Opened 15 years ago
Closed 15 years ago
#172 closed defect (fixed)
resampling spectra
| Reported by: | Owned by: | Malte Marquarding | |
|---|---|---|---|
| Priority: | normal | Milestone: | ASAP 2.4 |
| Component: | General | Version: | 2.0 |
| Severity: | normal | Keywords: | |
| Cc: |
Description
I would like to change the channel width of an SDFITS file from 33815 Hz to 33571 Hz in order to match an older file (for Gridzilla). Since the new channel has a narrower width, I try:
s.resample(width=0.99638)
Then I save it as a new SDFITS. But Gridzilla tells me the following. For the original file:
10:29:28: gridzilla: Brightness units are "Jy".
10:29:28: gridzilla: Spectral range: 115123.094 to 115261.067 MHz
10:29:28: gridzilla: in 4096 channels spaced by 33.693 kHz.
For the new file:
10:43:39: gridzilla: WARNING: Brightness units not recorded in the input data.
10:43:39: gridzilla: Spectral range: 115122.051 to 115261.067 MHz
10:43:39: gridzilla: in 4112 channels spaced by 33.816 kHz.
So the number of channels AND the width of each channel seems to have increased, which doesn't make sense. If I use width > 1, the number of channels and the width of each channel decreases. So something seems to be wrong here.
Another problem is that the brightness units don't seem to be saved in the new SDFITS file: Gridzilla doesn't want to combine files with inconsistent brightness units.
Tony
Revision r1694 fixes this problem. The coordinate resample factor's inverse was used.