Targets Of Opportunity Policy

Interested proponents should be aware that implementing TOO observations imposes heavy requirements on the Ground Segment operations and will inevitably have a negative impact on the overall observing efficiency. Furthermore due to the constraints introduced by the LECS and by the attitude system, the observing efficiency of the target at the requested time may be substantially reduced or be, in a worst case situation, unfeasible. While the scientific merit of TOO observations in the context of this mission is clear, the level at which they will be feasible, with an acceptable efficiency reduction, after the implementation of the gyro-less mode, remains to be assessed. Proponents should be in particular aware that the LECS efficiency - that depends on the period of observation - cannot be optimized and can be, in worst cases - near to zero. They must then specify in the proposal, on the basis of the scientific case, the minimum LECS efficiency considered acceptable. If this is not verified, the observation will not be carried out. As a reference, the typical LECS efficiency normalized to MECS ranges from 30% to 60% with an average of 40% as a result of the scheduling optimization.

As a rule, for a source or a class of sources to be taken into consideration for TOO observations, it is required that special proposals (TOO proposals, see Sect. 3.3.1) be submitted, even in the event that a source (or sources) might be target(s) in an ordinary proposal.

The overall time devoted TOO observations will be no more than 25 % of the total AO time.

A list of possible subjects for TOO proposals includes:

1. Bright X-ray transients, including those known to be recurrent, but for which the epoch when the appropriate intensity level in an outburst is reached cannot be predicted with the precision required for a time-constrained observation.

2. Highly interesting changes in the state of emission of persistent sources, which from previous experience are known to take place but whose epoch of occurrence cannot in general be predicted.

3. Soft gamma ray burst repeaters.

4. Supernova explosions.

5. Gamma-ray bursts

Interested scientists are invited to consider that the already approved CP and GOP TOO programs, see Sect 2.2 (Table 1,2,3,4) and the URL:

• /bepposax/too.html

Table 1: BeppoSAX AO1 CP and GOP and project TOO observations

Class	Targets	Approved Exposure	Status
		ksec
Dwarf Novae	1	200	NA
Known Be transients (P$<$20 s)	2	300	NA
New Be transient or Known P$>$20 s	1	200	PE,NA
New transients: WFC trigger	3	60	C
Soft X-ray transient	1	200	C
New soft X-ray transient	1	200	NA
Recurrent BHC transient	1	130	NA
New BHC transients	2	300	NA
Cyg X-1: high state	1	100	NA
Cyg X-1: Batse trigger	1	60	NA
BHC transient	1	200	C
Atoll source: Batse trigger	1	190	NA
Active state of SGR sources	1	100	NA
New Supernova event	1	150	NA
Classical and Recurrent Novae in outburst	1	120	C
GRO1744-28	1	150	C
Rapid Burster	1	90	NA
EGRET $\gamma$-ray sources	2	40	NA
GRB afterglow (SAX Trigger)$^*$	8	500	C
Comet Hale-Boop $^*$	1	50	C
XTE J0054-72 or SAX J0054.9-7226 $^*$	1	30	C

NA: not activated; C : program completed; PE : partially executed; $^*$ Project TOO

Table 2: BeppoSAX AO2 CP and GOP TOO observations

Class	Targets	Approved Exposure	Status
		ksec
CygX-1 in High state	1	100	NA
Recurrent BHC Transients (a)	1	200	C
New transients BHC (a)	1	200	C
Flaring Blazars	2	100	C
Fast spinning Hard X-ray Transients (b)	1	180	C
Fast spinning Hard X-ray Transients in outburst (b)	1	180	C
Slow X-ray PSR transients (b)	1	180	C
V0332+53 during Outburst (b)	1	180	C
GX339-4	1	50	NA
The supersoft source RXJ 0527-6954	1	75	NA
New transients: WFC trigger	8	160	PE
GROJ1655-40 during radio outburst	1	90	NA
GROJ1655-40 during X-ray outburst	1	90	NA
Soft Gamma repeaters	2	120	C
CYGX-3 during radio outburst	1	110	NA
Hard X-ray burster (BATSE trigger)	1	100	NA
VWHyi and UGem in outburst	1	200	C
BSAX & CGRO of CentaurusA	1	60	NA
Soft X-ray transients in outburst	2	185	C
GRB afterglows detected by OSSE	1	50	NA
A0535+26 in outburst	1	100	NA
Low state of Eta Carinae	1	50	C
High Latitude Transients (Part II)	2	60	PE
AGN HighState	2	100	PE
MXB1730-335	1	90	C
GRB afterglow (SAX trigger)	9	913	C
GRB afterglow (BATSE/RXTE-PCA trigger)	6	600	PE

NA: not activated; C : program completed; PE : partially executed; (a), (b): merged proposals.

Table 3: BeppoSAX AO3 CP and GOP and project TOO observations

Class	Targets	Approved Exposure	Status
		ksec
Hard X-ray transients	1	150	C
Nova U Sco$^*$	1	50	C
Broad band spectra of BHC	1	80	PE
Multif. campaign on GRS1915+105 (a)	2	390	PE
Study of new superluminar XTEJ1748-288 (a)	2	390	PE
Obs. of GROJ1655-40 in outburst (a)	2	390	PE
CygX-1 in High state	1	100	PE
Flaring Blazars	2	150	C
New transients: WFC trigger	6	120	PE
Nova Velorum 1999 $^*$	1	70	C
New transients BHC	1	150	C
GRB afterglow (SAX trigger) $^+$	12	700	PE
GRB afterglow (BATSE, XTE trigger) $^+$	3	300	NA
GRB afterglow (IPN trigger)$^+$	2	200	NA
Recurrent BH transients	1	150	NA
X-ray spectrum of X 1755-33	1	60	NA
Obs. of known SGRs	1	50	NA
Obs. of new SGRs	1	100	NA
The ms X-ray pulsar SAX J1808.4-3658	1	200	PE
Solving the mistery of XTEJ0421+560	1	170	NA
Study of SGR 1900+14 in outburst	1	150	NA
Cyg X-3: obs. during radio outburst	1	200	C
Bright BL Lacs	1	40	NA
Soft X-ray transients	1	150	C
Obs. of AGN in exceptional states	2	100	NA

A (active) : waiting trigger activation; C : program completed; PE : partially executed; (a): merged proposals
$^*$ Project TOO; $^+$ total ceiling for GRB programs: 800 Ksec.

Table 4: BeppoSAX AO4 CP and GOP and project TOO observations (as of Apr. 12 2001)

Class	Targets	Approved Exposure	Status
		ksec
GRB afterglow (SAX trigger)	12	1000	PE
GRB afterglow (BATSE, XTE trigger)	5	500	A
GRB afterglow (IPN trigger)	3	300	A
GRB afterglow (HETE-2 trigger)	4	320	A
GRB000926 $^*$	1	30	C
Afterglows in x-ray flashes	4	400	A
Afterglows of Short GRBs	3	480	A
Recurrent BH transients	1	150	A
New transients BHC	2	360	PE
Known and unknown HXRT slow spinning	1	100	A
Fast spinning HXRT	1	200	C
Soft X-ray transients	1	200	C
X-ray bursters	2	90	C
Transients in WFC fields of Gal Bulge	3	120	PE
Flaring Blazars	2	100	C
Obs. of AGN in exceptional states	5	250	A
Centaurus A in high state	1	160	A
New Core Collapse Supernovae	3	300	A
Brightest Novae in Outburst	1	99	A
Spectrum of the BHC X 1755-33	1	60	A
Solving the mystery of XTE J0421+560	1	170	A
CygX-1 in High state	1	150	C
XTEJ1748-288 in outburst	1	250	A
A0535+26 in outburst	1	150	A
GROJ1655-40 in outburst	1	120	A
SAX J1819.3-2525 in Outburst	1	50	A
SGRs in Active State	2	240	PE

A (active) : waiting trigger activation; C : program completed; PE : partially executed; (a): merged proposals
$^*$ Project TOO.

Please note that the total time allocated for TOO proposals in AO5 is limited to a ceiling of 2.5 Msec (including GRB programs). Due to the unpredictable nature of TOO, the overall time of approved proposals is greater than 2.5 Msec. TOO observations will be therefore carried out on a first-come first-served basis. Should the ceiling be reached before the end of the AO, the Mission Scientist, in consultation with the TAC chairperson, and taking into account the schedule and the overall observing performances, can decide to increase the ceiling further.

TOO programs approved in AO4 will be performed only if the trigger condition compliant with the protocol is verified before the end of AO4 program (extended to June 15, 2001).

TOO programs approved but not (or partially) carried out in AO4 must be resubmitted. The proponents should specify, in such a case, that the program is to be considered a continuation of AO4.

In a TOO proposal, the scientific justification must be accompanied by detailed criteria for TOO validation (trigger condition) and for the observational strategy that should be followed after the TOO event. In the case of recurrent transients and of changes in persistent sources, it is expected that the TOO proposal might contain also the request of a monitoring program with BeppoSAX aimed at detecting and qualifying the event. In this case, it is mandatory for the proponents to submit a separate proposal covering the monitoring program too.

For the accepted proposals, the TAC could confirm or revise both trigger condition and the observational follow-up plan. To activate a TOO approved program in AO5 the PI must alert the Mission Scientist (saxsci@ias.rm.cnr.it). The PI will assist the TAC Chairman (or a TAC member appointed by the Chairman) and the Mission Scientist in the following responsibilities:

• supervising the implementation of the observing plan;

• dealing with any decision, exceptional with respect to the plan. For example, in some cases the follow up program can be performed only in part due to visibility constraints. In such a case the follow up observations will be carried out only if sufficient to achieve the scientific goals of the proposal, and the program will be then considered completed.

The PI of the TOO observations successfully carried out will also be the owner of the WFC data (on that particular target) that had triggered the program.

Most of TOO targets suited to BeppoSAX capabilities should fall within approved AO programs. Nonetheless it is still possibile that unforseable events of exceptional scientific importance are not covered by any approved AO program. In such a case a Project TOO observation can be solicited any time of the year by sending a request to the Mission Scientist (saxsci@ias.rm.cnr.it). The request shall contain a scientific case demonstrating the uniqueness of the event and the relevance of BeppoSAX observations. It is stressed that these requests will be analyzed only if the event is not a part of a TOO-AO program, so interested scientists are invited to check the approved programs before sending any request. Project TOO data are property of the BeppoSAX team and are to be exploited under the responsibility of the Mission Scientist. Should the observation be approved, the proponent and her/his team will collaborate with BeppoSAX team scientists for a joint exploitation of the data.