day off

[I took the day off.]

type Ic supernovae

I spent the day typesetting linear algebra for the paper with Tsalmantza and making sanity plots of the GALEX data with Schiminovich. Our photometry looks good; time to send it to some of our users for testing.

Maryam Modjaz (Berkeley) gave a great seminar about what you can learn about GRB and SN progenitors from studies of host environments. She showed one of the cleanest results I have ever seen about this: If you look at SNe type Ic-BL (broad-line), the ones associated with prompt GRBs are very much lower in local metallicity (oxygen-indicated) than those not associated with GRBs. The non-GRB SNe type Ic-BL are higher in metallicity and don't show evidence for afterglows at late times. This all shows that there are no orphan afterglows (all the low-metallicity SNe type Ic-BL have prompt GRB emission) and therefore that the GRBs cannot be highly beamed. Strange! Of course these SNe-associated GRBs tend to be lower in total luminosity from typical GRBs, and this might be relevant. How big a deal is it if we find that GRBs are not beamed?

writing a paper with Schiminovich?

Schiminovich and I have been talking a good talk for many years now, but today we actually started to draft a written description of what we are doing with the GALEX and SDSS data with the intention of writing a paper. We also thought of some instructive figures to make and some baby science results to include in the data release paper.

spectral modeling

In the morning I spoke with Tsalmantza about our spectral modeling project, which we are using to find gravitational lenses, black-hole binaries, and quasar redshifts. Well, we aren't, but we hope to be. We have a smoothing or softening parameter—a continuous model-complexity parameter—and Tsalmantza proposed a simple cross-validation test to set it. In the afternoon I tried to start writing words about the project.

cosmology and gravity

After a morning with students, Rachel Bean (Cornell) gave a talk in the afternoon about testing generalizations of gravity with cosmological observations.

open science

I had the great pleasure of talking at Margaret Smith's OpenSci NY meeting today. I spoke about the benefits my group gets from its extreme openness—not just my blogging but our web-exposed code, paper, and proposal repository, our open-source software projects, and our citizen-science stuff. After me was Heather Joseph from SPARC, who talked about a huge range of interesting things, including the scale (8 billion dollars) of the science and medicine publishing industry, copyright agreement amendments for publishers, the Harvard faculty vote on open access, page charges and journal subscription costs, and a range of other crucial issues for our future. She also mentioned the point that in the open science future, papers have to be machine-readable as well as human-readable. It was a great morning.

unjustified uncertainty estimates

Schiminovich came to NYU and we got closer to having a complete set of measured GALEX photometry for all SDSS point sources. We obtained these photometric measurements by performing aperture photometry; today we worked out a heuristic strategy for inflating the error bar when a measurement is likely being affected by another nearby source. The idea is that we want—for our science goals—to report a flux and uncertainty for every known source; we do not want to just cut out or mask or flag sources that might be bad or contaminated. Our method is very empirical and has no precise justification, but unless we think of something more clever (or go whole-Hogg and perform the photometry by simultaneously fitting all GALEX pixels with a self-consistent model of the sky), something heuristic like this will go into our planned data release.

proposal

In a day shortened by our (fun, very fun) graduation party, I worked on Myers's NASA proposal, which is effectively due tomorrow! We also had a meeting of all the students and postdocs who are working on SDSS-III BOSS spectroscopy to get everyone up to speed on downloading, plotting, and analyzing the spectra. In this meeting I learned that Ben Weaver (NYU) has duplicated a lot of our legacy IDL code in Python.

GALEX photometry

In the morning, Schiminovich and I tried (in a very short time) to write code to combine our multi-aperture aperture photometry of GALEX data by fitting it with simple models. As we do every time, we discussed the merits of various levels of image modeling, recognizing always that it would not be difficult or slow to do the Right Thing but then deciding to continue with our (justifiable) approximation nonetheless. This fast morning was followed by grant-proposal writing and document tweaking.

students and grants

Wrote text for Myers's NASA proposal and worked with students. In particular, Wu and I discussed final thesis schedule and I started to read carefully Jiang's current draft.

line document done!

A two-day figure-making bonanza by Bovy completed the fitting-a-line document, about which my reader is all-too aware. We are mulling it over before we send it off to the arXiv, where it will live a quiet life, undisturbed by readers. If you want to see a pre-release copy, send me an email; I will gladly share it in exchange for a promise to send me comments. Of course it isn't light reading!

cross-correlations

I brainstormed with Adam Myers (UIUC) about quasar–galaxy cross-correlation projects for future work together, possibly funded by NASA. As my loyal reader knows, cross-correlations are very powerful; much more powerful than auto-correlations. There is a proposal deadline next week; will we make it?

zip

nuttin.

still fitting a line

In the morning I finished yet another draft of our insanely long-winded fitting-a-line-to-data document. It is now in Lang's hands. Bovy is working on figures. In the afternoon, the graduate students in the Center for Cosmology and Particle Physics gave shotgun seminars about their research. These were great, and I hope we do this every semester from here on.

domains

Not much today. I worked on my writing projects, and got Roweis's domain name registrations—which include Astrometry.net—under control.