Nir Raw Frame Product¶
Data product name¶
NirRawFrame
Data product custodian¶
LE1
Data model tag¶
R-1.6.7
Name of the Schema file¶
euc-test-le1-NirRawFrame.xsd
Schema documentation tag¶
Documentation for data product element DpdNirRawFrame:
A NISP-P raw exposure, both for calibration and scientific exposures
Data product elements¶
Header of type: sys:genericHeader
Data of type: le1nisp:nirRawFrame
Parameters of type: ppr:genericKeyValueParameters
Processing Element(s) creating/using the data product¶
LE1 NISP Processor
Processing function using the data product¶
NIR Processing Function
Detailed description of the data product¶
The LE1-NISP component of the LE1 processing function provides calibration and scientific exposures and the associated metadata.
Each calibration and scientific exposure is provided as one multi-extension FITS (MEF) file. In particular, a NISP-P exposure file contains two extensions per detector: one extension for the detector scientific data, and one extension for the detector Chi2 data. The total number of the extensions in the files is hence 32.
The detectors numbering and location on the NISP Detector System Assembly is shown in Fig. 3 below
Fig. 3 : NISP Detector System Assembly: detectors position and ID¶
Within each Sensor Chip Array (SCA), the pixel (0,0) is located on the upper left corner when seeing the front side of the SCA with their wire bounding located on top. Consequently, pixel (0,0) is located:
on the upper left corner in the detectors:
#11, #12, #13, #14
#21, #22, #23, #24
on the lower right corner in detectors:
#31, #32, #33, #34
#41, #42, #43, #44
This is shown in Fig. 4
Fig. 4 : Pixel layout of the different SCAs¶
It is noted that each SCA contains both reference pixels and science pixels. Reference pixels are located all around the detector. The science pixels are located in the central window:
(xcorner, ycorner, xsize, ysize) = (3, 3, 2040, 2040)
Data encoding¶
For each detector:
pixels in the scientific extension are in units of ADU, 16-bit unsigned integer.
pixels in the Chi2 extension only provides a single bit of information (for the photometric observations), stored as an 8-bit unsigned integer and obtained on-board by flagging the computed Chi2 value with a (configurable) threshold. For details on the Chi2 computation performed on-board, see Sir Raw Frame Product.
Header content¶
The required keywords are specified below (with an example of value when possible):
Primary header
TELESCOP |
= EUCLID |
/ |
Also ground telescopes from EXT |
INSTRUME |
= NISP |
/ |
Other values: VIS |
SURVMOD |
= WIDE |
/ |
Survey mode: Wide, Deep |
OBSTYPE |
= IMAGING |
/ |
Observation type - IMAGING or SPECTROSCOPIC |
OBSMODE |
= MULTIACCUM |
/ |
Observation mode: e.g. MULTIACCUM |
DATE-OBS |
= 2025-06-22 18:56:13.000Z |
/ |
Date of observation (start) |
MJD-OBS |
= 9304.78981695 |
/ |
MJD start EXPTIME |
EXPTIME |
= 105.0 |
/ |
Total integration time in seconds |
RA |
= 8.819091727789999 |
/ |
Center of field of view right ascension (deg) |
DEC |
= -19.474857937 |
/ |
Center of field of view right declination (deg) |
PA |
= 65.0443972293 |
/ |
Position angle (deg) |
EQUINOX |
= 2000.0 |
/ |
Standard FK5 (years) |
RADECSYS |
= FK5 |
/ |
Coordinate reference frame |
OBSID |
= 52926 |
/ |
Observation ID |
DITHSEQ |
= 1 |
/ |
Number sequence of dithering |
EXPNO |
= 3 |
/ |
Exposure sequence ID |
FILTER |
= Y |
/ |
Filter wheel position |
GRISM |
= OPEN |
/ |
Grism wheel Position |
Extension headers
For each NISP detector, two extensions will be provided: a science “layer”, containing the pixel data, and a data quality layer that, for the photometric data, will just contain 1 bit of information per pixel, reporting the cosmic-ray hits detected on-board.
The science layer will include the following header keywords
EXTNAME |
= DET11.SCI |
/ |
Detector ID and SCI data |
DET_ID |
= 11 |
/ |
Detector ID |
CRVAL1 |
/ |
Right ascension at ref pixel |
|
CRVAL2 |
/ |
Declination at ref pixel |
|
CRPIX1 |
/ |
Reference pixel x coordinate |
|
CRPIX2 |
/ |
Reference pixel y coordinate |
|
CDELT1 |
/ |
Incremnt of x coordinate |
|
CDELT2 |
/ |
Incremnt of y coordinate |
|
CTYPE1 |
/ |
Coordinamte 1 type |
|
CTYPE2 |
/ |
Coordinamte 2 type |
|
CD1_1 |
/ |
Translation matrix element |
|
CD1_2 |
/ |
Translation matrix element |
|
CD2_1 |
/ |
Translation matrix element |
|
CD2_2 |
/ |
Translation matrix element |
|
DATAUNIT |
= ADU |
/ |
Pixel data unit |
GAIN |
= 1.5 |
/ |
e- to ADU conversion factor |
BIASLEV |
/ |
Bias level in ADU |
|
SATURATE |
= 64000 |
/ |
Pixels are saturated if counts >= 64000 ADU |
The WCS keywords information is just a baseline set of coefficients estimated during ground tests. They are needed by the NIR Astrometic Calibration in order to refine and compute the correct astrometric solution.
No specific keywords are espected in the data quality layer.
EXTNAME |
= DET11.DQ |
/ |
Detector ID and quality layer (Chi2) |
DET_ID |
= 11 |
/ |
Detector ID |