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SUVI calendar heatmap

Introduction The Solar Ultraviolet Imager (SUVI) aboard NOAA’s GOES takes pictures of the Sun in 6 ultraviolet passbands. They’re quite stunning and are used for space weather monitoring and prediction. (I was lucky enough to get to work with them in my previous job at NOAA.) To make them more useful, the imager takes long and short length exposures and then composites them together as a Level 2 composite image product.

May 20, 2022 Read

EUI Artifact Analysis

Introduction The Extreme Ultraviolet Imager (EUI) aboard the ESA/NASA Solar Orbiter mission takes pictures of the Sun in ultraviolet wavelengths. Above you can see an annotated version of one of these images. Specifically this is the image with filename solo_L1_eui-fsi174-image_20210224T013042238_V02.fits. Notice the artifacts where above and below the solar disk there are darkened stripes. It’s my understanding from a colleague that the cause of these stripes is unknown and they still need to be corrected in the data.

April 1, 2022 Read

Efficient Inclusion Check

Problem Statement I recently stumbled upon a cute problem where you have three sets of numbers $$A, B, C \subseteq \lbrace 0, \dots, n \rbrace.$$ You want to answer if there exists $$a \in A, b \in B \text{ such that } c = a + b \in C.$$ It’s a conceptually simple problem: are there two numbers from the first two sets that sum to a number in the third set?

March 25, 2022 Read

Welcome

Welcome to my new site. I hope you find interesting tidbits from my work here. Old posts Old posts can be found at my old blog. New things will be posted here from now on. I have copied many posts from the old blog.

February 18, 2022 Read

New Instagram

I’ve had a 500px account for some time, but I just decided to make an Instagram account. I did it mostly to enter the Denver Botanic Gardens Orchid Showcase Photo Contest, but I think it could be a fun way to share my interest in photography as well. I’ll be posting my favorite of favorite pictures at 500px, and then everything at Instagram. Hopefully, this means I’ll take more photos.

February 16, 2022 Read

Mood tracking: first plots

For some time now, I’ve been using the app Daylio to track my mood. It allows me to rate my mood on a 5 point scale: awful, bad, meh, good, and rad. I can also put pictures, notes, or log what activities are related to that mood at the same time. It’s quite a nifty little app. I just decided to download the data and start examining it more critically. I hope to build a small set of tools to automatically process all the data and interpret conclusions.

February 6, 2022 Read

Sliding puzzles: my beginning

I recently have become interested in sliding puzzles. You can read all about them on Wikipedia. In undergraduate AI, I was ask to implement a solver for the rush-hour game, a version of a sliding puzzle. I forgot all about it until recently when I was preparing an AI lesson to teach for Code Connects, a coding education non-profit. I stumbled upon the 8-puzzle. Difficulty of AI At first, it seemed pretty simple, and I thought an AI would do easy on it for bigger boards, but I was sorely mistaken.

January 27, 2022 Read

Comparison of speed of np.sum in Cython

I was curious how much the overhead of np.sum impacted Cython code. That is, should you write your own sum method that loops or use np.sum? So, I wrote up a little test definition of the two approaches, as shown below: import numpy as np cimport numpy as np cpdef double sum_np(np.ndarray[double] a): return np.sum(a) cpdef double sum_loop(double[:] a) nogil: cdef size_t i, I cdef double total = 0.

May 11, 2021 Read

Truncate to specified number of significant figures

It’s a simple request. You have a number, e.g. 1.25, and want to truncate it to say 2 significant figures. You specifically need to truncate instead of rounding, i.e. you need to get 1.2 instead of 1.3. How do you do that quickly in Python? Check out this code snippet: from math import log10, floor import decimal decimal.getcontext().rounding = decimal.ROUND_DOWN def truncate_sig(x, sig=2): x = float(x) # make sure it's a float or decimal throws an error if x == 0: # can't take log10(0) so just return 0 return 0 elif x <= 0: # if it's negative, determine sigfigs of positive and multiply by -1 return -1 * truncate_sig(np.

May 10, 2021 Read

Paper published: Real-time solar image classification: Assessing spectral, pixel-based approaches

This was my first first-author paper! It talks about doing semantic segmentation on the Sun. Here’s the link.

November 16, 2019 Read

Axis aligned artifacts

There are artifacts created by choosing axis aligned cuts in robust random cut forests, similar to what was noted with IsoForest.. Left: Original data distribution. Right: Learned co-displacement, darker is lower. Notice the echoes around (10,-10) and (-10, 10) If instead of either of these, you use the depth in the robust random cut forest, you get what’s shown above. The first two examples are recreated by the code below:

October 7, 2019 Read

State of Astro-informatics

I had a glance through “Realizing the potential of astrostatistics and astroinformatics” by Eadie et al. (2019). While I do not feel qualified or informed to comment on the suggestions, I can summarize them quickly. There are three problems: Education: Most astronomers are not trained in code development resulting in maybe good but fragile code. Similarly, most computer scientists don’t have the astronomy background or connections. Funding: Grants for methodology improvement are scarce.

October 4, 2019 Read