split into various scans once every revolution if visible (see below) and only for those time windows during which no exposures of the plane are done (as in, e.g., Galactic Bulge, Galactic Centre, Norma/Perseus Scutum/Sagittarius). Basically, the scans will be performed by executing a continuous slew and stare manoeuvre of the spacecraft along the visible (accessible) part(s) of the Galactic plane with an extension in latitude up to ± 10 degrees, and a longitude extent of about 170 degrees. The angular distance between two staring points along the scan path is 7 degrees, the extremes in latitude of the pointings are at b = ± 6.45 degrees. The scans will be performed in a saw-tooth pattern with inclination of 17.8 degrees with respect to the Galactic plane, each subsequent scan being shifted by 27.5 degrees in longitude. The accessible part of the Galactic plane depends on viewing constraints, including the solar aspect angle, and on the season of the year. Figure 7 of the AO-3 INTEGRAL Guaranteed Time document shows the Galactic plane visibility for GPS scans. A schematic view of two consecutive scans in shown in Figure 8 of the AO-3 INTEGRAL Guaranteed Time document.

Proposal grade: A

Data Rights (Recommended by TAC)

All data are public.