README web version of /home/usg/OPS/MTS/readme_xml/readme_79071000

Principal Investigator Email Address

• brockenfeller@hs.uni-hamburg.de

Estimated Total Execution Time (hours, including overheads)

• 4.0

General Description

• To study the spatial flux distribution of the stellar disk of the cool
   giants RS Vir and TW Oph with spectro-astrometry, we need to obtain very high signal-to-noise
   / high spatial resolution NIR-spectra of the target. Our method requires spectra
   taken at orthogonal slit orientations. To correct for telluric absorption, it is
   necessary to observe a standard star of spectral type B. It needs
  to be bright in order to also achieve a high SNR. The telluric standard does not
   need to be observed at different slit orientations.
  The telluric standard should be observed at similar airmass (within 0.1) as the
   target.
  Finding Charts: lacking higher resolution images, the FCs show the DSS2 IR images
   in the z-band. In contrast, the observations will be
  carried out in the K-band. However, both targets RS Vir, TW Oph as well as the telluric
   standard stars HD121263 and HD173300 are by far the brightest object within their
   field of views in the K-band.
  
  NOTE: RS Vir is a Mira-type variable that will reach its maximum in the second half
   of 2007-May; hence the R-band magnitudes given 
  in the OBs are just estimates (K-band mag varies only slightly) - this translates
   to the B-R color that is needed for the AO. I tried 
  to give a useful estimation of this color.
  
  NOTE: The approved execution time of this programme has been increased from half
   an hour to four hours (communications with Michael
  Hilker / USD).

Waiver Requests

• No Waiver Request was submitted

Critical Observing Condition Constraints

• Good seeing/strehl ratio  (seeing<=1.0arcsec / strehl>=29.1) is
   necessary to achieve a very high SNR and a high spatial resolution that are
  needed to detect spectroastrometric signatures from the target. Airmass must be
   better than 1.5

Time-Critical Aspects

• There are no time-critical aspects.

Special Execution Requirements

• No special requirements

Special Calibration Information

• The CAL_HD121263 OB serves as telluric standard for RS Vir. The chosen
   object has SpT B2.5IV and a K-magnitude of 3.29;
  Ideally, it should be observed at a similar airmass as the target star RS Vir. Furthermore
   it would be optimal if
  the four target OBs of RS Vir could be observed at a similar airmass.
  In case that HD121263 cannot be used, any other B2-B8 star can be chosen as telluric
   standard. In that case, however,
  it is important to achieve a total SNR not much less than the one aimed at for HD121263
   (that is 350)!
  
  The same applies for the CAL_HD173300 OB which serves as telluric standard for TW
   Oph. The calibrator has SpT B8III and a K-magnitude
  of approx. 3.8

ToO Information

• ---(Empty)---

ToO Activators List

• ---(Empty)---

Do the README file and the instrument comments of the telluric stars
 OBs include the required S/N/pixel of the spectrum of the telluric star, its spectral
 type and allowed spectral range?

• YES

Do any OBs include wavelength or flatfield calibrations?

• NO

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

• N/A

If the slit viewer guide star is different from the target, are the RA
 and DEC offsets accurate to within 0.05 arcsec and do they take into account the
 relative proper motion between the two objects?

• N/A

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

• N/A