NGC 5792 with 22 quasars and AGN's. Now with red shift marked.
NGC 5792 in Libra, with some 22 quasars and AGN's, and their red shifts (z) from NASA's Million Quasar Catalogue marked.
Our shot (Original image here) is quite deep - 18 hours of luminance plus 3 hours each of RGB taken with a 20" PlaneWave.
The catalogue is patchy and only covers the bottom half of the image. A red shift of 3.5 indicates that the light was emitted about 12 billion years ago.
Most of the quasars have an obvious blue colour to them. A quasar is the highly red-shifted light from an active galactic nucleus of an extremely distant and itself usually invisible galaxy, emitted as material spirals torrentially into the central black hole. The blue colour in our image would have been invisible hard ultraviolet when emitted, but it has been stretched by the expansion of the universe.
Excepting in the zenith, seeing was about the worst we've ever experienced while taking this image over the last week, so its main claim to fame is depth, lots of quasars and AGN's, and (hopefully) accuracy of colour.
Annoyingly, I've just this minute discovered how to search the NASA one million quasar catalogue for all quasars within a specified radius. There are 35 quasars within 20 min arc of the centre of the image.
Was that using the NED? It's been on my list to tidy up an image of NGC1365 that has about a dozen quasars in the background. I located them a bit laboriously with NED and Sky-Map, but it was still pretty exciting to image a tiny speck of light that has a redshift of 3.17, from only 2 billion years after the Big Bang, and a co-moving distance of 21 billion light-years away, all from the backyard! NED is great because you can confirm you've identified the right speck, then get cosmological data if you want.
NED seems patchy on quasar distribution (??), or at least my selective searches around the few galaxies I've imaged, like M83, produced far fewer hits than NGC1365 - and I'd presume that the quasar distribution isn't that anisotropic!
Was that using the NED? It's been on my list to tidy up an image of NGC1365 that has about a dozen quasars in the background. I located them a bit laboriously with NED and Sky-Map, but it was still pretty exciting to image a tiny speck of light that has a redshift of 3.17, from only 2 billion years after the Big Bang, and a co-moving distance of 21 billion light-years away, all from the backyard! NED is great because you can confirm you've identified the right speck, then get cosmological data if you want.
NED seems patchy on quasar distribution (??), or at least my selective searches around the few galaxies I've imaged, like M83, produced far fewer hits than NGC1365 - and I'd presume that the quasar distribution isn't that anisotropic!
where you can enter the RA/Dec of the centre of your image and a search radius, and it produces a table. I found it easiest to save the "printer friendly" version. I then precessed the table from J2K to the current equinox, and plotted them along with the Tycho I star catalogue. I then used PhotoShop to superimpose the plot over the photo. Confident that there are packages out there to do all this, but it's part of the hobby for me to do all the maths myself.
As you said, the distribution of the sky that they have surveyed is extremely patchy. That's partly because you can't find quasars against the milky way background, so they've chosen very carefully where to look. But even round NGC 5792, they just happen to have surveyed the southern half of our image, and not the northern half !!!
Quote:
Originally Posted by RickS
Interesting image, M&T, and good to see some unusual objects in the field!
Cheers,
Rick.
Thanks Rick.
Quote:
Originally Posted by Bassnut
Thats a brilliant shot Mike n Trish, tack sharp and excellent star colour. Unusual and great to see other quasars in it. Deep indeed.
Thanks, Fred. I'm cobbling up the 35 quasar version for posting tomorrow.
Excellent capture guys! Really enjoyed wandering around this image, spotting the quasars is very cool too...umm?..have I mentioned that I would loveyour scope
We've now edited both the thumbnail and the original image to show 34 of the 35 quasars in the milliquas survey. They go down to mag 22, and a red shift of up to z = 3.5.
Apart from circling lots more quasars, the images themselves are unchanged.
Quote:
Originally Posted by strongmanmike
Excellent capture guys! Really enjoyed wandering around this image, spotting the quasars is very cool too...umm?..have I mentioned that I would loveyour scope
Nicely done guys and a pretty reasonable shot even if the seeing was bad. A 20" Planewave - scrumptious! Don Goldman of Astrodon filters fame (I have his old scope) has a 20" Planewave at his southern site.
Crazy that in 1973, a redshift of 2.877 marked the most distant distance-measured object known - and while there's a *huge* difference between just seeing a speck and taking its spectrum, it's impressive for amateurs to see out that far.
(1) We've added the fractional red shifts (z) from NASA's Million Quasar Catalogue. Closer inspection of the image and the catalogue show that two or three of the objects are near enough to be resolvable as galaxies. Most of the objects are billions of light years away. The furthest, with a fractional red shift of 3.5, is so far away that its light was emitted about 12 billion years ago.
(2) Gaffe: Although there were 35 objects found in our search of the catalogue, only 22 are on the map. I am the Count. I love to count. However, since the top half of the image is not covered by the catalogue, perhaps another 15 or 20 tiny little blue dots in the image are quasars too!
Andy, Jason, Steve, thanks for your kind comments.
Excellent field and very interesting job done on marking all those small quasars Mike. The background looks a bit uneven, I would try to correct a bit some gradients to give more focus on the galaxy itself..
Regards
Marco
Excellent field and very interesting job done on marking all those small quasars Mike. The background looks a bit uneven, I would try to correct a bit some gradients to give more focus on the galaxy itself..
Regards
Marco
Hi, Marco. Thanks for the useful comment. I expect I've pushed the background unnecessarily hard, finding every last quasar (bar one), and that's done the main galaxy and the image as a whole quite a disservice. I should do a separate version, ignoring the Q's.
