Adventures in narrowband

Veil Nebula (East)

« Back to Album Photo 1 of 1 Previous | Next
Veil Nebula (East)
This image of the Eastern Veil is a collaboration between myself and Allan and is our first attempt at combining narrowband filter data with an RGB image. Image details: Canon 1000D at prime focus of Celestron 80 EDR piggybacked on the BLAS LX200, guided using a Toucam pro and Metaguide. Total exposure time: 109mins RGB: 6 x 4 mins H-alpha: 10 x 5 mins OIII: 7 x 5 mins Images were calibrated, registered and stacked in IRIS, channels combined in photoshop by splitting the RGB into separate components and adding the H-alpha data to the red channel and OIII data to the blue. Paul.
Posted by Flamencopaul on August 13, 2010 Full Size|

Post a Comment

Oops!

Oops, you forgot something.

Oops!

The words you entered did not match the given text. Please try again.

Already a member? Sign In

3 Comments

Reply Doug
4:50 AM on August 15, 2010 
Paul,

That makes sense, and, repeatable camera orientation is something that I've been trying to observe more recently, although I've not tried to combine images from different sessions as I've usually applied the hot-pixel reduction process to the camera in between (something I should have not started I fear, as the pixel defects are always there so you might as well get the software to remove it as opposed to the camera averaging them out). I would have thought that the alignment time at the BLAS would be negligible due to the fixed nature of the mount - mine has come down significantly since I have made 3 holes in the lawn.

With regard to alignment and guiding I'm looking seriously at the new autoguider from Skywatcher - could be an early Xmas present for use with the EQ6. I've also put a 1.25" hole in the garage wall, lined with a piece of plastic fall pipe so that I can easily take video, data and low-voltage power out to the mount with a view to perhaps having a go at maybe manual guiding. From the measurements I have taken Polar alignment is not the issue (DEC was unchanged after one cycle with a 6 arcsec deviation which followed RA error over the cycle).

Currently due to the number of poor images on the EQ3-2 I'm experimenting with a PEC update to my controller software - pretty crude (splits each 662sec cycle into 4 segments with a different rate for each - 2 flats and 2 slopes) but I should be able to get if from 66arc sec pk-pk (measured) to 10; I am assuming that once I have detected peak positive error on the RA slow motion shaft, that shaft position will always be peak and the clutch will have no influence on this. If my assumption on the repeatability of the peak error is correct, then I can optimise image capture by opening the shutter as the error reaches its peak, giving me about 2 minutes with perhaps 5 arc-sec peak error (2 pixels with the Megrez 72).

Doug
Reply Flamencopaul
8:44 PM on August 14, 2010 
Hi Doug,

The British weather recently has often meant no more than a couple of hours clear for the week! The subs for this image were taken on 2 different nights about a week apart - the secrtet is to keep the same camera orientation, as long as there's a good overlap between the fields, IRIS can usually manage to align them. It's a good way of slowly building up to large total exposure times without having to be out all night. That said, given the amount of time it takes to set up and align, it makes good sense to capture as many subs as possible. During our early days at BLAS, we were so pleased to be getting recognisable images of things, that we spent a lot of time rushing from object to object - it's only recently that we've had the discipline to concentrate on one at a time.

Regards,

Paul.
Reply Doug
4:51 PM on August 14, 2010 
Paul,

I'd seen your Andromeda before I clocked this one, and this one is even more stunning in my opinion. I suppose the advantage of the British weather is that you get plenty of opportunity to practice and refine post-processing techniques as clear skies are far and few between. Having said that, a total of approx two hours of exposure must equate to 2.5 to 3 elapsed, i.e. a late night or early morning.

Regards,
Doug