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


Ha



Oiii



Sii




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.

WOBSASTRO