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.

Parameters

  • imageliststr or list

    The input can be a single image or list of images.

  • add_keyslist, default=None

    A list of of additional keys for printing. If a key is not found in the sample, the global header will be checked. If a key is not found, the “NA” string will be printed.

  • meanbool, default=False

    If True, print the mean statistic.

  • medianbool, default=False

    If True, print the median statistic.

Returns

None

Usage

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(imagename, median=True)

To print additional keys for information:

sampinfo(imagename,add_keys=["DETECTOR"])

To get the average value for each sample:

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

Optional output:

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