A bunch of Arp peculiars and a couple of Abell planetaries

I've gotten a little behind in logging my observations, so here's 3 reports in a single thread.

Arp29 NGC6946 8/24/2009 22:16 UT; Pickering 7, NELM 5.5, SQM 20.5
400mm Mak-Cass @ 150x

Moderately bright, large circular patch with just the vaguest hint of condensation to the center. Somewhat improved surface brightness at 110X, where the location of the core is also easier to pin down. Hints of one heavier arm to the NE, and a less dense but larger arm to the NW.

375X reveals a couple more foreground stars superimposed, but no clumping or other features in the arms.

Arp38 NGC6412 8/24/2009 23:46 UT; Pickering 7, NELM 5.5, SQM 20.5
400mm Mak-Cass @ 225x

Pretty much invisible at 150X but a bit of motion brings it out. Very poor condensation with a suggestion of a core perhaps 20% of the time in averted.

(Interestingly, both the GSC and the DSS image put the core brighter than some of the field stars, but I guess the contrast loss with the galaxy around it is significant. Transparency also seems to have been deteriorating by this time as I failed to record many stars in the high 13's / low 14's in the sketch.)

Arp81 NGC6621 8/25/2009 00:11 UT; Pickering 7, NELM 5.5, SQM 20.5
400mm Mak-Cass @ 225x

Another one barely visible under these conditions. Two poor condensations in an elongated (NNW-SSE) smudge.

Arp30 NGC6365A 8/25/2009 00:21 UT; Pickering 7, NELM 5.5, SQM 20.5
400mm Mak-Cass

Suspected a couple of times to the NE border of a kite asterism, but nothing definite. Transparency has gone to hell, though, struggling to even make NELM 5.

[Turns out to be a string of mV14+ field stars. Galaxies off other side of kite.]

With the transparency continuing to worsen I called it a night.

A few days later conditions were quite favorable so I thought I'd give a few Abell PNs a go:

Abell78 PK 081-14.1 8/28/2009 22:31 UT; Pickering 7, NELM 6, SQM 20.8
400mm Mak-Cass

Not seen.

Abell81 PK 117+18.1 8/28/2009 23:11 UT; Pickering 7, NELM 6, SQM 20.8
400mm Mak-Cass @ 150x, OIII

Averted vision at 335X and 150X, but difficult. Easy averted and moderately-difficult direct vision when the OIII is added at 150X. Also direct at 235X with UHC (OIII slightly overpowers). 335X gets rid of distracting field star, but even UHC overpowers a 1.2mm exit pupil. 450X not really any help.

Unfiltered views show two involved stars, one right on the edge and one a bit farther off. Unfiltered also looks a bit flared, but I think that's just a contrast effect with the two close field stars. Shape very round filtered, with suggestions of annularity. The minima also pops out from time to time unfiltered at high magnification (335X and 450X).

Abell68 PK 060-04.1 8/28/2009 23:40 UT; Pickering 7, NELM 6, SQM 20.8
400mm Mak-Cass

Not seen.

Abell46 PK 055+16.1 8/28/2009 23:55 UT; Pickering 7, NELM 6, SQM 20.8
400mm Mak-Cass

Not seen.

Well, that wasn't going terribly well, so I went back to the Arp I failed to find the first night:

Arp30 NGC6365A 8/29/2009 00:06 UT; Pickering 7, NELM 6, SQM 20.8
400mm Mak-Cass

Did a quick and dirty field sketch of the SW side of the kite. I included 4 very dim field stars, one of which appeared somewhat elongated.

[Field stars around mV14; elongated one turns out to be a mV13.5 double star. Galaxies in between 3 of the 4 sketched. I'd say this one's out of reach.]

No dice there either, but still, the Arps are considerably easier than those dang Abells.

Arp124 MCG+10-25-003 8/29/2009 00:16 UT; Pickering 7, NELM 6, SQM 20.8
400mm Mak-Cass @ 225x

Easy averted vision at 150X. 235X and 335X much the same, with 235X being just a little bit easier. 4:1 elongation NE-SW; limited condensation to center but no core visible.

Didn't get the companion, but a couple of field stars in the sketch are only marginally brighter. Still, conditions were quite good, suggesting that barring an exceptional night (and a bit more altitude), it's going to be out of reach.

Arp330 MCG+09-27-095 8/29/2009 00:30 UT; Pickering 7, NELM 6, SQM 20.8
400mm Mak-Cass

Some of these were suspected, but never nailed down. I suspect they could be with an image/chart at the scope.

NGC6951 8/29/2009 00:45 UT; Pickering 7, NELM 6, SQM 20.8
400mm Mak-Cass @ 150x

Well-condensed direct-vision bar running E-W, with nearly stellar nucleus. Much greater extent in averted, also elongated E-W, going out to bright foreground star to E and an equal distance to W. 150X lacks scale, but galaxy brighter than at higher mags.

A couple of weeks later I got another night in:

Arp13 NGC7448 10/11/2009 20:35 UT; Pickering 7, NELM 5.5, SQM 20.6
400mm Mak-Cass @ 325x

Readily apparent at 235x with moderate but non-stellar condensation and marked N-S elongation. Slightly messy interior at 150x, reminiscent of M65 but with less definition. 2 averted-vision knots at 375x, the S one with a difficult averted-vision stellar center. 450x broadly similar.

Arp28 NGC7678 10/11/2009 21:01 UT; Pickering 7, NELM 5.5, SQM 20.6
400mm Mak-Cass @ 325x

Much dimmer than Arp13, with a more circular shape. Nicely framed by a triangle of foreground stars. Poor condensation with nothing more than a hint of a stellar core.

Movement at 375x reveals brightening to the SW of core and slight clumping to the ESE. Alvin got better separation between the bright arm (to the S) and the core, but didn't get the clumping to the ESE. Supernova 2009ga is just below the bright arm, but was not visible to me.

Arp86 NGC7753 10/11/2009 21:31 UT; Pickering 7, NELM 5.5, SQM 20.6
400mm Mak-Cass @ 225x

Similar brightness to Arp28, but without the foreground stars to frame it. More elongated and slightly more condensed, but core still averted vision. Companion much smaller with a slightly higher surface brightness. Companion does not appear attached, showing some space in between, but does have an apostrophe shape pointing toward main galaxy. A pair of averted-vision foreground stars, one to the SSW and the other to the NNW of the core, make things much more difficult to pin down.

Interestingly the connecting arm, which I cannot see, extends through the NNW foreground star and continues down to join the companion at right angles to the elongation of the apostrophe.

Arp113 NGC71 10/11/2009 22:05 UT; Pickering 7, NELM 5.5, SQM 20.6
400mm Mak-Cass @ 325x

Rather hard to tell what's a foreground star and what's a galaxy core at 235x. 450x helps some, identifying "star" to SSW as a galaxy (NGC69).

Interestingly I failed to spot NGC70 (which is one of the larger galaxies in the field). Since I did manage the similarly dim NGC69, I can only guess that 70 faded into the glare of the two nearby foreground stars. I also mis-identified NGC72A as a star.

Cheers,
-- Jeff.

Oh, and here's an annotated version of the Arp113 sketch, with missing or mis-identified galaxies added in blue.



-- Jeff.

Wow, you have been busy. Lovely.
Donal

donalmcnamara wrote:

Wow, you have been busy.

He he; more just lazy -- that first report goes all the way back to August. :ohmy:

Cheers,
-- Jeff.

Excellent work there Jeff.
The Arp catalogue is something I want to break into, but getting around to anything with the weather we have is a struggle.

Dave --

Do you have Alvin Huey's "Observing the Arp Peculiar Galaxies" observing guide? The sketches in it are great at giving you an idea of what you might expect to see (unlike the more common DSS images, which go much deeper than even a 20" mirror can take you).

Cheers,
-- Jeff.