#1  
Old 09-02-2008, 10:45 AM
你B
Its only a column of dust

你B is offline
 
Join Date: Aug 2007
Location: New Iceland
Posts: 761
Southern Milkyway Coolness - Jan 15, 2008

Well seeing as I'm bored and the weather is being pissheadish (or normal Melbourne style) of late, I thought I just post one of my observations from last month.

Headed out on the morning of Jan 15th for a sweep of the southern milky way. In typical fashion it was cold, about (-)13慢 but nice and dry. Seeing was okay but transparency was nothing to crow home about.

Instrument: 10" GSO dob
Time: 3-4.30am
Seeing: 6/10
Transparency: 3/5

Just did some low power scanning of the area. One of my favourite things to do is drop in the 22mm Vixen, the UHC or OIII and go for a cruise of the whole Carina/Centaurus/Vela/Crux region. Always a SAB pleaser.

Eta Carinae neb
The difference between an unfiltered and the OIII view never fails to amaze me. With the OIII and the 22mm, I have to scan around to take in the whole Nebula. Basically the whole complex takes on a similar extent to that seen in photos. My mum was pretty darn impressed aswell!

Homunculus Nebula
The seeing is very good at killing this one off. Its intense orange colour is clear and at 156x-192x I could easily see its two lobes and structure within.

Pencil Nebula
After seeing this in the 18" Obsession, I figured I'll give it a crack. I remember that the best views of this were atlow power. So I tried with the 17 Vixen at 73x with and without filters. Nothing seen.

NGC 3293
Excellent, rich, tightly packed open cluster with several blue members puntuated by an orange supergiant star near its center. Loved the views at 96x, really gives it a spectacular rich appearance. My mum squealed a 'wow' when she saw it!

NGC 3532
The graddaddy of all open clusters. Huge, huge, spectaculary rich football shaped swarm of blue stars at lower powers. A red star lies near its center.

NGC 3699
Interesting planetary in Centaurus, which is easily found about 40' SW of o1 and o2 Centauri. The 10" at 312x showed an interesting Pac-Man shaped object with the "mouth" converging and extending inward to basically split the figure in half. The OIII filter delivered good contrast gain.

Now if Melbourne's infinitely crap climate would clear........... lol as if!
Reply With Quote
  #2  
Old 09-02-2008, 12:00 PM
ngcles's Avatar
ngcles
The Observologist

ngcles is offline
 
Join Date: Dec 2006
Location: Billimari, NSW Central West
Posts: 1,543
Hi 你B,

Liked the report again, and it is good to hear that some people are able to do some actual observing. I can't remember a clear night in Sydney for weeks and for most of the last week, it has just bucketed down -- "Melbourne" weather. As I type now, it is quite cool outside about 17 deg C, pouring with rain and a cool SE breeze -- very untypical for Sydney February! Curse of the new moon of course.

You mentioned the "Pencil Nebula" in your report and I assume you mean NGC 2736 in Vela which is probably associated with the Vela SNR.

Keep trying -- it is definitely visible in 25cm with a UHC filter even from outer suburban Sydney (Though very faint)). Here are my notes from home back in 1995 with a ZLM of +5.1:

x56 -- 26mm Televue plossl "Very faint streak of nebulosity in PA 20. at its brightest near a couple of mag 10 *s. Quite thin, like a ribbon only 1' diameter but in a sinuous , slightly curved line 15-20' long, not nearly as bright as the Veil SNR in Cygnus though similar in character. This could be most interesting in a DK sky. Seems patchy in brightness along it's length. Br portion seems in the middle of the ribbon."

And viewed from my nearly dark site (ZLM about +6.2) in the southern highlands in 1997 I think: x56 -- "Faint but quite visible even without filtration, Nr a couple of mag 10 *s, appears much straighter in a dark sky, long sinuous streak, maybe 25' (arc-mins) x 20" (arc-seconds) in PA 20. Brightest in centre. Very thin like a straight wisp of cigarette smoke."

It is a really beautiful object in 18".


Best,


Les D
Contributing Editor AS&T
Reply With Quote
  #3  
Old 09-02-2008, 12:22 PM
你B
Its only a column of dust

你B is offline
 
Join Date: Aug 2007
Location: New Iceland
Posts: 761
Hey Les

Upon further research, it turns out that the object I was hunting WASN'T actually the Pencil Nebula. In the MSA, I found a detached portion of the Vela SNR whose outline almost matches what I saw in the 18", but the Pencil nebula's coordinates are completely different. But before I knew this I assumed it was the pencil neb because of the shape of the outline. In the MSA there is actually nothing plotted where the Pencil Neb is supposed to be NGC 2000.0 gives the right coordinates but labels it as a galaxy!
Reply With Quote
  #4  
Old 09-02-2008, 12:45 PM
AJames
Southern Amateur

AJames is offline
 
Join Date: Apr 2007
Location: Sydney
Posts: 283
Smile

Quote:
Originally Posted by ngcles View Post
,You mentioned the "Pencil Nebula" in your report and I assume you mean NGC 2736 in Vela which is probably associated with the Vela SNR.
Les from my yet unpublished Neat Southern Planetary (NSP 42), notes that NGC 2736 is certainly "The Pencil" (09h 00.4 -45 deg 54') in Vela.

I like my view that...

"This small patch of nebulosity is sometimes called "The Pencil" I prefer calling the more descriptive "The Shard", as the word "shard" means "a broken piece of a brittle artefact", which adequately described this small part of the Vela Supernova Remnant."

Andrew
Reply With Quote
  #5  
Old 09-02-2008, 12:57 PM
AJames
Southern Amateur

AJames is offline
 
Join Date: Apr 2007
Location: Sydney
Posts: 283
Smile Other Interesting Objects in this Region...

Les I also like this object in the same area as the Pencil;

Cr 197 (08 44.7m -41 deg 17') and Gum 15 / RCW 32 (08h 44.6m -41 deg 17') is an open cluster containing the small bright nebula known as Gum 15 which surrounds the multiple star of I 815. Surprisingly missed in AOST2, it can be found some 2.2 degrees North of the wide pair of 4th magnitude d Velorum / HJ 4133 (08 44.4m -42 deg 39') and 0.8 degrees N of NGC 2671 - our Pencil - which is an open cluster..
This open cluster covers about 17 arcmin of sky whose nine stars, whose brightest four stars make up the multiple 1815. At 6.7 total magnitude, its singular blue star, followed by the remaining yellow stars, are classed as “3 3 m n” - the “n” being the bright nebula Gum 15.
South African visual observer Auke Slotegraaf claims to seen the clusters' shape as triangular in 1180 binoculars, but comments it was "... Not an easy object." I looked for this in 750 binoculars and did not really see much. Auke also observed the cluster in his 25cm (10") f/5 Newtonian at 30x.. Describing it as a "typical Collinder cluster", he describes its shape as;

"... reasonably large and the brighter members seem to lie in an uneven, curving V-shape grouping of l l stars, 5 of which are pretty bright. The 'V' points north to a very unequal double star, [I 815]…"

I 815 (08 44.7m -41 deg 17') is the multiple star whose four components are listed as AB (7.3v and 11.5v, 4.4 arcsec 2 deg), AC (7.2v and 13.3v, 8.3 arcsec 130 deg) and AD (7.2v / 11.0v 35 arcsec 225 deg). I 815 appears on Map 397 in Uranometria 2000.0 drawn with the "box" of nebulosity of superimposed Gum 15. The AB and AD pair was first discovered by Innes in 1911, and AD is the widest an most easiest to see. The AB system can be seen with 10.5cm with care and is easier in 20cm - the problem being the magnitude difference. AC is slightly more difficult, and should be visible in 20cm under good seeing and moderately high magnification. Again, the five-odd magnitude difference made it hard combined with the faint 13.3 magnitude. I glimpsed I 815 C once in 30cm in moderately good seeing and made a rough sketch. This later star was discovered by Innes in 1933.
All stars in this system are bluish-white, likely matching the spectral class of B3/5 II of the primary. Little has changed in the positions since discovery, and it is uncertain if these stars are dynamically behaving like multiples or as open clusters, but they certainly must be associated. 1 815 certainly adds to the Cr 197's appearance.

As for Gum 15...

"Gum 15 (08h 44.7m -41 deg 17') is the faint emission nebulosity centred on the primary 7.3 magnitude star of the double I 815, of which, can be imaged some 10 arcmin around it. Telescopically in the 30cm it appears as a faint haze about 1 arcmin across, which is significantly enhanced with averted vision. The proximity of the component stars make it a bit of a challenge to see.
It is possible that 25cm, or even 20cm, might be able to see this nebula, but larger apertures may see a little more nebulosity. Either way, to see Gum 15 you will need dark and fairly transparent skies."
Reply With Quote
  #6  
Old 09-02-2008, 01:20 PM
ngcles's Avatar
ngcles
The Observologist

ngcles is offline
 
Join Date: Dec 2006
Location: Billimari, NSW Central West
Posts: 1,543
Hi 你B, Andrew & All,

Hmmm ... Andrew, sounds like a very nice set of objects in one field, I must admit that I haven't observed that cluster and the associated pairs and nebulosity. It is the right time of year -- except for the %$#&^ clouds!

But I do happen to have an observation of the nearby OC NGC 2671 you mentioned in passing back from 1999 with my old 25cm:

"x181 34' TF. Mag 11.6p Size 4'. At x86 this appears as a small weak haze. At x181 a few *s resolve with residual haziness. Perhaps 5' diameter, scattered. Haze is about 3'-4' diameter with numerous very faint *s there, rising broadly and slightly to the centre. Low S.B.

Best,

Les D
Reply With Quote
  #7  
Old 09-02-2008, 02:49 PM
你B
Its only a column of dust

你B is offline
 
Join Date: Aug 2007
Location: New Iceland
Posts: 761
Thanks Ajames, will try these next time, should Melbourne's moronic weather cooperate.

Gum 15 sounds like a good challenge.

Here's a few more to add to that list, based on my own observations from my 4.5-5 NELM sky with my 10" dob:

Gum 39
50' WNW of Lamba Centauri. Virtually invisible without a filter, but at low powers with a UHC a faint elongated haze is visible oriented E-W. A 9th mag star lies at its southern edge. An arc of 3 10-11th mag stars forms the nebula's eastern border.

IC 2872
Located adjecent to Gum 39's southern edge. Have not successfully spotted it.

Cederblad 122
Extensive nebulosity located just E of the coalsack, at approx RA 13h 28m, Dec -64. I have seen the section between the open clusters Cr 271 and Ru 16, centered at approx RA13h 27m, Dec -6340' in my 10" at low power with a filter. It appeared as a faint, stubby, elongated smudge stretching between the two aforementioned clusters, with its western boundary clearly defined by an embedded dark nebula. I have also seen this nebulosity with an NP101 and a 31mm Naglar without filtration at a dark sky site.
Reply With Quote
  #8  
Old 10-02-2008, 03:01 PM
ngcles's Avatar
ngcles
The Observologist

ngcles is offline
 
Join Date: Dec 2006
Location: Billimari, NSW Central West
Posts: 1,543
Cr 197 & Gum 15

Hi 你B, Andrew & All,

AJ wrote:

"Cr 197 (08 44.7m -41 deg 17') and Gum 15 / RCW 32 (08h 44.6m -41 deg 17') is an open cluster containing the small bright nebula known as Gum 15 which surrounds the multiple star of I 815. Surprisingly missed in AOST2"

Well, this was at the top of my list last night after this discussion and I can't find myself in agreement AJ about it being overlooked for AOST. Sorry!

I observed it with the 18" with the 16mm T2 at x139 35' TF, 20mm T2 at x111 with 44' TF and 26mm T5 x85 58' TF, with and without UHC, OIII and H-Beta filters and the best view was with the 20mm T2 unfiltered.

The cluster is a poor and scattered one with no central condensation apparent and is completely resolved. There are slightly more stars N of the central star than south of it. It is dominated nr centre by the multiple star Innes 815. All three of the faint companions in Innes 815 are easily seen at x111. The cluster contains 20-odd stars scattered over about 15 arc-mins diameter and is not detatched from its surrounding fields -- the borders of the cluster are not defined at all and the field seems equally rich as the cluster. Large variation in brightness between members between mag 7 to 13.

The visible portions of Gum 15 is considerably less than the DSS shows and are pretty faint. I thought the best view was without the filter. The nebula is classified as "E" but it does not seem to have much/any emission component as to me it seemed dimmed to the UHC and completely disappered with the O III and H-Beta. Only a maybe 2-3 arc-min diameter very LSB haze surrounding but mainly to the N of Innes 816 with no defined border.

I also took another look at the (nearby) OC NGC 2671 at x138 and in the 18" it is a nice object. Seems about 7 arc-mins in diameter as a well detatched splash of 3 dozen-odd faint stars mainly in the 13th to 14th mag range pretty homogenous in brightness. Within the cluster a large triangular-shaped group on the N side stands out with points of that triangle at centre, PA 30 and PA 330, about 3-4 arc-mins a side. Quite nice. Seems completely resolved and no residual haziness is evident. The NGC indicates a diameter of 4 arc-mins -- I think this is a bit of an under-estimate -- more like 7 arc-mins and the magnitude should be more like about 9 rather than 11.6v.

Best,


Les D
Contributing Editor
AS&T
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 04:08 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
Celestron Australia
Advertisement
OzScopes Authorised Dealer
Advertisement
Lunatico Astronomical
Advertisement
Bintel
Advertisement
Meade Australia
Advertisement
SkyWatcher Australia
Advertisement
NexDome Observatories
Advertisement
Astronomy and Electronics Centre
Advertisement