README web version of /home/usg/OPS/MTS/readme_xml/readme_77056901

Principal Investigator Email Address

• stephane.erard@obspm.fr

Estimated Total Execution Time (hours, including overheads)

• 01:50:00.000

General Description

• The purpose is to acquire two scans of the illuminated side of Mercury
   with the red and blue grisms.
  
  The slit is first located at the disk border, then moved to scan the disk (see chart).
   All scans are performed with the slit aligned towards the zenit, to minimize flux
   loses by differential refraction. Half the disk only is illuminated, with the terminator
   roughly orthogonal to the slit direction. The slit orientation may be maintained
   constant during the scan.
  
  A single OB acquires a complete scan in each grism:
  Four frames are acquired with Mercury centered at different positions along the
   slit / on the detector. The slit is then shifted towards NW. This shift is equal
   to 1.5 times the slit width (0.9"). The same four-frames sequence is repeated for
   this new slit position. Seven such sequences cover completely the disk of Mercury,
   including day side and night side (NIR signal is expected on the night side).
  
  The second OB acquires the second scan similarly using the second grism.

Waiver Requests

• No Waiver Request was submitted

Critical Observing Condition Constraints

• Optimized timeline (any night around June 18th):
  
  21:55: arcs
  22:00: start Mercury just after sunset (18 min required for the 2 OBs)
  22:28: end Mercury (elevation < 13deg)
  ~22:35 start Vesta
  ~23:15 end Vesta
  ~23:15 start Hip43726
  ~23:40 arcs
  ~23:45 end
  
  Please notice the constraint with Mercury: both OBs must be completed at 22:28,
   and therefore must start before 22:10 (after sunset).

Time-Critical Aspects

• The observing period ranges from June 16th to June 21st to optimize the
   visibility of the day side.
  A short period (~25 min) is available just after sunset to observe Mercury at reasonable
   elevation.

Special Execution Requirements

• Vesta may be difficult if seeing is bad. The second star would become
   a priority if Vesta is too long to acquire.
  Both Vesta and the reference star are acquired with the slit aligned towards the
   zenit (provided in the OB for the corresponding times).

Special Calibration Information

• Spectroscopic arcs are acquired during the run, either before or after
   the targets, to optimize spectral calibration. 
  An asteroid and a standard star are observed with both grisms. Both references are
   G2 types, with respective V magnitude 8.2 and 6.
  
  To make optimal use of the short visibility period after sunset, the best sequence
   is to:
  - first observe Mercury with both grisms, 
  - then observe Vesta and the standard star (in the order star_1 then star_2), to
   get them under similar airmass

ToO Information

• ---(Empty)---

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 ?

• 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?

• YES

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