sampinfo¶
Sampinfo prints information about a WFC3/IR MultiAccum image, including exposure time information for the individual samples (readouts). The global information listed (and the names of the header keywords from which it is retrieved) includes:
- the total number of image extensions in the file (NEXTEND)
- the name of the MultiAccum exposure sample sequence (SAMP_SEQ)
- the total number of samples, including the “zeroth” read (NSAMP)
- the total exposure time of the observation (EXPTIME).
Information that is listed for each sample is the IMSET number (EXTVER), the sample number (SAMPNUM), the sample time, which is the total accumulated exposure time for a sample (SAMPTIME), and the delta time, which is the additional exposure time accumulated since the previous sample (DELTATIM).
Note that the samples of a MultiAccum exposure are stored in the FITS file in reverse time order. The initial, or “zeroth” read, appears last in the FITS file, with IMSET=NSAMP, SAMPNUM=0, SAMPTIME=0, and DELTATIM=0. The final read of the exposure appears first in the file and has IMSET=1, SAMPNUM=NSAMP-1 (SAMPNUM is zero-indexed), and SAMPTIME=EXPTIME.
Options¶
- This version will accept a single image name or a python list of images. The list of images should be a python style list, such as:
>>> ["image1.fits","image2.fits"]
add_keys=list(): You can also supply a supplimental list of keywords to print for each sample, if the key isn’t found in the sample the global header will be checked.If a key is not found the “NA” string will be printed. Additionally you can ask for the median or mean of the datavalues for each sample using the appropriate switch.
median=False: Set to True in order to report the median pixel value for each sample
mean=False: Set to True in order to report the mean pixel value for each sample (as measured with np.min and np.max)
Usage¶
- Typical:
>>> python >>> from wfc3tools import sampinfo >>> sampinfo(imagename)
Where imagename can be a single filename or a python list() of names
- To get the median value for each sample:
>>> sampinfo.sampinfo(imagename, median=True)
- To print additional keys for information:
>>> sampinfo.sampinfo(imagename,add_keys=["DETECTOR"])
- To get the average balue for each sample:
>>> sampinfo.sampinfo(imagename, mean=True)
Example Output¶
Default output:
In [3]: wfc3tools.sampinfo('ibcf02faq_raw.fits')
IMAGE NEXTEND SAMP_SEQ NSAMP EXPTIME
ibcf02faq_raw.fits 80 STEP50 16 499.234009
IMSET SAMPNUM SAMPTIME DELTATIM
1 15 499.234009 50.000412
2 14 449.233582 50.000412
3 13 399.233154 50.000412
4 12 349.232727 50.000412
5 11 299.2323 50.000412
6 10 249.231873 50.000412
7 9 199.231461 50.000412
8 8 149.231049 50.000412
9 7 99.230637 50.000412
10 6 49.230225 25.000511
11 5 24.229715 12.500551
12 4 11.729164 2.932291
13 3 8.796873 2.932291
14 2 5.864582 2.932291
15 1 2.932291 2.932291
16 0 0.0 0.0
with median=True:
In [4]: wfc3tools.sampinfo('ibcf02faq_raw.fits',median=True)
IMAGE NEXTEND SAMP_SEQ NSAMP EXPTIME
ibcf02faq_raw.fits 80 STEP50 16 499.234009
IMSET SAMPNUM SAMPTIME DELTATIM
1 15 499.234009 50.000412 MedPixel: 11384.0
2 14 449.233582 50.000412 MedPixel: 11360.0
3 13 399.233154 50.000412 MedPixel: 11335.0
4 12 349.232727 50.000412 MedPixel: 11309.0
5 11 299.2323 50.000412 MedPixel: 11283.0
6 10 249.231873 50.000412 MedPixel: 11256.0
7 9 199.231461 50.000412 MedPixel: 11228.0
8 8 149.231049 50.000412 MedPixel: 11198.0
9 7 99.230637 50.000412 MedPixel: 11166.0
10 6 49.230225 25.000511 MedPixel: 11131.0
11 5 24.229715 12.500551 MedPixel: 11111.0
12 4 11.729164 2.932291 MedPixel: 11099.0
13 3 8.796873 2.932291 MedPixel: 11097.0
14 2 5.864582 2.932291 MedPixel: 11093.0
15 1 2.932291 2.932291 MedPixel: 11090.0
16 0 0.0 0.0 MedPixel: 11087.0