README web version of /home/usg/OPS/MTS/readme_xml/readme_83062300

Principal Investigator Email Address

• pierre.kervella@obspm.fr

Estimated Total Execution Time (hours, including overheads)

• 3.0

General Description

• The observation of RS Pup's nebula and its PSF calibrator Alphard presents
   a difficulty due to the brightness of these stars.
  
  Using FIMS to prepare the observation, we have positionned the stars within the
   gap of the two red CCDs of FORS at the time of acquisition. This approach prevents
   the heavy saturation of the CCD from RS Pup (magV~7) and Alphard (magV~2). During
   the science template, the telescope is offset by 18" to obtain the second half of
   the polarimetric field. The field coverage will not be complete, but this strategy
   will ensure that RS Pup remains behind blade #11 of FORS for both positions. The
   OB labeled "1_RSPup_pol" will fill the remaining gaps through an instrument rotation
   of 90 degrees (East of North). So in principle, assuming the offset coordinates
   determined using FIMS are correct to about 1", the star image itself should never
   be the detector.
  
  The single observation of Alphard will provide a calibration of the extended wings
   of the PSF and should only be done once (for a single zero rotation angle). The
   observation scheme is the same as for RS Pup.
  
  We would apreciate to receive a short mail when the first observations have been
   obtained, in order for us to check the data quality asap before the second and third
   epochs.
  
  For reference, the true (without offset) J2000.0 coordinates of the two stars are:
  RS Pup:  08 13 04.216 -34 34 42.697
  Alphard: 09 27 35.243 -08 39 30.969
  
  *** Update on 2009-04-27:
  The basis of our strategy to prevent saturation is to offset the telescope by only
   18" instead of the standard 22" in order to keep the star itself behind one MOS
   blade (close to the two edges of the blade). There is no special action to do at
   acquisition, except to check that the star is located within the CCD gap.
  
  We checked the images obtained on 04-04 and 04-26, and they are fine for our scientific
   goal. There is a spot of saturation close to the star due to the scattered light,
   but it will not prevent the polarization measurements on the nebula itself. As foreseen,
   the star itself never falls on the detector. So you can go ahead with the execution
   of the remaining OBs, including the PSF calibration OB on Alphard named "0_Alphard_pol".

Waiver Requests

• No Waiver Request was submitted

Critical Observing Condition Constraints

• No critical observing conditions.

Time-Critical Aspects

• There is no per say timing constraint. However, the three observations
   of RS Pup should ideally be obtained with approximately 10-15 days interval in between,
   to cover a significant part of the variation period of RS Pup.

Special Execution Requirements

• NA

Special Calibration Information

• NA

ToO Information

• NA

ToO Activators List

• NA

Is this a Pre-imaging run ?

• false

Pre-imaging Requirements

• None.

Source(s) of Pre-imaging

• ---(Empty)---

Pre-imaging sources not listed above

• ---(Empty)---

Do all your OBs comply with the instrument-specific requirements listed
 on the instrument-specific Phase 2 web page ?

• YES

If this is a pre-imaging run, did you select PRE-IMAGING for the Observing
 Category for each Observing Template ?

• N/A

Do all your finding charts comply with both the general and instrument-specific
 Phase 2 Web Pages ?

• YES

If you submitted OBs for standard stars, did you specify the magnitude
 and spectral type of all standard stars in the OBs ?

• N/A

Have you included OBs for any calibrations that you need but which are
 not part of the Calibration Plan ?

• YES

If you are observing Moving Targets, have you attached suitable ephemeris
 files to your OBs?

• N/A

If you have preferences which OBs should be executed first, did you make
 use of the User Priority field in the OBs ?

• YES

If this is a run that requires coordinated observations with other facilities,
 did you give proper instructions in the Time-Critical Aspects Section ?

• N/A

If you have prepared your finding charts with tools other than FIMS,
 do they comply with the specifications on the FORS1 Phase 2 web page ?

• N/A