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So with no new data at hand (or on the horizon it would seem) i decided to go back and re-process my short stack of M81 & M82, being the glutton for punishment that i am! The last time i re-processed this was about a year ago, so i was curious to see if i could get any more out of it.
It's hideously low on data (nothing new there!), this is just 9 x 600s of colour (with an IDAS-D1) together with 7 x 1200s of Ha (which i only used to Lighten the Reds in the Ha jets of M82 and the small spiral regions of M81). AstroPixelProcessor used for stacking and gradient reduction, and PS for everything else.
I mistakenly shot the colour at ISO 800, instead of the usual 200 i always use. A mistake i imagine every DSLR user has made before! And i have to say i really noticed it during processing. There was noticeably less colour in the stars.
That being said, i was still able to bring out more colour in the core of M81 this time. And i think M82 looks a bit better as well, it was definitely over-sharpened before.
I really love these targets, but they just make me wish i had more reach!
Here is the original thread:
And here's the new one, including a cropped version:
After spending a couple of hours on bright galaxies and comets, I turned my attention to Supernova (as the Plough finally appeared from behind the shed roof).
First up was SN2018hna in UGC7534 (mag 14.9) in Ursa Major.
- I had observed this one already so I was on a "confirmation" mission. I soon located the oblong of stars (at the centre of the images), one corner of this oblong is the SN. I spent some time and noted another faint close-in star (to confirm on the image today) and everything matches up.
- With the 55mm Plossl and Night Vision the core of UGC7534 really lights up and all you see of the galaxy disk is a smudge to the south of the core.
Next up was a new SN for me. SN2019va in UGC8577 (mag 16.7!). Its located near the arm of the Plough.
- With the 55mm Plossl, I soon matched the star patterns to my sketch (that I made from the images earlier). There was no sign of the galaxy but there are other visible UGCs in the fov (to add confusion). There was no sign of the SN.
- I swapped in the Panoptic 35mm (x60 magnification) and the fainter stars got a little clearer. I was now sensing a disturbance in the centre of the fov which must have been the galaxy disk. A point of light blinked in and out three or four times. I noted the position based on the star pattern and was able to confirm the blinking dot in the correct location.
Hopefully, SN2019va will get a little brighter by the time I get another shot.
Disclaimer - My processing skills are at best, average. This thread is by no means a definitive test. Its just my observations.
I took some long exposures in Narrowband at 600s using the ASI183mm Pro camera and found that sometimes I could eliminate the Amp Glow from the middle right hand side using Darks and Flats and sometimes I could not. No idea why! Any help appreciated.
I found it easy to remove the glow when imaging at under 120 seconds a sub. This gave me the idea of trying to eliminate amp glow and noise by imaging at short, 10 second exposures, to see the results.
The one thing I failed to realise is the amount of disk space needed to process 200 x LRGB from a 20Mp camera ? The Registered and Calibrated files where 60Gb each!!
Processing on a External USB3 disk on a USB3 port on i7 with SSD and 16Gb RAM took best part of an hour. Not counting the restarts due to having other things running or lack of disk space etc.
Here is the result. Slightly cropped as it was taken over several nights and I did move the camera.
200 x LRGB at 10s
ZWO ASI 183mm Pro
TS 65/420 Quadruplet
Thanks for looking.
M81 Bodes Galaxy and M82 Cigar galaxy. Taken last night 23rd April despite a bright moon. 120 x 60 sec lights, 40 darks. No bias or flats as I'm having a bit of problem with my flats at present, they seem to make things worse not better. Taken with Canon 1100d unmodified with a Celestron C8 on an HEQ5-pro. Processed in DSS and Star Wars (Sorry Star Tools).
The Star Wars connection?, well you can see that M82 is better illuminated while M81 is on the Dark side. It was reported that a supernova was observed in Bode’s Galaxy in 1993, however it is much more likely that M81 was the location of Alderaan. destroyed by the Death star in the first 1977 movie and we viewed this event 12 ish million years later given that M81 is 11.8 million light years from Earth. If this sounds a bit far fetched remember that the story was set "A long time ago in a galaxy far, far away" so it sort of fits. If you don't believe this then all I can say is that "I find you lack of faith disturbing"
Data captured on the 8th March 2018 from light polluted Birmingham.
Telescope used : SW 80ED DS Pro
Mount: EQ5 pro - guided
Camera: Canon 200D with clip in CLS filter
12x270s with flats, darks and bias applied. Stacked in Deep sky stacker and processed in StarTools