Tuesday, December 4, 2018

First time at LCO

I’m Sunny Rhoades, a junior physics major at Pomona College. I was very fortunate to be invited to LCO by Gwen Rudie and Drew Newman, my mentors during the 2018 Carnegie summer undergraduate program. For several nights this November, I shadowed Gwen and Drew as they observed targets for an ongoing Lyman-alpha Tomography IMACS Survey (LATIS). 

Photo taken by Gwen Rudie. Notice the Magellanic Clouds in the background!

This past summer I worked on a bit of the data visualization for LATIS, which plans to spatially map the density field from z ~ 2 - 3. I worked exclusively with processed data to make 3D maps, so this trip allowed me to connect what I studied to observations. I hadn’t looked at a lot of spectra while working last summer, so was interested in familiarizing myself with the properties of LATIS spectra. The LATIS spectra taken using IMACS target the far-UV spectrum in the rest frame, and so are able to provide information (based on strong UV transitions) about the galaxies within our tomographically-reconstructed volume. IMACS was used for this project in part because it is a multi-object spectrograph, so works well where the density of interesting targets per field is large.

Most of my time at the Baade telescope was spent in the control room, learning about the interface and the procedures and strategies involved in observing. I learned about spectroscopic calibrations and was then able to take some on my own! The final product for spectroscopy of a source is the intensity as function of wavelength, so the data reduction requires you to determine the efficiency of the system as function of wavelength. Wavelength calibration for spectra—which is in part what I performed—is done using exposures of arc lamps, which emit light in many specific wavelength ranges. This calibration is to check if the line spectrum has emission lines that are distributed in a sufficient frequency over the whole wavelength range, no line blending, and no line saturation in the exposure. I also learned about taking twilight flats, which are required to determine the large-scale illumination of the CCD. They are especially useful for getting calibration frames in the UV. And once you have your final, reduced images, the goal is that the large-scale variations in the sky background across each CCD chip are smaller than the desired precision in your measurements of things you care about. 

I really enjoyed visiting LCO! I think I now have a much better understanding of how data for LATIS is taken, but I still have a lot to learn. Plus, I got to see some interesting animals (like the viscacha shown in the low-quality photo below).


Wednesday, October 31, 2018

A long overdue observing run


Figure 1: Diana and Clay.
Almost eight years after my first on-site observing experience (at the CTIO 1.0m), here I am, wrapping up my second observing run ever. This time, I've been trusted with a much larger telescope (Clay, see Figure 1) and a precious instrument (the Planet Finder Spectrograph - PFS).

Of course, I had to first get trained on PFS (thanks Johanna! thanks Steve!). It's been a learning curve. Here are the things I have done this past week that I had not done before:
- observed on site with a spectrograph;
- filled the instrument Dewar with liquid nitrogen (see Figure 2).
- drove an automatic car that is trying to be manual.






This observing run has certainly posed some challenges, both to the PFS team and to me personally. 


Figure 2: Filling up the PFS Dewar at 6:30am.
On my first night of training, we sent a command to move the iodine cell in the light path in order to complete calibrations and begin observing. However, the iodine cell would not move. Upon inspection, we discovered a glycol leak near the area where the PFS calibration lamps and CCD controller are. We suspect the glycol lubricated the iodine cell motor, disabling it from moving the iodine cell. The mountain crew rushed over and did a fantastic job cleaning up the leak. Following the cleanup, we were able to complete calibrations and start observing, but we did lose about 3 hours. 



I usually use space-based data or observations from robotic telescopes, which is why I do not go observing very often. Adjusting to the night schedule was a personal challenge for me, and it took me a couple of days to adapt. At first, in the morning at the end of observing, each of the last few steps before bedtime seems like an insurmountable challenge: getting the calibrations right, filling the Dewar with liquid nitrogen safely, driving back to the lodge.

In the end it was all worth it for the learning experience, but also for the wildlife (see Figures 3 - 8), scenery, and sense of escape (see Figure 9).


Figure 3: Burro.
As a "bonus", we had good weather and seeing (at least during the week I was there!), and we acquired numerous spectroscopic observations that will be used to measure the masses of newly-discovered exoplanets.
Figure 4: Vulture (thanks George!).






Figure 5: Vizcacha.
Figure 6: Guanaco (thanks George!).

Figure 7: Zorro.

Figure 8: Small owl.

Figure 9: Our galaxy.






Monday, July 2, 2018

Night 2... Let the observing begin!


So last night ended up as a total observing bust, but never fear there was still tons of fun to be had! We tried to wait out the high winds, somewhere between 50-60ish mph all night, we got to tweeting up a storm. We also decided to venture out to the catwalk, while the winds were at 60 mph, because when your advisor says,"You should go on the catwalk with the wind! It's fun. And a little scary. The moon will brighten you", you oblige.

And with that I bring you the greatest wind photoshoot.... The live photo really does the first one justice. I felt like if I let go of the railing that I would have literally blown away. Our collaborator said that we should fly a kite and I responded with "I in fact was a human kite."



On the catwalk between Baade and Clay
Post wind hairdo!


Night 2 started out much better with the winds dying down... but then the humidity struck! At one point we had all the weather problems we could have had at the time wind, clouds, and humidity. The text message anger was real on our collaborators end and the gifs he said definitely did it justice. Once the weather got better we could open and then we were on a run. 14 targets down and then dun dun dun the wind came back with a vengeance! And now we wait. Hoping for the wind to go away but you never know with the winter weather. Hopefully Victoria's post will have a happy ending for us and hopefully all of the fabulous additional targets!

Saturday, June 30, 2018

A Chile and Windy Winter Night

BDNYC in da House! This is my third trip to LCO, but my first time teaching someone else how to use the instruments on the Baade telescope. My partner-in-crime for this run is Victoria DiTomasso, who recently graduated from CUNY with her BA in physics this May. We have two nights and are planning to use FIRE, the NIR spectrograph, and Fourstar, a NIR imager, to observe some awesome brown dwarfs.

Victoria and I outside of El Pino




My journey to LCO started with a sad amount of sleep for me on the long flight from NYC, but no worries I immediately passed out on the SCL-LSC flight surrounded by a family with so many children. While I waited for the flight from SCL-LSC we found a few other astronomers that were going to Las Campanas as well, making our new group woman dominated- 4 female astronomers and one male astronomer. My adviser said we'd be the only women on the mountain, but ha we are not! I have never been the only woman on the mountain, since our research group runs deep in amazing women.






As stated by twitter, the IBMT or 
the itty-bitty Magellan Telescope



When we arrived in La Serena we had to wait a few hours before we could go up the mountain. While we waited we got to explore a little of El Pino and found a cool scale model of the GMT. After that we took a walk to get some empanadas and enjoyed the warm sun and fairly nice weather, the last to be seen of  until Monday when we come down (the weather of course, I am sooooo looking forward to empanada Sunday!).


The first night on the mountain was supposed to be the night I worked on switching over to the night schedule by staying up late.  But because I was so exhausted from the lack of sleep on my flight my plan of action changed. Instead of trying to stay up late, I went for trying to sleep in as late as possible. Sucess! I made it to 12 and a half hours of sleep! Yea for naptime!





The winds sometime at the start of the night. Gusts of 58 mph! Most of the day was like this, but slightly less windy.


The selection of teas. There is one made of a plant that I have
never heard of, which will definitely be my next cup!



After lunch on our first night of observing (today!) we went up to do calibrations and a telescope photoshoot. Check out Victoria's blog post for those photos! The photo that I really should have taken was one of me and the wind. No lie I was blowing away! I hoped for the wind to die down over the day not only for my safety as a tiny person, but for good observing. While I showed the telescopes to Victoria we could feel the wind pushing our tiny little blue car, so you get the picture.






Mars is keeping warm and staying hydrated 
while we wait out these winds!


As the sun set we knew that we would be in for a long night. The night so far has been observing the tea selection (oh so many!) while we wait for the high winds to die down.


Hoping the weather gets better but the TO said it looks bad for the next two days aka our entire run  :( Luckily, its still early on in the night. Updates to come tomorrow as we start night two of the run!



Thursday, May 24, 2018

The weather is good, but....

From left: Me (Juliette), Johanna Teske, Sharon Wang, and
Erin May in the Clay telescope dome. Erin and I are
observing on Baade this week, and Sharon and Johanna
are observing on Clay.
Hi! My name is Juliette Becker, and I'm a graduate student at the University of Michigan. This week is my first Magellan run, using IMACS to look at a white dwarf with a disintegrating planet and also at some transiting planets. I am observing alongside Erin May (a fellow UMich graduate student and IMACS pro!), and we have a four-day run this week. Johanna Teske and Sharon Wang are observing on Clay this week, so it's ladies' week at Magellan!

Erin has in the past had terrible luck with weather at Magellan; it seems to be cloudy or raining every time she comes to observe (the running joke is that she's "cursed"). We've been checking the forecast for the last few weeks, getting nervous when it looked like there might be clouds and getting happy when the forecast became more favorable. When we arrived here Sunday evening, the weather was pretty good, with just some scattered clouds. The forecast looked favorable!

Monday night, the weather got even better. We were able to get on sky on-time and observe both of our targets for the night! There were some scattered clouds, but it wasn't too bad. We reduced some preliminary data, and things were looking pretty good.
Pretty good weather, with only scattered clouds!
Come Tuesday, we were excited to get more data on our targets: it appeared that the "curse" was broken, because the weather was great! We did our calibrations Tuesday afternoon, headed back for dinner, and returned to the telescope before sunset.

When we arrived at the telescope, several of the local Magellan engineers and instrument specialists were in the control room, looking concerned. The guiding wasn't working, and they quickly determined (as Erin and I looked on in horror) that the reason for this was liquid on the camera. My first thought was "Liquid? How did that happen? It hasn't even been raining!", but things quickly got worse...

The engineers determined that a hose had a nick in it, resulting in glycol spilling everywhere. And it wasn't just a spill - it had spewed all over the instrument and the local area, resulting in a GIANT MESS:
Video of the aftermath of the spill, courtesy of Gabriel Prieto.
As the engineers worked hard to fix the spill and get the instrument functioning again, things were not looking good. It seemed like IMACS would not be functioning again for at least two nights, but one of the engineers mentioned that they could unplug IMACS and plug in another instrument. Erin and I scrambled to get backup targets that we could observe using another Baade instrument, so as not to waste valuable Magellan observing time!

As 11pm approached and the engineers continued to work, we had come up with a list of backup targets for FIRE, calibrators, and an observing plan. Even if IMACS wasn't working the next night, we would be able to observe on FIRE. At this point, I was totally convinced of the existence of Erin's observing "curse." Clearly, the curse hadn't been able to control the weather this time, so it had decided to take another approach...

But just as we almost reached the point at which we would not be able to observe our transit, the Magellan crew came back from the dome with good news: they had a temporary fix for IMACS, and we could get on sky after all! We finally got on sky ten minutes before the transit we were observing, thanks to the herculean efforts of the telescope operators, instrument specialists and engineers on site. The guiding system was out of commission, so our telescope operator Alberto had to focus the telescope manually all night. In the end, though, we were able to get data for our second target of the night.

The lesson I've taken away from this trip is that it takes more than good weather to have a successful observing run: you also need a talented crew of telescope operators, instrument specialists and engineers ready to save the day if something goes wrong!


Friday, April 27, 2018

Interview Cross-Post

I'm back at Las Campanas with the MagAO team! But tonight I'm just cross-posting an interview I did for the DTM website. Read the Interview

Tuesday, April 10, 2018

Using the tunable filter

One of the most difficult experiments we did in my undergrad physics class involved calibrating a finicky Fabry-Perot interferometer. The MMTF tunable filter on IMACS at Magellan works on the same principles, where you precisely calibrate the alignment and spacing of two parallel plates to allow only a small range of wavelengths to pass through. After talking with fellow Carnegie postdoc Rosalie, we had an idea for a possible project which would involve the tunable filter, and decided to go for it.

We allotted ourselves a big chunk of time in the first afternoon to get everything set up for the first time, and after some skype help from Ben Weiner, got our calibrations all set for the night. We were pretty happy about this, come sunset:

(Decker and Rosalie, after successful calibrations, trying not to think about the clouds in the background)


After some threatening clouds, things cleared up enough to start taking data, and we got on our science target:

(Science data with the MMTF!)

I'm super excited about what we're seeing in the quick-look of the data, and looking forward to seeing what happens after the full reduction!

Unfortunately, the clouds did end up rolling in halfway through the night:

(Clouds seen on the satellite image over the sad red dot which is us)

So, we'll have to try again tomorrow night and hope for clear skies.