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Latest Website Update [1 July 2015] >> New Galaxy of the Month for July >> New Double Stars for July >> A southern Picture of the Month: NGC 6744

Alvin Huey Guides.

For those of you that missed them at the AGM, the observing guides produced by Alvin Huey (of FaintFuzzies fame) are now available. And yes, that includes the ones you can't download.

July 2015 - Picture of the Month

NGC 6744 in Pavo

Something from the southern skies this month with data collected by The Star Shadows Remote Observatory (SSRO) at PROMPT2 - CTIO near La Serena in Chile.

This image is provided with the kind permission of Warren A. Keller. The images were acquired by SSRO: Warren Keller, Steve Mazlin, Steve Menaker, Jack Harvey.

Please click on the image to be taken to Warren's website for a higher resolution version.

In Warren's words

NGC 6744 in Pavo likely resembles our Milky Way, and is one of its largest and closest neighbors. At 30,000,000 light years distance, it is approximately twice the diameter of our own galaxy. Its flocculent (fluffy) arms are rife with pink, HII star forming knots.

This data set from 2014, is the second I have processed from the SSRO archive. I dedicate this work to the late Tammy Plotner, who passed away at much too young an age. She was a great friend to astronomy, and a supporter of mine. May you go among the imperishable stars!

Object of the Season (Summer 2015)

Galaxy Pair NGC 1 and 2 in Pegasus

Galaxy Pair NGC 1 and 2 in Pegasus will be announced in DSO 168, and the results will be published in DSO 170.

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 Sloan Digital Sky Survey (SDSS). NGC 1 is the northern object.

NGC 1

Position (2000)
0 07 15.9 +27 42 32 (Peg)
Visual magnitude
12.9 mag
PA
120°
Size
1.7' x 1.2'
Distance
206 Mly
Other Designations
GC 1, UGC 57, MCG 4-1-25, CGCG 477-54, KCPG 2A, PGC 564

NGC 2

Position (2000)
0 07 17.1 +27 40 43 (Peg)
Visual magnitude
14.2 mag
PA
112°
Size
1.0' x 0.6
Distance
347 Mly
Other Designations
GC 6246, UGC 59, MCG 4-1-26, CGCG 477-55, KCPG 2B, PGC 567

Wolfgang Steinicke - Nebulae and Clusters Section Director

July 2015 - Double Star of the Month

lambda Ophiuchi (STF2055 - 16 30 54.84 +01 59 02.8) lies about 6 or 7 degrees south of a cloud of stars all of which are called tau Serpentis, and it is about a degree north-east of the somewhat brighter star alpha Serpentis. During the 19th century, measurements showed the two stars slowly separating and reaching a maximum distance of about 1".9 in the early 1880's. In 1906, Thomas Lewis, in his book on the Struve stars, considered that the period was about 130 years which as it turns out was a good attempt. The current period from observations of almost 2 revolutions gives a period of 129 years and a predicted position for mid-2015 of 42° and 1".43. The pair is not particularly easy to observe, partly because of its altitude in the sky - it is barely above the celestial equator - and partly because of the magnitude difference between the two components. Both stars are A0 dwarfs, according to the WDS, and lie at a distance of 173 light years.There are two much fainter stars at 120" and 308" which appear unconnected to the system.

DUN 219 (17 58 55.69 -36 51 30.2) lies not far from the spectacular open cluster Messier 7 and follows G Sco by about 2 degrees. It has not been included in either Hartung or the book by Sissy Haas but is nevertheless is a splendid sight. The stars are magnitudes 5.8 and 7.8 and the separation derived by Dunlop in 1836 of 47".1 has now increased to 53".5, (with the position angle changing from 265° to 252° over the same interval of time), making it a striking object object in small telescopes. The USNO include the pair in their linear elements catalogue, confirming that the two stars are entirely unrelated. A third star of mag 11.3 can be found at 40" from A. Just 16 seconds of time following and 8 arc minutes south is HJ 5000 AB, stars of magnitudes 7.1 and 8.9 separated by 7".3 but apparently in orbital motion. The writer measured this pair in 2010 and noted pale yellow and pale blue - pretty.

Bob Argyle - Double Star Section Director

July 2015 - Galaxy of the Month

NGC6503 - Image Courtesy of Bob and Janice Fera

This image was provided by Bob and Janice Fera. I’d recommend you follow the link to see the rest of their work. You can click on the image for a larger version.

The bright nights of July from mid northern latitudes make hunting faint galaxies a bit of a challenge so this month’s object is a little brighter than previous GOMs.

NGC 6503 was discovered by Arthur von Auwers in 1854 using a 2.6” refractor whilst he was a student which is sort of odd then as to why if it was so bright it was missed by William Herschel. NGC 6503 was one of two NGC objects Auwers’s discovered, the other being NGC 4402.

NGC 6503’s Dreyer code of pF L mE *9 f4 however suggest that it’s large size may have been an issue as perhaps would have been its location close to the pole. Modern references describe this as a high surface brightness object visible in small instruments. NGC 6503 is classified as a dwarf spiral galaxy (SA(s)cd) seen nearly edge on. It is about 30000 light years across and maybe 18 million light years away. This makes it about a third of the size of our Milky Way galaxy. NGC 6503 is an isolated galaxy lying on the edge of the Local Void. The Local Void itself maybe 150 million light years across and contains few stars and galaxies. NGC 6503 appears to have almost no central bulge and a large halo. Its nucleus however is a weak form of AGN known as a LINER which may come from a starved black hole. Here LINER stands for Low Ionization nuclear Emitting Region. Something like 33% of galaxies in our local area appear to have this kind of spectra. There’s rather nice recent image of NGC 6503 taken by Hubble. The Hubble image shows the bright blue stars and HII regions of an active star forming galaxy.

The location of this galaxy caused it to be named by Steve O’Meara in his Hidden Treasures book the Lost-in-Space galaxy. I am not sure if this nickname will stick. Recent observations however with the Subaru telescope suggest it might not be quite as alone as it appears to have a dwarf companion named NGC 6503-d1. This new galaxy maybe a dwarf Spheroidal and although its location is uncertain it is most likely associated with NGC 6503.

A sketch of NGC 6503 with a 20cm telescope can be found on Astronomy Sketch of the Day. And there’s an interesting, although perhaps over processed, amateur image too.

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