Wednesday, 28 December 2016

Boxing Day Night - fun in Mono


I took full advantage of the clear night on the 26th of December and managed to capture 3 deepsky objects - an unheard of feat at Welford Observatory :-)

The first result was from the Wizard Nebula discussed in my previous post


As discussed in that post I was less than impressed with the results. Good guidance from Stargazer's Lounge forum advised that I need a lot more data on this to get good results.

The other two objects I imaged were much more rewarding.

This is the California Nebula. I've always enjoyed imaging this object whereas most imagers I talk to say they don't like it. I love the billowing nebulosity caused by the star Menkib exciting the H-beta line.




The shot above consists of 24x5min subs fully calibrated and processed in PixInsight with MaskedStretch, a bit of CurvesTransformation and AtrouWavesTransformation for noise reduction. I'll be capturing even more data on this in the month to come so this is really a work in progress.

Finally I managed to grab 14x5min Ha subs on the Horsehead and Flame Nebulae in Orion. 


Fully calibrated and processed in PixInsight with HistogramTransformation, a bit of CurvesTransformation and AtrouWavesTransformation for noise reduction. 

Hanging off the left most star in Orions belt this collection of nebulosity has fascinated me since I started imaging in 2010. I was surprised at the results with such a small number of subs - looking forward to capturing more soon.

Tuesday, 27 December 2016

A Night in the Life of Welford Observatory

Having received gifts for my interest in astrophotography this Christmas I was sure it would be cloudy for at least a week - giving no opportunity to use them as that is what usually happens in this hobby.

I thought I'd record an entire imaging session as it looks like I'll have an entire night of data to work with tomorrow when I can record the process for anyone just starting out in astrophotography. Be warned...I may get it wrong, but its a reference point.

I was surprised to see it would be clear tonight and have set up to image.

Here's the gift I received



It's a bahtinov mask that aids in focussing the telescope with the camera attached. I had been using one that I wasn't sure was designed correctly for my scope aperture - it appears it was close but the difference wouldn't have meant blurred images.


With the mask attached you move focus in and out to centre the spike in the middle. This give a really good (not perfect) focus. There are programs you can use to get focus even better but I've never had any problems using the bahtinov mask - you can read more about it here.

Next it was time to get the scope guiding on the first imaging target for the night - the Wizard Nebula in Cepheus. The orange square represents the field of view covered with my scope/camera combination.


Image courtesy of Starry Night Pro 7

Checklists should be an important part of an imaging session. I intend to make a few as I started an imaging run in H-alpha only to notice that I hadn't calibrated the guiding?! Luckily I noticed almost immediately and set it on its run.


26/12/16 1952hrs

I've been imaging for about 2 hrs now and have captured 12x5min subframes in H-alpha and 12x5min in Sulfur II. I'll finish with an hour in Oxygen III and then move on to the next target.

Image courtesy of Starry Night Pro 7

26/12/16 2129 hrs

I've chosen my next target.

NGC 1499 is known as the California Nebula and is found in the Perseus constellation. This emission nebula is caused by xi Persie which is also known as Menkib.

I've imaged this object quite often with my "one shot colour" camera (QHY8) and was fascinated by the billowing nebulosity found in it. Having only imaged it in RGB I've been looking forward to capturing the H-alpha that is abundant in this region. Early indications are I won't be disappointed, the image below is a single 5 minute exposure in Ha - which is pretty impressive...take my word for it lol.


I'll concentrate on Ha tonight as I'm not sure how much Oiii and Sii will add to this object.

The camera attached to the back of the telescope is doing a great job of letting me know when it's time to spin the roof to move the opening along as the stars pass overhead.


I used to simply time it but that was a bit hit and miss but as it give me a view "right down the snorter" of the scope I can't go wrong now :-)

As the object moves eastwards its coming closer to the increased light pollution on the horizon. You can see the light pollution in the image below.






WOBSCAM (as I've christened my scope monitoring camera :-) ...is also capturing Messier 45, the Pleiades which is kind of cool. It's surprising how bright they are in relation to the other stars in the neighbourhood.

You'll notice the aperture the scope is looking through has increased. I took the front hatch cover off so the scope can track lower to the East.

26/12/16 2354hrs
On to another object. Can't believe my luck!

Image courtesy of Starry Night Pro 7

The Flame and Horsehead nebula in Orion are very popular objects at this time of year. Its a favourite image of mine that I captured with my QHY8. It's great to be able to try out the new mono camera on it.

Here's a short 5 minute capture taken while I was framing the shot.


This shot was taken with the Luminance filter, the Ha filter is reveals far less detail at these settings.

After getting the scope going again I had a look at WOBSCAM and noticed that Orion was quite clear in the view. The area I'm imaging is just by the left most star in Orion's belt. You can also make out the Orion Nebula (Messier 42). I hope to image that soon as well.


The light pollution is quite bad in the South here (the town of Wantage) but this object is sitting just above it I and I've managed to image this object before successfully.


27/12/16 0954hrs Update 

I finally got to bed at 0300hrs having imaged 3 objects in one night (not all the data I need for two of them but a very good start.

The great thing about my new camera is that I can leave it hooked up to the scope in the observatory without fear of condensation building up in it. My last one was awful for that and great care had to be taken.

This means I could take my flat field images in the morning. The image below shows a flat for Ha. This image will be subtracted from all the subs I captured last night - removing "dust bunnies" and other errors.




I take 50 for each filter (last nights consisted of Ha, Oiii and Sii)

One issue I've been trying to deal with appears in the image below. I took the flats for the three narrow band filters without the banding shown. 



They've suddenly appeared on the Luminance flats (taking them now for convenience even though I don't need them etc.)

When I turn off the dew heaters for the telescopes they go away (see below)



Its fairly simple to establish that as the dew heaters are running off the same supply as the camera it could be causing this interference. However, it doesn't happen all the time so I'll have to do some more troubleshooting. For now I'll just turn the dewheaters off and hope the scope doesn't mist up.

The next step will be processing - but that will have to wait until I have got to the gym to restart my system following all the food I've eaten during the holiday season LOL!

27 Dec 16 - 2128hrs

I've spent most of the day processing the results from the Wizard Nebula taken over two nights (30 Nov and 26 Dec)

I learned quite a bit about how to process data from different nights but it took a looong time :-)

First I pre-processed the Ha, Oiii and Sii channels producing 3 "light" frames to combine.

The initially start out black and white as below, with varying levels of detail dependent on the wavelengths present in the object being imaged.

This first light frame is the Sii channel - not a lot going on here 



Next is the Oiii channel ...little more detail in this one



And finally the Ha channel where all the detail has been hiding :-)




These three images are combined in PixInsight using PixelMath where you put varying weights for each channel in the R, G and B channels creating a false colour image.

I used the following weights which were suggested to me by Patrick Gilliland on the Stargazers Lounge forum. 

(MASTER_Sii_161226_r*.90)+(MASTER_Ha_161226_r*.10)

(MASTER_Ha_161226_r*.85)+(MASTER_Sii_161226_r*.15)


MASTER_Oiii_161226_r

I had absolutely no idea how to apply the weights so this was a huge help to get started.

...and here's the final result.



Like you I'm not crazy about it either :-) I assume I simply need to get more data on it but to be honest I find this object pretty boring for some reason....after capturing and processing the Elephant Trunk Nebula with such great results, and knowing that I've got tons of data on the California Nebula to process, I'm going to leave this object for a while and concentrate on others.

Any advice on how I might improve this image would be really useful.

Now I can finally  get some sleep :-)









Friday, 2 December 2016

UK Astrophotography Utopia!


26-30 November, 2016


It’s been the longest clearest spell of weather I’ve ever had for imaging since starting in this hobby in 2002.

I had 4 nights of clear skies on the 25th, 28th, 29th and 30th of November, 2016 – unheard of. This clear spell has come not only during the longest nights of the year (with it getting dark at 5pm) but also without the Moon above the horizon. It doesn’t get any better than that.
I started on the 25th of November imaging the Elephant Trunk Nebula (IC 1396) in the constellation Cepheus.


What I know about the constellation Cepheus

Image courtesy of Starry Night Pro-7




Easy to spot as it looks like a house in the sky


It represents King Cepheus, king of AEthiopa


Cepheus’ wife was Cassiopeia and his daughter, Andromeda (who also has a constellation named
after her) can be found near the constellation Pegasus.


This constellation contains 27 delta Cephie, a star who’s variability was found to be useful when
measuring the distance from us to distant deep sky objects – with impressive accuracy. Wiki
Cepheid Variables for more.



What I know about the Elephant Trunk Nebula
Image courtesy of Starry Night Pro-7



The hole in the head of the nebula may have been cleared by the two very young stars in centre of it.


The star in the centre of the nebula is ionizing the interstellar gas that is surrounding it
and colliding with the dense gas of the Elephant Trunk nebula it has triggered star 
formation.


The reason I wanted to image this object is that I have found it to be my second favourite object in the night sky (only surpassed by the Horsehead Nebula). The combination of the wide, red nebula with its bright central star and the Elephant Trunk framed perfectly at the bottom of it provides a picture-perfect composition – that I simply can’t get wrong.


I’ve imaged it before with my one-shot colour camera – a QHY8. The best of my efforts with that camera appear below.


The first is taken with a 115mm refractor in October of 2013.



And this second one was take with the same scope as this article relates to, a 65mm astrograph  taken in 2012



The second one has been one of my favourite Astro-images that I’ve taken ….until now.


I recently bought a ZWO ASI1600MM-Cool (meaning cooled…not that it is…cool, although I think it is) and as it’s mono I have to use 7 different filters to capture the images I want. This sounds appalling when you consider the QHY8 required 0 filters, but I think you’ll agree looking at the results below that it is more than worth the extra effort.


And there’s a twist – the ASI1600 has a CMOS (complementary metal-oxide-sensor) chip instead of a CCD (charged coupled device). The technical differences between the two can be discovered on wiki – the key for astrophotography is that with the CMOS you take many very short, high gain subframe exposures (anywhere from 30 – 300 seconds at 139 gain) whereas with the ccd you take much longer ones at lower gain (with my OSC camera mentioned above I took 20 minute exposures at 0 gain).


What this means is that there are some talented individuals out there getting spectacular images on quite inexpensive set ups because they can take very short exposures without the need to guide (another scope locked on a star firing corrections via a webcam, to the mount to keep it centered on target) during the capture.


As my observatory is setup to run guided – I continue to – especially as I am taking 5 minute exposures for the narrow band filters – still a short time but my mount would not stay centred on target without guiding for 5 minutes.


And so to the 4 evenings details of data captured and the results.





Ha           : 12 x 5 min subs @ 139 gain = 1 hour
Oiii          : 12 x 5 min subs @ 139 gain = 1 hour
Sii            : 12 x 5 min subs @ 139 gain = 1 hour


I was extremely happy with the results from this night and processed my first narrow band image from this data. Of course when I did I didn’t realise I’d be getting another 3 nights of clear skies to get more data.
November 28th, 2016
Narrowband on IC 1396


Ha           : 12 x 5 min subs @ 139 gain = 1 hour
Oiii          : 12 x 5 min subs @ 139 gain = 1 hour
Sii            : 12 x 5 min subs @ 139 gain = 1 hour


Another great night, some minor equipment issues with Nebulosity 4 freezing once forcing a reboot of the PC and all 3 cameras and the mount controller – but that went quickly.

LRGB on IC1396


Luminance          : 90 x 60 sec subs @ 139 gain = 1.5 hours
Red                        : 15 x 2 min subs @ 139 gain = 30 min
Green                   : 15 x 2 min subs @ 139 gain = 30 min
Blue                       : 15 x 2 min subs @ 139 gain = 30 hours


No interruptions due to technical issues. Here’s a shot from WOBSCAM that I use to keep an eye on sky conditions

November 30th, 2016
Luminance on IC1396 and Ha on NGC 7380
Luminance          : 60 x 60 sec subs @ 139 gain = 1 hours
Ha                           : 24 x 5 min subs @ 139 gain =  2 hours


Looking like the last clear night for a while so I tried to get as much done as I could.

December 1, 2016
Oiii on NGC 7380
Oiii          : 9 x 5min subs @ 139 gain = 45min


It was very clear to begin with but soon clouded over. Luckily enough time to get some Oiii on the Wizard nebula to go with the Ha

And now to the results


I have had 4 good clear nights to image in with the ASI1600MM-Cool.


My equipment (TS65mm) has performed as never before, with ease and reliably.


I have captured about 12 hours of data on the Elephant Trunk Nebula - an unheard of amount of data for Welford Observatory on ANY object in the past 10 years.


I'm using PixInsight to process and although not an expert I feel confident in the few scripts and processes I use.


What can possibly go wrong....:-)


You be the judge, jury and when and if you slaughter my results with accurate and technically focussed feedback .....my saviour...:-)


I've posted really bad low res screenshots below to keep SGLs servers from bloating to popping point but you can see the higher res images on my site under "Images"


I still have a full set of LRGB data to process so and off course bi-colour and HaLRGB...so now its finally cloudy I can do some processing haha!


These images below have had flats/darks/bias applied, the SHO image is 2hrs on each channel - the Ha is 2hrs.


.....and as this is my first real foray into nb imaging - I'm quite pleased with the results...and looking forward to processing the LRGB and bi-colour now :-)







These are quite low resolution examples of the originals