| COLUMN
NAME |
FORMAT |
NULLS |
COMMENT |
| date |
date |
no |
The
observation reference date for this source expressed
in ISO standard format. This is the UT day value at sunrise for the
night on which the source was observed. Because it is possible for the
UT day to
change during a night of observations, the actual UT date for a source
measurement can differ from date by one
day. |
| day_no |
smallint |
no |
Small
integer alias for date. Increases sequentially from March 1,
1997. Day_no is encoded in the raw scan data file names. |
| hemis |
char(1) |
no |
Hemisphere
code for the 2MASS Observatory from which this scan was observed.
- "n" = North/Mt. Hopkins
- "s" = South/CTIO
|
| scan |
smallint |
no |
The
nightly scan number in which the source was detected. Is
only unique within a specific date and hemisphere. |
| tile |
integer |
no |
Also
known as strip_id or tile_id. Unique identifier for
(planned)
position
of scan on sky. This column is useful for
identification of
multiply observed regions of the sky, particularly the calibration
scans. The tile definition table is given in the Explanatory Supplement. |
| s_dir |
char(1) |
no |
Scan
direction.
- "n" = scan starts at south end and proceeds to the
north end.
- "s" = scan starts at north end and proceeds to the
south end.
|
| s_type |
char(3) |
no |
Scan
type.
- "sci" = 6 degree long science data scan.
- "cal" = 1 degree long calibration data scan.
- "flt" = Scan taken
during twilight used to flat field the NICMOS arrays.
- "dar" = Dark scan taken with cold shutter in front of
arrays.
- "lsc" = 6 degree long science data scan
taken with 6X the normal integration time.
- "tst" = Test scan, frequently used for
determining focus settings.
- "lca" = Calibration scan taken with 6X the
normal r2-r1 integration time.
- "lda" = Dark scan taken with 6X the normal
r2-r1
integration time.
|
| frames |
smallint |
no |
Number
of 256x256 pixel image frame pairs in scan. Each frame pair
consists of
an r1 image and an r2 image stored in sequence in the .rdo files. |
| as_cat |
char(1) |
no |
All-sky
catalog science (6 degree long) scan.
- "y" = Scan is present in the 2MASS all-sky catalog
- "n" = Scan is not in 2MASS all-sky catalog.
However it may be a cal scan used in calibrating the science
scans in the catalog.
|
| tape_label |
char(8) |
no |
Label
on DLT tape where data are located. |
| disk_label |
char(3) |
yes |
Label
on hard disk where data are located. |