IC443 Jellyfish Nebula

IC443 R:G:B SII:HA:OIII 260:280:340 20mins sub

This one only reached 35° maximum altitude from my location. I continued to track it as low as 25° but it just wasn't worth it with current conditions. So, this is a stack of what could be salvaged.

Focal Length = 1600mm (RC8)
Image Scale 0.7 arcsec/pixel (QHY9)
Sensor Temp = -15°C

More bits and pieces - Delrin Tipped Screws

Just received some more parts for my scope. These are Delrin Tipped Screws from ADM Accessories. I needed longer ones to replace the ones on current guidescope rings. These give me more flexibility when searching for suitable guide stars. The light pollution in the area limits my choice of guide stars significantly. Looking for a guide star can be a pain sometimes due my narrow FOV on my guide chip/scope combo. Perhaps, a better solution would be faster and wider guidescope plus a more sensitive guide camera. I am working on a 9x50 finder scope conversion, so will see how that goes first.

Also, took some more photos of the rig including a selfportrait while waiting for my next target to rise above my roofline. Don't normally like to take self portraits, but the scope looked a bit lonely this time, a bit of experimentation with camera angle included.

And I don't know how to smile when a camera is pointing in the wrong direction. I hope I didn't scare off anyone with this pose.

NGC2070 - Hubble Palette - Draft processing

NGC2070 R:G:B SII:HA:OIII 100:100:100 20mins sub

Finally managed to collect some Oxygen and Sufur data for NGC2070. Not much but enough to add some colour into the image. Did a rough processing to see what's available. I still need to get Luminance for this target.

Focal Length = 1600mm (RC8)
Image Scale 0.7 arcsec/pixel (QHY9)
Sensor Temp = -15°C

Telescope Pointing Error Modeling

Lastnight, setup the gear out in the backyard again to collect rest of SII and OIII data for NGC2070. I had just finished polar aligning when the wind picked up. I really need to hurry up and build that observatory. Well, instead of calling it, I decided to have a play at telescope pointing error modeling.

At the moment I use EQMOD's built-in align and sync feature, which allows me to select any stars in planetarium then manually sync and let the EQMOD build a correction model in the background.

Cartes du Ciel (Free) used for selecting alignment stars

EQMOD alignment points map & target triangulation

Maxpoint GUI

This works okay provided I have a 'good' polar alignment and most of the time it puts the target in the FOV of my 1600mm setup but never quite centered. Not really an issue for me right now as I only image one target per night and only takes few clicks to center the target anyway.  But, if I was to start automating my imaging in the very near future I can see that this is one area that needs improving. 

MaxPoint is one of the two softwares that I've heard of written for this job. TPoint being the other and as far as I'm told much better too. Since I already had trial version of Maxpoint installed I fired it up to see what the go 'to' is... :)

The MaxPoint becomes the telescope hub so it can intercept any goto commands from apps such as planetarium to transparently apply pointing corrections. I figured that I need to disable the alignment corrections in the EQMOD for this to be effective, but not quite sure about it yet.

Only requiring minimal setup, I kicked it off with a 25 star calibration routine, wasn't game enough to go for the default 100 stars!? I can see this is really written for permanent observatories with high grade mounts. My poor little EQ6 would probably overheat after 100 continuous slews.

Sky Map

Calibration Observation

Each slew followed by plate solve started to populate Calibration Observations table with calculated pointing errors. It also put little red 'X's on Sky Map representing the points its visited in the sky. I actually enjoyed sitting back and watching this whole process unfold before me. My polar alignment must have be good as all 25 slews yielded successful plate solves. So, I might actually give the 100 star calibration a go next time at the risk of my mount melting down. 

At the end of the scope dancing routine, below window shows a summary of  the calculated errors contributing to my pointing accuracy.

I can see that it has worked out my polar alignment accuracy as well and I might try its built-in Polar Align feature next time. I haven't gone into working out what the other figures exactly mean yet but test slews to targets in different parts of the sky definitely showed improvement over the EQMOD's modeling, but still it didn't put the targets dead center. May be it needs a 100 star calibration or it may be that I'm expecting too much from my poor little EQ6. Well, for now, plate solving and re-slew technique works well for my portable setup and may look at  MaxPoint or TPoint again later on for a permanent setup, perhaps with an upgraded mount.

IC2948 IC2944 Thackeray's Globules

Shot in March 2010 approximately 10 hours worth of exposures.

NGC3324

R:G:B SII:Ha:OIII 100:100:100 20 mins subs Sensor temp: -25c

One of my favourite shots taken in March 2010, processed in Hubble palette blend. Looking back at it again, I think this one needs reprocessing with luminance to boost the colours like I've done to make the blog banner.

FocusMax Settings

I now have my V-curves in FocusMax and want to enable the focus convergence. To do that I need to work out Critical Focus Zone (CFZ) and translate that into focuser steps.

CFZ for a scope can be worked out with this fomula:

CFZ(in Microns) = 2.2 x (Scope_Focal_Ratio²)

My RC8 having a focal ratio of 8 gives me a CFZ of 140.8 microns.

That sounds tiny in everyday speak, good thing that I have an awsome high resolution stepper motor focuser.

According to Moonlite focuser manual, 1" travel of the drawtube requires 6135 full steps, wow! that's a lot of tiny steps, 1 micron = 4 steps to be exact.
This leaves me with CFZ = 35.2 steps
So, for the step width in focus convergence setting, I want to set it with  approximately 1/10th to 1/4th of the CFZ step value say 5 steps.

Now to set the various Half Flux Diameter (HFD) values, I'll need to look at my V-curve log.

 The smallest value on the linear parts of the v-curve before it reaches focus seems to be about 6. Increasing this value by 1/4 gives me 7.5(8) to set as Near Focus HFD. This value can be increased by a 1/3 to set as Focus Start HFD, which is 10. The smallest value on the plot is 4.2, increase this value by 1/2 to set as Focus Routine Max HFD, which is 6.3.

Next thing to do is fine tune the V-curve. I'll leave that one for another night....so much too learn...

NGC6188

L:R:G:B HA:Sii:HA:Oiii 225:150:225:150 15mins subs  Sensor temp: -25°C

Shot last April from my backyard. Processed in hubble palette with Ha as Luminance. EQMOD driven EQ6, QHY9, Astronomik 12nm Narrowband filters.

QHY9 Shutter Silencer

Factory installed plastic stop

On my list of things to do is silencing QHY9's shutter noise. As the shutter moves from open to closed position, it hits hard against a jumper used as a stop. When going from closed to open position, it comes to a sudden stop on the side of the camera's metal casing. This whipping of the shutter back and forth creates a fairly loud tick-tock noise amplified by the resonating case. It's quite loud enough to make me worry about bothering the neighbours late at night, especially when I'm firing off 40 continous shots with Focusmax.

After taking a look at the shutter assembly , I came up with a rather simple solution. A small self-adhesive rubber feet cut in half placed carefully at the shutter travel limits. Well, not quite at the shutter travel limits, but may be half a millimeter before the original stops. Just enough to take the edge out of the shutter impacting the orginal stops. If you wanted to eliminate the noise all together then just place it further in, too easy. Things to note though,  must allow the shutter to fully cover the sensor when closed and clear the sensor when open. Also, I prefer some noise to indicate that it is working. Checkout the photos to see what I mean.

NGC3579

I'm moving few of the Narrowband images taken this year from my old website to my new blog.

This one is NGC3579 shot during full moon of July from my backyard.

Ha:Sii:Oiii 60:60:60 with 15 minute subs.