XMM-Newton Phase II RPS Users Manual

3.1.2.5 For mosaic observations

Although the concept of Mosaic mode for XMM-Newton observations is simple (see section Mosaic mode of the XMM-Newton Users Handbook), its implementation on a system designed to deal with single pointing observations may be cumbersome. Since the only way to set a pointing direction in the system is to set the target coordinates of an observation, the approach adopted is to have as many individual observations as pointings or viewing directions required. Unfortunately, the same word ''observation'' is used to designate the whole and the part: a Mosaic ''observation'' approved by the OTAC is made up of a set of ''observations'' in the XMM-Newton proposal handling system.

During the second phase of proposal submission, users with approved Mosaic observations are requested to provide just pointing coordinates and EPIC filters. Thus, the users are expected to complete the XRPS proposal (5.2) and observation (5.2.3) details forms. Changes in the default configuration for this type of observations are strongly discouraged and should be deferred to the enhancement process.

7.

Individual pointings

Users must define the sequence of pointings that define a Mosaic observation entering the target coordinates of the individual observations in the XRPS. The angular distance between two consecutive pointing coordinates must be smaller than 1 degree.

8.

Science mode of all instruments

The setup of the X-ray instruments in a series of observations forming a Mosaic observation is determined by the configuration of the first observation in the series and there is no possibility to change modes and/or filters from pointing to pointing. Therefore, the first observation has to be treated differently than the rest of the observations in the XRPS.

• In the first observation, the mode of EPIC-pn must be set to MOSAIC. In normal cases, the EPIC-MOS cameras should be set in Full Frame mode and the RGS spectrographs in ''Spectroscopy'' mode. Only under very special circumstances other modes would be preferred and, in such cases, the strategy needs to be agreed with the SOC. The filters of the three EPIC cameras for all the observations forming the Mosaic are selected in the first observation; therefore, they should be selected according to the presence of optically bright sources in all the fields to be observed (see the XMM-Newton Users Handbook section on EPIC filters ). OM exposures can be included in this first observation as in the case of any other normal observation, as far as the time allocated permits and OM filters are allowed (see XMM-Newton Users Handbook section on OM modes and OM optical elements ).

• In the rest of the observations, no exposures of the X-rays instruments can be included. Only OM exposures are included; these are needed because the XRPS does not accept ''empty'' observations, i.e., observations with no exposures at all. The OM exposures are set so that they provide the total requested duration for the observation; this is achieved with a proper combination of the duration of the actual exposures (including overheads) and the offset parameter. Users should not change/add/delete the OM exposures in these observations; for a scientific use of OM, users should contact the SOC during the enhancement process.