README web version of /home/usg/OPS/MTS/readme_xml/readme_80503500

Principal Investigator Email Address

• henning@mpia.de

Estimated Total Execution Time (hours, including overheads)

• 5.5

General Description

• FOR ALL PRACTICAL ISSUES REGARDING THIS PROGRAMME, PLEASE CONTACT Roy
   van Boekel (boekel@mpia.de). He coordinates the programme on behalf of PI Th. Henning.
  
  
  Many young stars show strong emission in the 12.81 micron [Ne II] line. It has recently
   been proposed that this emission is closely related to X-ray emisison, and that
   the X-rays are the source of neon ionization. However, J-type (dissociative) shocks
   have also been opted as the ionizing mechanism.
  
  The T-Tauri system harbors at least one X-ray bright star and has shocked gas surrounding
   the system on scales of a few arcseconds. It also shows strong [Ne II] emission
   in ISO and Spitzer spectra. However, these space based spectra lack the spatial
   resolution needed to distinguish between an X-ray origin (the Ne II emission comes
   mostly from the spatially unresolved inner disk regions) and a shock origin (the
   Ne II emission arises in the shocked gas surrounding the system on scales of a few
   arcseconds). 
  
  This program is aimed at obtaining VISIR HR spectroscopy of the T-Tauri system with
   a few carefully chosen slit postions/orientations, in order to spatially separate
   emission from the various components, and thus to determine which ionization mechanism
   is dominant.

Waiver Requests

• While the individual OBs are all well below 1 hour in length, 
  the science-calibrator combinations that need to be observed in
  sequence can be longer (~1.5 hours).
  
  A waiver was requested for using such longer chunks of time,
  and was approved.

Critical Observing Condition Constraints

• In order to be most sensitive, and to have the best spatial separation
   of the various components, we use the 0.4 arcsecond slit, and requiree an (optical,
   0.5 micron) seeing of 0.8 arcseconds. For best telluric calibration, sensitivity
   and image quality, the airmass should not exceed 1.6

Time-Critical Aspects

• Because of an atmospheric CO2 line coinciding with the wavelength of the
   [Ne II] line, the observations ought to be performed roughly after januarey 15;
   by this time the relative velocity of Earth with respect to T-Tauri (systemic velocity
   +19 km/s) is such that the CO2 line has blue-shifted away from [Ne II] line. Due
   to RA constraints, it is best if the observations be performed not too long after
   this date, preferably no later than mid-february.
  
  Other than this, no special timing is required.

Special Execution Requirements

• The acquisition should be relatively straightforward, both components
   are fairly bright (about 8 and 7 Jy for the north and south component, respectively).
   The positioning of the slit deserves some attention, though.
  
  !!! CAUTION !!!
  For slit position 1 and 2, the acquisition should center on TTau-N, for slit position
   3 it should center on TTau-S. The acquisition target is indicated in the finding
   chart for each OB as well.
  
  
  Due to the relatively northern declination, it is not possible for all observations
   to be performed within the same night. It is possible though, to perform 2 out of
   3 measurements during the same night. If this is done, observations should start
   between LST 2:30 and LST 3:00, such that the airmass stays below 1.6 during the
   whole observation sequence. Please perform the "zenith calibrator" (OB name CAL_HD32887_zenith)
   during the night in which 2 science observations are done, if applicable (such that
   2 out of 3 science observations benefit from this measurement as much as possible).
   Do the zenith calibrator AFTER the science target and "primary calibrator" (the
   latter one being the standard star that is at approximately the same airmass as
   TTau).
  
  Note also, that due to the narrow slit we employ (0.4 arcsec), it is not possible
   to make a NeII image during acquisition. Therefore, we have added an extra imaging
   OB (SCI_TTAU_NeII_img). 
  
  
  The ideal observing schedule would look like this (observations performed during
   2 nights):
  
  night 1) CAL_HD28305_1     (start between LST 2:00 and 2:30, such that everything
   fits in at airmass below 1.6)
           SCI_TTAU_slit1
           SCI_TTAU_slit_2
           CAL_HD28305_2
           CAL_HD32877_zenith
  
  night 2) SCI_TTAU_slit3
           CAL_HD28305_3
           SCI_TTAU_NeII_img
  
  Of course "night 2" can be performed before "night 1". Also, it is possible (though
   less ideal) to perform the observations over 3 nights, in which case "night 1" would
   be split in 2 pieces (but then only one science OB has the most direct benefit of
   the extra zenith calibration). Please do not split up night 2.

Special Calibration Information

• Ground based mid-IR observations are only as good as their calibration.
   We choose to spent a fair amount of time (about half of the total execution time)
   on a solid telluric and flux calibration. Our strategy is two-fold:
  
  1) along with each observation of TTau we observe a "primary calibrator" that is
   very close to T Tau and consequently at roughly the same airmass (we tuse HD 28305
   for this purpose).
  
  2) additionally, *for one of the TTau observations*, we observe a standard around
   airmass 1.0 (HD 32887) after the TTau/HD28305 pair. This observation will be used
   to accurately measure the extinction per unit airmass, allowing a good correction
   for the (small) difference in airmass between TTau and  its primary calibrator HD
   28305

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 ?

• YES

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 the provided finding chart is at a different wavelength than the observations,
 did you clearly describe in the README file how to identify the target?

• N/A

Did you specify a guide star brighter than V=12mag within a field of
 r=5arcmin around the science target?

• NO