Thursday, June 15, 2017

(from We Mad Climb Shaky Ladders by Pamela Spiro Wagner)

To Forgive Is...
to begin
and there is so much to forgive
for one, your parents, one and two,
out of whose dim haphazard coupling
you sprang forth roaring, indignantly alive.
For this, whatever else followed,
innocent and guilty, forgive them.
If it is day, forgive the sun
its white radiance blinding the eye;
for give also the moon for dragging the tides,
for her secrets, her half heart of darkness;
whatever the season, forgive its various
assaults--floods, gales, storms
of ice--and forgive its changing;
for its vanishing act, stealing what you love
and what you hate, indifferent,
forgive time; and likewise forgive
its fickle consort, memory, which fades
the photographs of all you can't remember;
forgive forgetting, which is chaste
and kinder than you know;
forgive your age and the age you were
when happiness was afire in your blood
and joy sang hymns in the trees;
forgive, too, those trees, which have died;
and forgive death for taking them,
inexorable as God; then forgive God
His terrible grandeur, His unspeakable
Name; forgive, too, the poor devil
for a celestial fall no worse than your own.
When you have forgiven whatever is of earth,
of sky, of water, whatever is named,
whatever remains nameless,
forgive, finally, your own sorry self,
clothed in temporary flesh
the breath and blood of you
already dying
         Dying, forgiven, now you begin.

Friday, July 22, 2016

finding my gemini MDFs!

So I had to learn IRAF and it was definitely not the most natural thing to me. But, I got the SOAR data reduced...eventually. (This view of Cerro Pachon is pretty cool!)

So for the Gemini data, I had to download a separate package of tools, and run them. One of the postdocs was kind enough to give me his scripts for processing GMOS data, but he was doing multiobject stuff, and I only have one. So hopefully I won't have to make too many changes. I did learn how to run my own .cl scripts.
Gemini telescope (2007 press release photo)

For running a task with a parameter file, for instance lacosmics, I need to just put two lines in:
reset lacos_spec=/path/to/cl/file/ and then
task lacos_spec=lacos_spec$

For your own scripts with no parameters, you can just load in "task $" and you will be able to run it!

 So for my data currently, I changed the script so that it read the file headers and separated the data based on whether it was an object, flat, or arc, and the dithered wavelength, and then runs gprepare on them. I do want to go through and remove the image files from when they were centering the object on the slit.

But after a few snags, this all seems to be working nicely, except gprepare is warning me that there are no MDFs--Mask Definition Files. Now I believe these came when I downloaded the Gemini tools, so I am hoping it is something as simple as changing the path to them. Because of the whole AstroConda/Ureka thing, I am worried that the Gemini tools just won't work, but that hasn't been an issue so far.

Thursday, July 21, 2016

Weird People at Coffee Places

So I got up early to work in my office before people got there, and it would still be quiet, and then left pretty early too. Sometimes I like to work in little coffee shops, but there are only two in this area. One is actually more overpriced than "stabrucks", and may or may not have wifi. And it's so close that I feel wasteful driving, but it's too far to walk in this weather

The other one started off great, but recently decided they were a restaurant and essentially quit paying the people who work there because they can get tips. In addition to that, the atmosphere completely changed and it really isn't a great place to work any more. It definitely feels more like a restaurant--a little stressful and not so relaxing or inviting. And their tables are too small for my laptop.

So I went to the more mainstream coffee shop because this isn't Ann Arbor and there aren't 50 options for coffee. It's interesting because the people here are totally different than the place (in Ann Arbor) that I usually go work at. You still hear obnoxious conversations in both places, but this place is definitely worse. For the last ten minutes, there has been this lady who is obnoxiously talking on her phone. I am listening to music on headphones, fairly loudly, and I can still her parts of her conversation like "Do you what know the sorority  number is? Like for the house? No, they only have one house line."

I was going to read another paper on voxcharta and post about it here, but I need to get work done today and didn't feel like reading one.

On a more positive note, I am really learning how to use ds9 now. I used it for the first time last year, and thought it was just really magical, but now I've been able to appreciate how useful it is. For instance, comparing two images by "blinking" them is a pretty cool way to see if your cosmic ray reduction dinged your object or not, and I also like how it displays the headers on your fits file! WCSTools has imhead, which should display them in the command line, but I don't think it knows how to deal with the Gemini MEF format since I can't view the image central wavelength with it, but can in ds9.

Thursday, July 14, 2016

Notes on "Sunspot Rotation as a Driver of Major Solar Eruptions in NOAA Active Region 12158"


P. Vemareddy, X. Cheng, B. Ravindra


NOAA active region 12158 has a sigmoidal structure which develops under the influence of the magnetic non-potential fields (magnetic fields produced from the electric fields present in the coronae above active region) of  a rotating sunspot (active region).
Measurements are taken from HMI (Helioseismic Magnetic Imager) and AIA (Atmospheric Imaging Assembly) (aboard SDO), and show the erupting feature began in the rotating sunspot (moves at 0.5 deg/hr). Evolution of the non-potential field corresponded with the rotation. Was approximated by time series of force free equilibria. The nonlinear force-free field "NLFFF" magnetic structure of the sunspot is what caused the sigmoid structure. 

High rigidity Forbush decreases: due to CMEs or shocks? - Babu, Arun et al. arXiv:1304.5343 [astro-ph.SR]
Field lines from around the sunspot make up the body, and lines from the middle make a  flux rope structure. 

Two CMEs (coronal mass ejection) occurred in the active region during the rotation. During the first event, the coronal current concentrations were enhanced, and degraded during the second, both consistently with the photospheric net vertical current. Magnetic energy is released for both cases. 

This paper suggests that the magnetic connections of the sigmoid are driven by the slow sunspot rotation, which transforms the "highly twisted flux rope". An exceedingly critical twist in the flux rope probably leads to the loss of equilibrium and thus triggers the onset of the two eruptions.

1. Introduction:

Major solar eruptions are believed to be powered by free energy stored in the stressed magnetic fields of active regions (ARs). The fields transport magnetic energy and helicity  during the evolution of ARs by flux emergence from the sub-photosphere and shearing motions at the photosphere. 

Image credit: NASA

Sunspot rotations last long enough (days) and could be efficient mechanisms to inject helicity and energy. There has been an increase in the number and quality of observations of rotating sunspots. Numerical MHD simulations have also helped to investigate the relationship between sunspot rotation and eruptive activity (such as CMEs) by studying flux ropes. They have shown that the photospheric vortex motions can twist the core magnetic field in an active region up to a point where equilibrium can no longer be maintained and thus the twisted core field (flux rope) erupts. It will erupt as a confined flare or CME.  Recent models show the rotating sunspot as a trigger.

In 2012, Vermareddy et al showed correspondence of sunspot rotation with many non-potential parameters. 

2. Observations:

Used data from HMI on the sunspot and AIA for corresponding coronal activity.

3. Results: 

Vector magnetic fields from HMI show a main sunspot with positive polarity surrounded by negative polarity. The geometry of the magnetic loops has a reverse S-sigmoid shape. (Fig 1. middle column) 
Vermareddy et al Figure 1.

In Fig 1 col 1, the corona sigmoid region (composite image from AIA) is overlaid with magnetic contours that show that the sigmoid has roots in the rotating sunspot. The contours are used to identify the photospheric connections. The rectangular region shows "the region of rotating sunspot having roots of a sigmoid". Col 2 is the vector magnetic field of the rotating sunspot.

They used DAVE4VM to derive the velocity field of the flux motions (3rd column of fig 1). 
Vermareddy et al Figure 2: sunspot rotation. Dashed yellow lines show movement of prominent penumbral features.

The sunspot rotation was measured by watching the change of the penumbral (edge) features as the sunspot rotated around the umbral (dark) center. 

Vermareddy et al figure 4. Top row: NLFFF model, lower row: observations.
Magnetic field lines from the edge of the sunspot make up the body of the sigmoid, interior lines overlay the sigmoid. NLFFF model is close but failrs to reproduce some of the twisted lines.

As the sunspot rotates anti-clockwise, the field lines tend to retain their connectivity and appear as swirled in a clockwise direction. Static modelling cannot capture everything, but eruptions can be approximated by flux rope current channels.
Vermareddy et al figure 5
Figure 5 shows model  (col 1) vs AIA extrapolated lines (col 2), at different epochs. Column 3 shows  integrated maps of current density to find buildup of strong current concentrations. Column 4 shows an AIA image overlaid by "quashing factor" contours. 

Summary and Discussions:

A flux rope was observed during the first eruption.  The first eruption was partial, with the flare slowly reconnection and a small CME  being observed.  Consistent with the photospheric measurement of net vertical current during pre-to-post eruption, an increased coronal current concentration is being observed across the sigmoid as a fact of twisting by sunspot rotation. Flux rope is also observed during the second CME, analysis results suggest that the magnetic connection of the sigmoid are drive by slow motion of sunspot rotation, which developed to a highly twisted flux rope structure.

 The two eruptions that happened were probably triggered by a critical twist in the flux rope that caused a loss of equilibrium.The NLFFF did not completely model all features of the eruption caused by the rotating sunspot and data drive MHD models would help explain better.

Boxcar smoothing

I needed to smooth some spectroscopic data yesterday and came across a neat tutorial on using AstroPy to do it by Joseph Long. It was really delightful how quickly I was able to do it! If I have more time or have to do it again in the future, it would be interesting to see how changing the box width (I left it at 11) changes the smoothness. But my data turned out beautifully!

Friday, March 11, 2016


 I picked up a Navajo loom a little while ago and have been learning how to use it. So I don't really know what I'm doing or what to do next, but I hope to be good enough one day to weave something like the red table runner I picked up at an estate sale.

Sunday, February 28, 2016

Maple Syrup Empire

I have created my own maple syrup empire! I put three taps in an extremely large silver maple, two in the sugar maple and I tapped three mystery maples. I'll identify them once they leaf out. For now it's just good enough that they are maples. I used the branch structure and knowing that the twigs are brownish to tell that they are maples.

Thanks to the snowpocalypse I haven't gotten a ton of sap during the week, but when I checked over the weekend I had gotten 12 gallons that are now happily  being reduced in the crockpot. The sugar maple is definitely the best producer. The norway maple that I tapped (and now untapped) takes last place--the jugs were barely filled and the sap barely tasted sweet. I suspect one of the mystery maples is also a sugar maple, though, just on account of how much it produces. I've gotten about 3/4 of a gallon of syrup in the last two weeks since I've tapped. The first batch I reduced is perfectly syrupy, but the quart I did two days ago still seems too watery and sediment has filtered out. It could be that the storms we had last week blew the lids off the buckets and diluted the sap a lot, but that should have all boiled off before it was able to get to 219 F to finish. I do want to make maple candy on the snow before this lovely weather melts it all away, so maybe I will get it up to 235 F and drop it on the snow like they did in Little House on the Prairie. I do like having the maple "extract", though. I used it to sweeten the laban I made and added chocolate powder to.

I used Maureen Abood's recipe for laban from her Rose Water and Orange Blossoms cookbook, using some labne as a starter. It is really amazing to see a pot full of yogurt only after incubating some boiled milk overnight. I did expect it to be creamier, but instead it seems like it has these regions of blotchy areas while still being a cohesive blob. I'm straining the rest to turn into labne for lunch. Yesterday I went crazy making recipes from the same cookbook, falafel and lentil soup and an olive, caramelized tomato and labne galette (which I had to add za'atar to) as well as talami. I did not follow the recipe which is why it did not turn out how I was expecting even though it was still amazing with some of the cherry lime jam I made last year. The sesame seeds all fell off because I didn't press them in, so the bread was less flat. I didn't mind the loss of the sesame seeds, though because I couldn't find toasted ones.

My new spinning wheel is still working like a dream. At the Chelsea fiber fest last week, I bought way too much stuff, including some amazing roving dyed and blended locally. It is called "painted desert" and has some tussah silk in there. To me it looks more like a sunset over a rocky desert with a lot of browns and pinks and oranges, but it spins up amazingly. I also got two lbs of raw alpaca there that I still haven't washed because have only carded a third of the raw sheep I got a few weeks ago. It's all washed and dried, but there is a lot of crud in there that I need to get out. My new hand carders work phenomenally, but it is still very time consuming and the midterm for my grad electricity and magnetism class is this week, and I have only studied classical theory, and haven't reviewed relativity or field theory yet. And pretending that stellar doesn't exist and that I don't have to teach or do research. And I'm getting another 12 lbs of raw sheep fiber next week too...