Malpi12

Thank you for the explanation and the picture examples are a great help !

18 hours ago, vlaiv said:

Gimp and ImageJ

 Then I binned data x4 - as it was grossly over sampled to start with

All very interesting ! I now have FiJi-ImageJ  and a whole new world to explore

What is the indication that it was over sampled ?

Thanks.

8 hours ago, Iem1 said:

Or remove the stars with Starnet?

Untouched Autosave version from DSS if anyone wants to try save Pac man  

Thanks, not heard of Starnet before, downlading now !

Thanks for the tif, Saving Private Pacman  is a bit of a challenge for my Gimp skills, especially the moon? gradient in the bottom left.
This is my 3rd iteration (you dont want to see the first  2 !!) I have gone for the dark sky look again, tried not to be as severe as I did previously with the NAN,  but I'm still having bother keeping star colours.

51 minutes ago, Felias said:

Also, you have changed the aspect ratio of the photo, it's compressed in the horizontal direction.

Argh ! Well spotted, thanks, that is a big mistake and was not supposed to happen.
I have found the error - a box "Preserve aspect ratio" in Irfanview re-size had become un-ticked.

Nicely done on PS, I see a lot of good work done with it but for my little efforts the cost can not be justified (similar for PI !)

Thanks for comments, yes I see what you mean and shall watch out for that next time round. I did notice the stars getting less nice the more I fiddled with the red !
All good for practice in Gimp and thanks to @Iem1 for offering up the tif  image.
 

7 hours ago, Iem1 said:

so, this should be the stacked image with zero processing done to it? (It is the autosave file that is added automatically after stacking);

Autosave.tif 168.32 MB · 3 downloads

 

Yes that looks about right for the  "argh there is nothing there, did I point in the right bit of sky" and reach for the Plate Solve on the stars !!

6 hours ago, Felias said:

I know. I did two in a row the past weekend and that was enough hill climbing for me this week. A three-year old at home doesn't help, of course. 😅

I did a fast one while she has been quiet. Much better, I think:

Wow nice one ! what software / processing/ workflow ?

This is my first simpleish attempt at @Iem1 's tif file  in Gimp. I assumed that the primary colour of the emission is deep red  Ha, so best to use plain red visually ?

@John in another topic you have said

"I've owned two 12 inch dobs and one was not a good choice because it was far too heavy but the 2nd one (my current one) was much lighter and much more practical all round."

May one ask which is the lightweight one ?

This is another aspect of the "observing"- observability  question that is near to my heart, due to a recent medical misadventure I could no longer handle my 9.25 and 300p  It was 2y ago - soon I think the 9.25 will be manageable again , and with luck maybe also the 300p, that is the good news,

 the other good news is that imaging with little things is quite interesting

On 20/07/2021 at 12:38, John said:

I've just noticed over the past, say, 18 months how many folks are seeking to acquire images now in one way or another, through dedicated astro cameras, mobile phones DSLR's etc.

Is the trend towards imaging growing or am I imagining it ?

 

I think you are right that there is a growing trend towards imaging.
Also I think you are right that it has grown in the last 18m.
Both by already-amateur-astronomers, and by those recently come aboard !

The broad growing may be due to those of a certain vintage looking for new aspects, those displaced by increasing light pollution, and/or lots of other reasons.
New chums on-board may be due to online sources describing the wonders of the latest (insert name of device)

As for 18 months ?  Yep I think so, lots of time on hands due to a certain virus (and in some quarters extra funds that have not been spent on petrol and other essentials of modern living etc  ?! ), to go online surfing - -  showing my age again! - - I think mean twittering  --- leads newcomers down the path of latest technology, , , 
 

I expect John will be able to speak for himself what he meant  

Do you observe a tree falling in the forest if only your ears tell you so.

But gosh, I am really trying not to be controversial honest guv.

(wanders off-stage into the gathering night  to experiment with his new dslr 😀 )

On 20/07/2021 at 12:38, John said:

This is not in anyway intended to be a controversial topic I hasten to add

Without wishing to be controversial also may I question the title ?

In John's opening post and most people after, it seems that "purely observing" means visual ? Ie. with an eyeball ?? Well I have been observing various astronomical things for over 65y, I forget (!) when exactly but it was well before SputnikI !! using mark I eyeball followed by assistance with various bits of glass, glass and aluminium, and just recently a bit of glass and lots of tiny silicon. But I am still using my eyeball to observe them. Excluding the time when I built a shortwave radio to listen to the Sputniks, when I used my ears to observe them !  

But gosh, I cannot say which form of observing should be considered pure ! 
 

here we go,
stacked only,no stretch etc. via autosave :

To apply (or not) the stretch to the saved picture.

1 hour ago, Iem1 said:

(I notice my images seem to come out of DSS looking already stretched?

Very interesting topic, thanks, especially the bit about darks vs, bias, which I have also found and thought I was doing something silly with my darks !

I am a beginning beginner at imaging (still only a camera on fixed tripod) so I hesitate to jump in but -
a couple of things caught me out in DSS  which may be relevant.
There is a box to be ticked to autosave your stack, which saves it without any processing.
Then there is another setting to save the picture with the processing /stretchings applied into the saved tiff OR embedded in the tiff but not applied. (Which confused me! I still dont understand what it means by embedded !)
They are in there somewhere, it was a while go so I'll go back and have a look and post again if you have not yet found  them.

On 15/07/2021 at 02:19, Pixies said:

I appear to have missed both brightenings 

10 hours ago, Pixies said:

A little brighter tonight. 

Thanks for the report&headsup

I have just looked at the AAVSO plot and it looks like it may be preparing to have another 'burp' ! Was cloudy here last night, fingers crossed for tonight

AAVSO visual data :-

8 hours ago, John said:

Maybe I'd better use the 12 inch dob for tonights attempt, given the rate at which the nova is fading !

Good luck, and we may have a bit longer yet, looks like it may be leveling off a bit : data from AAVSO

59 minutes ago, robin_astro said:

 ( lots of interesting stuff  )

Wow! Thank you, amazing  👍

Who needs bed when there is interesting astro to be done !

From  wiki :-
"After shining for only a few million years (compared to several billion years for the Sun) they erupt in a supernova. The recent supernova SN 2006gy was likely the end of an LBV star similar to P Cygni but located in a distant galaxy
...
It has been identified as a possible type IIb supernova candidate in modelling of the fate of stars 20 to 25 times the mass of the Sun"

But before we get too excited I think Robin may a have been referring to this  spectroscopic bit :-
wiki again : "P Cygni gives its name to a type of spectroscopic feature called a P Cygni profile, where the presence of both absorption and emission in the profile of the same spectral line indicates the existence of a gaseous envelope expanding away from the star."

Morning all ! Brief report before bed

2:30am and I had almost given up hope, then the overcast started to clear with passing clouds and I can say that it continues to decline.  
Now much less than the mag 8.5 HD175919/HIP93033
Not far away are two unnamed in Stellarium at mag 9.5 and, further away, mag 9.0 **,  on this basis I would give it 9.0 but as remarked earlier my eyes are not good at this so I will hope that I have got some lucky subs to stack tomorrow.

**update - I think they are mag 9.512 - Gaia DR2 4508099383033253632 and mag 8.977 Gaia DR2 4511094899382630144 in CdC.

PS  @robin_astro what are the implications for the future of it being similar to P Cyg, I have just wiki_ed  it and that one got to magnitude 3 !

That was interestingly quick,
on the first night ( of Jeremy's well timed alert  ) it was in plain sight in a 2 sec exposure at iso6400 f2.8 50mm lens.
Last night I had to stack 20 to get it to show !

I have a theory that it wasnt a nova,
it was ET shining a torch, " Anyone home ! "
He couldn't find any sign of intelligent life so he moved on  
 

3am local, had another look, it is a lot brighter,,

the sky I mean !  

Got it  

Here a quick annotated noisy 2sec jpg off the top of the heap. Now to process the raws and clean it up ,,>

9 minutes ago, Stu said:

Got it! Thanks Jeremy.

Well done ! Yes, nice one Jeremy 

I have not,,, what I have got is another tree ! Another hour perhaps ,?  unless I go for a long walk down the lane

This should perhaps be in the beginners section because I am learning my DSLR , stacking, and variable star observing all at the same time !
I normally observe visual, but my eyesight is no good any more for estimating magnitudes to better than about 1 ! So it is time to learn new tricks.

The first pics are of the Nova Cas from the night of 7/8 July, a stack of 40 2sec exp (with 20 bias, no darks more on that later) on a fixed tripod with a very old 50mm M42 lens.

I then converted it to grey scale, pixel-peeped a few stars that I could identify in Stellarium and on aavso and plotted the value of the brightest pixel (not scientific but I was just trying things) against the listed magnitudes, in GNUplot.
Fitted a quad function curve to them and popped on the pixel value for the nova.
Imagine my surprise when it turned up at about 6.7 !!! Just what you guys were observing  !!!

I thought I would have to do some converting from dslr response to visual, but just before posting this I found the BAA variable data section in which there are a couple of obs. marked with dslr that are also agreeing with visual reports.

On my todo list - sort out how to control the temperature of dark frames to coincide with my lights the ones I collected on the night were all over the place and contributed nothing better than the few bias were able to do
Get an eq mount.
Oh, and cut down a tree ! lol!
  

Yes, it looks like members only, I got
" Access denied You are not authorized to access this page. "
I have identified a few, but a bit of a struggle rotating and stretching their chart to superimpose on Stellarium  
 

On 11/06/2021 at 10:26, skybadger said:

 Anyone familiar with Maxim and photometry  ? 

Nova Cas Photometry table.pdf 250.94 kB · 12 downloads

 

Sorry I dont know Maxim so cant help

I cant find a cross ref of these AAVSO AUID star names in that pdf, to one of the more usual cats such as HIP, HD and others in Stellarium or CdC.

Anyone found one please?

Very interesting topic, I've been watching with interest, since I missed the recent outburst (behind a hill behind one of my trees ! ) It has now come into better view so I am waiting patiently for another outburst  
 

GNUplot anyone ? !

I'm not sure I should admit to this, but I have been playing with a photo observation of a variable in Serpens Caput using GNUplot

How's a fella supposed to get his maths right with all this mirth going on

Top left corner >

3 hours ago, JeremyS said:

I gnu that

I did also grok that (other conjugations of Heinlein's gnu verb are available ) 

I think I have got a new name for the next Blue superEthnic moon,  a tefilotoed moon ?