Getting back into imaging after a long break

[Gina]

OK - proved I can select a target and slew to it with plate solving to get on target.  Guess I might as well do some imaging.  Cygnus Loop looks a good subject.

[DaveS]

Good luck Gina, I'm stuffed for the night going to close down and try to sort things out in the morning. Time for the big hammer I think.

[Gina]

30s looks about right for Ha for the Cygnus Loop with the 105mm f2.8 lens (about a stop faster than the 28mm f3.5 lens).  This is using ROI to avoid downloading unwanted image area.

[DaveS]

Had a look up as I was closing up and saw the stars vanishing to the south. Hope the cloud keeps away from you.

[Gina]

OIII 30s stretched in GIMP.

[Gina]

Not much in SII but might permit tri-colour imaging in Hubble Pallet.

[Gina]

120s SII - a bit more but bigger stars.

[Gina]

Anyway, I've had enough for tonight.  I'll leave it running on 120s SII 50 subs.

[Gina]

Just been out to the observatory having shut down the imaging rig and parked the mount.  Looks like we must have had a shower this morning as the floor is wet in places and the lens has internal moisture.  I've left the roof partly open to let everything dry out, just covering the rig from any possible rain blown by the westerly breeze.  Seems my next job will have to be the motorised roof control with rain detector.  Only the lens seems to have suffered at all from wet and that is gradually drying out so hopefully will be fine in due course.

The other thing that need sorting out is automatic meridian flip.  The mount hit it's limit before the imaging run had completed and I've lost around half a dozen subs.

[JamesF]

21 minutes ago, Gina said:

The other thing that need sorting out is automatic meridian flip.  The mount hit it's limit before the imaging run had completed and I've lost around half a dozen subs.

Fortunately this bit is easy in Ekos.  In the camera tab there's a checkbox to enable the meridian flip once RA goes beyond a certain value.  It's only checked after each sub is completed though, so if there's a hard limit in the mount then you need to allow enough time for the current sub to complete without hitting the hard limit.

James

[Gina]

Ah, so I need to work out at what RA value the meridian flip is required.  Does this work automatically in that the FOV remains the same though rotated by 180 degrees?

[JamesF]

Everything works automagically, as you say.  Guiding stops, mount flips, plate solve, adjust as necessary, restart guiding, restart data capture.  It's possible the FOV may not be absolutely identical to what you had before, but you can make the limits for plate solving tighter if you need to get more accurate.

I think I just set mine to flip when the angle goes beyond 00:00, so the target is at the meridian, unless I know the capture sequence is ending soon after.  If I could sort out whatever it is with the mount that makes the guiding fall to pieces after the flip then I'd be a happy bunny.  Backlash/end float in the worms is favourite at the moment.

James

[Gina]

With the wide field and short exposures I'm using, guiding isn't necessary.  I expect things will be different when I get imaging with the Esprit or MN190 scope.

[Gina]

Started raining slightly so went out and closed roof and brought imaging rig indoors.  Lens is still steamed up inside so I've applied a little warm air from a hot air gun and warmed the lens up a bit.

[Gina]

Just checked some of the subs from last night and I lost 32 out of 50 SII 120s subs due to mount limit.  All the other SII subs of the Cygnus Loop were fine.  Strangely, the 30s subs of Ha and OIII show as vastly overcooked in the stretched view in PixInsight's Blink.  They look fine viewed individually without autostretch.

[Gina]

The wet is gradually evaporating out of my 105mm lens, some of it as liquid water coming out from the bottom of the front lens.  Every so often I warm it up with my little craft type hot air gun.

[Dr_Ju_ju]

If you have one, the proverbial airing cupboard, where its dry & warm, usually does the trick...

[Gina]

Yes, good point.

[Gina]

The lens is gradually clearing but not there yet.  The airing cupboard is not all that warm as the hot water cylinder has a very effective jacket.

[Gina]

Hmmmmmm... Guess I could do with a good run of early nights!!  Well, I have been quite busy lately...

[Gina]

Just steadily proceeding with the roof control unit.  Then I might make up a dual imaging rig with two 105mm lenses, one with fixed filter the other as I have now with EFWmini.  I can't do this with 28mm LF lens or 135mm as I only have one of each.  I do have a pair of 200mm FL f4 lenses though.  If I were imaging two colours I would have one as Ha and the other as OIII but for three colours it would make more sense to have Ha and OIII in the EFW and the SII in the other rig since SII needs longer exposures.  I was originally thinking of having OIII in the fixed filter rig due to the focus difference but I've found the focus is pretty close with the 105mm lens between Ha and OIII.

[Gina]

Been looking at the FOV on a number of objects in KStars.

Firstly, the Cygnus Loop.

Lagoon and Triffid Nebulae.  These are candidates for a telescope rather than lens.

Eagle Nebula.

400mm FL Esprit 80 ED Pro telescope also ST80

1000mm MN190 telescope.  Still a small image with the ASI1600MM-Cool camera.  This target needs a camera with a smaller image sensor, a longer FL telescope or Barlow

[Gina]

Lagoon and Triffid Nebulae fit quite nicely as a pair in the 400mm Esprit or individually in the 1000mm MN190.  The views through the telescopes are not necessarily at the same angle as with the lenses.

[Gina]

Tried looking at Orion (by changing the time in KStars) but seems I need an extra catalogue or two as Barnards Loop and the Flame Nebula are not in KStars ATM.

[Gina]

I reckon on getting the whole of the Orion Molecular Cloud Complex and then some with the 28mm lens.   The 105mm might be a bit narrow for Barnard's Loop but other lenses and telescopes can have a "field day" in Orion.  This sort of thing and more :-

Probably extending past the Orion Nebula.  This is an area I've imaged before but not much with the ASI1600MM-Cool camera.