M33 - Triangulum Galaxy

 

 

Here's a quick processed image of a session from back in November 2023. The integration time on this image of M33 is on the long side for me, with just under eight hours of integration time between R-G-B-Ha channels. With that in mind, you can pick out the glowing red regions of star formation. Nevertheless, I wasn't really happy with the overall noise level/background/calibration, and there's some pretty severe fixed pattern noise.

For that last issue, I need to look into my dithering setup. For the former, some of the problems have been fixed by my new field flattener (the William Optics one that came with my scope has always suffered from bad and uneven vignetting, and bloated stars at the corners, which seems to be fixed by the new Orion flattener). 

Also, I know it's time I finally figured out how to do a good job with foreground star reduction... but not today. 

Either way, I thought I'd share - Triangulum!

The Double Cluster

 

It's been a while since we've posted anything here, but this is a quick glimpse into one of my favorite all time objects: the Double Cluster near Cassiopeia. This object comprises NGC 896 and 884, and is a striking sight through even a modest telescope. I have a special fondness for this cluster, as I first learned about it while just randomly scanning through the fall sky with an old 8" Dobsonian.

https://en.wikipedia.org/wiki/Double_Cluster

15x60s Blue
15x60s Green
20x60s Red

Camera: QHY 268M

Scope: William Optics Z81 with Orion Field Flattener

Mount: Orion Atlas Pro AZ-EQ-G

Processed with bias/flat/dark in Siril, including color calibration, background extraction, green noise removal, and auto-stretch. Final post-processing in DarkTable. 

Imaging Timelapse

Time lapse of a recent astrophotography imaging session. In addition to stars, you can see a research helecopter going by repeatedly from the Operator Performance Laboratory:

https://iti.uiowa.edu/our-research/centers/operator-performance-laboratory

They were repeatedly flying along the opposite shore of the Coralville Reservoir.

M51 Experiments

 

 

This is a sort of experimental image of M51, and its interacting companion NGC5195. I've actually been imaging this pair for a while, but this stack is actually made up of just 17 frames of 5 minutes each, or just under an hour and a half of data - using my Orion Xt8 optical tube. 

 This scope, which I bought in 2009, is intended only for visual use, but it's within the weight capacity of my mount, so I figured I'd give it a shot. Overall, it definitely lives up to its reputation as a light bucket, but in the pre-cropped version of this shot it didn't do so well on bright stars. There was some pronounced asymmetry, which could be due to the telescope itself, or perhaps to guiding errors induced by wind hitting the monster of a tube. 

 I've also been using a different camera, an old Canon EOS-M2 mirrorless. The data quality is FAR lower than my Pentax DSLR, including noise levels, hot pixels, and banding. Fortunately, most of the issues appear to be (mostly) correctable via calibration frames and dithering. This camera has a shorter distance between the sensor and bayonet mount than my DSLR, so it allows me to reach focus with the Xt8 telesope. It's also computer controllable via libgphoto2, so I can use it inside of kstars/Ekos.

NGC-2903: It's Galaxy Season

 This photo pictures NGC-2903, and also NGC-2916. The former is much larger in apparent field of view, at 30.4 million light years away. The latter is very small and faint, and if I'm converting redshift to MLY correctly, it's just over 200 million light years distant. 

 

 

Down and to the right of the smaller of the two, you can see a third galaxy I haven't been able to find any information on (though it's surely categorized somewhere). In fact, close examination of a wider crop shows at least half a dozen other tiny faint galaxies. 

That's promising, because this photo represents only 30 light exposures at 150-seconds each, for a total integration time of only 1.25 hours. The scope is similarly modest, with just 80mm of aperture at a 447mm effective focal length. 

Here's a closer crop of the same data, processed slightly differently: 

  

 

 The biggest technical addition these photos represent is guiding, as well as tracking via software rather than using the SynScan hand controller that came with the AZ/EQ6-R Pro. I'm currently using INDI/Ekos via Kstars, which is free and open source, and therefore has good linux support. The guidescope is a basic 50mm William Optics scope with a ZWO-ASI 120mm Mini guide camera.

The good, the bad, and the M42 (again)

 

This is another attempt at M42, the Great Nebula in Orion (and friends).

There were a few changes this time, some good and some bad. First, I think my polar alignment was better (good). Second, I got a Bhatinov mask to help with fine focus (good). Third, I decided to try imaging without the light pollution filter, which ended up being bad. Despite an overall much longer integration time, there's a noticable drop in contrast for the dimmer parts of the nebula.

I also added flat frames to this one, but they didn't really seem to help with the vignetting - I might need to look into how I'm taking those to see what my problem is.

All exposures at 6400iso, 400mm FL, f7.1
Lights: 394 @ 30s, 91 @ 15s
Flats: 81
Darks: None (very cold out)
Bias: 87

Initial processing was done in Siril, separately for the 15 and 30 second stacks. Each resulting stack was processed globally in Darktable for color and contrast. Final processing and exposure combination was done in Gimp.

Starfields (Take 3)

 The weather has been awful, so I don't have much in the way of new captures. Instead, I put in a little time today to reprocess the Jolly Roger Cluster star-field image to try to preserve more color and relative brightness for a more natural look.

There's one small spot where a dust particle on the sensor which didn't get captured by the flat frames is dealt with via the "clone" tool, but the rest of the image is true. 

After a similar workflow in Siril, processing was done this time in GIMP.