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.

Students!

Today I've met all my students. There will be 6 Bachelor students this year. yay. I better be super-duper organized. Last year was a blast and everyone graduated after doing quite a bit of fun science.  That was 4 Bachelor students doing 2 projects (one project just re-submitted to MNRAS).

So let's see if I can take it to 150% of last year's success. And I am helping with a single Master's student project.

There are three projects:

XUV disks of galaxies, in what kind of galaxy and environment do they occur?
 - 2MASS enviromental parameters
 - WISE stellar masses and star-formation rates
 -  GZ2 morphologies

Nuclear Star Clusters, What are their host galaxies like?
 - 2MASS enviromental parameters
 - WISE stellar masses and star-formation rates
 - SDSS BPT classifications

the Vermin Galaxy, a galaxy found behind Beta Pic. Map the dust attenuation.

Bachelors Project

The revision of the Bachelor project's results in now resubmitted to MNRAS. The referee was extremely helpful and gave constructive criticism. So nice we got the nice referee for 2015. (if you are the referee for this paper THANK YOU!, so nice to be able to point to something and say "look not everyone is mean"). They also presented their work at an undergraduate research conference here in the Netherlands. No win for them but still!

The paper needed some TLC that me & Matt gave it. It reads pretty well now. Not bad for a postdoc and 2 Bachelors.

My LEAPS student Alejndro is also done with his A&A paper. One more read and it can go off into resubmission. Won't that be nice...

Now I can point to these (and a bunch of other) papers and say "look I can work with students! They don't run away!" In fact I tallied up all the students I've worked with over the years. More than I thought. Also a much more diverse bunch than I would have thought. All good.

If anyone is interested, I will have some 3-4 Bachelor projects up for grabs this year as well...

Magnitude system

The magnitude system has been with astronomy since the 'nomy'. It is a logical extension of the sensitivity curve of our own eyes and therefore makes some historic (if not logical) sense. Calibration of said magnitude system (the zeropoints) initially made sense to calibrate off a star that was almost always available: Vega. When moving to space observations, most of these considerations were moot so astronomy introduced the AB magnitude system.

And now for my rant...

Astronomers working in stellar physics unconsciously assume everyone works in Vega magnitudes. Everyone else...mostly AB. So when someone uses the word "magnitudes" it really should be prefaced. Or clearly marked in the header of their table. or something. Otherwise tacit assumptions are going to bite someone. In this case: me.

I needed J-band absolute magnitudes for M-dwarf subtypes. A stellar value. I compared those to HST photometry (AB)...and in the near-infrared, AB and Vega don't differ by huge numbers +0.89 if anyone is interested...

Just had a helpful referee point this out but it is so very frustrating. In combination with a library glitch in coordinates, this warrants a Erratum on a paper of mine. So I am going through the whole paper submission process again juuust because Astronomy doesn't set single standards but insists on using different ones and relies on a "everyone knows". gah.

Me the Astrotweep

Last week was the third trip in a four-week series. I was the astrotweep and a TON of other stuff happened (Lunar eclipse, the Martian came out, water on Mars etc).  So. Business as usual really.

the astrotweeping by yours truly is compiled here. Some of it is quite flow-of-consciousness. Hope everyone liked it!

see here for the full storify of the week!