Custom power cable for the Sky-Watcher

September 13, 2021 - Reading time: 2 minutes

Scrounged up a couple parts I bought a while back for this specific project, but just getting around to it now. The Sky-Watcher EQ6-R Pro telescope mount uses a 2 pin GX12-2 aviator plug for 12vdc power. I bought a couple off Amazon earlier this year, and today I soldered up the 5.5mm x 2.1mm power jack after testing which pin is ground and which has voltage. (https://www.amazon.com/dp/B07DC7KP8H).

I made this to supply power to the mount from my Pegasus Pocket Powerbox, which I have on a 15mm rail and SmallRig aluminum cheese plate (https://www.amazon.com/dp/B019C2ZM8Q).

Here's the cable plugged into the Pegasus PPB, powering the Sky-Watcher mount. Tested and woks beautifully!


Wide-field Narrowband Setup

September 8, 2021 - Reading time: ~1 minute

Setting up and testing my wide-field astro gear: the William Optics SpaceCat 51 primary scope, 200mm guide scope, and everything else is ZWO--autofocuser (EAF), ASI120MM-S mono guide camera, ASI1600MM-Pro monochrome primary camera, and EFW with my Astronomik 6nm narrowband filters and the new Antlia 3 nanometer hydrogen-alpha filter. I switched to a guide scope from off-axis guiding with this setup because focusing with the different thicknesses of the filter material pushed my guide focus a bit too far. I was using this 50mm/200mm FL William Optics guide scope with the 800mm Newt because I had the same situation, narrowband filters mixed with near infrared filters with different brands and glass thickness.


ZWO EFW Update

September 4, 2021 - Reading time: ~1 minute

Added the Antlia 3nm Hydrogen-alpha filter in the ZWO filter wheel, and took a pic, added labels to make sure I remember where the filters are. Before this switch-up I had two near-infrared filters (a 680nm and 850nm) in slots 4 and 5, with my Astronomik 6 nanometer Ha filter in the first position. And just to make things as uncomplicated as possible I have the OIII (Oxygen 3) filter in position 2, and SII (Sulfur 2) in 3.


My Backyard Astro Setup - Summer 2021

June 19, 2021 - Reading time: ~1 minute

This is the gear I currently have on the pier. I'm currently running with the color imaging train, and I will continue to until I get the coma correction dialed in. I'll try other cameras after that, including monochrome/narrowband.

Here's what things look like during the day. The micro-observatory project is on hold until I can buy a replacement for the CEM25P mount.


Daylight Focusing

June 12, 2021 - Reading time: ~1 minute

Doing some daylight focus testing with the 8" Newtonian and the ZWO ASI071 camera + Ha filter to cut down on the light. Focusing on that tree line about half a mile away.

I'm still waiting for the final piece of the Newtonian reflector puzzle, a coma corrector. This scope is fairly fast at f/4, and so the coma introduced by the parabolic primary mirror needs some correcting. Without the corrector the star field in images from a large sensor camera will bend away from the center--"coma".

In the meantime, I'm out on the deck today testing focuser position with an old William Optics field flattener/reducer, which brings the scope to 640mm focal length at f/3.2. And it doesn't look too bad. That tree line is about half a mile (~.75 km) away. It's so bright out and this astro camera is so light-sensitive that I'm shooting frames at .001 seconds with a long-pass hydrogen-alpha filter, which is only letting light in from 640nm out to about 800nm, so most of the visual spectrum is cut, and what's left is this range of near infra-red.


New Scope!

June 8, 2021 - Reading time: 4 minutes

Looks like I'm going to become an OTA-wieldin' Collimatin' Reflector guy! I have been a refractor guy from the beginning. My first serious scope was the William Optics GT81--six or seven years ago! I used a Nikon D3100 and then the full-frame Nikon D750 for a little while before diving in completely with narrowband and a monochrome astro camera, an Atik 414EX CCD. 

Last week I bought a new telescope and it arrived today, an Apertura 8" Newtonian Imaging scope with a focal length of 800mm at f/4. There are a bunch of inexpensive fast Newtonians on the market, sold under different names and brands, and at least some of them, including Apertura, TPO, TS-PHOTON are rebranded/painted OTAs made by GSO (Guan Sheng Optical) in Taiwan. 

The Apertura came in at $499, one of the least expensive 8" Imaging Newts, but it has some upgrades over what's pictured on the Highpoint Scientific site: better focuser, better dovetail bar (see the red vixen bar in the pic below--that's included). Even the guide scope shoe has two threaded hold downs, but the product shots only show one. Pleased about that. (It came with one thumb screw, and I can add one. No problem. For the guide scope I replaced both with hex socket cap screws).

The focuser surprised me because my old Astro-Tech RC scope came with the bottom of the line GSO crayford, and that's what I expected here, given the product pics on Highpoint, but when I opened the box I noticed this one came with the better and newer GSO focuser, the linear bearing crayford. It's no Moonlite, but it'll do. 

I spent no time at all adding the ZWO EAF autofocuser, the 2nd generation model that's powered off the USB and doesn't require the 12v dc line in. This has been sitting on my workbench for months, waiting for a scope to autofocus! I'm testing it out right now in Ekos (on the screen in the background). That's my William Optics 50/200mm guide scope + ZWO ASI120MM-S camera attached to the Apertura behind the focuser.

The Apertura came with a really nice red-anodized Vixen-style dovetail bar--13"/330mm long. Perfect.

Of course, an hour after UPS dropped it off it started raining--a full on summer downpour.

I'll test things out when we get some clear skies. I'm still waiting for a coma corrector--it seems there isn't one Baader coma corrector Miii anywhere on this planet for sale. I'm on hold until late June for more stock, so it may be July before I get some serious imaging out of the Apertura 8" Newtonian. There is a much less expensive (around $100) Apertura coma corrector, which I may try.

Link to Highpoint Scientific: Apertura 8" f/4 Imaging Newtonian OTA - 8F4N


Project of the Week: Flat Frame Light

May 17, 2021 - Reading time: 6 minutes

Astrophotography relies on many stacked images of the same target in the night sky, anywhere from 20 to over a hundred or more, all merged together with sophisticated algorithms to form one image. The purpose of stacking is to shift the SNR—Signal to Noise Ratio—to our advantage, so that there is more signal (nebula, galaxy) and less noise (light pollution, read noise, etc.)

Part of that stacking process involves calibration frames, which provide additional data in the stacking process for reducing noise, including read noise, thermal noise, removing dust on the sensor, vignetting, uneven field illumination, and other stuff we don't want in the final image. 

One type of calibration frame is a Flat Frame, which involves shooting ~20 - 40 exposures of an even, luminous source, with the same camera used to shoot your deep sky objects set to the same temperature and somewhere near your normal focus position (there's some leeway with focus). Exposure times are based on filters and camera settings. One way to do this is to point at a blank wall or by covering the front of the scope with paper or a white t-shirt, and taking a batch of exposures—both during daylight hours. We usually take new Flat Frames every month or so, or whenever anything in the imaging train changes significantly.

I made an LED Flat Frame Light for my SpaceCat 51 using some inexpensive hardware and a printed enclosure—links to everything below. There's not much to it, other than making sure you have the DC voltage connected the right way—positive to positive, ground to ground and all that. The step-up converter I'm using for this project has a potentiometer to change the output voltage. First thing I did was plug the input side into a 3amp 12v adapter, and then with the meter attached, used a screwdriver to adjust the output toward 40vdc—I think you'll get something out of the LEDs at anything over 30 volts, but keep going, make it bright! The specs on the LED board say anywhere from 36-42v DC is in range, and this particular XL6019 converter can output up to 40v.

I'm still testing illumination across the acrylic face plate. The space between the LEDs and white acrylic is a little over a centimeter, and that seems to look evenly illuminated to my eyes. That's the one thing that remains to be tested and potentially adjusted—most likely away from the LEDs by small amounts until it works. I'm also going to add a strip of aluminum foil around the inside to make the most of the reflected light.

I used E6000 glue (link below) to hold the LED board to the stand-offs on the printed enclosure. The board is aluminum and acts as a heatsink. E6000 is supposed to work at high or low temperatures, but we'll see how that works out after some serious testing.

Where to go from here? A larger diameter light is probably where I'm going next, to support the the William Optics GT81. I might try different LED boards, some with more LEDs. Also, this is a pretty cheap step-up converter, and I have a couple different kinds I can try out. Making some 3D printed fittings for specific scopes is another thing to try.

Here's a screenshot of the enclosure I made in Tinkercad:

And with the lights on!

Using electrical tape to hold the acrylic disc in place, and a strip of aluminum foil around the inside to reflect the light:

I made a 3D Printable Flat Frame Light enclosure:
https://www.tinkercad.com/things/5ThpmrMrqdR-astro-flat-frame-case

STL File I used for printing:
https://saltwaterwitch.com/files/AstroFlatFrameCase.stl

Amazon Shopping List:

5A High Power DC to DC Step-up 5V 6V 12V 24V 3-35V to 5-40V XL6019 Converter
https://www.amazon.com/dp/B07Z5M89N1

LED: Aluminum Circuit Board 5730 SMD LED Chip Module 12W 300mA 6500K Diameter 100mm
https://www.amazon.com/dp/B07VFHP5P5

Acrylic blank Opaque White Round 2 Pieces (4" Diameter, 1/4" Thick Opaque White)
https://www.amazon.com/dp/B07BPVL622

DC Power Cable 12V 5A Plugs Male Female Connectors (5.5mm x 2.1mm, 10 Pairs)
https://www.amazon.com/dp/B07C7VSRBG

E6000 High Viscosity Adhesive, 3.7 Fluid Ounces, 1 Pack, Clear, 3 Fl OZ
This: "temperature resistant – unaffected by extreme heat or cold once cured"
https://www.amazon.com/dp/B0044SB3M8


New Astro Pier in the Backyard

October 25, 2020 - Reading time: 2 minutes

I'm upgrading the "pier" that I have right off the back deck.

What's interesting is I set that up as a temporary solution for winter imaging. We can get a lot of snow. That was 2 1/2 years ago or so, and having a semi-permanent platform for imaging made things so easy--with fast setup because it was always close to polar aligned. That's also when I started using this generic 6x8 inch aluminum plate for connecting my mounts. This temporary pier was so easy in fact that I continued to use it for the next couple years.

So, I have finally started the upgrade. I'm also using 4x4 treated lumber for this, although 4 4x4s bound together with lag bolts. It's basically a solid block of hard wood that's weather treated. 

I have also upgraded the mounting plate. The old one is just connected to the post with 3" deck screws. It's solid for a smaller mount like the iOptron CEM25P. I cut several pieces of 80/20 extruded aluminum for the new mounting plate, and this is perfect for larger mounts like the SkyWatcher EQ6-R Pro.

So, this is what it looks like with one bag of Quikrete, just about to add the second:

And here's a video on some of the details: