NuSTAR small flare of 12 September 2020 - orbit 4
Erica Lastufka

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Tags

  • NuSTAR
  • XRT
  • AIA
  • STEREO

Basic information

NuSTAR observation time (orbit 4): 2020-09-12 14:00:00 - 14:23:00

Instrument Wavelength regime Cadence Resolution/px
NuSTAR SXR 20s low
XRT Be-Thin SXR 200s 1”
AIA EUV 12 s 0.6”
STEREO-A EUVI EUV 5 min 1.6”

Flare Location

XRT, NuSTAR camera A low-evergy and AIA 335 image with rectangles indicating where fluxes were calculated

Flare location determined by finding the position of the center of mass of the 90% contour of the XRT submap around the flare area. To align with AIA, this requires ~25” offset in x and ~25” in y from the location in XRT header (coordinates below given in XRT frame).

<SkyCoord (Helioprojective: obstime=2020-09-12 14:10:41, rsun=695508000.0 m, observer=<HeliographicStonyhurst Coordinate (obstime=2020-09-12 14:10:41): (lon, lat, radius) in (deg, deg, m)
( 0.,  7.23219551,   1.50542567e+11)>): (Tx, Ty) in arcsec
(-764.11429488,  1.2117822)>

Flare time evolution (AIA and STEREO)

3-minute integrated AIA 193 images

Source Image Base Difference Sobel Filter
AIA 193
AIA 193 gif
AIA 193 difference gif
AIA 193 Sobel gif

Lightcurves

AIA and XRT at native cadence, calculated using 40” box.

STEREO-A at native cadence (5 minutes), calculated using 40” box.

NuSTAR images at 20s cadence (made by Sam), adjusted to counts, calculated using 160” square box.

Masks

Find regions of brightening/dimming by comparing the change in the flare region vs the quiet Sun region. A pixel is included in ‘brightening’ mask if the value of that pixel in the difference image (integrate flare X-ray peak minus integrated pre-flare) is >3x greater than standard deviation of the average flux difference in Quiet Sun ((𝜎_QSdiff) in those same time ranges (details in code below). Likewise with ‘dimming’ mask, only the pixel value is less than -3x 𝜎_QSdiff. The total mask is sum of both masks in each channel.

Masks for all AIA channels

Lightcurves with masks