Downloading and plotting a HMI synoptic data

This example shows how to download HMI synoptic data from JSOC and make a plot.

import matplotlib.pyplot as plt
from astropy.io import fits

import drms

First we will create a drms.Client, using the JSOC baseurl.

client = drms.Client()

Construct the DRMS query string: “Series[Carrington rotation]”

qstr = "hmi.synoptic_mr_720s[2150]"

# Send request to the DRMS server
print("Querying keyword data...\n -> {qstr}")
segname = "synopMr"
results, filenames = client.query(qstr, key=drms.JsocInfoConstants.all.value, seg=segname)
print(f" -> {len(results)} lines retrieved.")

# Use only the first line of the query result
results = results.iloc[0]
fname = f"http://jsoc.stanford.edu{filenames[segname][0]}"

# Read the data segment
# Note: HTTP downloads get cached in ~/.astropy/cache/downloads
print(f"Reading data from {fname}...")
a = fits.getdata(fname)
ny, nx = a.shape

Querying keyword data...
 -> {qstr}
 -> 1 lines retrieved.
Reading data from http://jsoc.stanford.edu/SUM30/D587048106/S00000/synopMr.fits...

Now to plot the image.

# Convert pixel to world coordinates using WCS keywords
xmin = (1 - results.CRPIX1) * results.CDELT1 + results.CRVAL1
xmax = (nx - results.CRPIX1) * results.CDELT1 + results.CRVAL1
ymin = (1 - results.CRPIX2) * results.CDELT2 + results.CRVAL2
ymax = (ny - results.CRPIX2) * results.CDELT2 + results.CRVAL2

# Convert to Carrington longitude
xmin = results.LON_LAST - xmin
xmax = results.LON_LAST - xmax

# Compute the plot extent used with imshow
extent = (
    xmin - abs(results.CDELT1) / 2,
    xmax + abs(results.CDELT1) / 2,
    ymin - abs(results.CDELT2) / 2,
    ymax + abs(results.CDELT2) / 2,
)

# Aspect ratio for imshow in respect to the extent computed above
aspect = abs((xmax - xmin) / nx * ny / (ymax - ymin))

# Create plot
fig, ax = plt.subplots(1, 1, figsize=(13.5, 6))
ax.set_title(f"{qstr}, Time: {results.T_START} ... {results.T_STOP}", fontsize="medium")
ax.imshow(
    a,
    vmin=-300,
    vmax=300,
    origin="lower",
    interpolation="nearest",
    cmap="gray",
    extent=extent,
    aspect=aspect,
)
ax.invert_xaxis()
ax.set_xlabel("Carrington longitude")
ax.set_ylabel("Sine latitude")
fig.tight_layout()

plt.show()