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First night with re-jigged 12" dob


SAB
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After 2 full weeks of either cloud, uni commitments or cloud, I finally got a chance to really take the new 12" dob for a spin. Setup and collimation is very easy, no tools needed. One thing I noticed on the scope is that the secondary as seen thru the focuser was slightly de-centered but was busy during the day so had no time to play with it. But I could still get the entire primary reflected in it when I got the optical axis aligned. However defocusing a star the secondary shadow appeared perfectly centered so makes me wonder how much effect a slight mechanical misalignent of a secondary has when the optical axis is perfectly aligned.

I was pleased to note that both the laser and cheshire agree when checking collimation, and collimation stays put throughout the night. No need to re-collimate here! One thing my old dob lacked was cooling fans, plus the mirror was in an unventilated cell so it never cooled down. Now I have 3 fans blowing at the mirror one at the back and two at the front which also stop dew formation while cooling.

Seeing during the night was generally garbage, truly madly deeply abhorrent infact, but transparency otherwise was improving as the night wore on. Seems like we are in jetstream season with the continual "observing above campfire" effect. Some reckon winter provides the best seeing. IMO summer is the weiner in the seeing stakes.

As for the views, this scope has potential given the opportunity to stretch its legs. But I don't live in Florida. Stars at 381x focused into tight airy disks, although smearing in the seeing, but you could see that "snap" underneath the blur! Should have no probs pushing double that mag on certain objects in atleast decent seeing.

I gave the scope it's first real run on some faint galaxies and I must say it performed above and beyond my expectations. Infact I was totally surprised at how well it was raking these fuzzies in!!!

Scope: 12" F4.4 dob

Time: 8pm-12am

Seeing: 2/10

Transparency: 5/5

Dew: no

Temp: 11C

WILD's TRIPLET

MCG-01-30-32

GX, Virgo, RA 11 46 35, Dec -3 51 36, Size= 1.7'x1.1', Mag B= 15.0

2nd of 3. Very faint, although could hold it well at 267x. Increased mag to 381x purely for the purpose of increasing contrast. Lower SFC brightness than MCG-01-30-33 approx 3' ENE.

MCG-01-30-33

GX, Virgo, RA 11 46 45, Dec -3 50 52, Size= 3.0x0.6', Mag B= 14.3

1st of 3. Surprisingly easy to see at 166x. Slightly elongated E-W at 267x and is much brighter than -32 to its WSW.

The 3rd northeastern member was not visible.

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2MASX J11461879-0345353

GX, Virgo, RA 11 46 19, Dec -3 45 36, Size= 0.6'x0.5', Mag B= 16.0

A tiny, high sfc brightness elliptical located only 8' NW of Wild's triplet and forming a "double" with a mag 13.8 star 35" to the north. Extremely faint, SIMBAD lists a blue magnitude of 16.0 eeksign.gif Spotted at 381x, could hold it maybe 25% of the time but it winked in and out of visibility as I stared at the field for a good 10 minutes with a black shroud over my head. This galaxy according to its redshift is 663 million light years away!

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ESO 507-45

GX, Hydra, RA 12 55 36, Dec -26 49 26, Size= 1x0.6', Mag B= 12.8

Bright, large elliptical, 1st of 5 in a group. Elongated N-S, high surface brightness with a condensed core. Forms a nice pair with ESO 507-46 approx 3' NE. A mag 11.9 star lies exactly halfway between the two galaxies.

ESO 507-46

GX, Hydra, RA 12 55 44, Dec -26 48 32, Size= 1.2x0.9', Mag B= 13.9

2nd of 5. Forms a pair with -45 some 3' SW. Smaller with lower sfc brightness than -45 but still quite easy to see at 166x. Slight E-W elongation hinted at at 267x.

2MASX J12554311-2651556

GX, Hydra, RA 12 55 43, Dec -26 51 55 , Mag B= 16.18

Very small, extremely faint galaxy located 5' SE of ESO 507-45. Could hold it about 75% of the time at 267x, with the hood over my head and careful scrutiny of the area. Easy to find halfway between a 15th mag double star to the NW and another mag 12.9 star to the SE.

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ABELL 761

This is a rich cluster of galaxies located about 20' S of a mag 6.3 star. A relatively large number of foreground stars aid in pinpointing galaxies here.

ESO 511-26

GX, Hydra, RA 14 18 51, Dec -27 24 35, Size= 0.5'x0.5', Mag B= 14.3

Compact elliptical galaxy located 2' N of a mag 9.4 star. Faint, round and small at 267x. Took a while to see it, but once I was adapted it was quite easy to hold.

MCG-04-34-008

GX, Hydra, RA 14 19 05, Dec -27 24 27, Size= 0.4'x0.4', Mag B= 15.0

Faint, small, round at 381x. Located 4' NE of ESO 511-26. Slightly smaller and fainter than -26, managed to hold it perhaps 75% of the time.

2MASX J14190223-2727348

GX, Hydra, RA 14 19 02, Dec -27 24 34, Mag B= 15.9

Located 4' SE of ESO 511-26. Extremely faint, it took me 10-15 minutes of intent observation with a black hood over my head to catch fleeting glimpses of this galaxy. I was at the eyepiece for a good amount of time to confirm the sighting. Pretty much a non-descript ball of fluff. Finding the location was easy by using a 13.5 mag double star to the SW and a trio of mag ~13-13.8 stars to the NE. A mag 15.2 star lies 1' NW. ANother mag 16.0 star adjoins its southern end, which I suspect I glimpsed a couple of times.

ESO 511-23

GX, Hydra, RA 14 18 27, Dec -27 22 42, Size= 1.4x1.0', Mag B= 13.8

This galaxy appears to be the largest and brightest of the Abell S 761 clan, although is displaced well the the east of the apparent centre. Located about 6' WNE of ESO 511-26. Fairly easy at 166x, but a better view at 267x. Slightly elongated E-W.

ESO 511-21

GX, Hydra, RA 14 18 14, Dec -27 24 55, Size= 0.4x0.3', Mag B= 14.4

Second brightest member of Abell S 761. Located 4' SW of -23 and is slightly fainter and smaller. A mag 10.8 star lies 1.5" E.

Another two galaxies ESO 511-31 and -32 lie on the eastern side of the cluster which look like are within my reach but lost the field and couldn't find my bearings so I had to cut my losses.

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NGC 5170

GX, Virgo, RA 13 29 49, Dec -17 57 57, Size= 9.24x1.29', Mag V= 10.8

I've been wanting to hunt down this edge on spiral for ages now, but it was somewhat underwhelming. At 166x it appeared as a faint spindle with a fairly bright, condensed core. The dust lane was not seen.

NGC 5746

GX, Virgo, RA 14 44 56, Dec +1 57 19, Size= 7.9x1.7', Mag V= 10.3

Easily found at 41x as a high sfc brightness needle. Located SSE of a mag 8.7 star. A lovely object, IMO superior to NGC 5170. Features a small, buldging core at 166x, with needle like extensions. At 267x a stellaring in the core was hinted at. The eastern edge is harder than the west, a manifestation of the dust lane. A mag 14.9 star lies just offset to the east at the end of the northern extension and another Mag 14.1 star lies along the galaxy's central axis south of the core.

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Had to pack it in at midnight as cloud started moving in, but satisfied with a great first session.

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Wow !!!!!!!

That is an extremely impressive collection Sab. Down to 15th and 16th mags in a 12" is awesomely good. Is your sky pretty dark?

One thing I do find is that the fainter and more obscure you go with galaxies the higher the uncertainty is on magnitude. Wild's Triplet according to this list for example - Triplets - put all members of the triplet at brighter than 14th magnitude.

I've had similar experiences with some fainter NGC and IC designated galaxies. One of them was quoted with a visual magnitude range of 2+. Sometimes frustrating as it just makes it more difficult to really determine how faint im going.

So far with my 16" I have been confidently down to Mag 13.8

Really enjoy reading your reports - and really good to see reports on more exotic DSOs too.

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Thanks all. The new scope is a real joy to use, so much easier then the old version and with better views to boot!

Wow !!!!!!!

That is an extremely impressive collection Sab. Down to 15th and 16th mags in a 12" is awesomely good. Is your sky pretty dark?

One thing I do find is that the fainter and more obscure you go with galaxies the higher the uncertainty is on magnitude. Wild's Triplet according to this list for example - Triplets - put all members of the triplet at brighter than 14th magnitude.

I've had similar experiences with some fainter NGC and IC designated galaxies. One of them was quoted with a visual magnitude range of 2+. Sometimes frustrating as it just makes it more difficult to really determine how faint im going.

So far with my 16" I have been confidently down to Mag 13.8

Really enjoy reading your reports - and really good to see reports on more exotic DSOs too.

Hi Darkersky thanks for your kind words. :) My skies aren't too bad at all, darker than what one would associate with typical light pollution. This is because I'm at the edge of the metropolitan area.Sounds like the Visual Magnitudes are quoted in your link, as V mag is usually around 1 brighter than the often quoted Blue Magnitudes. Down beyond around 11th mag, it becomes dodgy for galaxies, to the point where different sources such as NED, SIMBAD, Cartes Du Ciel etc all quote completely different mags for the same galaxy.

Edited by SAB
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Down beyond around 11th mag, it becomes dodgy for galaxies, to the point where different sources such as NED, SIMBAD, Cartes Du Ciel etc all quote completely different mags for the same galaxy.

yeah, I know exactly what you mean! Can be a right nightmare. Steve Gottleib's notes are useful - Steve Gottlieb's NGC Notes - to get a comparison

He does seem to have good coverage of the southern sky too from scopes in australia

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