Bulletin Board

Latest Website Update [1 Dec 2015] New Galaxies and Double Stars of the Month for December >> More observations of September and November objects

We have a date for the 2016 Annual Meeting: 18 June 2016.

The news section contains more detailed items. I try to post items that may be of interest to members there. If you have suggestions, please contact me.

December 2015 - Picture of the Month

NGC 1555 (Hind's Variable Nebula) in the Constellation of Taurus

I’m a fan of variable stars and I don’t get the chance to put an image of one on the website often. I'd have to admit that might be because they’re… not particularly spectacular normally.

NGC 1555 (Hind's Variable Nebula) and T Tauri acquired and preprocessed by Bill Snyder and postprocessed by Warren Keller

I think that T Tauri in the image above is an exception being associated with an interesting class of objects: the nebula surrounding the young star that also varies in brightness.

This beautiful image was provided by Bill Snyder, who acquired and preprocessed the data that was subsequently postprocessed by Warren Keller.

For a more detailed version please visit Warren's website: Billions and Billions.com.

James Whinfrey - Website Administrator.

Object of the Season (Autumn 2015)

Planetary nebula NGC 1501 in Camelopardalis

Planetary nebula NGC 1501 in Camelopardalis will be announced in DSO 169, and the results will be published in DSO 171.

The optical galaxy pair NGC 1 and NGC 2 in Pegasus: NGC 1 is the northern object - Image Courtesy of Sloan Digital Sky Survey (SDSS) This image was supplied by the Hubble Space Telescope (HST). Credit: ESA/Hubble & NASA Acknowledgement: Marc Canale

NGC 1501

Position (2000)
4 06 59.4 +60 55 17 (Cam)
Visual magnitude
11.5 mag
Central star
14.4 mag (CH Cam)
4200 ly
Other Designations
IV 53, GC 801, PK 144+6.1, ARO 44, VV 16

Wolfgang Steinicke - Nebulae and Clusters Section Director

December 2015 - Double Star of the Month

Epsilon Arietis = STF 333 (02 59 12.73 +21 20 25.6) can be found 17 degrees following beta Arietis. It is in a rather sparse area of sky and for those without setting circles this is probably the easiest way to find it.

It is a splendid binary star with both components of mags 5.2 and 5.6 being white to most eyes although W. H. Smyth fancied that he saw a pale yellow hue to the primary star and the secondary was 'whitish'. Smyth also noted that the Reverend Dawes first saw this pair at his observatory at Bedford.

Struve noted is as being amongst the closest of his discoveries (0".5) and subsequent observations showed it widening with a small increase in position angle. Over the last century there has been little motion of note except that the companion now seems to have reached greatest elongation and is slowly heading back towards the primary star.

In Webb Society Double Star Circular No 17 (2009) Ian Coster produced an orbit for STF 333 with a period of 313 years and three years ago Francisco Rica published one with a period of over 1200 years, so the future motion is almost entirely indeterminate. The pair will certainly remain an excellent test for 10-cm aperture for a few years yet, and the current separation is 1".34. A faint field star of mag 12.7 is 146" distant.

John Herschel swept up the coarse triple HJ 3644 (04 21 31.29 -25 43 42.4) in 1836. It is located in an empty region in Eridanus and can be found by firstly locating the bright pair nu3 and nu4 Eri and moving about 9 degrees due north.

Herschel noted the stars had magnitudes 6, 8 and 14 and only estimated angles and separations. Modern catalogues give the brighnesses as 6.2, 8.2(C) and 13.0(D) and the distances between AC and AD are now 41" and 44". Burnham found the A star to be a close double in 1879 when using his 6-inch refractor on Mount Hamilton in California, fortuitously as it turns out because the pair was then at its widest separation of 0".65.

For a few years after discovery motion appeared rather slow but accelerated considerably in the second decade of the last century and the pair closed up to 0".2 by 1920. Modern computations give orbital period as 81 years and at the present time the stars are slowly widening. The position for 2016.0 is 222°, 0".40 so at least 25-cm is necessary to see the pair divided. The WDS lists the magnitudes of AB as 6.6 and 7.3.

Bob Argyle - Double Star Section Director

December 2015 - Galaxy of the Month

NGC 691 Group in Aries

This interactive image of the NGC 691 group was provided by the Sloan Digital Sky Survey using Aladin Sky Atlas.

The NGC 691 group is a collection of 9 galaxies consisting of NGC 678, 680, 691, 694, 695 and NGC 695 along with IC 1730 and IC 167.

The group is spread over quite a wide area with almost a degree spanning NGC 691 and 695. The core of the group is centred around NGC 691, 678, 680 and NGC 694. NGC 678 and 680 were discovered in William Herschel in 1784 but it was two years later in 1786 before he found 691. Heinrich d’Arrest found NGC 694 in 1861 as it is much fainter than the others. Perhaps unusually for an IC object Bigourdan found IC 167 using a 12” refractor in 1889.

The whole group is spread around the bright double star 1 Ari. This may make it more difficult to see than it should be.

The group is about 122 million ly from us which is relatively close by and explains the large angular spread of the group on the sky.

NGC691 was home to SN 2005W, although it only reached magnitude 15.2.

Both NGC 691 and NGC 678 feature in the Webb Deep-Sky Society Observer's Handbook (WSDSOH) Volume 4 where both are described as brightish in a 16” telescope.

Night Sky Observer's Guide (NSOG) reports the two brighter members as easy in 22cm and the others as more challenging.

Interestingly most of the galaxies are spirals or lenticulars with only NGC 680 a confirmed elliptical, and a peculiar one at that as it shows signs of recent interactions or mergers with a number of shells. NGC 680 also appears to be interacting with NGC 678 as well.

There is an interesting amateur image of the whole group at Astrophotography by Alson Wong.

Split away from the main group on the other side of 1 Ari are NGC 697 and 695. NGC 697 is a nice bright spiral but NGC 695 is much fainter and although catalogued as a double galaxy its faintness suggests it might not actually be a member of the group. Its recession velocity from NED, if correct, is 3 times greater than the others in the group. It certainly appears in front of a field of much fainter galaxies. There also appears to be some confusion over the identity of NGC 697 with Harold Corwin suggesting it is actually NGC 674 and d’Arrest was confused and saw the same object twice.

The Megastar chart with this does not identify IC 1730, so there is a second more detailed chart from SkyTools that does.

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