This directory contains the processed data from the Uspec, B-BESSEL
and r-SLOAN filters from RBS1774. The data were obtained with the
Blue arm of LBC@LBT.

Conditions for data inclusion in the stacks:
============================================

- Seeing < 1.7
- ellipticity of stars less than 0.05
- less than 0.1 magnitudes absorption from the mean
  photometric zeropoint.

This was found to give a good compromise between inclusion of as many
fields as possible and rejection of very bad data in all three colours.

Photometry:
===========

Photometry for Uspec and r was done with Sloan standards of the
fields PG0231+051, SA92 and SA95. No standard zeropoint/extinction
values were available and the observed airmass range of the standards
was VERY narrow. For extinction and colour terms we used:

r-SLOAN: ext: -0.1; colour: -0.05 in g-r
Uspec:   ext: -0.4; colour: 0.0 in u-g

!! PLEASE CHECK PHOTOMETRY WITH THE SLOAN STARS IN THE FIELD (I did NOT
do this)!!

The photometry in B did not change from the old data. Note that the
Sloan Mags are in AB, the B-BESSEL in Vega!!

Available data
==============

Please note that we reprocessed the B-Band to have consistent astrometry
between all three filters.

For each filter we have:

RBS1774_B.fits and RBS1774_B.weight.fits (substitute 'B' with 'U' and
'R' for the other filters).

Apparent magnitudes are estimated with:
mag = MAGZP - 2.5*log(flux)


The headers contain:

TEXPTIME=              4916.93 / total Exposure Time
EXPTIME =                 1.00 / effective Exposure Time (s)
GAIN    =              8604.63 / effective GAIN for SExtractor
TELESCOP=             'LBT-SX' / Where the data was observed
INSTRUME=           'LBC-BLUE' / Instrument Name
FILTER  = 'SDT_Uspec         ' / Filter Name
OBJECT  =            'RBS1774' / Target Name
ASTRCAT =              '2MASS' / Astrometric reference catalogue
ASTRERR =                 0.30 / estimated absolute astrometric error (arcsec)
MAGZP   =                26.66 / AB Magnitude Zeropoint
MAGZPERR=                 0.10 / estimated Magnitude Zeropoint Error
MAGSYS  =                 'AB' / Magnitude System
BUNIT   =              'ADU/s' / Unit of pixel values
SEEING  =                 1.14 / measured image Seeing (arcsec)
SEEINERR=                 0.01 / measured image Seeing error (arcsec)
NCOMBINE=                   35 / number of individual frames in this stack
GABODSST=                 3583 / first GABODSID of images in this stack
GABODSEN=                 3587 / last GABODSID of images in this stack
DATE-ST =         '2008-10-22' / first date of stack data (local time at tel.)
DATE-END=         '2008-10-26' / last date of stack data (local time at tel.)