Where did M31 go?

[philhilo]

So, been working on imaging for a year or so, had a good outcome with M51 1st off - as in I could see it, wrestled with DSS, got 20 minutes unguided together lovely. Have slowly learnt that from a Bortle class 8 location that was a lucky start. Through a long slow process have moved on in tiny increments. Various other attempts with galaxies have shown that the light pollution swamps the dimmer galaxies - I can see them but never manage to pull them out of the background when processing. I thought I would take a stab at M31 - its bright, big (actually too big for my 200PDS) and not too low (unguided I want stuff not rocketing around). I got 20 minutes of 30 second subs with the centre of the galaxy clearly visible - looking good I thought, stars were there, pretty round stars (no coma corrector so coma shaped round at the edges), even some nice colours - put them with darks and bias frames (crushed I forgot to do flats, added to my imaging process checklist) into DSS and waited for the output and …… out came a very dark image, and any trace of M31 had vanished.  Was I using the wrong set of light frames? Have I changed a setting somewhere? Tried restacking many times, pulling out various frames that weren't so good but to no avail, not much light and no galaxy. Tried processing the image in GIMP. Pulled the data out from the far left corner of the histogram into the visible realm and no sign of M31.What is going on? Baffled of Solihull. One of the lights and the DSS output attached (yes they are labelled as M103 - not that organised yet with Backyard EOS to switch naming between targets).

M103_LIGHT_30s_800iso_+18c_20190808-01h30m38s196ms.CR2 Autosave001.tif

[carastro]

It is rather dark, I could not open the CR2 file, but the stacked one when stretched does show stars (which have been jogged) but no M31.

Carole 

 

Edited August 13, 2019 by carastro

[Adreneline]

I processed the tif in PixInsight and plate solved it with Astrometry.net.

I guess there is no sign of M31 because it's not M31! The image appears to be centred near Delta Cas. However M103 is in the image - the open cluster.

I'm no expert but there appears to be some 'walking-noise' which dithering might sort but others will know better.

HTH

Adrian

 

Edited August 13, 2019 by Adreneline
Clarification

[carastro]

This is the image stretched, just trying to plate solve it but after a 10 minutes wait Plate solving doesn;t seem to be working.  Maybe it's because of the jogged stars.

Carole 

[carastro]

Well done Adrian, I was trying with Astrometry.net but so far it hasn't worked.

Carole 

[Bobinius]

Your light photo clearly shows M31 in the upper half (but it is off center). The integrated tiff is not at all the same image. So either you aligned it on the wrong image or you put in some really off track subs. You should check all the individual subs to see that the sideral tracking was really following. If your entire set is made from the same subs as the first one you uploaded, it is impossible to obtain that tiff.

[Adreneline]

4 hours ago, philhilo said:

no sign of M31

Here's your M31 from the single CR2 file. Processed in PixInsight - background extraction, background neutralisation, colour calibration, SCNR to reduce the green cast, inverted Luminance mask applied followed by multiscale noise reduction, and finally multiple incremental histogram stretches.

HTH

[Kev M]

I was going to ask why the filename started with M103 ?

 

 

[philhilo]

2 hours ago, Adreneline said:

Here's your M31 from the single CR2 file. Processed in PixInsight - background extraction, background neutralisation, colour calibration, SCNR to reduce the green cast, inverted Luminance mask applied followed by multiscale noise reduction, and finally multiple incremental histogram stretches.

HTH

Hi Adrenaline, that sounds like a stack of work - I have just about figured the histogram stretches! Thanks for that, I am using GIMP, Photoshop seems like a lot of £££ for something which I wont be touching the vast majority of it, PixInsight at least seems Astro dedicated if still a fair few £ (also reading the info on the website I do agree that some of the actions I have seen being taken on Photoshop did seem closer to painting an image rather than processing).

[Adreneline]

13 minutes ago, philhilo said:

PixInsight at least seems Astro dedicated if still a fair few £

Rest assured IMHO it is money well spent especially when compared with the money spent on hardware in this hobby. I use other software as well but PI is at the root of all my main processing actions.

Good luck!

Adrian

[philhilo]

Thanks everyone for the replies, I went back through the light frames and found one image of M103 amongst the M31s. DSS seems to have latched onto that and used it as its primary image......possibly.....I think.

I restacked everything pulling out a couple of satellite trailed images, then did some stretches and curves on GIMP and what I got is below.

2 purchases coming up, an 80mm APO before I go to NW Scotland in September ( for the larger stuff, the 200PDS will still go - family will expect to see stuff), and a narrow band filter for use at home in the autumn/winter. Then I just have to get the guiding working and get my head around more complex processing.....there may be more questions. M31 final.xcf

[Stargazer33]

Just as a guide; if you want to show an image on the forum, it's best to post it as a .png or .bmp file. Not everyone will have the software that an image was created in. I've never heard of a .xcf image file before, or have softwear that will open it to see your efforts!