README web version of /home/usg/OPS/MTS/readme_xml/readme_81022401

Principal Investigator Email Address

• kohnaka@mpifr-bonn.mpg.de

Estimated Total Execution Time (hours, including overheads)

• 3.0

General Description

• MIDI+VISIR observations to probe the dusty environment of the rapidly-evolving
   born-again AGB star FG Sge.  The aim is to resolve the dusty cocoon of FG Sge with
   MIDI observations and to study how and where dust forms in this unique object. 
   FG Sge was resolved out when it was observed with UT3-UT4-62m on 2008 April 22.
    However, we request another observation with UT3-UT4-62m to check temporal variations
   resulting from possible, recent dust cloud formation.  While we prefer the UT3-UT4-62m
   baseline for this run, any other UT baseline is acceptable.  
  
  Our request to change the baseline configuration back UT2-UT3-47m to UT3-UT4-62m
   was approved on 03 July 2008 by M. Wittkowski. 
  
  Acqusition images should also be obtained both for the science target and the calibrators
   for the following reasons: 1) FG Sge may turn out to be much more extended than
   currently modeled.  2) Individual chopped frames in an acquisition image data set
   (i.e., a movie of sky-subtracted frames)  provide us with information on the image
   quality and residual image motion, which is valuable for assessing systematic errors
   in the observed visibilities.  Therefore, acqusition images should be obtained not
   only for the science target but also for the calibrators.  
  
  The number of frames for photometric exposures can be changed by the night-time
   astronomer, depending on the actual brightness of the source 
  (whether it is the science target or a calibrator) as well as the atmospheric conditions.
   
  
  The V magnitude of FG Sge varies between 9 and 17 in an irregular manner.  Therefore,
   we request off-axis guiding using a V=12.5 star 8.4" away from FG Sge.  Since the
   attached finding chart in the V band was taken when FG Sge was very bright in the
   optical, it is difficult to recognize the guide star on this V-band finding chart.
    For a better recognition of the guide star, an I-band finding chart is also attached,
   where FG Sge and the guide star are both marked.  If FG Sge happens to be brighter
   than this guide star at the time of the observations, the usual guiding using 
  FG Sge should be executed. 
  
  One of the calibrators, HD192947, is a triple system.  The separations and position
   angles of the other two components are (6.6", 172degree) and (7.1", 179degree),
   but they are much fainter (V=11) than the primary component (V=3.6).  Therefore,
   they should not disturb the acquisition of the right target.

Waiver Requests

• No Waiver Request was submitted

Critical Observing Condition Constraints

• All OBs should be carried out under thin cirrus or better conditions.

Time-Critical Aspects

• NONE

Special Execution Requirements

• NONE

Special Calibration Information

• We request two calibrator measurements in the CAL/SCI/CAL sequence using
   two calibrators HD168723 and HD192947.  It is acceptable to observe either the same
   calibrators or different calibrators before and after the science target.  For this
   reason, two OBs for each calibrator is preapred for each science OB.

ToO Information

• NONE

ToO Activators List

• NONE

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 ?

• N/A

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

Did you indicate for each science star OB the corresponding calibrator
 star OB (and vice versa) in the 'Instrument Comments' field ?

• YES

Did you check that your chosen calibrator is bright enough for the instrument
 mode used ?

• YES

If you use calibrator stars which are not in the CalVin database, did
 you specify their characteristics in the README file and in the OBs ?

• N/A

Did you verify that your coordinates are as accurate as possible (2Mass
 coordinates recommended) and that they include proper motions if available ?

• YES

Did you specify the LST range of the calibrators such that they cover
 the range from 30 min before the start of the LST range of the science target to
 30 min after the end of the LST range of the science target ?

• YES