Crop `.plot()` issues with CHASE Data

[Goobley]

Describe the bug

I am using sunraster with CHASE data, and it has worked almost perfectly out of the box, thanks! I have encountered a strange issue whereby .plot() works fine on the spectrogram cube, and on a wavelength plane of the cropped cube (e.g. crop[71].plot()), but crop.plot() has a very strange wavelength grid. The first few planes appear correct (it's hard to be certain), but then the data seems to be wrong.

CHASE data can be acquired from SSDC here but this requires registration and login, so I have also made one file available on my OneDrive here.

To Reproduce

from astropy.io import fits
from astropy.wcs import WCS
import astropy.units as u
import matplotlib.pyplot as plt
from sunraster import SpectrogramCube
import numpy as np
from sunpy.coordinates import frames
from astropy.coordinates import SkyCoord

data = fits.open("RSM20240321T000051_0005_HA.fits")
data[1].header["CTYPE1"] = "HPLT-TAN"
data[1].header["CTYPE2"] = "HPLN-TAN"
data[1].header["CTYPE3"] = "WAVE"
wcs = WCS(data[1].header)

array = data[1].data
cube = SpectrogramCube(array, wcs, unit=u.DN)

pt1 = [SkyCoord(0*u.arcsec, 0*u.arcsec, frame=frames.Helioprojective), None]
pt2 = [SkyCoord(250*u.arcsec, 250*u.arcsec, frame=frames.Helioprojective), None]

crop = cube.crop(pt1, pt2)

Screenshots

Result of crop.plot

System Details

sunraster: 0.5.1
==============================
sunpy Installation Information
==============================

General
#######
OS: Ubuntu (22.04, Linux 5.15.146.1-microsoft-standard-WSL2)
Arch: 64bit, (x86_64)
sunpy: 5.1.4
Installation path: /home/cmo/miniconda3/envs/Dask312/lib/python3.12/site-packages/sunpy-5.1.4.dist-info

Required Dependencies
#####################
astropy: 6.1.0
numpy: 1.26.4
packaging: 24.0
parfive: 2.1.0
pyerfa: 2.0.1.4

Optional Dependencies
#####################
asdf: 3.2.0
asdf-astropy: 0.6.1
beautifulsoup4: 4.12.3
cdflib: Missing cdflib!=0.4.0,!=1.0.0,>=0.3.20; extra == "docs" or "tests" or "timeseries"
dask: 2024.5.1
drms: 0.6.4
glymur: Missing glymur!=0.9.5,>=0.9.1; extra == "docs" or "jpeg2000" or "tests"
h5netcdf: 1.3.0
h5py: 3.11.0
lxml: 5.2.2
matplotlib: 3.9.0
mpl-animators: 1.1.1
pandas: 2.2.2
python-dateutil: 2.9.0.post0
reproject: 0.13.1
scikit-image: Missing scikit-image>=0.18.0; extra == "docs" or "image" or "tests"
scipy: 1.13.1
sqlalchemy: Missing sqlalchemy>=1.3.4; extra == "database" or "docs" or "tests"
tqdm: 4.66.4
zeep: 4.2.1

Installation method

pip

[Abinash-bit]

hello I was trying replicating the issue but i am getting this error while replicating !!!

Can anyone help me out please.

[nabobalis]

This is not an error but a warning. It is emitted by astropy and can be ignored for this case.

[Abinash-bit]

https://github.com/user-attachments/assets/aaa58236-0f7a-42c4-a796-65bc71483577

Getting this result.

[nabobalis]

Which replicates the original issue, so we still have a problem here.

[Abinash-bit]

At 6.5 * 10 ^ -7 m of wavelength the plot becomes purple....

I have some queries regarding this:

1. What should be the correct plot?
2. And if i have to solve the crop.plot() than where does the function located in sunraster repository .... i have tried searching it but all i could get is ....

in spectrogram_sequence.py.

[nabobalis]

At 6.5 * 10 ^ -7 m of wavelength the plot becomes purple....

I have some queries regarding this:

1. What should be the correct plot?

I don't know, if there is data that, it should be plotted instead of purple. One will have to figure out if there is data in that part of the array and why its not being plotted.

2. And if i have to solve the crop.plot() than where does the function located in sunraster repository .... i have tried searching it but all i could get is ....

in spectrogram_sequence.py.

sunraster is a light wrapper around ndcube, this is why you can't find the source code.

It would be worth testing this without sunraster and directly into ndcube to see if there is a difference in behavior.

[Abinash-bit]

I have plotted the FITS data

array = data[1].data

which gives me this plot

and it has non empty values

also for wavelengths the data array is non empty

the only thing we need to see ......is there any data in between the two points we have taken that is

pt1 = [SkyCoord(0u.arcsec, 0u.arcsec, frame=frames.Helioprojective), None] pt2 = [SkyCoord(250u.arcsec, 250u.arcsec, frame=frames.Helioprojective), None]

[nabobalis]

also for wavelengths the data array is non empty

the only thing we need to see ......is there any data in between the two points we have taken that is

pt1 = [SkyCoord(0_u.arcsec, 0_u.arcsec, frame=frames.Helioprojective), None] pt2 = [SkyCoord(250_u.arcsec, 250_u.arcsec, frame=frames.Helioprojective), None]

Well that's what the crop should do, we need to track down why. If its a bug in the crop code or how astropy has handled the WCS