Page History

Text revised and expanded from this page:  HST Astrometry Project Overview

Improved WFC3 and ACS Data Products

...

Further refinements to the alignment will be available in the next release of Hubble Advanced Products, referred to as 'Single Visit Mosaics'.

____Suggested basic examples for the Jupyter notebook___:

1.) Show the extra extensions

from astropy.io import fits
fits.info('/internal/hladata/ENVS_OUTPUT/ALIGNDEV_12Oct19/popen-gw1/test_alignpipe_randomlist_J8C020/j8c041sdq_flc.fits')

No. Name Ver Type Cards Dimensions Format
0 PRIMARY 1 PrimaryHDU 279 ()
1 SCI 1 ImageHDU 253 (4096, 2048) float32
2 ERR 1 ImageHDU 57 (4096, 2048) float32
3 DQ 1 ImageHDU 49 (4096, 2048) int16
4 SCI 2 ImageHDU 249 (4096, 2048) float32
5 ERR 2 ImageHDU 57 (4096, 2048) float32
6 DQ 2 ImageHDU 49 (4096, 2048) int16
7 WCSCORR 1 BinTableHDU 59 14R x 24C [40A, I, A, 24A, 24A, 24A, 24A, D, D, D, D, D, D, D, D, 24A, 24A, D, D, D, D, J, 40A, 128A]
8 HDRLET 1 NonstandardExtHDU 22 (60480,)
9 HDRLET 2 NonstandardExtHDU 26 (112320,)
10 HDRLET 3 NonstandardExtHDU 26 (112320,)
11 HDRLET 4 NonstandardExtHDU 26 (112320,)
12 HDRLET 5 NonstandardExtHDU 26 (112320,)
13 HDRLET 6 NonstandardExtHDU 26 (112320,)
14 WCSDVARR 1 ImageHDU 15 (64, 32) float32
15 WCSDVARR 2 ImageHDU 15 (64, 32) float32
16 D2IMARR 1 ImageHDU 15 (64, 32) float32
17 D2IMARR 2 ImageHDU 15 (64, 32) float32
18 WCSDVARR 3 ImageHDU 15 (64, 32) float32
19 WCSDVARR 4 ImageHDU 15 (64, 32) float32
20 D2IMARR 3 ImageHDU 15 (64, 32) float32
21 D2IMARR 4 ImageHDU 15 (64, 32) float32
22 HDRLET 7 NonstandardExtHDU 26 (112320,)
23 HDRLET 8 NonstandardExtHDU 26 (112320,)

2.) Show the different headerlets and the corresponding WCSNAMEs.  Explain how to know which WCS is primary.

from stwcs.wcsutil.headerlet import headerlet_summary

headerlet_summary('/internal/hladata/ENVS_OUTPUT/ALIGNDEV_12Oct19/popen-gw1/test_alignpipe_randomlist_J8C020/j8c041sdq_flc.fits',columns=['HDRNAME','WCSNAME'])

EXTN              HDRNAME                                                   WCSNAME                           
8         j8c041sdq_flt_OPUS-hlet.fits                                 OPUS
9        OPUS2019-06-04                                                    IDC_0461802ej                    
10       j8c041sdq_flt_OPUS-GSC240-hlet.fits                 OPUS-GSC240                   
11        j8c041sdq_flt_IDC_0461802ej-GSC240-hlet.fits IDC_0461802ej-GSC240    
12       j8c041sdq_flt_OPUS-HSC30-hlet.fits                    OPUS-HSC30                     
13       j8c041sdq_flt_IDC_0461802ej-HSC30-hlet.fits    IDC_0461802ej-HSC30      
22      IDC_0461802ej                                                          IDC_0461802ej
23      IDC_0461802ej-FIT_REL_GAIADR2                          IDC_0461802ej-FIT_REL_GAIADR2

3.) Show how to determine which WCS is primary

fits.getval('/internal/hladata/ENVS_OUTPUT/ALIGNDEV_12Oct19/popen-gw1/test_alignpipe_randomlist_J8C020/j8c041sdq_flc.fits','WCSNAME',1)

'IDC_0461802ej-FIT_REL_GAIADR2'

4.) Example showing how to back out the primary WCS in order to restore alignment between grism observations and their direct image counterparts.