SCP Meeting Notes, 1998 August 20


Bombing Sudan and Afghanistan

We start with discussions that the US seems to have just bombed Afghanistan and Sudan in response to recent embassy bombings. Chemical plants, perhaps, that were supposed to be where the bombs were made... but all of this is heresay. It's also probably not relevant to the meeting... it probably has something to do with the fact that two people are still eating, which always tends to lengthen meetings. Important Safety Tip: remember the hazard of scheduling meetings during lunch (especially what is just some folks' lunch). They grow.


Keck Proposals

Saul got the call for proposals at Keck. It seems that they are now allowing for proposals for Target of Opportunity time. One thought is to put stuff in for GRB things with Bruce. The other thought is, can we use this in any way for supernova work.

Saul points out, however, that the proposals seem to be saying that you still have to convince the observer on the telescope to give up their time. General sentiment around the table seems to indicate that this doesn't really sound too good. Never mind that people can steal your ideas.

Saul says that the reason behind all this is so that some people (e.g. Shri, who does this a lot) can't just call up and talk people into observing certain objects. If somebody else has a proposal in to actually do that, they should get priority. However, this does seem to be in reaction to those who talk their way into leading lots of observations without ever writing a proposal to do it.

Bruce wonders if any other big telescopes have TOA mode. It seems that mostly, they don't. Also, most of the crop of 8m telescope aren't quit online yet. Bruce needs a big instrument with TOA. Peter thinks his best bet is to inheret a few hundred million....


Gemini

(continued from previous section)

Greg says that when Gemini comes on, it will be all queue scheduled, so it might be able to deal with that kind of thing. Greg doesn't know when first light on Gemini is supposed to be... but we should probably start looking at that, and other scopes, to see what comes online in the next two years.

Re: Gemini and collaborators. Saul notes that Isobel Hook is working at Gemini starting this fall. Also, a former student of Richard Chrome (Mariana Takamia) is there (somewhere) (Hawaii?) and interested in working with us- she might be able to cover some observing if we just need an hour done or some such. Continuing the stream of consciousness, she's working on for her PhD thesis about new ways of paramatrizing host galaxy morphology. Back to the focus of this paragraph, Saul hopes that between her and Isobel, our group might be able to have an early in on Gemini. (Isobel, if you're reading this, we're counting on you. This might be a time to renegotiate your contract, and work some sort of merchandising deal to get around the salary cap.)


HST

Greg is still trying to get FOCAS to read the things. It seems that FOCAS hasn't been converted to use the new IRAF FITS kernal, so he's chunking things over to bloody IRAF format files.


Theory and the Stretch/Magnitude Relationship

Peter says nothing is new. Working on some of the theory behind relationship between lightcurve shape and absolute magnitude. He says that he thinks that he can show that the slope between stretch and magnitude can be explained using theoretical reasons. L=1/(4*Pi*r^2)*sigma*T^4. (That's Peter's theory... that's all it takes, he claims.) Saul (and certainly me) didn't quite follow Peter's explanation... my problem is mostly that he is talking quietly and the sound of my typing and the fan on the laptop is a little bit louder than his voice. However, it seems to have something to do with figuring out the temperature from the color. Somehow (here I get lost) he gets the color stretch relationship. Going from temperature to luminosity seems a little more straightforward. Aha... he says he can't explain the stretch/color correlation, that's an explosion mechanism thing. Now it begins to make sense. You must a priori believe the color/stretch relationship, and then (taking that as given) you can get what the stretch/magnitude slope is supposed to be.

Gerson wants to know how this matches with what Greg has been doing based on the Kim templates. Greg says that first of all, that's just empirical, and what's more he doesn't have final numbers because all of that is still in flux. Greg notes that this doesn't really correlate much with what Peter is doing. There is discussion about the number we use for the stretch/magnitude slope, but most of this discussion is based on a assumption prior knowledge that (a) I don't have time to echo here, and (b) I only vaguely know myself. However, the value we have is affected by biases, notably extinction. Peter says you get a different number if you apply color corrections.


SEAM

Saul asks what H0 it looks like will come out of the SEAM method. SEAM = Spectral Expanding Atmosphere's Method. Fit the spectrum, figure out what is going on temperature-wise in the spectrum. Use the rise time and the velocity information from the spectrum, and you can calibrate the size of the emitting region... and thus can calibrate the luminosity. (sigma*T^4*1./(4*Pi*r^2) again, I suspect.) Peter suspects that you're going to get an H0 of 60 out of this method (I don't know who is actually doing it, if it's Peter or somebody else). Then again, Peter always expects H0 to be 60 (at the very highest).

Saul notes that this is based on the fact that Type II's look more like a blackbody. However, Peter notes that no Type II's look alike when you really start looking at them, and there are lots of things that can screw up simple spherical relationships from an explosion model. (Type I's, in contrast, Peter says, have been shown to not have any asphericity effects, since a stringent upper limit has been set on the polarization from them. Type II's, in contrast, always seem to have polarization.)

Allright, now we've got a side discussion where Peter convinces us that you must get polarized emission from an aspherical explosion. The discussion is a little bit confusing, and Peter says that he has to show me a paper. However, the polarization changes along the P-cygni profile of a line, and it has to do with the fact that there's a preferred direction in a non-spherical explosion. The details aren't obvious to us, but we'll believe him.


Matthew's Status and the Flatfield Software

Matthew says that a month ago he fixed the flatfield software. He got it to deal with multiple readouts, like quadproc.

Just now, he was looking at what Ivan left as documentation, and was looking at the code to find out if what he said was true. He's found some differences (minor things), but he's still working on it.

Saul asks if Matthew has a current target for his thesis. Matthew, being a grad student hedges, but thesis is his current activity.

Lou Strogler's Visit and the Option of Becoming a Software Company

Rob and Greg discuss Lou Strogler's visit. Our software had some trouble with the undersampled data, as predicted. However, it seems that our software did as well or better than the other things he'd tried it on, so hopefully the general impression was positive.

We've been completely sidelined into a discussion of trying to make our software easily exportable and polished so that we could distribute it. Bruce is in favor of this, but others seem to think that we're talking a huge time, etc., investment.


Miscellaneous Updates (Including the Paper)

Rob talked a lot about the software and the new database system he's about to put in, and spent wAAAAAAAAAAAAAAAAAAAAAAAAAAAy too long talking about it.

Gerson spent the week running and rerunning plots for the paper, because the data kept changing on a daily (or hourly) basis.

Saul says that he's on the last three figure of the paper, and the text is all updated now.

Now every day I'm saying it should be done today rather than saying every week that it should be done this week.

--Saul Perlmutter

Hopefully it's to the point where it will be able for a last pass-through through Filippenko and folks like that.

Robert is still working with Nelson's (and Sebastien's and Alex's) oimega fitting routine, adding off diagonal routines to the error matrix.

Alex finished writing a coadd routine, which does some cosmic ray rejection. It is slow and takes a lot of memory to do all the cosmic ray rejection, but is more efficient if you don't do rejection.

Alex is now reading up on IRAF and HST, so he can start working on that stuff. He says he found some things that will read the HST formats in IDL... Rob really needs to get the new version of that.

Marcus has almost finished writing the documentation for the functions he's written. He's going to take some more time to finish the documentation, and put the software somewhere where people could find it.