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Seagull Nebula - GUM2 - 20220129
Seagull Nebula - GUM2 - 20220129
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Comments
Well done Luca - some nice detail coming through in Ha. I expect longer exposures will be needed to really make your seagull fly.
Thank you Tom! Unfortunately from by balcony the polar star is not visibile,
so I'm trying to align my AVX mount with Drift Alignement functionality in Phd2, I hope to increase the exposure above 60s soon
..
For me it's also the first time I observe (electronically) Seagull nebula, this is exciting!
so I'm trying to align my AVX mount with Drift Alignement functionality in Phd2, I hope to increase the exposure above 60s soon
..For me it's also the first time I observe (electronically) Seagull nebula, this is exciting!
Definitely exciting Luca - I find the PHD2 tools work well, but time consuming if you can’t see Polaris.
I'm also shooting from a (tiny!) balcony @lucabandirali with little sky in view. Thus, I only can wait what targets are available there.
The past year I tried several things to PA my mount without Polaris in sight:
1: A very easy and fast solution for PA alignment was (and still is) the great Solar Polar Align Android app. It is only available as an *.apk* file and not in Google's play store:
a) In short, you enter the local coordinates manually or wait for your phone's GPS to get them. Then, some parallel lines appear on display, showing the sun's shadow cast for the current time and place (NOAA formula)
b) Now hold (or fix) your phone's long edge against an even (roughly N/S) pointing part of your mount's housing, eg. east or west side of the housing.
c) Finally you only need to get "something's" shadow to fall on your phone's display. The author mentions a house's edge ... which should then be tuned exactly parallel to the lines on display
The last part "c" seemed to be the most challenging at first .... no really useful shadow cast here. Then I had an idea: I took an old (broken) fiber glass pole (perfectly straight and light weight) from one of my kites ... and hold it vertical with my finger tips so that it's shadow falls on the phone display.
Seeing the error angle between the lines on display and the pole's shadow, you can adjust RA quite easily.
Writing this down was much more tedious than the actual work
It needed some trials to get used to it - but now I get a very close PA alignment in very little time. Usually, I can take 120s frames with my nice Samyang 135mm f/2.0 lens on Canon full frame or crop sensor (APS-C).
~ * ~
2: For perfect (whatever that means) polar alignment, I strongly recommend KStars' PA procedure which works with plate solving. In short, you point your camera close to the local meridian. The PA procedure takes a shot and solves it via plate solving (I use this offline, but only via astrometry.net is also an option).
Next, the mount slews 15 or 30 degrees west or east (you can set this at will) and takes a 2nd shot (solved!) ....finally one more slewing 15/30° and a 3rd shot (solved).
Now you see a 3 color error triangle on screen. Click on one brights star, so the triangle moves to it. Now you simply turn your mount's DEC knob slightly up/down so that the star drifts along the yellow line until it arrives at the corner where yellow and green meet.
From now on, you only use the RA knobs (left/right ... east/west) until the star on screen has moved to so highlighted / marked triangle corner.
While you are adjusting this way, the PA procedure takes one more photo every second and solves it immediately, so you can see the star walking along the error triangle's axis'.
~ * ~
I use this 2nd approach with my CEM26EC mount, connected to a Raspberry Pi 4 with the free Astroberry operation system. The RasPi4 is connected to my home WiFi with a fixed IP, so I can catch it's desktop via VNC on my Linux desktop and control everything (via KStars) from my office desktop (or tablet with VNC client app).
This made my life so much easier and PA much more fun than tedious.
HTH,
Frank (aka firstLight)
The past year I tried several things to PA my mount without Polaris in sight:
1: A very easy and fast solution for PA alignment was (and still is) the great Solar Polar Align Android app. It is only available as an *.apk* file and not in Google's play store:
a) In short, you enter the local coordinates manually or wait for your phone's GPS to get them. Then, some parallel lines appear on display, showing the sun's shadow cast for the current time and place (NOAA formula)
b) Now hold (or fix) your phone's long edge against an even (roughly N/S) pointing part of your mount's housing, eg. east or west side of the housing.
c) Finally you only need to get "something's" shadow to fall on your phone's display. The author mentions a house's edge ... which should then be tuned exactly parallel to the lines on display
The last part "c" seemed to be the most challenging at first .... no really useful shadow cast here. Then I had an idea: I took an old (broken) fiber glass pole (perfectly straight and light weight) from one of my kites ... and hold it vertical with my finger tips so that it's shadow falls on the phone display.
Seeing the error angle between the lines on display and the pole's shadow, you can adjust RA quite easily.
Writing this down was much more tedious than the actual work
It needed some trials to get used to it - but now I get a very close PA alignment in very little time. Usually, I can take 120s frames with my nice Samyang 135mm f/2.0 lens on Canon full frame or crop sensor (APS-C).
~ * ~
2: For perfect (whatever that means) polar alignment, I strongly recommend KStars' PA procedure which works with plate solving. In short, you point your camera close to the local meridian. The PA procedure takes a shot and solves it via plate solving (I use this offline, but only via astrometry.net is also an option).
Next, the mount slews 15 or 30 degrees west or east (you can set this at will) and takes a 2nd shot (solved!) ....finally one more slewing 15/30° and a 3rd shot (solved).
Now you see a 3 color error triangle on screen. Click on one brights star, so the triangle moves to it. Now you simply turn your mount's DEC knob slightly up/down so that the star drifts along the yellow line until it arrives at the corner where yellow and green meet.
From now on, you only use the RA knobs (left/right ... east/west) until the star on screen has moved to so highlighted / marked triangle corner.
While you are adjusting this way, the PA procedure takes one more photo every second and solves it immediately, so you can see the star walking along the error triangle's axis'.
~ * ~
I use this 2nd approach with my CEM26EC mount, connected to a Raspberry Pi 4 with the free Astroberry operation system. The RasPi4 is connected to my home WiFi with a fixed IP, so I can catch it's desktop via VNC on my Linux desktop and control everything (via KStars) from my office desktop (or tablet with VNC client app).
This made my life so much easier and PA much more fun than tedious.
HTH,
Frank (aka firstLight)
Thank you very much Frank for your help, and for the detailed description of the two methods, maybe I will start from the first one the next few days trying to download Solar Polar Align Android app and then I will also try with KStars PA procedures! Clear skies!