Colour mosaics in APP

2021-04-02T10:00:40+00:0020 December 2020|Technique|

Reminder for me:

Mosaics in APP – defaults unless otherwise stated
1. Load – all as normal – you don’t need to use separate sessions for each frame if you did it all at the same time
2. Calibrate as normal
3. Analyse stars – I needed to increase from 500 or it wouldn’t work – went 1400 – might have been the subject but I suspect it helps to stitch the mosaic together
4. Register – Registration mode – mosaic, use dynamic distortion model, uncheck same camera and optics (will be suggested if you don’t)
Scale stop = 1 (for a 10% mosaic overlap)
5. Normalize – Mode – advanced – neutralize background
6. Integrate – Enable MBB – 10% because I did 10% overlap in the mosaic
LNC degree – 2nd degree, iterations 3
Registration mode – Mosaic
INTEGRATE – and if you’re lucky it all works

Ha LRGB processing

2018-10-16T11:05:57+00:0016 October 2018|Technique|

From Cloudy Nights:

Ha/RGB Processing

Start with well-processed H-alpha (as grayscale) and RGB images. Process each separately at first.
Register the two images.
Convert the H-alpha image to RGB.
Delete (make black) the green and blue channels.
Select all, copy, and paste this red image onto the RGB image.
Change the blend mode on this layer to “lighten.”
Adjust the histogram (mainly gamma) of the H-alpha layer to bring its brightness up a bit (gamma ~1.3).
Flatten this image.
Select all, copy, and paste this image onto the original grayscale H-alpha image.
Change the blend mode to “lighten.”
Flatten this image.
Select all, copy, and paste this image onto the RGB+H-alpha image.
Change the blend mode to “luminosity.”
Change the opacity to ~50%.
Season to taste.


Hubble palette colour manipulation

Observatory build

2018-05-28T11:00:36+00:0027 May 2018|News, Technique|

Old observatory going away, new observatory with Pulsar 2.2m short height dome going up on new wooden walls. The whole thing will sit on top of the remnants of walls from an old WWII air raid shelter. Watch this space…

The old run-off roof one lasted about 10 years without any signs of moving in some very strong winds (the previous 2 had roofs blow off into the field!). It did however leak pretty badly at the corners.


Plato project

2017-09-30T20:46:29+00:0030 June 2017|Plato project, Technique|

Image Plato crater from Lunar sunrise to sunset and make a timelapse.

From:  79 deg phase, 7.8 days
To:       259 deg phase, 23.5 days, -40.7 deg illumination

Will need daytime imaging so I have a ZWO 850nm IR pass filter for use with the DBK camera if the camera is sensitive enough at these wavewlengths (it is!). Take all images in IR.

DayActual DayDateComments
99.412017-08-01 Too small. Needs re-done and with correct alignment.
10 10.59 2017-09-30
11 11.51 2017-08-03
13 13.54 2017-08-05
15 15.53 2017-08-07
16 16.56 2017-08-08
18 17.592017-08-09
20 20.62 2017-08-13 A good sharp image
21 21.57 2017-09-12

ZWO 850 IR transmission characteristics

EQ6 strip down and belt mod

2016-07-12T17:02:52+00:0012 July 2016|News, Technique|

Taking the summer twilight zone in Scotland as an opportunity to strip down my EQ6 mount which was getting stiff, especially in Dec. Disassembly was quite straightfoward apart from one of the RA bearings which got a little damaged. However, these are known to be poor quality so I’ve also bought 4 new bearings for the RA and Dec worms to replace them. Thanks to Chris Bailey on this UKAI thread for the info.

Also decided to do a belt mod at the same time to try and remove some of the awful errors in the drive train. I chose the Rowan belt mod. Let’s see how it goes.

Got some white lithium grease to replace the seriously gunky stuff that covers everything.

Field of view and CCD data

2019-05-01T10:19:20+00:005 July 2015|Technique|

Orion Optics 250mm f4.8 Newtonian

Atik 460EX

4.54 micron pixels
2750 x 2200 pixels
FOV 0.6 x 0.48 degrees / 36′ x 28.8′

1×1 0.79″/pixel
2×2 1.58″/pixel
3×3 2.37″/pixel
4×4 3.16″/pixel

Canon EOS 600D

5184 x 3456 pixels
4.3 micron pixels
FOV: 1.06 x 0.71 degrees / 63.6′ x 42.6′

Altair Astro/GSO RC8 203/1624mm f/8

Atik 460EX

4.54 micron pixels
2750 x 2200 pixels
FOV 26.41′ x 21.13′

1×1 0.58″/pixel
2×2 1.15″/pixel
3×3 1.73″/pixel
4×4 2.31″/pixel

Canon EOS 600D

5184 x 3456 pixels
4.3 micron pixels
FOV: 47.3′ x 31.53′

Skywatcher 200P 200mm/1000mm f/5

Atik 460EX

4.54 micron pixels
2750 x 2200 pixels
FOV 42.92′ x 34.34′

1×1 0.94″/pixel
2×2 1.87″/pixel
3×3 2.81″/pixel
4×4 3.75″/pixel

Canon EOS 600D

5184 x 3456 pixels
4.3 micron pixels
FOV: 1.28° x 0.85°