Slits
Overview
This file describes the Slits object.
It contains the main information on the traced slit edges, organized into left-right slit pairs.
This is written to disk as a multi-extension FITS file prefixed by
Slits in the Calibrations/ folder.
See Calibration Frame Naming for the naming convention.
Viewing
The preferred way to view the slit edges information contained in Slits is as follows:
from astropy.io import fits
from astropy.table import Table
hdu = fits.open('Slits_A_1_DET01.fits')
Table(hdu['SLITS'].data)
This will show a table that looks like this:
spat_id maskdef_id left_init [4096] right_init [4096] left_tweak [4096] right_tweak [4096] center [4096] mask_init mask specmin specmax
int64 int64 float64 float64 float64 float64 float64 int16 int16 float64 float64
------- ---------- ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------------------------- --------- ----- ------- -------
31 699084 5.0 .. 37.18657261586156 29.277545928955078 .. 62.018354415893555 5.0 .. 37.18657261586156 29.277545928955078 .. 62.018354415893555 17.13877296447754 .. 49.60246351587756 0 0 -inf inf
111 699078 33.88330268859863 .. 65.59163284301758 135.11531257629395 .. 167.1435375213623 37.948677458954 .. 69.65700761337295 135.11531257629395 .. 167.1435375213623 84.49930763244629 .. 116.36758518218994 0 0 -inf inf
217 699086 139.54998016357422 .. 170.55170822143555 243.45840644836426 .. 274.8020210266113 143.1504450626825 .. 174.15217312054384 243.45840644836426 .. 274.8020210266113 191.50419330596924 .. 222.67686462402344 0 0 -inf inf
322 699091 248.21048545837402 .. 278.352352142334 345.8145122528076 .. 376.4430561065674 251.7797389884793 .. 281.9216056724392 345.8145122528076 .. 376.4430561065674 297.0124988555908 .. 327.3977041244507 0 0 -inf inf
457 699080 350.76593017578125 .. 379.9788398742676 514.4993572235107 .. 544.0507583618164 355.0206685112119 .. 384.23357820969824 513.3126446738094 .. 542.864045812115 432.632643699646 .. 462.014799118042 0 0 -inf inf
In addition, if reducing data from these Slit-mask design Spectrographs and slit-mask design matching is performed (see e.g., Slit-mask design matching for DEIMOS and Edge Tracing for MOSFIRE), a second astropy.io.fits.BinTableHDU is written to disk.
Table(hdu['MASKDEF_DESIGNTAB'].data)
TRACEID TRACESROW TRACELPIX TRACERPIX SPAT_ID MASKDEF_ID SLITLOPT SLITROPT SLITRA SLITDEC SLITLEN SLITWID SLITPA ALIGN OBJID OBJRA OBJDEC OBJNAME OBJMAG OBJMAG_BAND OBJ_TOPDIST OBJ_BOTDIST
int64 int64 float64 float64 int64 int64 float64 float64 float64 float64 float64 float64 float64 int16 int64 float64 float64 str32 float64 str32 float64 float64
------- --------- ------------------ ------------------ ------- ----------- ------------------- ------------------ ------------ ----------- ------------------ ------- ------- ----- ------ ------------ ----------- ------- ------- ----------- ----------- -----------
0 2048 5.0 56.08821487426758 31 699084 -21.955958625056724 69.84514502686432 358.68126787 42.3347698 10.682000160217285 1.0 0.0 0 733790 358.6812625 42.334675 3003915 21.39 I 5.0 5.682
1 2048 59.798553466796875 161.30295944213867 111 699078 72.84633999813946 175.5490274983032 358.69310956 42.33811871 11.979000091552734 1.0 0.0 0 733784 358.69310417 42.33803333 3003737 22.54 I 5.682 6.297
2 2048 164.9419937133789 269.14466094970703 217 699086 178.11184062306785 283.34493633572674 358.67168891 42.34139707 12.293000221252441 1.0 0.0 0 733792 358.67168333 42.34143889 3104178 21.19 I 6.297 5.996
3 2048 272.8930130004883 370.9837417602539 322 699091 286.1885530241663 384.710234625776 358.65265564 42.34461342 11.529000282287598 1.0 0.0 0 733797 358.65265 42.34467778 3104468 20.24 I 5.996 5.533
4 2048 374.71178817749023 538.83056640625 457 699080 387.93013336193303 552.8797949320767 358.68945391 42.34933141 19.270000457763672 1.0 0.0 0 733786 358.68945 42.34819167 3103868 22.44 I 5.533 13.737
See Current SlitTrace Data Model for a description of the columns.
Current SlitTrace Data Model
Internally, the Slits object is held in SlitTraceSet,
which subclasses from DataContainer.
Here is its datamodel, which is written as an astropy.io.fits.BinTableHDU. In addition, if reducing Keck DEIMOS or Keck MOSFIRE data and slit-mask design matching is performed, another astropy.io.fits.BinTableHDU is written to a fits extension named MASKDEF_DESIGNTAB.
Version 1.1.5
HDU Name |
HDU Type |
Data Type |
Description |
|---|---|---|---|
|
… |
Empty data HDU. Contains basic header information. |
|
|
… |
All data from the |
|
|
… |
Table with slitmask design and object info |
MASKDEF_DESIGNTAB content
Column |
Data Type |
Description |
|---|---|---|
|
int64 |
Trace ID Number |
|
int64 |
Spectral row for provided left and right edges. |
|
float64 |
Spatial pixel coordinate for left edge |
|
float64 |
Spatial pixel coordinate for right edge |
|
int64 |
ID Number assigned by the pypeline to each slit |
|
int64 |
Slit ID Number from slit-mask design |
|
float64 |
Left edge of the slit in pixel from slit-mask design before x-correlation |
|
float64 |
Right edge of the slit in pixel from slit-mask design before x-correlation |
|
float64 |
Right ascension of the slit center (deg) |
|
float64 |
Declination of the slit center (deg) |
|
float64 |
Slit length (arcsec) |
|
float64 |
Slit width (arcsec) |
|
float64 |
Slit position angle onsky (deg from N through E) |
|
int16 |
Slit used for alignment (1-yes; 0-no), not target observations. |
|
int64 |
Object ID Number |
|
float64 |
Right ascension of the object (deg) |
|
float64 |
Declination of the object (deg) |
|
str |
Object name assigned by the observer |
|
float64 |
Object magnitude provided by the observer |
|
str |
Band of the magnitude provided by the observer |
|
float64 |
Projected distance (in arcsec) of the object from the left edge of the slit (in PypeIt orientation). |
|
float64 |
Projected distance (in arcsec) of the object from the right edge of the slit (in PypeIt orientation) |