---------------------------------------------------------------------
Anthony Case
Astrophysicist
High Energy Astrophysics Division (HEAD/SSXG)
Center for Astrophysics | Harvard & Smithsonian
Cell: (617) 304 0768
60 Garden Street | MS 58 | Cambridge, MA 02138
There was also a 6-month periodicity in the old proton swoosh summation, and there's a 6-month periodicity in the SEPI components (individual detectors, Andrew is investigating this further) that is indistinguishable from a longitudinal variation. Mark's explanation may be the reason for all of these - I just wanted to point out that 6-month periodicities have shown up before._______________________________________________
-Jody
On 5/17/2021 1:28 PM, de Wet, Wouter wrote:
Mark,
Ahh, yes that makes sense! When I cut everything below the peak the 6-month periodicity in the low LET flux data all but disappears.
Thanks for the quick response. It looks like I will need to cut everything below roughly 0.3 keV/micron out of the analysis.
Wouter
From: Mark D Looper <mark.d.looper@aero.org>
Date: Monday, May 17, 2021 at 1:11 PM
To: "de Wet, Wouter" <wouter.dewet@unh.edu>, "crater-team@lists.sr.unh.edu" <crater-team@lists.sr.unh.edu>
Subject: Re: Interesting Artifacts in CRaTER Data: 6-Month Periodicity in Low LET Fluxes (including a strange anti correlation)
Caution - External Email
If I remember correctly, that’s due to thermal noise in the lowest PHA channels, which is periodic because of the differing sun exposure as the orbit changes. I will see if I can find some plots that I made near the beginning of the mission which showed this. It is why I discard the lowest PHA channels and never look much below the proton peak – the data are not valid down there.
--Mark
Mark D. Looper
Space Sciences Department
The Aerospace Corporation
M/S M2-260
P.O. Box 92957
Los Angeles, CA 90009-2957
Mobile: 310-529-3406
Voicemail: 310-336-6302Publications: https://www.loopers.org/curvitae.html
From: Crater-team <crater-team-bounces@lists.sr.unh.edu>
Date: Monday, May 17, 2021 at 7:07 AM
To: crater-team@lists.sr.unh.edu <crater-team@lists.sr.unh.edu>
Subject: [Crater-team] Interesting Artifacts in CRaTER Data: 6-Month Periodicity in Low LET Fluxes (including a strange anti correlation)All,
While working on the final processing of the observed CRaTER Flux vs. LET data, I have found an interesting artifact.
I have been looking at the Flux vs. LET vs Time data for the entire mission so far.
- For the smallest LET values, there seems to be a 6-month periodicity in the observed flux, see the ‘wavy’ red edge in Figure 1 below.
- When I divide everything by the flux observed in August 2009, I get the flux ratio shown in Figures 2 and 3 below. When looking at the flux ratio, the 6 month periodicity becomes very clear.
- One interesting thing I also notice is that it seems like there is an anti-correlation between the flux in lowest LET bins (< 0.25 keV/micron) and the slightly higher LET bins (> 0.25 keV/micron).
Has anyone else observed this yet? Any thoughts about what is causing this?
Thanks,
Wouter
Figure 1: Flux vs. LET vs. Time
Figure 2: Flux Ratio vs. LET vs. Time (3-Dimensioal)
Figure 3: Flux Ratio vs. LET vs. Time (2-Dimensioal)
_______________________________________________ Crater-team mailing list Crater-team@lists.sr.unh.edu https://lists.sr.unh.edu/mailman/listinfo/crater-team
Crater-team mailing list
Crater-team@lists.sr.unh.edu
https://lists.sr.unh.edu/mailman/listinfo/crater-team