NGC2808

Image Credit: P. Vaisanen/T. Koen/S. Crawford, SALT Foundation

NGC 2808 is one of the oldest known globular clusters in the Milky Way.   It is located in the constellation Carina and it is  31,000 light years away from the Earth.      The image is a composite image from SALTICAM of three images taken in the SDSS u,g,r filters and the black region in the center of the image is the gap between the two SALTICAM CCD chips. 

DEM L241

Image Credit: P. Vaisanen/T. Koen/S. Crawford, SALT Foundation

A SALT image of  DEM L241, an HII region containing a supernova remnant, in the Large Magellanic Cloud.  The almost ghostly, green clouds seen in this image are emission from hydrogen gas in the cloud and remnant.   Astronomers are using SALT to study the binary star at the center of the supernova remnant.   The empty black region in the image is the gap between the two CCD chips that make up the SALTICAM imager. 

A Tarantula on SALTICAM

This astronomy gig calls for pretty pictures now & again so here's one of the Tarantula Nebula (aka 30 Doradus or NGC 2070), a huge star formation region in one of our neighbouring galaxies, the Large Magellanic Cloud (about 160,000 light years away).  If this complex were as nearby as the famous Orion Nebula, it would be bright enough to cast shadows on Earth!  The stars in the central cluster are about 1-2 million years old & emit energetic UV radiation that excites the surrounding clouds of hydrogen & causes the gas to glow..

This colour composite image is the result of six 5-second frames obtained through 3 filters, known as SDSSg, SDSSr & SDSSi.  These filters transmit green, red & near-infrared light respectively so this isn't quite what the nebula would look like with the naked eye.  The plan was to fill in the gap between SALTICAM's two CCD chips by combining images with the object on either side of the frame, but unfortunately we moved the telescope a bit too far so we get to keep the gaps this time!

NGC 5364

The beautiful face on spiral galaxy NGC 5364 is shown above in a false-colour optical image. The extensive spiral arm structure is clearly visible, winding around the central galaxy bulge. The bright coloured spots within the spiral arms indicate the positions of HII regions which are areas of large (some can be several hundred light years across!) clouds of ionized gas associated with intense star formation. The galaxy is located in the Virgo cluster around 70 million light years from Earth (redshift of 0.004) from us.

NGC 5364 was observed using the RSS on SALT in Fabry-Perot mode on 11th May 2011. A succession of 60s images scanning across the H-alpha (6563A) emission line were taken and three of those images were combined to produce the colour picture above. The colours shown provide a sense of the rotation of the spiral arms. Blue colours show regions that are moving towards us (the peak of the line emission is blueshifted relative to its rest wavelength) and red colours show regions that are moving away from us (the emission is redshifted).

Foreground stars are visible in white in the image, and if you look carefully you can spot the Fabry-Perot ghost of the bright star on the bottom left of the image. The ghost is situated at the top right of the image. As a consequence of not auto-guiding during these observations, the position of the ghost is slightly different in each individual image frame used to produce the resultant colour image and therefore the three constituent colours are clearly separated in the final picture.

NGC 6781

NGC 6781 (top) is a planetary nebula (PN) in the constellation of Aquila. The main ring measures approximately 2 arcminutes in diameter and is about 1 kpc distant. The true 3D geometry of a PN cannot usually be grasped from images alone and studies have indeed shown that NGC 6781 is a toroidal shell (bottom, Schwarz & Monteiro 2006) typical of so-called bipolar nebulae. If you look carefully you can make out numerous filaments of dust which are responsible for the patchy reddening observed in this nebula. NGC 6781 was observed on 10 May 2011 with RSS in Fabry-Perot mode which scanned through the emission lines Halpha 6563 (green), [NII] 6583 (including HeI 6678, red) and [SII] 6730 (blue). The ionising central star is best shown at bluer wavelengths (see here).

Credit: Observers were Ted Williams, David Buckley, Brent Miszalski (processing and write-up), John Chisholm and Nicola Loaring.

NGC 5750

NGC5750 is barred lenticular with narrow-line AGN. The most prominent features of NGC 5750 is ring and several intricate dust lanes. A weak bar is surrounded by the ring. The ring is broken at severally places which gives the impression of tightly overlapping spiral arms starting at opposite ends of the bar. NGC 5750 was observed on 10th May with SALTICAM in B,V, R and Halpha filters with 15 second exposure time in each filter.

Credit: Observations made by David Buckley and Petri Vaisanen and color image and write-up by Sudhanshu Barway.