README web version of /home/usg/OPS/MTS/readme_xml/readme_79024301

Principal Investigator Email Address

• ez@astro.uu.se

Estimated Total Execution Time (hours, including overheads)

• 13:59:40

General Description

• A search for red halos around local galaxies
  
  In this programme, we will attempt to perform very deep surface photometry of two
   Local-group dwarf galaxies (NGC 6822 & Fornax dSph) in filters BVI, in hope
   of detecting so-called "red halos", i.e. very faint and extended structures that
   have previously been detected around more distant galaxies, and which may indicate
   the presence of a halo population consistly mostly of low-mass stars.
  
  Because of the large expected sizes of these halos, and the extreme surface brightness
   levels aimed for, sky chopping with very large offsets (up to 5600") will be done
   every 5 minutes. The exact coordinates of the sky and targets fields are, however,
   not very crucial - so accumulating pointing errors will no be an issue. As we are
   only interested in the large-scale structure of these halos, image smearing effects
   due to bad seeing or poor autoguiding will most likely not be a problem either.
  
  Most OBs execute an offset sequence starting with one of two sky fields (S1 &
   S2), followed by a target field (T1 or T2), then back to S1 or S2 and so on: e.g.
   S1-T1-S2-T1-S1 in the B-band. For each target galaxy, there are two target fields
   - T1 & T2 - where T1 is centered on the target coordinates and T2 lies offset
   into the halo region by 25.5 arcmins in Ra and Dec. All OBs do however start off
   by going to the central coordinates of each galaxy.
  
  All the data should be obtained under CLR conditions or better. The flux calibrations
   are taken care of by 4 OBs (NGC6822T1cal, NGC6822T2cal, Fornax_T1cal, Fornax_T2cal),
   which do short exposures of the relevant target fields, and should be executed under
   PHO conditions.
  
  The OB NGC6822_S1VI takes a number of quick exposures of one of the sky fields surrounding
   NGC6822 in order to check the timescale over which the sky varies in the in the
   V- & I-bands. This will be very important for future attempts to do deep surface
   photometry in chopping mode with wide-field instruments.

Waiver Requests

• A waiver request with ID 079.B-0243B.01 was submitted on January 30, 2007,
   requesting the use of large telescope offsets and thereby eliminating the verification
   error about the possibility of losing the guide star, which is generated by nearly
   all our OBs. The purpose of the large initial offsets is to do sky chopping. This
   waiver was granted on February 28, 2007.

Critical Observing Condition Constraints

• Because of the very faint surface brightness levels aimed for, all OBs
   must be executed in dark time.
  Most OBs can be executed under CLR conditions, whereas the four OBs that take care
   of the flux calibration (NGC6822T1cal, NGC6822T2cal, Fornax_T1cal, Fornax_T2cal)
   must be obtained during CLR conditions.

Time-Critical Aspects

• None

Special Execution Requirements

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Special Calibration Information

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ToO Information

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ToO Activators List

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Is this a Pre-imaging run ?

• false

Pre-imaging Requirements

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Source(s) of Pre-imaging

• ---(Empty)---

Pre-imaging sources not listed above

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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 ?

• 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

Did you set 'New Preset' flag in all acquisition templates to 'True'?

• YES

Have all your submitted OBs the same filter for the acquisition template
 and for the first science template?

• YES

Did you combine calibration templates with science templates for any
 OB?

• NO

Did you combine imaging and spectroscopic templates for any OB?

• NO

Did you submit any Focus template?

• NO