Saturday, February 25, 2006

Two wrongs (sometimes) make a right

At 5:30pm on Friday, I spotted a potentially huge mistake in the SQL query I'd been using to query the CAS. I had written (FibreMag_i - deVRad_i > 0) for the object to be return rather than (FibreMag_i - deVMag_i > 0). I then compounded this mistake by using the correct SQL but on the Star table and thus had a major, major panic and stress when I couldn't understand why the numbers changes SO much.

However, with some calm thinking from Edge, Shanks giving me some room and a timely visit by Butterley to pick up the wine (ahem!), we figured out that the deVRad cut would be passed almost all of the time, and then I recut the sample in my FORTRAN anyway. So this really should have a minor effect, if any.

So, we're off today. Football has just been cancelled (needed a point vs. Trevs B for the League) but that'll give my time to finish packing.

Thursday, February 23, 2006

Coona, we have FLD files.

So, it looks like we're almost there! I've constructed 15 .fld files which have enough objects for two AAOmega visits each and they're looking okay!! (Only spotted one entry with 60.000 in the arcsecs column!)
We've (Shanks, Edge and I) eye-balled the guide stars (and they look like stars) and the LRG candidates (which look like very faint little red dots) and even some potential z~3 QSOs (which also look like stars!).

The ELG run starts on Sunday evening and there is still a (helluva) lot that can go wrong between now and the start of our run but I'm feeling reasonably sorted.

Gierlinski gave what I thought was a very good (and nicely timed) seminar on "Variability spectra of accreting black holes". Essentially taking at High Mass X-ray Binaries (HMXB), seeing how their spectra change from a "soft" to "hard" state, calculate a rms/mean value of the variability versus energy (I think) and see what this can tell us about what the BH and the accretion disk are doing. Anyway, bottom line was the models seemed to fit the data well but a couple of key features are seen at 20keV where data is still poor.

Wednesday, February 22, 2006

Hectic, hectic, hectic - but getting there.

Oh dear standards are already slipping.

Figured out how to use the SDSS DR4 CAS. Have downloaded all the data I (think I) need and now have ~14 fields ready for configuring in the "Vanilla" setup. Bielby, "inspired" by Shanks, has an "ER" gri-selected sample to track the turn-over that Shanks believes is in the WHDF data for the spirals at z~1 (e.g. McCracken et al, 2000, MNRAS, 311, 707). This is gonna get exciting...

Friday, February 17, 2006

CAS is driving me crazy!

Just a wee post today since it'll be Friday night later...

Am achieving absolute nought due to a) the re-appearance of Frith (Durham until 2005) and b) the SDSS DR4 CAS just being incredibly slow. I'm sure it doesn't like me!! Think I've chosen the areas (and given them fancy Greek names) but not much use until I get the imaging downloaded.

Interesting Lunchtime talk today by Libeskind "What is HE0450-2958?", all about naked quasars and the possibility of a 3-body SMBH interaction kicking the smallest mass BH out of a mergering ULIRG system. Schurch asked about the presence of x-rays for HE0452-2958 as that could be the real give-away to what's going on.

Week tomorrow I'm flying to Hong Kong.

Thursday, February 16, 2006

Visiting some old friends...

There are potentially 10 nights of AAT time to prove that the new AAOmega instrument can make a significant detection of the baryon acoustic oscillations (BAOs, a.k.a. the "baryon wiggles" or "the baryon bump"). But just how?? GALEX selected Emission line galaxies at z~1 or the more biased LRGs at z~0.8?? Both?? Either?? And how do you run a pilot? What is the best strategy? What is your philosophy?

All these questions will be answered (well apart from the possibly the last one of two) in the near future. Field selection continues apace. I/we now have a better and better idea to which fields we're gonna go after and why. COSMOS, S11, UKIDSS LAS and some ol' friends here we come!!

Potentially couple of interesting papers on astro-ph today. Ilbert et al. astro-ph/060232 on the "environment" dependence evolution of the Luminosity function from VVDS and my current hobby-horse, progenitors of LRGs and early-types, which Kaviraj et al. (astro-ph/0602329) have been modelling and find that "averaging across all environments at z~1, less than 50 percent of the stellar mass which ends up in early-types today is actually in early-type progenitors at this redshift". What exactly this means/implies I'll have to think about!

Oz-minus 9 days and counting.

Wednesday, February 15, 2006

SQL and field selection

Tiring but productive day. Bielby and I had a good go at, and were really getting to grips with, the SQL Servers in the SDSS (and to a lesser extent GALEX). By the end, I felt I was beginning to understand much more what Eisenstein (Arizona) did for the 2SLAQ (2dF-SDSS LRG And QSO) Survey selection, beyond the colour cuts and various magnitude filters. Essentially which flags and databases he'd utilised and why. Was still working with the COSMOS 10h field and the COMBO-17 s11 11h40 field. Tomorrow, I'll pick my "favourite" 2SLAQ field just to double check everything is okay.

Edge and I also had a good look at staralt so that we now have a rough idea which fields we can look at over the nights. Shanks (El Supervisor!) wants to be in a position to have upto ~20 fields ready just in case we hit a streak of 5/5 great, clear nights. Ah, even with my good weather record, that would be the dream...

Oz-minus 10 days and counting.

Tuesday, February 14, 2006

Reason One

I think the reason I decided to start NPRs Research today was (unsurprisingly) one of Hogg's (NYU) posts. I wrote, with old fashioned but still extremely useful pen and paper, in my log book about a week or so about merger rates of galaxies. Specifically, it looks as if we're beginning to get a handle/upper limit on LRG-LRG merger rates from the recent papers by Masjedi (NYU)
and Wake (Durham). We also think we know about the build-up of "regular" Red Sequence galaxies from z~1 from say the COMBO-17 (Bell, MPIA). And I had a very similar thought, that surely what we would really like to know now is the rate at which the really massive galaxies (i.e
the LRGs) merge with the regular red galaxies. I don't know exactly why but surely this number is pretty important. I will work this out at some point, once I get a break from configuring AAOmega fields.....

Learnt something new today (LSNT): Relative astrometry is fairly easy. Absolute astrometry is hard.

MY First Post

Hi everyone,

This is my first ever post onto my Blog.

This blog, "NPRs Research" is very much in
the same vein as David Hogg's (
and was obviously inspired by it.

I thank Dr. Hogg for many enjoyable reads and only hope
my blog can be a 1e-01 as interesting.

"Will you start the fans please!"