Highly recommended: a recent presentation given on the Google campus by Prof. Raja GuhaThakurta of UC Santa Cruz.
It runs an hour and a quarter, but it’s so packed with interesting ideas, pictures, and simulation videos of galaxy collisions, etc that you don’t notice the time. Give up that Seinfeld rerun and give it a try. Google Tech Talk videos like this one are offered in several resolutions to match your PC and web connection speed–use 720 HighDef if you can. Just make sure you view it full-screen.
Continuing Astronomical League programs, I’ve started taking images of Arp’s Peculiar Galaxies, which actually more often than not groups of galaxies acting oddly because of mutual gravitation effects. Here’s number 227 (from Arp’s list of 338; 34-minute monochrome exposure):
The halos around the galaxy at left are real–they are thin streams of stars and dust around the galaxy proper. “Thin” of course being relative to the galaxies’ size, so in this case some tens of thousands of light-years.
Now, the Arp images being taken in this program are Dual Purpose, since the 40-60 minutes of imaging needed to define an Arp galaxy when using NEKAAL’s 27″ reflector matches the typical time needed to detect a minor planet and to get a first measurement of its motion. Last month bagged 9 new minor planet designations for Farpoint.
Flat galaxies aren’t strictly flat, as in having zero thickness. They do have thickness. And that’s not really a contradiction: if zero thickness were the only meaning of flat, flat tires wouldn’t be flat either…
No, flat galaxies are simply galaxies of a roughly disk shape, and ones that we happen to see edge-on. (Actually, that’s the only vantage from which you can tell they aren’t perfectly flat.)
So, this year I launched into the Astronomical League’s Flat Galaxy program, taking images of flat galaxies using the big Tombaugh telescope and its ccd camera. My trial attempts were, well, trying:
The Integral Galaxy (so called for its shape) is warped by gravitation from a nearby dwarf galaxy (not seen here). It’s a very nice galaxy, but this image is noisier than it should be, and the star shapes are not really round.
Over this last summer, I got some skills:
The above is NGC 973. This image’s noise is lower, stars are tiny (well focused) and round, structure of the galaxy is obvious, and you can even see several other galaxies in the image–I count 5, your mileage may vary.
By the end of the summer and the end of my flat galaxy program, I had better control of the situation:
The above is the Needle Galaxy, NGC 4565. So last month I sent the Astronomical League 100 (!) flat galaxy images and details about how I took them and more details about geometric measurements I made on them, and then last week I received certificate number 9 for AL Flat Galaxies. But mostly this was imaging (elementary) school for me. My next AL project concerns the more difficult Arp galaxies, some images to be posted soon…
With 200 billion stars in our own galaxy, you might expect the night sky to be lit up like daylight. If you live in a big city, it just might be—but not because of starlight. But just why is it so dark at night? It took astronomers a very long time to figure it out.
Credit: NASA and The Hubble Heritage Team (STScI/AURA)
On Saturday night I was able to make time to do some imaging. I decided to image a section of the Veil Nebula. I ran a LRGB session of the Veil Nebula which finished early in the night so I thought I would try a Ha image. I have never imaged through the Ha filter and was interested to see my test results. Since this would be a long exposure it would be a good test of my auto guiding system as well. The LRGB run was 3 images at 600 sec images for each filter with guiding on a 9.5 mag star. My guide exposures were between.10 and .35 sec. The Ha filter required 2 sec guiding exposures meaning the AO would run at .5 Hz, I was interested to see how that all worked. The Ha image was to be a 1500 sec exposure so my system would have to guide well for 25 mins. The image above is the result. This is 1 exposure at 1500 sec Ha with an auto dark, no flat field. The only post processing was de-blomming in DL and levels adjustment in PS CS5. I was pleased with the resultant image and the guiding of my system, good structure in the nebula and nice round stars. PS- the LRGB images has not been processed yet. Enjoy and keep the telescopes pointed up.
Just a quick image of a recently bright comet C/2009 P1
(Garradd). The image was taken just before dawn 7-10-11 and is a compilation of 5 – 60 sec frames. No filter. The 22″ and STL1001E camera was used and it was traveling 1.37″/minute to the northwest. ( Thus the ‘drifted stars)..
cheers,
Gary
