NGC2347 PN with C9.25/ST7 & Vixen 4inch/DSLR

[Dennis]

Hi

After a long time indoors due to the cloudy nights, I managed to get out again last night/this morning for a session of imaging. It took me 2 hours to carry out, set up, configure and calibrate the system – I’d forgotten how hard life can be without a permanent set up! I’m still experimenting with guiding with the WO 80mm ED and Orion Deep Space Star Shoot using a GPUSB adapter and PHD Guiding, so chose M46 for two images with two different systems, both auto guided by the WO 80mm.

Vixen ED102S f9 and Pentax *istDS DSLR.
Celestron C9.25 f10 and SBIG ST7E ccd.

Here are the results, at the opposite end of the imaging scale.

Cheers

Dennis

The Pentax *ist DS image is a stack of 50 exposures of 30 secs each, aligned and combined in ImagesPlus.

The ST7E images is a stack of 25 exposures of 60 secs each, aligned and combined in MIRA AP. Auto darks were applied in camera, no Flats were taken (I forgot!).

Object name: NGC 2437 (M46), Magnitude: 6.1, Size: 20.0 x 20.0
Object type: Open Cluster
Dreyer description : Remarkable!, cluster, very bright, very rich in stars, very large, involved planetary nebula.

Object name: NGC 2438, Magnitude: 10.8, Size: 1.3 x 1.3
Object type: Planetary Nebula
Dreyer description : Planetary nebula, pretty bright, pretty small, very little extended, resolvable, but mottled, 3".75 diameter.

[RB]

Great work Dennis, I especially like the Pentax shot.

[beren]

Very nice Dennis, one of my favorites :thumbsup: Ive been eager to get out to , recivied my GPUSB adapter but been cloudy :P

[matt]

Nice shots Dennis

I especially like the Pentax shot with the different colours (blue/green PN and orange star).

Great stuff

[atalas]

Nice work Dennis .

[spearo]

Very nice Dennis,
both shots are impressive, i love the colors int he first and the detail in the second.
Both are very nice indeed
well done
frank

[Dennis]

Thanks for those nice comments everyone, much appreciated. Even though I have a very nice mount in the Tak EM200, it is not all plain sailing! I had to ditch 3 or 4 of the sub-frames due to slight star elongation – not sure of the root cause just yet.

When I later took a 3 min auto guided exposure, the stars show noticeable elongation in the RA direction, which is very visually unpleasing. I’m currently trying to chase this down, as my instinct tells me this should not happen.

In the C9.25 at F10, the ST7E FOV of the 765 x 510 pixel ccd is 10x7 arc mins (according to The Sky Pro 6). So, this converts to a 600x420 arc secs rectangular field. The star elongation in the 3 minute guided exposure is around 8 pixels. So, 8/765=0.0104575 and if we multiply this by 600 we get a trail of 6.27 arc secs.

The sales and marketing hype surrounding the Tak EM200 quotes the mount as having ± 5 arc sec PE, although I believe Takahashi actually state ± 7.5 arc secs. So, the mount appears to be in spec (6.27 vs. 7.5) although the elongation that I measured occurred in a 3 minute cycle, whereas I think the full worm cycle is between 8 and 10 minutes.

This elongation has occurred when I have auto guided using the 2nd guide chip in the ST7E and also via a separate guide scope, so I think guide scope flexure can be ruled out in this instance. However, the ST7 only push fits into the 2” JMI focuser so there could be some flexure here, which the system is trying to chase. I may have to permanently fit a 2” to SCT adapter into the JMI, so I am not relying on a couple of grub screws to hold the weight of the ST7 and Meade 647 Flip Mirror plus 32mm Plossl viewing eyepiece.

Having said all of that, the EM200 is working like a champion and if that is the only drama in my life, I can consider myself a very fortunate soul indeed, compared to those are really suffering around the world.

Cheers

Dennis

[Kal]

Nice shots, I'll definately have to slew there and have a look at that area next time I'm out under clear skies.

[tornado33]

Well done both images
ironically when I first did that object I had some RA guide errors too. Mine being off axis, I think the guide star wasnt bright enough, and too comatic to accurately guide with.
Scott

[Ric]

Great images Dennis, they both have nice detail and clarity. You have also captured some nice colour in the first image of the open cluster and PN.

very nice indeed