README web version of /home/usg/OPS/MTS/readme_xml/readme_84065700

Principal Investigator Email Address

• mjm@esa.int

Estimated Total Execution Time (hours, including overheads)

• 4.0

General Description

• This is a continuing NACO program to monitor the orbital motion of Eps
   Indi Ba,Bb, the nearest known binary brown dwarf system. The separation was 0.732
   arcsec at PA=137 degrees E of N in August 2003, but will be much less (0.1-0.3 arcsec)
   during P84, as the system is near closest approach. The system also has a very high
   proper motion of 4.7 arcsec/yr: the 1999 epoch 2MASS finding chart shows its predicted
   2010.0 epoch position.
  
  Observations have been made in P73-P83: 4 further epochs are needed in P84, spaced
   roughly by 4 weeks during the period. Again, as the system goes through closest
   approach, excellent observations are critical.
  
  The N90C10 dichroic is used in order to ensure good AO correction using the IR WFS
   on the brighter of the two T dwarfs, Eps Indi Ba, which has an H band magnitude
   of 11.51. The NACO S13 camera is used to get the best possible spatial resolution
   and sampling, and thus the most accurate astrometry.  Images are taken in each of
   the J, H, and Ks filters to help reduce systematic errors in the astrometry and
   to look for evidence of photometric and colour variability in the T dwarfs. In each
   filter, a total of 1 minute integration time is taken at each of 5 dithered positions
   on the detector. 
  
  At each epoch, a corresponding OB must also be executed on HD208371/2, in order
   to calibrate the NACO image scale and position angle. Care must be taken to ensure
   that both stars in the HD208371/2 binary are in the NACO science field.

Waiver Requests

• 384.C-0657A.01.WAV: waiver granted 25/07/09
  Request for extension in submitting OBs approved
  
  384.C-0657A.02.WAV: waiver granted 25/07/09
  The DIT/NDIT values for our observations should be changed by the SM astronomer
   at the time of the observations, in order to ensure that the sources do not saturate
   while good S/N is delivered. The product DIT x NDIT should remain constant.

Critical Observing Condition Constraints

• Excellent AO correction is acutely important in P84, as the system is
   near closest approach (0.1-0.3 arcsec).
  Observations should be carried in seeing of 0.6 arcsec or better to separate two
   sources and obtain accurate relative positions. All efforts made to optimise the
   AO system would be greatly appreciated: the better the final AO-corrected image
   resolution, the better the astrometry. 
  Clear conditions required for relative photometric measurements.
  No strong requirements on lunar illumination or distance of moon from target.

Time-Critical Aspects

• The relative orbit of Eps Indi Ba,Bb should be measured 4 times during
   P84, at times which are sensibly separated. We have imposed 5 week long time windows
   on each of the observations (Sep 22 - Nov 01, Oct 15 - Nov 22, Nov 08 - Dec 15,
   Dec 01 - Jan 08) within the time that Eps Indi B is available in P84 (i.e. Oct -
   Jan). These windows overlap in order to provide flexibility (e.g. in case of bad
   weather, technical issues, scheduling), but it would be ideal if things could be
   spaced out. That said, near closest approach, independent multiple data sets taken
   close in time are better than missing an epoch out altogether.

Special Execution Requirements

• Nominal values of DIT=10 secs and NDIT=6 have been specified for the Eps
   Indi B observations, but we ask the SM observer to change DIT and NDIT to ensure
   well-exposed (i.e. high S/N) but not saturated images. If this adjustment is made
   in the H band, the same values of DIT/NDIT should also be ok for J and Ks (taken
   in the same OB). The product of DIT and NDIT should remain fixed at 1 minute. The
   same should be done for the astrometric calibrator (HD208371/2) to ensure that both
   stars are well-exposed but not saturated. The nominal values are DIT=1 sec, NDIT=15,
   a total of 15 seconds. A waiver has been granted to allow this exception.

Special Calibration Information

• Each time Eps Indi B is observed, the astrometric calibrator binary (HD208371/2)
   MUST BE OBSERVED immediately before or after, without any adjustment of the NACO
   instrument and mounting.
  IMPORTANT NOTE: The coordinate given for the calibrator is for the southernmost
   star in the binary, HD208272, which is the WFS star. Once it is acquired, the field
   MUST BE OFFSET TO THE NORTH, to ensure both stars in the binary are visible in the
   NACO FOV simultaneously.

ToO Information

• N/A

ToO Activators List

• N/A

Is this a Pre-imaging run ?

• false

Pre-imaging Requirements

• N/A

Source(s) of Pre-imaging

• ---(Empty)---

Pre-imaging sources not listed above

• 2MASS

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

If you have PSF reference star OBs, do the names of those OBs begin with
 PSF_ ?

• N/A

If there are Finding Charts attached to your OBs, is the field-of-view
 of at least one of these charts 2' x 2' (with clearly labelled field orientation)
 ?

• YES

Have you clearly marked and labelled your wavefront reference objects
 R1, R2, R3, ... (as specified in the NAOS Preparation Software) on your Finding
 Charts ?

• YES

Have you specified the magnitude of the brightest object in the field-of-view
 for each OB ?

• YES

Are there objects in any of your fields (including standard stars) which
 are brighter than the limits specified in the User Manual and on NACO web Pages
 ?

• NO

If the previous answer is yes, have you given a list of OBs and a justification
 for the brightness limit violation in the general description field ?

• N/A