README file for the NACO SV Galactic Center Programme

Contact Person Name:            	Matt Lehnert
Contact Person E-mail Address:  	mlehnert@mpe.mpg.de
Contact Person Telephone Number:        +49-89-30000-3592

Estimated Total Execution Time (EXCLUDING overheads): 1.5 hours


Programme Description
=====================

This is an IMAGING program to get deep H,K, and L' exposures in 
the Galactic Center field.  In previous commissioning/paranalization/SV
data, we have discovered the following (in relation to this new request):

(1) One of the stars, S2, reached peri-center passage over the
    commissioning period of NACO during which time it reach a velocity
    greater than 5000 km/s! Since S2 was observed during apo-center
    at the beginning of the GC monitoring campaign with Sharp on the NTT this
    full data set has allowed us to fit a highly significant orbit solution.
    This provides a mass constraint on the black hole down to 18 light days
    or about a factor of 10 better resolution than previously obtained.
    These additional SV observations will allow us to continue tracing the
    orbit of S2 at a time when it will be significantly distant from the
    position of SqrA* further constraining the orbital parameters,  and 
    perhaps even more importantly, to begin to look at the faint stars near the
    central mass of the GC and emission from SqrA* itself.

(2) The previously obtained L-band commissioning data have caused a
    particular excitment in that there is a possibility that SqrA* (the
    puntative black hole) is visible in the L-band.  Such a detection
    would put strict limits on the accretion rate of the black hole
    and have a myriad of implications for how BHs grow, are fueled,
    and radiate.  Unfortunately, the closeness of S2 to the position
    of SgrA* has heretofore made it impossible to be certain that the
    observed L-band emission is not from S2.  With the rapid motion of
    S2, it should be possible to distinguish conclusively emission from
    S2 and emission at the position of SqrA*

(3) The complexity of the absorption along the line-of-sight to the GC
    hampers the determination of a mass function of stars near the GC.
    From observations taken with CONICA-NAOS during the commissioning and
    paranalization/SV reveals a possible dearth of low mass stars in the
    cluster surrounding the GC.  Such a robust determination of the mass
    function has strong implications for how the star formation proceeded
    in the GC or how the young stars may have dynamically sank into the
    center.  To determine a robust mass function requires a estimate of the
    distribution of the extinction to each individual star or group of
    stars.  Comparing the H, K, and L-band images would be an important
    step in this direction, not to mention making for a really nice looking
    color image!

With all of these goals in mind, we have designed a program to take deep
images of the GC in H, Ks, and L' bands with NACO.

OB Information
==============

List of Science OBs with Associated Finding Charts
--------------------------------------------------

Total Number of Submitted Science OBs: 3
Total Number of Submitted Finding Charts: 1 

The finding chart, GCCONICAKs.ps, is a CONICA-NAOS Ks image of
the Galactic Center with the positions of SqrA* (the center of the
field) and IRS7 (the reference star) clearly marked.  The L'
observations will use a star offset by about 26.4" to the North of
SqrA*.

OB name               Seq No     Finding chart           OB structure
-----------------    --------  --------------------   ----------------------
GalacticCenterKs    = SeqA.1 = GCCONICAKs.ps          4 x 15secs x 20 int
GalacticCenterH     = SeqB.1 = GCCONICAKs.ps          4 x 15secs x 20 int
GalacticCenterLprime= SeqC.1 = GCCONICAKs.ps        150 x 0.2secs x 80 int

We request standard calibration for these images including full sets of
flats and darks.