Comments on: STIS or ACS?

By: the astrodyke

the astrodyke — Sat, 12 May 2007 04:34:31 +0000

Thanks for the link, Phil.

Wow, NO votes for ACS over here yet. Veerrry interesting…

By: Cindy

Cindy — Sun, 29 Apr 2007 02:26:44 +0000

Dirty-g,

Astrodyke is the name of the blogger who asked the question. The instruments are called STIS and ACS in typical NASA acronym-ese.

Lab Lemming, yes, that was the original intent but had already been scrapped as pretty unfeasible at the time of launch in 1990. HST was not designed to be launched on a traditional rocket, so it would have had to go back up on a shuttle launch.

Ok, I’ll show my bias having worked on one of the original HST spectrographs (FOS), I’ll vote for STIS.

By: dirty_g

dirty_g — Sat, 28 Apr 2007 10:31:24 +0000

is it seriously called an astro dyke? what were they thinking???

By: Lab Lemming

Lab Lemming — Fri, 27 Apr 2007 23:02:49 +0000

Wasn’t hubble originally built so that the shuttle could retrieve it and bring it back to Earth? If so, why not bring it back down, upgrade everything, then relaunch it on a traditional rocket?

By: The Bad Astronomer

The Bad Astronomer — Fri, 27 Apr 2007 22:01:21 +0000

Funny– of course, COS will do UV spectra! So STIS loses points for that (I should have mentioned that in the post) but STIS also has (or had) phenomenal spectral and spatial resolution. And it does spectra across the UV, optical, and near-IR.

I miss it sometimes. Every now and again I almost wish it were working so I could propose something on it (like RS Oph). Sigh. But then I remember how much work it was, and I’m glad someone else will do it… if they fix it. Sigh again.

By: Rob

Rob — Fri, 27 Apr 2007 21:11:43 +0000

STIS. Even though I never used it and I have used ACS (and lost a project when it failed). A lot of ACS work can be done with WFC3, or even with AO from the ground, but STIS is unique, and JWST won’t have the UV capabilities of HST, so if it’s not done now it won’t be done in the foreseeable future.

Also, as mentioned above, it seems likely that ACS would need to be totally replaced rather than being repaired, which just isn’t on the cards.

By: NGC 3314

NGC 3314 — Fri, 27 Apr 2007 20:42:22 +0000

Yeah, STIS. That’s somewhat colored by the practicality that it’s said to be more nearly impossible to fix ACS… But not only do we not have an optical or UV spectrograph in space now [1], but COS is essentially a 1-D device, sacrificing spatial resolution to increase throughput for high spectral resolution. QSO absorption and the IGM, here we come! However – STIS still reigns as the supreme black-hole hunter. Virtually all the solid measures of black-hole mass in other galaxies come from STIS, which is one reason why we’ve had the same sample for several years now. AO-fed spectrographs still don’t approach its resolution and lack of scattered light in the optical, which means it will be the only game in town for this and similar problems for a while yet. On top of all this, much of ACS’s survey capability will be served (albeit with not quite the field) by WFC3.

[1] Except FUSE, but it’s shorter-wavelength and a good complement to COS.