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Latest Website Update [1 May 2015] >> New Galaxy of the Month NGC 6085 >> New Double Stars for May >> Hickson 44 is Picture of the Month

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May 2015 - Picture of the Month

Hickson 44 in the Constellation of Leo

Hickson Compact Group 44 - Image Courtesy of David Davies

Image Courtesy of David Davies, Cambridge, UK. Please click on the image for the high resolution version.

For more images from David please visit his Flickr Photostream.

This is my first observation of the Hickson 44 group of interacting galaxies in Leo some 80 million light years away.

The group comprises NGC3190 (incorporating NGC 3189) in the centre; NGC 3187, a heavily distorted galaxy to the right; NGC 3185, a barred spiral galaxy to the bottom and the big elliptical galaxy NGC 3193 to the upper left. Many other fainter galaxies are visible in this image.

I captured the data for this image on the nights of 10th and 14th April 2015. The exposures were restricted to 5 minutes each to prevent the brightest stars (magnitude 7.6) saturating. The image comprises 28 luminance subs to try and capture these faint structures plus nine each of RGB exposures for colour.

The telescope is a 10-inch F/4 Newtonian with a QSI 583 camera with Lodestar providing off-axis guiding mounted on an EQ6 mount.Image processing was with Deep Sky Stacker, Pixinsight and Photoshop. 

David Davies (20 April 2015).

Object of the Season (Spring 2015)

NGC 6572 in Ophiuchus

Planetary Nebula NGC 6572 in Ophiuchus will be announced in DSO 167, and the results will be published in DSO 169.

NGC6572 - Image Courtesy of Hubble Space Telescope (HST) This image was supplied by the Hubble Space Telescope (HST).

Position (2000)
18 12 06.4 +06 51 15 (Oph)
Visual magnitude
8.1 mag
Central Star
13.6 mag
Size
0.6' x 0.4'
Distance
2500 ly
Other Designations
Σ 6, h 2000, GC 4390, PK 34+11-1, VV 159, ARO 7

Wolfgang Steinicke - Nebulae and Clusters Section Director

May 2015 - Double Star of the Month

STF 1694 (12 49 13.80 +83 24 46.3) is one of the most northerly of the bright double stars and lies in a rather sparse area of the sky. It is worth making the effort to find it as the planetary nebula IC 3568 lies 1.5 degrees south-west. Both stars are in the Hipparcos Catalogue and though the parallaxes seem significantly different (8.14 mas for A and 5.57 mas for B), the large error on that of B means that they are the same within the quoted uncertainties. However, B is a spectroscopic binary and this may well account for the Hipparcos satellite's problems with defining its distance accurately. The primary star (V = 5.3) is an A1 giant whilst the companion (V = 5.7) consists of a pair of A0 and A2 dwarfs. The current position angle and separation is 324° and 20".9, little changed from the epoch of discovery. The proper motion of RA of both stars is significant and similar so it would appear that this is a common-proper-motion pair. In 1944 Wallenquist found a third star of magnitude 11.5 at 223° and 73" but both these values are decreasing quite quickly. Sissy Haas calls the primary 32 Cam and notes that both stars are lucid-white.

4 Centauri (H N 51) is located at 13 53 12.54 -31 55 39.4. Also known as h Cen, this is one of the pairs found by William Herschel in his last concerted campaign of double star observation and was observed on 1787, Mar 15. It is in an arc of faint naked-eye stars some 5 degrees north-west of theta Centauri and is a splendid sight in a small aperture. The stars, magnitudes 4.7 and 8.5, were measured by the writer in 2013 and were found to be at 185 degrees and 14".8. Hartung notes that the colours are pale yellow and ashy, and that both stars are spectroscopic binaries. The primary star is a subgiant of spectral class B4 which Hipparcos puts at a distance of 637 light years.

Bob Argyle - Double Star Section Director

May 2015 - Galaxy of the Month

NGC 6085 in Corona Borealis

NGC6085 - Image Courtesy the Capella Observatory

Image credit (Josef Pöpsel and Stefan Binnewies, Capella Observatory.)

This finder chart should help you locate these galaxies.

If Corona Borealis pops into the deep sky observers mind it is either because it is on the way to Hercules or because they are hunting the challenging Abell cluster AGC 2065. Home of numerous faint galaxies even in the standard references Corona Borealis hardly gets a mention.

This months challenge however are the two faint galaxies NGC 6085 and 6086 which form the core of the galaxy cluster Abell 2162. Both of the objects were discovered by Albert Marth using William Lassell’s 48" speculum telescope from Malta and were described by him as quite faint so you need to be up for the challenge.

NGC 6086 is a giant elliptical galaxy classified as a cD is at the centre of AGC 2162. Recently NGC 6086 has been shown to a harbour a billion solar mass black hole, although depending on the amount of dark matter involved that mass may drop. It also appears to be one of the brightest galaxies in the nearby universe.

NGC 6085 is a face on spiral, although except with very large telescopes, it will probably only show the core region. There are suggestions that NGC 6085 may also be a Seyfert galaxy, however this may just be a misreading of a number of papers on Seyferts where NGC 6085 was used as a control galaxy.

These two galaxies are by far the brightest members of AGC 2162. All the other members are substantially fainter as can be seen by the fact that perhaps only another half dozen made any of the older galaxy catalogues such as the UGC or CGCG. Neither the NGC galaxies nor the cluster itself make any of the venerable references such as the WSDSO Vol. 5 or, L&S or NSOG.

Abell 2162 itself is part of a filament of galaxies that joins the northern and southern Hercules superclusters together. For an expanded history of this supercluster try the atlas of the universe. This group of clusters along with the Coma supercluster have been nicknamed the Great Wall. Deep images seem to suggest that like the better known Hercules cluster Abell 2151 Abell 2162 does have a high proportion of spiral and lenticular galaxies.

Both NGC 6085 and 6086 are going to be challenging to see visually although there are a number of nice images of the field. Give it a go and see what you can find.

Astro Planner and Skytools users

There are plans created for all the Galaxy of the Month pieces from 2011 onwards. To download click for Astro Planner or SkyTools. These can be loaded in to the appropriate programs so that it may be easier to find what galaxies have been covered so far. These will be updated as new GOM’s are added.

Owen Brazell - Galaxy Section Director

Deep-Sky Observer (DSO) No 153 - Free Sample

DSO153 Cover

This free journal is DSO 153 from 2010. You can download it as a PDF file onto your computer by right clicking the link below and choosing either 'Save Target As' or 'Save Link As'...

Download DSO 153 (2MB PDF file)

Clear Skies Observing Guides (CSOG)

Courtesy of Victor van Wulfen.

Clear Skies Observing Guides Banner

Webb Deep-Sky Society member Victor van Wulfen produces the CSOG. He's recently relaunched the website with version 2.1, so now would be a good time to take a look.

The Brightest Planetary Nebulae Observing Atlas - 2nd Edition

Massimo Zecchin has just completed the 2nd Edition of an atlas of planetary nebulae observed with small apertures and from suburban locations, entitled: "The Brightest Planetary Nebulae Observing Atlas".

Massimo has kindly made the atlas is freely available in two versions, Black (for display) and White (printer friendly with the images in negative).

The 2nd Edition contains:

  • Six additional objects.
  • Data of visual magnitude, central star magnitude and object size from the Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (SEC catalogue) and in a few cases from the Saguaro Astronomy Club database (SAC catalogue).
  • Calculated surficial brightness for any object (in magnitude per square arcsec).
  • Six additionaltables showing the objects sorted by magnitude, surficial brightness, size, central star mag, constellation and declination.
  • A general position map.

Either version of the atlas can be downloaded as a PDF file onto your computer by right clicking the respective image above and choosing either Save Target As or Save Link As...

Please note that the Black version is 14MB and the White version 10MB