KI V2 Data Products
Differential Phase (.dphase) File
Differential Phase files are ASCII text files that contain the narrow-band L-1 differential phase data for KI. The following gives an example of a line from a KI diff. phase file:
DPHASE 07/15/2009/06:14:03 6.234126 HD139364 5.837307 5.003444 0.622 200 0 KI_K1K2
5 2.095 2.3770 -3.992 10.854 1.923 -0.172 2.2880 -7.690 13.083 2.102 0.007 2.1690 -13.979
17.799 2.237 0.141 2.1020 -12.549 16.981 2.207 0.112 2.0040 -4.518 15.160 1.860 -0.235
The line consists of a number of space-delimited fields. The
meanings of these fields are summarized in the table below. Each line
corresponds to a block average of data (typically 5 to 25 seconds of
fringe data, not necessarily contiguous). All entries, including time
and delay line position, are mean values for the block. A # as the
leading character indicates a comment.
|
field# |
content |
comments |
|---|---|---|
|
|
DPHASE |
File identifier. Each line starts with DPHASE to support the grep extraction mechanism from the intermediate data file produced by the L1 reduction code (Kvis). |
|
|
observation date |
UTC date of the observation (dd/mm/yyyy/hh:mm:ss) |
|
|
observation time |
Mean observation time (decimal UTC hours) |
|
|
source designation |
Source designation (ASCII string) |
|
|
FDL optical path |
Mean fast delay line optical path difference (m) |
|
|
LDL optical path |
Mean long delay line optical path difference (m) |
|
|
phase jitter |
RMS phase difference between consecutive fringe sample (radians) |
|
|
frame rate |
Fringe tracker rate (Hz) |
|
|
cal flag |
Internal calibration quality flag (*) |
|
|
baseline |
Baseline name |
|
|
number of SPEC channels |
Number of spectrometer channels |
| 12 | composite
SPEC
phase |
Phase averaged over spectrometer channels (radians) |
Then, for each pixel ("channel") i (1..n), the following fields are given:
|
field# |
content |
comments |
|---|---|---|
|
13 + 5*(i - 1) |
wavelength |
Wavelength (microns) |
|
14 + 5*(i - 1) |
avgX |
Spectrometer channel average X |
|
15 + 5*(i-1) |
avgY |
Spectrometer channel average Y |
|
16 + 5*(i - 1) |
SPEC Phase |
Spectrometer channel phase |
|
17 + 5*(i-1) |
Diff. Phase |
Spectrometer channel phase relative to wideband pixel phase |
The calibration flag has the following possible values:
- 0: OK
- 1: time difference between fringe data and background > CalTime
- 2: time difference between foreground and ratio data > CalTime
- 3: both 1 and 2 true
- 4: no ratio data exists within CalTime
- 5: both 1 and 4 true
where CalTime = 10 minutes.
Note: The instantaneous X and Y phasors are rotated by the wideband
pixel phase.