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arkosg

Goodbye to spring targets, M100 SN, and more

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Hi everyone,

It's been a challenging spring here on the West Coast, and opportunities to get in some observing have been fewer and much further apart than I'd have liked, so I was happy when a nearly New Moon coincided with some clearing and diminished winds.  I dusted off my 5" Borg refractor @f5 riding on an Ioptron AZ Mount Pro (alt-az) with a Starlight Xpress Trius 694 mono camera (running 1x1 and sometimes 2x2 binned mode) and filter wheel (typically shooting through a luminosity filter, though I did some Halpha viewing as well).

Using StarlightLive v 3.4 on the Mac (I've noticed some "banding" in 1x1 shots, and had a few SX filter wheel control "freezes" that required a restart of SLL).  Usually a stack of a half dozen or so 30s or shorter exposures (depends on how my mount is feeling and where in the sky I'm observing).  No guiding.  My standard observing location is a suburban sky in a small city at sea level with Vancouver BC nearby to the east and trees blocking much of the W-NW sky near the horizon.

Hope you enjoy the shots!

Clear skies,

- Greg Arkos

 

Antennae galaxies - with faint tidal tails!  Not bad for so low in the sky...

Antenna.Galaxies.x.0.25_2019.5.9_23_41_00.jpg.6e9ee27ee30aa488ec86cd40231c3a34.jpg\

Leo Triplet

NGC_3628_M65_M66.x.0.25_2019.5.9_23_34_02.jpg.21e8e96fc968b136bf326fce0a97de0c.jpg

M100 with supernova!

M100.x.0_25.SUPERNOVA_2019.5.9_23_22_24.jpg.557fce4dc45612c7170bbed89c558a10.jpg

Closeup of earlier (before) shot and above

1223972847_M100.L.x.0.25_2019.3.13_01_10.45-Version2.jpg.60344a29ccb3c1e9b6f8f246f022c487.jpg678853263_M100.x.0_25.SUPERNOVA_2019.5.9_23_22.24-Version2.jpg.b85401be6fe492bf34573be452cce97c.jpg

Some Halpha viewing: PacMan Nebula, Wizard Nebula (which I hadn't viewed very well before), Elephant Trunk  Nebula, and finally the Eagle (M16) just rising as I was packing up.

PacMan.Nebula_2019.5.10_00_56_50.jpg.00a28d391aeed286cbef2d5c69d316a8.jpg

Wizard.s.Nebula_NGC_7380_Ha.x.0.25_2019.5.10_01_11_08.jpg.55fe28f9ff0af0bee142111febd9d102.jpg

Elepant.Trunk_Neb_Ha.x.0.25_2019.5.10_01_22_03.jpg.b519ed2bae921e9591ed919e924c4f69.jpg

M16.Eagle_Neb_Ha.x.0.25_2019.5.10_01_54_19.jpg.c94af8e4257d422011a1bb3743cad186.jpg

 

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Hi Greg

Excellent shots! I particularly like the Antennae tails and the Leo group in the wider context that the Trius/Borg combination provides. And your H-alpha are really clean.

Funny you should mention the fitlerwheel freezing. I've also had that a couple of times recently although for some reason I blamed the FW rather than SLL. As you say, a restart cures it. I've a feeling it might depend on the order the USB cables are plugged in, if SLL is already open when plugging. But that could be wide of the mark.

The only time I've seen banding is when using short exposures, where I think it is deliberate to keep the throughput high during focus and framing (I don't understand the details, but I think the image is read in two reads, one for odd rows and the other for even rows, then combined -- or not, in the case of short exposures). Banding affected some flats I took at 0.5 seconds or so (and since I take twilight flats I have to get going a little bit later and use longer exposures.... a t-shirt would help this issue). I wonder if the higher pixel count on the Trius leads to incomplete reads and hence banding. Are the bands horizontal?

Martin

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Hi Martin,

Thanks!  Conditions were really pretty good (for here), and it definitely makes a difference as to what you can achieve when the seeing is better.

I'm using SLL v 3.4.  The SX mini FW is normally pretty well behaved, although I have had occasions in the past where it "freezes up".  Sometimes, in the past, I was able to physically unplug it and replug it and have it be recognized successfully again.  But this last couple of sessions it's required a restart of SLL to get the FW working again.  One session I had numerous "freezes" in a fairly short time span.  It's the same cabling, etc. I've used for the last year, so that hasn't changed, or how I connect the FW and the Trius 694.  I tried it out "inside" and things seemed to behave pretty well, though I was eventually able to get a freeze after repeated FW control commands one after the other.  It seems random to me - or at least, I haven't figured out a pattern to it at this point.

Unrelated note: I've also noticed a bit of amp glow (?) in the top left corner.  Again, seems to vary.  Could be issues with darks - with all of the FW freezes, it's possible I started imaging again without taking/applying darks, which could be the difference in this case!

The "banding" issue seems to appear only during 1x1 binned images.  If you look at the M100 image (wide field), particularly in the darker corners, you may be able to discern a "tartan" pattern of horizontal and vertical banding.  It seems to vary (and I haven't tried to pin down what makes it stand out).  Below are other Halpha 1x1 examples taken from a different observing session; I've stretched the contrast a bit more so you can see the issue clearly.  Again, it seems to only occur in 1x1 mode (or at least it's more evident then).

Are the flats you mention for use with Jocular?

Clear skies!

- Greg 

IC_5146.Cocoon_1x1_Ha.x.0.25_2019.3.13_02_57_30.jpg.2aa4eb3ba54110050273f9d7d5224047.jpgNGC_7635.Bubble_M52_Ha.x.0.25_2019.3.13_02_35_55.jpg.fa70d219b44633bb9fbf5ed126f9eacf.jpg

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Hi Greg

I thought I'd seen that tartan pattern before with darks but can't now lay my hands on them so I might have been imagining it. Maybe cable issues?

BTW I really like the conjunction of the bubble and the open cluster.

Yes, I was collecting flats for use with Jocular.

cheers

Martin

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