Thoughts on which imaging rigs to concentrate on

[Gina]

Heart & Soul in Ha - 30s exposure at a gain of 500 and temperature of -29°C.  Tried 60s first but the white saturated - OK at 30s.

Edited October 17, 2016 by Gina

[Gina]

This is the 60s one.

[Gina]

Clouds rolled in and I've packed up now.  Captured 100 30s Ha subs but there was some passing cloud so don't know how many are any good - I'll see tomorrow.

[Demonperformer]

One could also argue that there is a ‘bit of a gap’ between the 55mm (14°) and the 135mm (7.2°) … or even the 400mm (1.9°) and the 1000mm (1.0°). Don’t you just love it when other people are willing to spend your money for you?

[Gina]

Oh yes, I forgot (again) - there is a gap filler between the 55mm and the 135mm lens - I have 105mm lenses at f2.8    I also have 2 Evostar 80 DS Pro scopes with field flattener/reducer giving 600mm at f6.3 as I recall.  Actually the 1m FL scope - 190MN - oversamples with the ASI1600MM camera.

[Gina]

Been working on the "Linuxification" plus RPi but not yet enough parts for both the main imaging rig and ASC.  So I've lashed up the power distribution and focuser circuit for the main rig.  Camera works with control and image capture but the INDI driver doesn't seem to include the ZWO filter wheel and there isn't a separate FW driver.  The Windows ZWO driver includes the filter wheel in the camera driver.

Here's the power distribution and focuser RPi circuit.

[Gina]

Without filter wheel control I'm stuck with the only option being to use Windows at least for FW control until a way of controlling the FW with Linux/RPi/INDI turns up.  So I now need to decide what I shall do tonight if the clear night sky materialises. 

Wonderful sunset this evening but cloud ATM.

Maybe I'll get one rig working at a time and continue building the ASC RPi system and go back to the Win7 laptop and continue imaging the Heart & Soul for tonight.

Edited October 18, 2016 by Gina

[Gina]

My imaging laptop has decided it's not going to "play ball" tonight   Neither SharpCap nor APT will work properly.  SharpCap continues its exposure way past the time set and APT won't get past the "Busy" at the end of exposure.  Tried rebooting but no joy!   Black magic!!!!!

[cosmojaydee]

Hi Gina , may I ask as to the focal lengths you used for the Heart and Soul neb

[Gina]

135mm

[Gina]

I have at last got my Win7 imaging laptop working again - needed a cold reboot and left switched off for several seconds.  Now capturing Ha 30s subs again.

[Gina]

The Heart & Soul Nebulae are still rather too low in the NE and now partly obscured by my weather station mast so I've moved over to Cygnus and the NAN area.  The sky seems clearer tonight and I'm getting pretty good subs.  The seeing is good and the temperature nice and low and I'm getting -32°C sensor temperature

Here's a single 30s Ha sub.  Again with the 135mm f2.5 lens.  Gain = 500 (50dB).

Edited October 18, 2016 by Gina

[Gina]

I'm hoping to grab some more subs of the NAN area later tonight when I'm hoping the clouds will go away

[Gina]

Been looking through my data and I think I need to do something better about flats and dust bunnies.  Previously, dust specs have remained put when parking the mount after an imaging run and flats taken the day after have been good enough but now I seem to be getting moving dust.  Trouble is, I can't seem to find it.  I've cleaned everything scrupulously but I'm still getting the dreaded dust bunnies.  I have a feeling the dust is inside the camera sensor chamber and resulted from the broken corner of a desiccant tablet.

I was thinking of getting my flat screen out and setting it up (I have one of the German ones) but really the proper course of action would be to remove the dust.  If this is inside the camera I will need to open it up again, remove the desiccant tablets and store them in a sealed bag while I clean out the chamber.  I'm rather worried about letting damp into the sensor chamber and shortening the life of the desiccant tablets as these are already the replacements.  Maybe the originals could be dried out as they are mostly intact with just a corner broken off one.

[Gina]

Clear sky and imaging the NAN area in Cygnus.  This image :- 30s Ha sub g=500 t=-24°C and still cooling - now at -32°C.  Late start tonight as I've been out to a meeting.

Edited October 19, 2016 by Gina

[Gina]

Funny! - "Cain't see no dust bunnies"   Here's a gamma stretched image to bring up the background.

[Gina]

Clouds have arrived - with a vengeance!!   Here is an all sky cam view.  The ASC is now working with the RPi and KStars/Ekos/INDIserver.  This is a screenshot of my Linux Mint laptop running KStars/Ekos client.

Edited October 19, 2016 by Gina

[Gina]

Complete cloud cover now so guess I'd better close the observatory roof and give up on DSO imaging.  At least for a while - can keep an eye on the ASC and open up again if the clouds go away.

[Demonperformer]

At least you managed to get a couple of hours last night ... a couple more than here.

[Gina]

Not quite that much but I haven't checked how much yet.  I wasn't watching, having started the imaging run as I was setting up my all sky cam but yes, a bit more data and seemingly without dust bunnies.  I missed some good imaging time while I was out but I don't regret that as I enjoy socialising even more.  AND getting auto-focus working with the RPi was very pleasing   A real "proof of concept".

[Gina]

I have now completed the dew heater construction and wiring for the ASC and having received the screws I needed, have fastened the RPi to the case.  Should be ready for tonight - just need to test that the dew heater works and that it can be controlled from Ekos.  I'll take and post some photos shortly.

Edited October 20, 2016 by Gina

[Gina]

Posted in the ASC Mk 5 thread :-

2 minutes ago, Gina said:

Just about finished now and tested including the camera cooling and dew heater though the dew heater is only showing 6v rather than 12v so it looks like the switching transistor is dropping 7v (supply voltage of 13v).  Dew heater resistance is 70Ω so current is 6/70 = 0.086A and power of just over 0.5W the power dissipation in the transistor will be 0.068x7 = 0.6W which is bang on the limit.  It should be switching hard on and be dropping about 1v.  Something I shall need to look into.

Here are some photos.

Base part showing RPi plus HAT and camera with lens mounted on top of a round aluminium pole mounting with a Peltier TEC between camera and aluminium heat sink.  This and the RPi are powered from a drop-down buck converter supplied from 13.8v in the observatory. 

Inside of top showing the focussing stepper motor and dew heater connections with their wires and plugs to plug into the RPi HAT.

Camera connected via USB cable with cooler and dew heater plugged in.

Top of ASC showing lens, camera, focus gearing to the lens focus ring and dew heater resistors.  Outside that is the ring that holds the clear acrylic dome.

Dome added

[Gina]

Taking flats ready for tonight imaging run if there is one.  Exposure of 0.1s, gain 40, temp -29°C.  Showing some dust bunnies but it'll be getting dark soon so I'm not messing about trying to find the dust today.

Edited October 20, 2016 by Gina

[Gina]

Calibration frames for these flats now - 50 darks and 50 biases.  Couldn't quite manage the same low temperature of -29°C but will have to put up with -26°C.

Edited October 20, 2016 by Gina

[Gina]

Still total cloud cover - wonder it it will clear later - not looking good despite the weather forecast!  North is the left hand side of the image.

Edited October 20, 2016 by Gina