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
1

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).
2

observation date

UTC date of the observation (dd/mm/yyyy/hh:mm:ss)
3

observation time

Mean observation time (decimal UTC hours)
4

source designation

Source designation (ASCII string)
5

FDL optical path

Mean fast delay line optical path difference (m)
6

LDL optical path

Mean long delay line optical path difference (m)
7

phase jitter

RMS phase difference between consecutive fringe sample (radians)
8

frame rate

Fringe tracker rate (Hz)
9

cal flag

Internal calibration quality flag (*)
10

baseline

Baseline name
11

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:

where CalTime = 10 minutes.

Note: The instantaneous X and Y phasors are rotated by the wideband pixel phase.