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Old 09-03-2009, 05:01 PM
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ngcles
The Observologist

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Observing Report 28 February 2009 - NGCLes

Hi All,

Comes as a bit of a surprise to me that this is my first observing report for 2009, but that’s the way it is with the way Sydney’s night time weather has been – lousy. And that trend extends into this report as you will see dear reader.

The week before the night of Sat the 28th had been very cloudy with some rain too but there looked like there was some hope on the horizon. As the Saturday afternoon progressed the sky looked pretty poor with a mix of low and mid-level cloud. The satellite image however strongly suggested that things should improve as the Sun headed toward the horizon – and it did. By the time 6pm things were improving quickly and on my arrival at the Bargo site, it was completely clear.

After assembly and collimation the sky looked really good as twilight progressed we took a bright-sky look at a few bright favourites like M42, NGC 2169, NGC 2362 and NGC 2547. Finally we had a good look through the 15x70s at C/2007 N3 Lulin. Still pretty low in the southeast it looked so much better than from home with nice tails, a good sized coma, cyan tone and an almost stellar but not exceptionally bright pseudo-nucleus. I thought it should be naked-eye later on nearer culmination

By 9pm it was dark enough to commence serious observing with the SQM-L showing 21.3 (ZLM +6.3) and I had a stack of galaxies in Antlia to look in on. So just after 9pm …


x185 27' TF

IC 2510 Galaxy *
RA: 09h 47m 43.4s Dec: -32° 50' 16"
Mag: 14.9 S.B.: --- B-V: ---
Size: 1.2'x0.6' Class: SB(rs)ab.A.: 148 Inclination: ---
R.V.: --- Source: RC3

This is a fairly small eg, elong in a mod populated field. Appears to the W of an arc of *s mags 11 & 13 and the arc is open to the W where the eg is. The eg is elong in about PA 160, maybe a little over 1.25' x 30" grows broadly to small weakly elong core zone that is only slightly brighter than the halo and a star just off the S tip mag 14.5. Diffuse edges growing slightly to the core zone in centre.


After finishing off this first galaxy I glanced down south and saw one little cumulus cloud, maybe 10 deg x 10 deg in extent slowly drifting northward and thought little of it. Looked decidedly non-threatening …

The next couple of galaxies were a pair of spirals in an adjacent field to the first one

x185 27' TF

IC 2511 Galaxy *
RA: 09h 49m 24.5s Dec: -32° 50' 20"
Mag: 13.0 (P) S.B.: --- B-V: --- Size: 2.9'x0.5'
Class: (R')SAB(s)a: sp P.A.: 43 Inclination: --- R.V.: --- Source: RC3 *

IC 2514 (IC 2513) Galaxy *
RA: 09h 50m 00.7s Dec: -32° 53' 00"
Mag: 13.3 S.B.: --- B-V: --- Size: 3.1'x0.5'
Class: SA(s)ab: sp P.A.: 61 Inclination: --- R.V.: --- Source: RC3 *

These are both edge on egs in a mod populated field. Overall the brighter seems to be -14 though is has lower SB only because of it apparently larger size. -14 is adjacent to 2 mag 12 *s that pretty much point at it from the SE. Seems to be elong in PA 60, quite elong with a somewhat brighter core zone and a faint stellaring in the centre. Diffuse and LSB outer halo, 1.5' x 15" with a dominant small elong core zone.

-11 is 10' NW and has Lower SB, 2' x 15" in PA 45 and has a smoother brightness profile growing broadly and weakly to centre where there is a small weakly brighter core zone.

After recording these two, the cloud had increased to cover about 30% of the sky, mainly in the south. And to think that first lonely looking little cumulus didn’t look threatening.

x185 27' TF

ESO 374-3 PGC 28416 Galaxy *
RA: 09h 51m 57.7s Dec: -33° 04' 28"
Mag: 14.1 (P) S.B.: --- B-V: --- Size: 2.5'x0.7' Class: SAB(rs)cd:
P.A.: 154 Inclination: --- R.V.: --- Source: RC3 *

This eg is found due S by 7-8' from a 6th mag *. it is a uniformly SB 1.5' x 15" oval of mist with no apparent nucleus or core zone visible. Very LSB with diffuse edges.


x185 27' TF

IC 2526 Galaxy *
RA: 09h 57m 03.1s Dec: -32° 15' 22"
Mag: 13.6 (P) S.B.: --- B-V: --- Size: 2.0'x0.6'
Class: SAB(s)0^: P.A.: 55 Inclination: --- R.V.: --- Source: RC3 *

This is a pretty small oval shaed eg in a field of faint *s. The closes of note is mag 12.5 whcih is pretty much N by maybe 2-3'. Small, oval-shaped halo maybe 50" x 30" in PA 30 with a small, mod brighter fairly well defined core zone containing a faint stellaring nucleus. Obvious in the ep, lowish SB but not bad.


By now more than ˝ the sky was clouded …


x185 27' TF

IC 2532 Galaxy *
RA: 10h 00m 05.4s Dec: -34° 13' 41"
Mag: 13.9 (P) S.B.: --- B-V: --- Size: 1.5'x1.2'
Class: (R')SB(rs)a P.A.: 38 Inclination: --- R.V.: +2900 Source: RC3 *

This is a quite small weak LSB eg found immediately S of a couple of mag 11 & 12 *s that run E-W. Those stars are not far outside the halo. Very small oval glow in about PA 30 about 30" x 20" with very little brightening to centre and with a threshold stellaring in the centre. Quite a well populated field.


And by now most of the sky was cloudy, indeed I had only just managed to record this observation before the galaxy and stars simply disappeared in the ep. 10 mins later it was 100%. I thought to myself that it was still early and no doubt this will all clear away in an hour or so.

Around midnight, I had a sublime glimpse of Saturn that lasted for about seven seconds through a tiny gap in the clouds. It looked sensationally rock-steady and full of detail at x185. From what I saw, it looked like the seeing would support magnifications over x300 pretty easily but it was all over in a matter of seconds.

We waited and waited as South African wickets tumbled in the Johannesburg Cricket Test and Australia jumped all-over the Proteas. But no stars sadly.

By the time 1.45am rolled around it was time to start a very disappointed pack up and journey home. Frankly I was pretty dirty that I had wasted $20-odd of fuel and about 8 hrs for a small handful of galaxies. Grrrrr …

Looking forward to better Autumn skies … hopefully.


Best

Les D
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  #2  
Old 09-03-2009, 06:10 PM
Dennis
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An excellent report Les, showing your dedication despite the weather gods! I also had fun guessing at the acronyms (e.g. TF=True Field?) as I’m not a visual observer so haven’t come across these much.

Cheers

Dennis

PS – ZLM I guess is Zenith Limiting Magnitude, but what is the “L” in Sky Quality Meter – L?
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Old 09-03-2009, 06:32 PM
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ngcles
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Acronyms ...

Hi Dennis & All,

Quote:
Originally Posted by Dennis View Post
PS – ZLM I guess is Zenith Limiting Magnitude, but what is the “L” in Sky Quality Meter – L?
Yep, ZLM is Zenithal Limiting Magnitude -- this seems nowadays to be falling into dissetude and most observers write NELM (Naked Eye Limiting Magnitude) -- they mean the same thing, but ZLM was the term when I was a boy so ...

One I'm surprised no one has asked about (picked me up on) is my use of "eg" for galaxy. This is nowadays a quite rare contraction. It is short for Extra Galactic Nebulae. The galaxies, were originally known as exta galactic nebulae before the term galaxy took over. I guess I could use gx, but I am old-fashioned and well, I just like "eg".

SQM-L is the model of the SQM that has a lens in front of the sensor restricting the FOV to about 20 deg FWHM. Tends to cut out the "milky way effect" the lense-less SQM (that view a much wider angle) suffer from.


Best,

Les D
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Old 09-03-2009, 09:24 PM
Dennis
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Thanks Les – I did a Google search and found the SQM-L website.

Cheers

Dennis
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  #5  
Old 09-03-2009, 10:45 PM
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Chippy (Nick)
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Interesting obs Les. I was wondering about the eg term - thanks for explaining that! I always seem to learn something new reading your posts.

Sorry to read that you were clouded out. It certainly has been a repeating theme... I'm looking forward to better autumn skies too!

All the best,
Nick.
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