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First light with Little Martin  @psychohistorian.org

First light with Little Martin

posted: 1208 days ago, on Monday, 2016 Nov 07 at 04:16
tags: astronomy, deep sky, observing report, observing equipment, star party, Southern Star Party, Little Martin.

Refractors. They, uh, are, utterly, you know, entirely; just totally and absolutely, fabulous. Sigh.

My latest one I've had for less than two weeks. "Little Martin"[1], he's called. He's a 4-inch f/6.5 Celestron refractor, on a one-armed bandit type alt-az mount. His former name was "Celestron NexStar 102SLT".

The 'scope comes with two eyepieces (a 25-mm and 10-mm, I think) and a zero-power finder, which you're welcome to have. It's mounted on a terrible tripod, which I broke on the first night - the plastic arm of one of the dinky little leg connectors just snapped in two with a startling CRACK. This doesn't seem to make much difference, though, as the tripod seemed equally wobbly afterwards.

The focuser is quite good, moving in and out quite smoothly. The 1.25-inch diagonal looks good enough, too. I noted that the OTA can take 2-inch accessories though I haven't tried this yet.

The software/hand controller that runs the machine is nifty, doing exactly what you'd want it to do. The "Sky Align" option is a breeze to use. The second thing I learnt was how to turn down the brightness of the hand controller buttons and display, from the default "BLINDING" setting to something useful. The red power LED on the body of the mount, though, is stuck at "SUPERNOVA" level.

I spent a good while observing with Little Martin during the 2016 Spring Southern Star Party (see below), and had a fantastic time. The 'scope delivers great images and is a very useable instrument, and is to be recommended.

One has to learn to work around the limitations, though. The most severe is the ricketyness. Focussing leaves the field of view oscillating dizzingly, making fine focus a bugger. A minor niggle is the GOTO-speed: impulse power, not warp speed.

But the ease of use, portability, and price, make Little Martin a little champion.

[1] My refractors have boy names, and my reflectors have girl names, obviously.

At the end of the observing session. Little Martin is so cute, he fits snuggly into my windbreaker.

First deep-sky session with Little Martin

During the recent Spring SSP, held at Night Sky Caravan Farm, Bonnievale, I spent a few hours (2016 October 30, Sunday, 20:30 to 23:45) observing with Little Martin, using Sir Brian's eyepieces:

Little Martin (4-inch f/6.5 Celestron refractor) & 45-mm Celestron Plossl (15x), 19-mm Televue Panoptic (35x), 11-mm Nagler Type6 (60x), 19-mm Panoptic+ Televue 2.5x Powermate (87x), and 11-mm Nagler+ Powermate (150x).

During the course of the session, I took two sets of SQM-L measures at the zenith: 2016 Oct 30, 21:30 SAST: 21.58 +/- 0.01, and 2016 Oct 31, 00:05 SAST: 21.61 +/- 0.01.

The 'scope performed well, and I'm pleased. The generous wide field of view and bright image was very reminiscent of 11x80 binocular views, not surprising since LB was working as a 15x102 monocular at times. I didn't have packing space to bring along the 25x100 SkyMasters and will give that a comparative go at some future point.

Although the sky was dark, the transparency, particularly southward, was low so I couldn't usefully push the magnification. For example, I won't swear that I could see the Homunculus Nebula despite an 8-mm Ortho with the Powermate.

I started in the Scorpion, which was on the way down. My first target was NGC 6124, a large and easily seen cluster a smidge outside the stream of the Milky Way, poised between the Scorpion, Lupus, and Norma. It commanded the wide-field telescopic view well. The obvious stars are of pretty uniform brightness, sporting at least 45 moderately bright suns (V=9.5 and a bit fainter) in a roughly circular area about 21' across. It's not entirely impossible to see it as some kind of ultra-dispersed globular cluster, since, curiously, the inner third is densely packed while the outer two-thirds are more sparsely populated. Near the centre, and a bit to the north, are two knots of stars, each about 2' wide.

Loius de La Caille and James Dunlop also recorded the quite striking round shape of this cluster; "a fairly big tailless comet" wrote the former, while the latter said: "a round cluster of small stars of nearly equal magnitudes... considerably congregated to the centre, not rich in small stars." John Herschel's 18-inch didn't show him a particular shape, no doubt because of his narrower field of view. He recorded "loosely scattered" and "irregularly scattered".

The small but bright planetary nebula NGC 6153 was up next, accompanied by its Delphinus-shaped asterism. This pattern is really very eye-catching, with the 22-arcsecond planetary occupying the southern tip of mini-Delphinus.

Then it was on to the intriguing Bug Nebula (NGC 6302), a nickname coined by the venerable E. E. Barnard in 1892. The remarkable object hardly looks like a nebula: instead, it's just a very short slash of light, like someone's squished and flattened a pretty bright star!

The gorgeously shaped NGC 6281 followed, and then the obvious but gentle NGC 6152 in Norma. Other Norma delights not to miss are NGC 6067 - simply beautiful! - and the S Normae Cluster (NGC 6087).

After a quick break to take SQM-L readings, I headed briefly into Sagittarius, starting with NGC 6723, one of Jack Bennett's comet-like southern objects. Then it was one of Messier's comet-like objects, NGC 6809 (Messier 55, also Lacaille I.14). This is a very large swarm of almost invisible stars, very strongly mottled all across the disk. In stark contrast, NGC 6715 (Messier 54) is a tiny, furiously bright globular cluster, quite like a star with a halo.

Several objects and an hour later it was the turn of the Saturn Nebula (NGC 7009). This object has several reasons for its celebrity status, including the honour of being the first deep-sky object to be discovered using a reflecting telescope. It was discovered (1782) by William Herschel - and it was also the first object he discovered! When he viewed it (in 1784) with his 18.7-inch f/13 speculum telescope, he recorded: "I have examined it with the powers of 71, 227, 278, 460 and 932; and it follows the laws of magnifying, so that its body is no illusion of light." The best I could manage was 150x, and it was clearly an elongated object, non-nebulous in appearance: like the Bug Nebula, a flattened star.

And eventually I ended up in Pisces with NGC 628, Messier 74, Charles' Challenge. The early telescopic descriptions of "very obscure and extremely difficult to observe" are exaggerations unless you add the caveat of "in a narrow field of view". Little Martin's relatively wide field and modest magnification gave enough contrast to show this galaxy as a faint but obvious, pretty large, glow of indistinct shape.

And at this stage, dew-drenched star charts and notebook called a halt to my & Little Martin's first deep-sky observing session.

nothing more to see. please move along.

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