Thoughts on which imaging rigs to concentrate on

[Gina]

Couldn't find the 28mm lens so I set up the 105mm lens rig ready for imaging, took it out to the observatory, attached it to the mount and connected the various cables.  While out there I found the 28mm lens on the warm room bench   Anyway, I have the 105mm f2.8 lens all setup and roughly focused ready for imaging whenever we get some clear night sky. 

Not that I'm expecting it to be clear tonight but it's been a nice sunny day and relatively mild so I've been doing outside jobs, including running my CAT6 outdoor cable to the observatory properly.  Bored a hole through the east facing window frame in the living room and likewise in the wooden wall of the observatory.  Cable supported in the middle on a fence stake hammered into the ground so that it's out of goat reach.

Edited January 14, 2017 by Gina

[Filroden]

My SCT is outside cooling in the hope the wind stays away. I really want to see if I can capture anything useable in 5s exposures and M1 should be nicely placed.

[Gina]

Here are the fields of view of the Orion region with 28mm and 55mm lenses.

[Filroden]

Blimey, your 28mm lens can fit the entirety of Orion in it's field of view!

[Gina]

Yes indeed   I moved over into Monoceros to include the Rosette Nebula - couldn't see anything interesting the other side.

The only disadvantage of the 28mm lens if the smaller aperture of f3.5 but it did alright in Cygnus

Edited January 14, 2017 by Gina

[Gina]

Cloudy tonight as forecast.  Tomorrow I'll set up the 28mm lens on the camera unless it's raining all day.

Edited January 14, 2017 by Gina

[Gina]

It's not looking good

[Gina]

I also have an 18mm lens though a zoom so probably not as high quality but at least is supposed to be f3.5 at that zoom.  I'm planning to try it eventually.

[Filroden]

It's a tough choice between going North to capture all the rich areas in Auriga or going South and getting the Seagull in Canis Major. I guess it will depend on how low your horizon is in that direction.

[Gina]

I think within a degree or two of horizontal.  I think the far hill to the east may be a bit higher than here.  Just done a triangulation from indoors.  Line of sight from bottom of east window to top of trees on far hill is 6" in 170" above horizontal.  Tan A = 0.035 giving A = 2 degrees.  There are no towns in that direction for many miles.

[Gina]

Have the 28mm lens all set up and focused ready for any clear sky that might occur.  Focused on tree on far hill with the top of the tree centred in the frame.  CdC says the elevation is 53m so even less than a degree above horizontal.

[Gina]

Fingers crossed for tonight   I've brought the imaging rig indoors and given it a good going over with my rocket blower - there was quite a lot of dust on the filters - now there's a lot less.  I also added the Astrodon 5nm Ha filter into the last free hole.  So I now have Ha5, Ha3, OIII3, SII3 and Luminance IR/UV cut, in positions 5 1 2 3 4

[Gina]

Focused on the far tree and also moved up into the sky to see what dust bunnies appear - just a few faint ones so vastly better than last time (see image above).

[Filroden]

Much cleaner!

And I blame you for my poor skies for the next few weeks. You've inspired me to invest in a Ha filter

[Filroden]

1 hour ago, Gina said:

I now have Ha5, Ha3, OIII3, SII3

You're going to have some interesting choices to make about colour palettes with H, O, S and N to map!

[Gina]

There are dust bunnies but I suspect this image may be exaggerating them.

[Gina]

Here's a screenshot of a 60s sub at gain of 600 and -30C of Orion - just risen in the SE - ground in the image.

[Filroden]

Rotate it 45 degrees clockwise and I think I can see Iron Man's mask

[Gina]

I don't know how long Orion is going to be visible - there's cloud about.

[Gina]

So far so good - Orion is pretty clear

[Gina]

I've captured 50 or 60 odd subs in Ha 3nm and now capturing in Ha 5nm.

Here are 2 subs, one 3nm and one 5nm captured one after the other with just a few seconds (to change filter) in between, displayed side by side in PixInsight.  The Ha 5nm filter is labelled "R" (that was where the Red filter was when I did RGB).  Most odf the DSOs look the same in both except the Angelfish which looks a little brighter in 5nm so maybe that has significant NII.  Otherwise the main difference is in the stars.

[Filroden]

It's quite amazing how much more light is being passed in just 2nm. Those stars are much bigger in the 5nm.

I think it will be hard to tell the differences from single subs. Like S, I don't think N will be very prominent compared to Ha, so you might not see much until they are integrated and differenced (and stars removed). But I suspect N will be more common in planetary nebula so widefield maybe not the best way to test this?

[Gina]

I agree - on both points   The Rosette Nebula near the top of the frame is supposed to have lots of NII yet doesn't show it in these subs.  There are so many things I want to image that choosing is rather difficult

[Gina]

I've moved over to Eridanus looking for the Loop but can't see anything with 60s exposure so I'm trying 120s.

[Gina]

No sign or the Eridanus Loop so I've gone back to Orion.  Finishing off the Ha 3nm subs - to reach 100 and then I'll probably go over to OIII.  Doubt there'll be enough time to take anything else on Orion before it slips below the horizon.