The Lorentz Center Workshop on "Galaxy Morphometrics"

The goal of the workshop was to bring as many as practical of the experts in galaxy morphometrics together to discuss both ways to convert the complex appearance of galaxies in astronomical imaging into a few simple numbers and how to interpret these. The aim was realized in that not just representatives from a single scheme to generate morphometrics were attending, but practically all. There were 22 participants and four walk-in attendees (for a day or so) which proved the right size for both lively discussions and a close atmosphere.

The discussions started during the first talk by Chris Conselice (going overtime by 30min at least) which set the tone for the workshop. The participants started setting some of the questions we should think about:

Some of the questions regarding galaxy morphometrics we had...

Subsequently, we loosely stuck to the program but did not enforce time limits since every scheduled talk sparked (welcome) discussion and thus ran typically over. The one exception was by Marc Huertas-Company who had to give his excellent talk on deep-learning techniques via remote/Skype call.

The sign-up board with all the ideas for the hack day (afternoon really).

On wednesday afternoon we had the hack day. To decide which topic was the most interesting to work on, we used the wall in the coffee corner. The workshop split into three groups to tackle a) clump-finding, b) code standards/comparisons and c) combining morphometics and kinematic information. The results from these hack sessions and the talks were discussed on our final session on Friday afternoon.

Conference dinner was on wednesday night.


Photos thanks to Rebecca Lange (mine failed)

Mister M and Miss C made an appearance as well.

We had to make some accommodations and Jeyhan Karteltepe gave her keynote on Thursday. Brooke Simmons gave an un-scheduled, but excellent tutorial on how to start a Zooniverse citizen science project (something we did not get to on the hack day). I am totally pumped up now to start with a dust-lanes-in-edge-on-disks-zoo (better name pending).

The sessions were furiously tweeted by the participants (myself included). These can be found under the hashtag #galmorph and are summarized here:

Twitter Storify of the Galaxy Morphometrics workshop

The workshop was in my estimation an unqualified success and sparked several future projects and collaborations on  publicly available (and publicly maintained community-effort) software packages. There was also discussion about a possible follow-up workshop or conference at another location to continue to tackle the galaxy morphometics of all the coming future surveys (e.g. LSST, EUCLID & WFIRST).

Mild .Astronomy Envy

Matt is going to .astronomy and I cannot even pretend I am not a little jealous. So much coolness coming from that every time. We need to see about bringing it to the Lorentz Center in two years perhaps. It would be an excellent excuse to go back to the Netherlands.

I think both Matt and me feel a little out of place for .astronomy. But hey. Let's see what he learns. Maybe we can hash out an idea about .astronom 10. We would need a theme. Astronomy for Everyone. Astronomy Science Toolbox. A new scisoft would be blessing I feel. Shame Norm does not support that anymore. It almost feels like some people think it will be that STSCI anaconda installation but that is just python. I would need everything else too! Source Extractor!

I will have to live vicareously through Twitter.

Using Small Telescopes for Education.

I'm sitting in the "Robotic Telescopes in Education" workshop here in Leiden. It's just before the ALMA deadline, I'm beat from Mister M's 4th birthday party and there were some shenanigans I am apparently supposed to put up with in Academia that had my headspace a bit off.  But here we go!

The use of educational telescopes in outreach, classrooms and college education is something I got to thinking about since a recent visit to Moore's Observatory in Louisville. 

Las Cumbras is an amazing resource. Easy to schedule, essentially a single telescopes, spread around the globe. Edward Gomez gave us a rundown of the project and immediately, some ideas start spreading in my brain (occasionally bumping up against me stewing because of that unrelated issue).

Matt Kenworthy's projects are those that can benefit scientifically. Given the fact I'm an extra-Galactic astronomer, I cannot realistically think of much that dovetails with what I've been doing so far.

But that is not the use we should be thinking here. How can one use this online resource in classrooms? Pick something bright, pick something that can be observed to change.

And if it also does something for science, then we'd be really talking!

We'll hear from Pedro Russo next about integrating local facilities into classroom activities. Some sort of project where (highschool) students can use local and LCOGT telescopes to do something that in aggregate benefits astronomy. That is my end goal here.

IAUS321 - the outskirts of galaxies

It has been a week and I have collated some thoughts on the IAU symposium 321 on the outskirts of galaxies. There had been some buzz already at PHISCC but I had somewhat underestimated how big or information-filled it was going to be. I had a full brain by Tuesday. And SO many people to chat to. It felt like one run-on sentence. Drink from the fire hose & lean into it....

The organization was impressive. They had a twitter presence. An excellent website and an outstanding program and site. Toledo is a lovely city. I had been there before for an ESA science workshop a few years back. So I knew where the yummy marzipan could be found.




First view of Toledo.





This is on my way from the hotel to the venue. Not a Game of Thrones set...actual battlements.
I tried to get to grips of the high-view takeaways and to live-tweet as much as possible (to the great annoyance of a FB friend). Things I took away as more general impressions were:

Streams - they are indeed everywhere.

 
both from resolved stellar observations (like the GHOSTS HST survey I'm involved in) and integrated light, often using small telescopes or the DRAGONFLY telephoto-lens array.

Streams and models -- We keep seeing streams around nearby galaxies with small telescopes. However, these were not the streams we were looking for...the streams predited by simulations are much fainter.


Models on the left, observations on the right. How to compare these?

The issue remains how to quantitatively compare the two and how to obtain proper statistics (well the ongoing surveys will take care of that...).

The DRAGONFLY array is steadily adding deep imaging and results on stellar haloes. They find very small stellar halo fractions for anything smaller than the Milky Way. It remains to be seen if this is really true. I suspect some more results on nearby galaxies (like M101) are needed. We have a GHOSTS program on this galaxy. Let's see how integrated light and HST star counts compare.

The most convincing result was on NGC 2841 how there is stars throughout the HI gas disk. interesting...


Castle! Everywhere you looked!

Wednesday was busy with the result of my Bachelors students' results. They counted M-dwarfs in the Milky Way and we all published this result in MNRAS. And my phone died...so I was incommunicado... It went pretty well.

Thursday was my talk. I think it went well... I offered to be everyone's Dust Weatherman. And showed my results on dust in the outskirts of galaxies. Yes there is some! Galactic cirrus is not all that's bothering us in the outskirts!

That evening was the conference dinner. Spain's cuisine is...meat-based. There was a vegetable...an aspergus...one...deep-fried.


The next morning was the return Home. at Way-too-early-in-the-morning. It had been fun. I had caught up with a bunch of friends and collegues, ate a lot of Spanish deer and pork (nom). And some ideas for future HST projects. Brain full but fizzing.

Bachelor Students result on the Milky Way are out!

Last year, I had two talented Bachelor students. The project I had in mind was to just MCMC on the M-dwarfs found in the BoRG survey. It was a nice way to reuse HST data taken already to find high-redshift galaxies. Honestly I thought they might improve the fit I had made earlier using my M-dwarf catalog somewhat.

Well! they took to the project and rapidly a) determined that there had been a bug in my original catalog, b) corrected it, and c) did an expert series of MCMC runs (using the emcee implementation).

The results were much better than I had expected. Not only did they manage to fit the disk of our Milky Way using the numbers of M-dwarfs found, they concluded they needed to use a Halo model as well. It worked beautifully: they inferred 60 billion M-dwarfs in the Milky Way, 7% in the MW halo, all with very nice errors, courtesy of the MCMC modelling.

The press release was yesterday (MNRAS press release) and (Dutch Press Release). Now we see how often it will be picked up by Dutch and foreign media...

exciting!

LADUMA outreach day

I spent all of last week in Cape Town at the PHISCC 2016 meeting. And then the LADUMA team meeting. Things are shaping up nicely. Source finding in HI cubes is maturing, the data-rates don't look scary anymore (they're still the same, we're just not wimpering) and we did another LADUMA outreach morning. This was a huge hit back in 2014 when PHISCC was last in Cape Town and the first time I was going to participate.

Sarah managed to get hold of a list of schools to contact. And set up the logistics (yay Sarah). We heavily depend on the South Africans for most of the logistics (they have cars...)

I did notice an inherent issue that is impossible to correct for. All the poorer schools will have a poorer response to an offer for a bunch of scientists to come by and talk opportunities. I'm sure Sarah noticed. Actually I think she pointed it out. There is more turnover in staff, fewer people manning the phones etc so we often end up going to schools that are...for a lack of a better word...posh.

These private schools are amazing and quite a number of bright kids will turn out to be scientists later in life. It was a great experience talking to the classes. And yet...how do we get to more schools?!?!



We need to figure that out. Without sending every LADUMA team member on a days long trek or something. Something clever to let all the kids in South Africa know their country is up to someth amazing science & engineering and they all can be part of it. Some thought required. I'll start by seeing about translating those UNAWE radio astronomy booklets in Xhosa and Afrikaans.

PHISCC

This week I am at PHISCC at SAAO in Cape Town. All the HI people on the planet (it seems) get together and present their work in preparation for (ultimately) the SKA and its pathfinders. I am here mostly because of the latter. After 6 years to the day, I handed over the proposal of what would become the LADUMA survey to Sarah Blyth, who just came back from maternity leave. Then I went on paternity leave because Charlotte arrived shortly after.

It's been 6 years. Both Charlotte & Sam have grown! As has the LADUMA survey. Andrew Baker joined the PI trifecta (much easier to deal with things since we can all take parts of the responsibilities) and we have a team lined up. It's coming together!

There is a LOT going on. HI source detection is maturing fast! Stacking software is growing up too. MeerKAT is now several dishes! Real radio telescope dishes. Meetings such as these are always very energizing (and slightly intimidating). I think I did ok with my talk on LADUMA. We still have no data (but that should be changing soon!).

The next PHISCC will be in China, India or Perth. hmm

Well that is going to speed things up

Ever since I discovered how to make a progress bar in my python scripts, most of them seem to have them now.

It shows how far along it is but also the estimated time till completion. Brilliant. It also made me slightly more worried about how long something takes.

For example, a (older) script I wrote to fit SED models to suspected brown dwarfs. It works well but it's a little heavy on for loops. I wanted to apply it to LOTS of sources. So I ask Matt if he knows any tricks to speed things up. Matt shows me a trick using arrays.

Script goes from weeks-till-completion to mere seconds. wow. Usually I am not too fussed if a script runs for a little while (2 min? fine, I'll check twitter or something) but cutting down from weeks of runtime. nice.

Go Matt.

Now I'm going to stare at a progress bar run across the screen.

Hunting GHOSTS-I

This weekend was spent at La Palma and specifically the William Herschel Telescope (WHT) to hunt for the spectral signature of GHOSTS-I a super-faint and very isolated dwarf galaxy (see the discovery paper, Monachesi+ 2014).

It was a dark and thankfully not stormy night. On Sunday, the weather looked good but clouds poured out of the caldera (a beautiful sight) right over the WHT (boo!). So it felt like I may just be out of luck with the humidity (clearly) over 100%. It could well be a night where we'd sit & listen to the water drip off the dome (exciting!).






To add to the feeling of a lost expedition, the electronics on the blue side of the spectrograph were acting up in a decidedly odd way. No real data was being read out!

But the support team got to work and got the Blue side behaving again. In the meantime, the night had started, things cleared up and we could actually go and hunt for GHOSTS-I!

It is so faint that it is invisible in any target acquisition image so we positioned the WHT/ISIS slit on the sky using a nearby star and checking it against the visible objects nearby. Tricky.

And then we integrated. For a total of 7 hours. 5 one hour exosures and 4 half hour ones. Seeing fluctuated so some exposures may be more useful than others. We kind-of-sort-of see a very faint continuum signal already in the raw data (we squint...) but no clear emission line just yet.

I now need to reduce the data and see how good of a spectrum I can construct. Hopefully I can tease out a redshift for this galaxy. It will be interesting: this was definitely one of the faintest things ever observed with WHT/ISIS.




Then on Monday morning, i went down the mountain, give a short talk at the IAC office on GHOSTS-I and the overall GHOSTS survey, off to the airport and home for sleep.