August Challenge Object - NGC4945

iceman (Mike) · #1 01-08-2005, 10:55 AM

Hi all.

We'd love you to take part in the August Observing and Imaging Challenge. Please post your reports, sketches and deep-space images of NGC4945 in this thread. Discussions about the images can also be in this thread.

Please ensure the images obey the posting guidelines when you attach them.

While it would be nice if the report, sketch or image were taken in the month of August, it's not essential so feel free to post older reports and images if you're unable to take some new ones.

We look forward to seeing your contributions!

dhumpie · #2 01-08-2005, 02:22 PM

Looks like I will be the first one yet again. This is a very nice edge on galaxy and it does show some mottling in a 6" at moderate magnifications from dark sky sites. It is also not a very difficult galaxy to pick up from the burbs (mag limit approx) if you use the correct magnifications to "concentrate" its light. I have seen it in my tripod mounted 15x70 binocs (from my suburban balcony) and it looks nice, abeit dim in the Orion 80ST at low powers. In fact from the burbs this galaxy actually looks better in my small scopes that in the 6"! Also edge on's tend to have the illusion of the galaxy going on forever when you get to the ends. NICE! See my sketch at:

http://www.geocities.com/dhumpie/dastro/4945.jpg

Darren

davidpretorius · #3 02-08-2005, 11:25 PM

Having real troubles finding this one, clouds are not helping. ngc5139 is nice and i am scanning between it and the top of the southern cross. have found the three star forming a right angle and am looking hard at different mags in this area. will keep going as the clouds look like going away

dhumpie · #4 03-08-2005, 12:25 PM

David where are you observing from? If you cannot see mag 5.4 stars at zenith don't even bother looking. You need very transparent skies and the best of conditions to see this galaxy. And do use very low magnification. The galaxy is wedged just offset from the middle between the two closer stars in the triangle.

Hope that helps.

Darren

ving (David) · #5 03-08-2005, 12:36 PM

nice report darren. I have seen this one before from home so weather permitting I'll have a bash at it agian on thursday night and write up a report on friday arvo.

davidpretorius · #6 03-08-2005, 12:50 PM

I was looking at around 9.30 at around say 60 degrees above horizon.

terrible conditions, windy & and not very clear.

thanks darren

ausastronomer (John Bambury) · #7 03-08-2005, 01:05 PM

David,

This can be a difficult target if you have never observed it before. Under less than favourable conditions you could sweep straight past it with a 10" scope and not realise you had just bypassed it. Once you see it for the 1st time you will know what your looking for and it becomes progressively easier to locate. It is a large galaxy so its best to use the lowest power eyepiece that provides a dark sky background with good contrast. You need to make sure that you don't use an eyepiece creating too large an exit pupil under less than pristine skies. Your 40mm eyepiece creates an 8mm exit pupil in an F5 scope and I would consider this virtually useless under any sky conditions. An oversized exit pupil causes the sky background to appear a little milky and images lose contrast making it impossible to find dim targets, the worse the light pollution the smaller the exit pupil you need to limit yourself to. From Mag 5 skies I limit myself to about a 5mm exit pupil and from dark skies of Mag 6 and better I limit myself to a 6mm exit pupil which in my F5 scope is a 30mm eyepiece. With you being a little younger than me (I am 46) you may be able to use a slightly larger exit pupil than I can but it certainly won't be a lot greater. As you age the eye loses its ability to fully dillate under dark conditions.

I suggest that you use your 25mm eyepiece as your finder and you will need reasonable conditions. Under poor conditions I have trouble finding it in my 10" scope, under fair to good conditions it is a lot easier to spot.

CS-John B

davidpretorius · #8 03-08-2005, 02:39 PM

Thanks john, will try when good conditions and high in the sky

dhumpie · #9 03-08-2005, 02:47 PM

Good one David (ving). Looking forward to your report. And Davo, I do agree with John that this is a hard one from less thant perfect skies if you are a beginner. Should be pretty easy from a dark sky site though. I can even see it in my 10x50's!

Darren

ving (David) · #10 04-08-2005, 09:13 AM

well 'ere we go then...

date:3.8.05
time: 9:30pm
EP: 15mm GSO SV
seeing: 3/10 (v/bad)

This is far from the first time I have spotted this galaxy, but last nights view was probably the worst ever. I checked outside after watching "house" (love his humour) to see that where there were clouds before they were now clearing, though I could tell the seeing was going to be bad... I told cheryl that i wouldnt be long so i didnt even allow a cooling period. The galaxy its self is nestled in a now very familiar triangle of stars. Tonight it was almost imposible to see, more coming out with averted vision. The more my scope coled the more I could see but it was still extremely dim. to describe it last night I'd have to say it was nothing more than a large almost averted viewing smudge... there was no real detail to it.
I'll go back to it on saturday night though i think.
In retrospect maybe my 30mm SV would have been a better EP to use.

dhumpie · #11 04-08-2005, 02:22 PM

Nice report David!

Darren

ving (David) · #12 04-08-2005, 02:43 PM

thaks darren. i was really disapointed with the seeing last night tho... it was a shocker!
I was supprised to be able to see my hand infront of my face

dhumpie · #13 04-08-2005, 05:22 PM

I can see my hand in front of my face even when all the lights go out after 1am. My secret in observing from the burbs is my dark jedi cloak (i.e monks hood

which I drape over my head while observing. I use this even at dark sky sites....

Darren

atalas · #14 04-08-2005, 05:37 PM

Ah blessed are the dedicated ! stuck my head out last night and all I saw was cloud so in It came again.

Louie

cahullian · #15 04-08-2005, 05:41 PM

same here Louie not a break in the clouds to be see. I don't need cool down time as I threw my scope out of the house weeks ago. It lives outside and gets hit with the surface spray every now and then to keep those pesky spiders off it .

davidpretorius · #16 05-08-2005, 12:28 AM

Loc: 41'25"S, 147'07", UT +10
Apert: 10" Reflector
Mount: dob
Date: 4/08/2005
Time: 22:00
Cond: no cloud, very clear and still
Seeing: 8
FL: 1250
EP: 40,30 ultrawide, 25,12.5,6
Mag:
Filters:
Object: NGC4945
Type: Galaxy
Const: Centaurus
Magnit: 8.6
Size:
RA: 13'05"27.1"
DEC: -49'28"
Comments: Can just make out at all ep's except with 6.5mm.
Avi sett:
Avi link:
Image sett:
Image link:

dhumpie · #17 05-08-2005, 10:35 AM

We actually had rains last night but it has since cleared up to a fine day. Hopefully this weather carries through to tomorrow and Sunday as I will be at the Queensland Astrofest. Give you guys a report when I get back

Darren

gaa_ian (Ian) · #18 28-08-2005, 11:14 AM

Finaaly got a quick look at this one last night through the LX-90.
Large galaxy with not much detail, would be good to see this with a big light bucket (18")!

gaa_ian (Ian) · #19 28-08-2005, 11:16 AM

Finally got a quick look at this one last night through the LX-90.
Large galaxy with not much detail, would be good to see this with a big light bucket (18")!
I will have to take a little more time to see if I can tease out some detail !

davidpretorius · #20 28-08-2005, 12:43 PM

has anyone had any luck imaging this one???

am i right that some guys have seen this in dark skys with naked eye, or was that with small binoculars???