Thursday, 16 November 2017

A shot at the Heart and Soul....nebulae

Tonight’s target has a few different common names besides the usual “Heart and Soul”. “Valentine Nebula”, “The Running Dog Nebula” and the ever catchy “AFGL Cloud” are some that refer specifically to the Heart element of this structure.

Of course, galactic catalogue names are the easiest way to find these objects on star charts and computer based planetariums.

Where the Heart and Soul nebulae are concerned the catalogue designations refer to both the nebulae and the star clusters they contain.

Heart Nebula: IC 1805
Soul Nebula: IC 1848

As these nebulae contain star clusters their distance from us is known to good deal of certainty. Located in the Perseus Arm of our galaxy they appear to be around 6000 light years away or around 1,850 parsecs (one parsec is the distance a star shifts in arcseconds when viewed from opposite sides of our orbit around the Sun.)

I am using my Teleskop Service 65mm astrograph with a ZWO ASI1600MM camera. With this configuration, although widefield for my observatory, I will have to shoot each object separately and then create a mosaic. This is something I’ve never attempted and give that the weather will prevent me shooting both objects on the same night, I can see this project may take a number of years. This also means that I’ll have to be a little more disciplined in naming the sub frames so that I can process more data into them at a later date.

2000hrs 16/11/17

Well, the skies of course didn't clear....

But I used the time to check a few things and practice framing this object on the sensor and found it really difficult with all the high cloud around.

First I wanted to see if the Ha, Oiii and Sii filter were parfocal. I'd heard that these ZWO filters were but never checked.

Here's the results with a Bhatinov mask as a focusing aid




I think that focus is close enough for my work with these filters. Technically I should slew away from the object to a bright star, refocus on each filter change then command the scope to return - but my fear is that it won't quite frame up right again - so this level of focusing accuracy will have to do.

Another issue I have to investigate is the blobs of frost forming on the camera sensor as it cools down to -30c

The dissipate after about an hour and appear to be forming on what I think are dust motes on the sensor. 

I have to figure out whether I should take the camera out of its air tight container and get it on cooling immediately or let it reach the outside ambient temperature and then start cooling. 

I think its the former as I tried the latter tonight and it didn't seem to work - although I'm not sure it reached ambient temperature either.....

As you can see in the image above I barely got any nebulosity on the picture after a 10 minute exposure using the Luminance filter. Not sure if that was due to clouds or this object is just that faint? The image is useful for helping me frame next time as I've got a better idea of where the star cluster and bright area of nebulosity at the bottom of the picture should be....I need to move both to the left in the image - almost to the top.

So not a complete waste of an evening, the weather could've been to forecast but that rarely happens.


Saturday, 4 November 2017

October Andromeda Galaxy Processing (Cont'd)

A really difficult thing about the long hiatus of imaging during the summer is that when I am able to start again in the Fall I haven't got a clue what I'm doing when it comes to processing the data.

I seem to have re-learn everything - although I do have procedures written down that I follow.

And so it was with my 4.75 hours of data captured on the Andromeda Galaxy. 

I've been through 3 full day long processing sessions on this to get it where it is...and I'm still not completely happy that I've done my best.

Thanks to the guidance from my friend Nick and the members of Stargazer's Lounge that critiqued my work, I do think this version is not to bad now.

Here's the specs on the data capture

Object name
Andromeda Galaxy
Object ID
11, 12 and 15 October 2017
Altair 115mm
89 x 1 min = 89 min
16 x 2 min = 32 min
24 x 2 min = 48 min
28 x 2 min = 56 min
30 x 2 min = 60 min
Total time
4.75 hrs
PixInsight / Bias, Flats, Darks / no noise reduction / no masked stretch (manual)

I used Pixinsight to process this an found PixelMath invaluable in combining the Ha and luminance.

I didn't use Linear Fit as I thought (wrongly as it turned out) that it was killing colour in the images)

I did use BackgroundExtraction, DBE, MorphologicalTransformation, HDMultiscaleTransform, PixelMath for the Ha effort on red channel

Here is the LRGB version (Luminance, Red, Green and Blue channels)
Be sure to click on these and open them in a new window to see it in full resolution

and here, disappointingly, because I don't think I got the H-alpha channel processed correctly, is the HaLRGB version. This is meant to highlight the regions of H2 in the galaxy arms where star birth is taking place. It achieves that but there is the mirky smear of gunk across the rest of the galaxy. I will no doubt need to try again :-)

I've thoroughly enjoyed trying to process this data and feel that I've got back in the swing of it for the coming season. At 4.75 hours I think that's quite enough time on M31 with the 115mm scope, now to point the 65mm wide-field scope at it ....if the weather permits before Andromeda disappears into the West as winter approaches.