
Following is a summary of the special star cluster plates designed
in Nov 2001.  Each plate has several pointings (tiles) associated
with them, where each pointing is offset by ~0.2 degrees and has
holes drilled for a different magnitude range of stars.  There are
a total of 4 plates with 19 pointings (tiles).  The total number
of tiled stars is 640 x 4 = 2560.

Cluster   TILE PLATE  RA    DEC    rmag       Nobj  Guide fibers
--------- ---- -----  ----- -----  ---------  ----  ------------
Praesepe  9217  798   130.0 +19.6  12.0 15.5   266  3,5,8,10,11
          9218  798B  129.8 +19.6   9.0 12.2   297  1,4,6
          9219  798C  130.2 +19.6   5.9  9.2    69  2,7,9
(HD84937) 9220  798D  146.9 +14.3   8.2          8  11
--------- ---- -----  ----- -----  ---------  ----  ------------
Pleiades  9221  799    57.0 +23.7  13.9 17.1   119  3,5,8,10,11
          9222  799B   56.8 +23.7  11.1 14.1   190  1,6
          9223  799C   56.6 +23.7   8.3 11.3   262  4,7
          9224  799D   57.2 +23.7   5.5  8.5    51  2
          9225  799E   57.4 +23.7   2.9  5.9    10  9
(BD+21)   9226  799F   63.3 +23.1   9.1          8  11
--------- ---- -----  ----- -----  ---------  ----  ------------
N752      9227  800    29.2 +37.7  12.0 15.2   219  3,5,8,10,11
          9228  800B   29.0 +37.7   9.0 12.2   349  1,4,6
          9229  800C   29.4 +37.7   6.0  9.2    64  2,7,9
(HD19445) 9230  800D   46.6 +26.9   7.9          8  11
--------- ---- -----  ----- -----  ---------  ----  ------------
N1817     9231  801    78.0 +16.7  15.2 18.2    16  3,5,8,10,11
          9232  801B   77.8 +16.7  12.8 15.4   232  1,6
          9233  801C   78.2 +16.7  10.4 13.0   309  4,7
          9234  801D   78.4 +16.7   8.0 10.6    74  2,9
(BD+21)   9235  801E   63.2 +23.0   9.1          9  11
--------- ---- -----  ----- -----  ---------  ----  ------------

The information is pulled simply from the 2MASS files supplied
by Jill Knapp.  The astrometry is directly from 2MASS; no proper
motions have been applied.  Some of these clusters are supplemented
with Tycho stars that were not in Jill's files.  Those Tycho objects
were put in epoch 1998 equinox J2000 to be roughly consistent with 2MASS.
The epoch does not matter much as long as it's consistent.  Guide stars
are drawn from the same lists in the magnitude range [10.5,12.5].

For objects NOT drawn from a membership list, only those 
with an optical counterpart in the 2MASS catalog were considered.

In most cases, the priority is
  * bright stars + Hipparcos supplement
  * members
  * fainter stars
However, NGC 1817 is the exception.  There the priority is
  * members
  * other stars (and not super-bright)

There are no explicit sky-fiber positions for any of these plates.  In
each pointing, the objects that appear in that pointing will be called
OBJECT/SERENDIPITY_MANUAL.  All other fibers (which are real objects
in other pointings) will be called OBJECT/SKY and used for sky-subtraction.
For all but the last pointing, those are the only type of objects.

Some objects will appear on two pointings of the same plate, since I've
intentionally chosen the magnitude ranges to slightly overlap.

The last pointings will be used for spectro-photometry.  They have 9 or 10
holes drilled directly north & south of guide fiber #11.  A smear of one
of the five SDSS fundamental standard stars will obtain 9 spectra of that
star. Those pointings only have the 10 OBJECT/SPECTROPHOTO_STD holes and
630 OBJECT/SKY holes.

We've approximated SDSS ugriz magnitudes for the Tycho stars with:
    u = V - 0.024 + 2.317 * (B-V)  (Npts= 226)
    g = V - 0.081 + 0.544 * (B-V)  (Npts= 184)
    r = V + 0.140 - 0.477 * (B-V)  (Npts= 219)
    i = V + 0.341 - 1.002 * (B-V)  (Npts= 198)
    z = V + 0.509 - 1.360 * (B-V)  (Npts= 200)
The above fits were done to the MT secondary standards (assuming
that Tycho B+V are approximately Johnson.)

The 2MASS catalogs list B+R magnitudes that are related to Tycho B+V
magnitudes as follows:
   B_Tycho = R_2MASS + 0.749 * (B-R)_2MASS + 0.033
   V_Tycho = R_2MASS - 0.093 * (B-R)_2MASS - 0.003
For those objects in 2MASS that only list JHK magnitudes, I transform with:
   B_2MASS = J + 4.51 * (J-K) + 0.22
   R_2MASS = J + 2.26 * (J-K) + 0.08
   (B-R)_2MASS = 2.25 * (J-K) + 0.14

The guide stars are chosen from the same input list of objects,
but in the limited magnitude range of r=[10.5,12.5].  This is significantly
brighter than the usual SDSS guide stars which are at about r=15 and
don't give very good S/N on the guide camera.  Note that an object can
be a guide star for one pointing and a science target on another pointing.
The only guide fiber that is re-used on more than one pointing is #11,
which is used for the last (spectrophotometric) pointing.

The code that generated all the plugmap and associated files is in the
"idlspec2d" product in the "pro/plate" directory.

We will need some minor modifications of the fiber-mapper code at APO
to deal with these plugmap files.  The observing code (SOP) hopefully
will require no modification, and the on-the-mountain reductions (SOS)
should also work fine.  Once the data are taken, Spectro-2D will need
some more serious modifications to deal with it.

-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
PRAESEPE

Praesepe:  We're missing a small band of data near RA=129.5.

Plate center: RA=130, dec = 19.6

Scott Burles found a membership list from Wang et al 1995.
This gave 88 matches (1") to 2MASS at J>10.
File: praesepe.match

I then took all stars with J<10 on the plate.  This gave 215 stars.  
File: praesepe.j10

I then took all stars with 10<J<13, downweighting by  
(d<0.5?1:(d/0.5)**-2), where d is the distance from the plate center.
This gave 531 more stars, but I forgot to remove the members, so there
will be ~450 new stars.
File: praesepe.j13

-------------------------------------------------------------------------------
PLEIADES

We're missing a lot of data: the quadrant at ra<56.5 and dec>24,
plus another patch at dec>24, 58<ra<58.6, plus a couple strips.
I moved the plate center a bit to avoid these: ra = 57.0, dec = 23.7.

Also, the brightest stars (V<5.5 or so) seem to be missing from 2MASS; 
we'll have to add them in from Hipparcos.

The Pleiades is big enough that the clustering on the plate won't be
much of a problem.

I take all stars with J<10.  This gave 255 stars.
File: pleiades.j10

I then take all stars with J<14, downweighting by (J<11?1:0.15*(15-J))
(not that this is not continuous at J=11, but I needed to downweight the
fainter stars somewhat).  This gave 1113 stars.
File: pleiades.j14.

I don't seem to have a membership catalog handy, but I think that the
density of members is so high that we won't care.

Note that the nebulousity may affect our sky subtraction!

-------------------------------------------------------------------------------
N752

We are missing data at RA>30 (and a small band at 27.8ish), so I 
moved the plate center off the cluster center a bit.

Plate center: ra = 29.25, dec = 37.68

Scott Burles found a membership list from Daniel et al 1994.
This gave 98 matches (1") to 2MASS at J>10.
File: n752.match

I then took all stars with J<10 on the plate.  This gave 238 stars.  
File: n752.j10

I then took all stars with 10<J<14 that were not members, downweighting
by  (d<0.5?1:(d/0.5)**-2) * (J<11?1:0.25*(15-J), where d is the distance
from the cluster center (RA=29.45, dec=37.68, not the plate center).
This gave 647 more stars.
File: n752.j14

The priorities here should be j10, match, and finally j14.
Also, the Hipparcos catalog will have some extra bright stars that 
we didn't have 2Mass data for.  We should have room to add them.

-------------------------------------------------------------------------------
N1817

This cluster is closer to the galactic plane and further away, 
hence the contamination by field stars is worse.  This leads to special
instructions as regards priorities and bright limits!
Don't include Tycho/Hipparcos stars.

Fortunately, Scott Burles found a membership list from Balaguer-Nunnez 
et al 1998.  I took objects whose P_field was less than 0.5.  Matching (1") 
to 2MASS gave 478 stars, highly concentrated toward the center of the field.
WE SHOULD GIVE THESE STARS HIGHEST PRIORITY.
File: n1817.match

To fill out the plate, I took stars with 8 < J < 11, downweighting the
fainter stars by the probability (J<9?1:0.25*(13-J)).  This gives 538
stars (that weren't member matchs), which are not strongly clustered to the 
center of the plate.  Chances are that most of these stars are not cluster 
members, and moreover there is probably no room at the center of the plate 
for any more objects.
File: n1817.j11

Note that these stars are *not* as bright as for other clusters.  We 
probably want a bright limit of about 8th mag.  There is no point in
including brighter field stars if they simply require another pointing.

There were no serious data gaps in this field.
Plate center: RA = 78.03, dec = 16.70

-------------------------------------------------------------------------------
M67

We have some data for this, but we've decided to observe the existing
plate, number 321, rather than re-drill.

We probably need some fresh observing instructions for this plate.

-------------------------------------------------------------------------------
h/chi Persei

No 2MASS data available yet.  We haven't tried to solve the
astrometry for Eva's UBVI photometry.
-------------------------------------------------------------------------------

