README web version of /home/usg/OPS/MTS/readme_xml/readme_81030000

Principal Investigator Email Address

• nardetto@mpifr-bonn.mpifr.mpg.de

Estimated Total Execution Time (hours, including overheads)

• 6.0

General Description

• These 4 OBs (science + calibrator star) aim to monitor the physical behavior
   of the Cepheid X Sgr. We need 4 measurements. The time resquested is then 1.5h*4=6h.
   Using high-resolution mode in the K band with FINITO, we focus on the brackett gamma
   2.1655, SiI 2.1777, SiI 2.1822, SiI 2.1879 spectral lines (in micrometers). We need
   simultaneous CRIRES observation (the same night) in order contrain our Cepheid model
   (see 081.D-0300(B)). 
  
  X Sgr is an atypical Cepheid which is not well known. Its mean angular diameter
   is theta=1.47+-0.03mas, but its angular diameter variation has never been derived
   by interferometry (even if it is supposed to be quite low, i.e. less than the typical
   10% of Cepheids). Similarly, its H and K bands variation curves are not well establihed,
   and even its mean magnitudes are not precise at all : H = 2.575 +- 0.196 and K =
   2.499 +- 0.264. To detect the shockwave in the atmosphere of the star, we need the
   longuest baseline A0-K0 (128m). In the four science OBs, we use the average value
   of the angular diameter, and the K and H magnitudes, to provide the minimum visibilities.

Waiver Requests

• No Waiver Request was submitted

Critical Observing Condition Constraints

• The seeing constraint for the calibrator and science stars is 1".
  This value correspond to what is indicated in the phase 1 proposal.

Time-Critical Aspects

• The period of the star is short P=7.7.01281 days (around one week). There
   are also differences from one cycle to the other which are not clearly established.
   We need 4 measurements corresponding to any random 4 nights during the ESO period.
   
  
  Important : simultaneous CRIRES observations (same night as AMBER observations)
   are required to obtain high-spectral resolution observations of BrG and metallic
   lines studied (see 081.D-0300(B)).
  
  Please, do not consider the "User comment" section in the OBs - in which we indicate
   we need consecutive nights -.

Special Execution Requirements

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Special Calibration Information

• Using the Calvin tool we found the following calibrator, which is suitable
   for our scientific purpose:
  
  name : hd181109
  V mag. : 6.57
  K mag. : 1.95
  Sp Type : M0III
  UD : 1.62 +- 0.02 mas
  source of diameter estimate : Borde et al. 2002, A&A, 393, 183B
  
  We have chosen the science star (X Sgr) as a guide star. 
  In V band the mean magnitude of X Sgr is 4.63, and the expected variability is from
   4.27 to 4.87. 
  The V amplitude is 0.6 (Moffett et al., 1984, ApJS, 55, 389).

ToO Information

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ToO Activators List

• ---(Empty)---

Is this a Pre-imaging run ?

• false

Pre-imaging Requirements

• ---(Empty)---

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 ?

• N/A

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 ?

• YES

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

Do you use the same DIT for pairs of science target and associated calibrator?

• YES

Are the magnitudes of science target and calibrator within +/- 1 mag
 ?

• YES

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