Preparation of FEROS OBs for using in p2pp

For information concerning the preparation and execution of the run on-site, I refer to the Quick and dirty overview what to do on-site.

FEROS observations are in general executed with p2pp (get the latest version for La Silla instruments here). The preparation of the OBs (Observing Blocks) is pretty straight forward and is in detailed explained for object-calibration and object-sky operation modes

FEROS has to observing modes:

  • Object-calibration
  • Object-sky
If you want to prepare FEROS OBs for the use with p2pp you have to decide, in which observing mode you want to use FEROS, since the OBs look quite different. In case you want to use it in object-calibration mode then keep on reading. If you want to use it in object-sky mode, you can skip the next part and read on here.

Object-calibration mode

Within the object-calibration mode one fibre will collect the light emitted by the object while the other will simultaniously take a ThAr (or ThAr+Ne) exposure.

NOTE: the exposure ThAr exposure time is not the same as the object exposure time. It has to be defined in the OB and is usually 10-25s depending on the age and quality of the ThAr lamp, which is currently used at the telescope. In contrary to other instruments like Coralie the ThAr lamp is not shaded with different filters to allow the use of the same exposure time as the object has. Therefore, the simultanious ThAr calibration only represents the instrument shift at the very beginning at the object exposure. Nevertheless, the stability of the instrument has been tested extensively by taking a lot of ThAr calibration images in different time intervalls and the instrument should be stable for exposure times up to approximately an hour. If you plan to use FEROS for longer exposure times, you might want to test the stability by taking calibration exposures before and after you science exposure for comparison.

A typical object-calibration OB for the RV standard star HD 10700 can be downloaded here. You can simply download the file and edit it to your purposes. In my opinion it is always easier to import the file into p2pp and edit it within the program. Then the explanations will be given there directly. The content of the OB is explained below step-by-step. The input is given in quotation marks. In some cases a fixed input is mandatory, which is indicated.

Keyword Fixed input? Example Comment
IMPEX.VERSION "2.0" don't change this, it defines the software version
type "0"
STTimeIntervals none "2013-12-04T00:30:00" here you can define time intervalls, when the target has to be observed; easier to fill out directly in p2pp
calibrationReq none "Please take 2 ThAr exposures before and after the science exposure, thanks!" here you can give advices to the astronomer who is executing your run, which (additional) calibrations are needed
InstrumentComments none Give comments concerning the instrument (nowadays not possible anymore)
userComments none "RV standard, take once every night" Give comments concerning the execution etc.
userPriority none "1" Priority of this object (the smaller the number the higher the priority)
LineNumber none "0"
name none "Mohler_HD10700_objcal" name of the OB
finding_chart_list none "HD_10700.jpg" Name of finding chart file (has to be in .jpg format)
comments none "very variable target!" comments concerning the target
more keywords ⇒

Object-sky mode

Within the object-sky mode one fibre will collect the light emitted by the object while the other will simultaniously take a sky exposure.

A typical object-sky OB for the RV standard star HD 10700 can be downloaded here. You can simply download the file and edit it to your purposes. In my opinion it is always easier to import the file into p2pp and edit it within the program. Then the explanations will be given there directly. The content of the OB is explained below step-by-step. The input is given in quotation marks. In some cases, a special input is mandatory, which is indicated.

Keyword Fixed input? Example Comment
IMPEX.VERSION "2.0" don't change this, it defines the software version
type "0"
STTimeIntervals none "2013-12-04T00:30:00" here you can define time intervalls, when the target has to be observed; easier to fill out directly in p2pp
calibrationReq none "Please take 2 ThAr exposures before and after the science exposure, thanks!" here you can give advises to the astronomer who is executing your run, which (additional) calibrations are needed
InstrumentComments none Give comments concerning the instrument (nowadays not possible anymore)
userComments none "RV standard, take once every night" Give comments concerning the execution etc.
userPriority none "1" Priority of this object (the smaller the number the higher the priority)
LineNumber none "0"
name none "Mohler_HD10700_objsky" name of the OB
finding_chart_list none "HD_10700.jpg" Name of finding chart file (has to be in .jpg format)
comments none "very variable target!" comments concerning the target
more keywords ⇒