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MACS - Magellanic Catalog of Stars |
HEASARC Archive |
Name
This parameter is the star name based on the truncated Equinox 2000
position and a running number within an (RA, Declination) box of 1 minute in
time x 6 arc minutes. For example, a star with (RA, Declination) =
(5 hr 47 min 02.4 sec, -67 deg 12 min 02 sec) would have the designation
MACS J0547-672#001, if it were the first star in its box. The positional
coding uses in RA the hhmm format and in declination decimal degrees
(truncated!), thus defining (in the southern sky) the northwest corner of
the box. This format is in agreement with the Rules and Regulations for
Nomenclature as defined by IAU Commission 5. Currently, the largest
number of stars within a box are 84 and 40 for the LMC and SMC, respectively.
RA
The right ascension of the object in the selected equinox. The original
equinox of the MACS in the version as supplied to the CDS was J2000.0 in
the FK5/PPM system, notice. The epoch of these positions is the average of
the plate epochs, which is around 1989.0. For some SMC fields (28, 50, 51),
however, the epoch is 1991.8. This difference matters only for stars of very
high proper motion. The internal errors of the positions for 99% of the
entries are estimated to be less than or equal to 0.5 arcseconds, and such
entries have a value of 0 for the parameter called position_flag; the 2394
(0.99%) of the stars with larger internal errors are flagged with a value of 1
for the position_flag parameter.
Dec
The declination of the object in the selected equinox. The original
equinox of the MACS in the version as supplied to the CDS was J2000.0 in
the FK5/PPM system, notice. The epoch of these positions is the average of
the plate epochs, which is around 1989.0. For some SMC fields (28, 50, 51),
however, the epoch is 1991.8. This difference matters only for stars of very
high proper motion. The internal errors of the positions for 99% of the
entries are estimated to be less than or equal to 0.5 arcseconds, and such
entries have a value of 0 for the parameter called position_flag; the 2394
(0.99%) of the stars with larger internal errors are flagged with a value of 1
for the position_flag parameter.
LII
The galactic longitude of the object.
BII
The galactic latitude of the object.
Num_Pos
The number of positions from which the RA, Declination, and
instrumental magnitude (int_mag) were computed. This may reach 8 for a
fourfold corner overlap; on the average, one MACS position is derived from
measurements on 1.8 plates.
Int_Mag
The internal (blue) magnitude of the star; the zero points
of this magnitude for the 2 catalog parts (LMC and SMC) are arbitrary, notice.
Thus, this parameter should be useful at least for ranking stars by their
blue magnitudes, i.e., for relative magnitude information. For stars for
which the magnitude measurement procedure failed, a dummy value of 99.0
for this parameter is given. The parameter int_mag_flag is used to indicate
stars which have internal errors for int_mag that are larger than a
magnitude-dependent limit chosen to select only exceptionally high values:
1248 (0.51%) such stars have int_mag_flag set to 1. Notice that a value
of 1 for int_mag_flag may also indicate a large-amplitude photometric
variation.
Position_Flag
A flag used to indicate the size of the internal error
for the position. The internal errors of the positions for 99% of the
entries are estimated to be less than or equal to 0.5 arcseconds, and such
entries have a value of 0 for this parameter; in contrast, the 2394
(0.99%) of the stars with larger internal errors have position_flag = 1.
Int_Mag_Flag
A flag used to indicate the size of the internal error
for the internal magnitude. Those stars which have internal errors for
int_mag that are larger than a magnitude-dependent limit chosen to select
only exceptionally high values (there are 1248 such stars or 0.51% of the
total) have int_mag_flag set to 1. Notice that a value of 1 for int_mag_flag
may also indicate a large-amplitude photometric variation.
Macs_Part
A parameter identifying toward which Magellanic Cloud (LMC or SMC) the particular star lies.
Class
The HEASARC browse classification for the object; all entries
in this catalog have been given the same class value of 2900, i.e.,
unclassified star.