Sunday, February 10, 2019

received more NGC 4388 data

I imaged NGC 4388 about a year ago with BGO. The result was fair but I wondered if I could improve on it. So I put it in the queue again. Not sure of the latest photon collection is any better. I also noticed the frame sizing was different, wider.

Still on the Apogee camera, according to the FITS header... Was it cleaned? The axis values show as 1536 pixels.

Friday, February 08, 2019

built a working board

It took me a while to resolve the dew heater controller circuit problem but it is done. Circuit works.

I sorted an issue with the switching transistors. Initially, I mistakenly used the same pin position assignments for the 2N2222 and TIP31C pieces.

transistor representations in ExpressPCB

I learned that you need to go back to the schematic and ensure the pins of the physical part correspond to the schematic.

After testing a simple 555 schematic from Math Heijen, I successfully debugged my soldered 556 board layout. Carefully comparing the schematic and board layout, I found the error. It was caused by a fault back in mid-January, when I first considered the board layout and I changed from the stock diode object. With my "custom" diode part, I flipped the polarity. I edited the part polarity in ExpressPCB and repaired the board.

Below, is the full, correct board layout I used. Eleven versions! [ed: Oops. Forgot to update diode D7, the Schottky. Corrected version 12 shown.]

v12 printed circuit board layout for the custom dew heater

The board has left and right sections meaning the left R1 potentiometer controls the power output to heaters H1 and H2 and which is reflected in diode D5. Close examination will reveal the correct orientation of the signal diodes. It's a little messy around the TO-18 transistors but the traces drawn indicate where the long legs were attached (when possible). The offsetting (again) of B1 and F1 show the power source is outboard and the fuse is inside the CLA plug.

Cut the long 4-40 bolts for the heat sinks (first time doing that with the GB wire stripping tool). The PCB was (nearly) done and working.

photograph of the completed working PCB

The heavy gauge red and black wires (in the photo) at the upper corners of the PCB are for the heater networks of course. The yellow, purple, and black wires at the bottom corners are for the pots. In my case, the black wires are for the middle pins. You can clearly see one of the indicator diodes; the other is cropped out. The black wire going from the middle of the board straight up in the negative 12 volt power input. I used the red lead at the bottom-right as a temporary feed into the PCB.

With the controller working, I was able to test with the Schottky diode. It was fine, of course. But it will require some special effort: the pins are a bigger girth so I'll have to drill the PCB...

I'm ready for the next phase. Yeh, I can cut the long leads off the bottom of the PCB. I'll attach the case parts now, the pots, the RCA plugs, the power switch, and power feed. Saw a neat trick of gluing stand-offs to the project box so I'll see if I can pull that off...

snow squall Moon (Bradford)

Spotted a crescent Moon, slowly darkening, slowly dropping, as I trudged home from the bus stop.

Wednesday, February 06, 2019

doubled down on M100 (Halifax)

I continue to double-down on Messier objects. I first viewed Messier 100 on 4 May '13. Had a quick look at faint M100 in the summer of 2018. Sent BGO to the target so to have a good long look at the face-on galaxy in Coma.

galaxy Messier 100 in luminance

Luminance only, 60 seconds subexposures, 10 stacked shots. FITS Liberator, Paint.NET. North is up; east is left.

Wow. What a beautiful spiral. Two main majestic arms radiate from the inner ring. The arms have kinks? They have rich texture with light star-filled regions. Fanning. The core is compact but bright. M100 is also known as NGC 4321.

IC 783A lies to the west-south-west, a small round bit of fluff.

Due east is the large somewhat oval fuzzy of NGC 4328.

North of 4328 is tiny PGC 40214.

NGC 4322 is north-north-east of the big spiral. A dim oval patch.

Wow. An amazing sight.

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Wikipedia link: Messier 100.

revisited NGC 4216

Previously had a go at galaxy NGC 4216 on 20 May '17 and 22 Apr '18. Still not satisfied. Asked the BGO robot to try again. This result was not any better.

returned to NGC 3432

Hello! Wasn't expecting anything. But emails started rolling in from the Burke-Gaffney Observatory as it imaged Finest NGCs starting with 3432. I'm hoping to improve on the quality. Last capture was on 19 Apr '17. Unfortunately, no better... Average transparency and poor seeing. The new ECMWF forecast showed increasingly clouds.

Sunday, February 03, 2019

soldered stuff

It was Soldering Day!

Happy with the physical layout, I soldered parts to the new custom dew heater controller printed circuit board. Took a while! Did the components in the afternoon and the jumpers and leads in the evening.

Did up the Kick-Me-Not red LED blinkie tripod lights with little battery packs. Now I can use rechargeable AAA batteries.

And to the Oregon Scientific portable weather station, I hooked up an external 4xAAA battery pack. Like the OneWorld hack, no more CR2032 batteries! Previously the Oregon needed two and the OneWorld consumed one. Now I can use standard batteries. Actually, I could use rechargeables here too...

Later I shrunk the shrink-wrap on the connection points. Done!

Tested everything.

No problems with the KMN lights. After converting three pieces to use external power over 2 years ago, it was good to have these up and running again.

The Oregon beeped to life as I made the second connection. Good stuff! I don't have to feel anxious about using the backlight anymore.

But the dew heating system? My first powered test failed. It was not working correctly. Both LEDs lit but burned steady! They did not blink no matter what I did with the pots. Oh boy. What have I done...

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Oops. Found that I had installed diode D3 backwards! And I was missing a wire on net N6 from capacitor C4. Fixed. Tested. It still didn't work right. Crikey.

Thank goodness for desoldering braid.

Checked for shorts, touching wires. As much as possible, I tested components on the board. The resistors all seemed OK. The pots seemed OK and the pin outs were acting as I expected. The diodes D1 through D4 seemed OK. Couldn't get reliable readings from the transistors in their circuits. Checked for continuity on all the nets: OK.

I redid the schematic from scratch but ended up with the same result. I redid the layout in ExpressPCB: again, same result. Dang...

Saturday, February 02, 2019

happy groundhog day...

I dunno about you but if I was a marmot in Canada, I wouldn't be crawling out of my den in this weather.

an irked groundhog

"No!"

imaged M90 (Halifax)

Lovely spiral galaxy Messier 90 was imaged by the BGO robot. It too is in Virgo, another M-object viewed but once, back on that big night in May 2013.

spiral galaxy Messier 90 in luminance

Luminance only, 60 seconds subexposures, 10 stacked shots. FITS Liberator, Paint.NET. North is up; east is left.

The core is compact, tiny. Love the dust lanes within the bright glow of the disc. The outer reaches of the spiral arms to the north look distorted, extended.

Little galaxy IC 3583 hovers to the north.

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Wikipedia link: Messier 90.

imaged M89 (Halifax)

BGO nabbed another Messier for me. I had viewed M89 aka NGC 4552 once before. It lies in Virgo.

galaxy Messier 89 in luminance

Luminance only, 60 seconds subexposures, 10 stacked shots. FITS Liberator, Paint.NET. North is up; east is left.

Messier 89 is an intense elliptical. The core is incredibly bright and big. I'm no good at FITS Liberator and can't seem to draw out the edges for the galaxy. It looks nearly circular.

First viewed this target on 4 May '13.

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Wikipedia link: Messier 89.

Friday, February 01, 2019

captured M58 (Halifax)

The Burke-Gaffney Observatory imaged Messier 58 for me. I wanted to revisit this galaxy also known as NGC 4579 in the constellation Virgo. From 4 July '10, I only had one log entry for M58.

galaxy Messier 58 in luminance

Luminance only, 60 seconds subexposures, 10 stacked shots. FITS Liberator, Paint.NET. North is up; east is left.

This is a fantastic barred spiral galaxy. It looks to be face on or nearly so. Love the detail in the grand arms twisting away from the prominent bar. The core is bright but compact. Beautiful.

To the south-east, a good distance away, is the tiny fuzzy oval of LEDA 1397945.

Near the gaggle of stars to the north-east, on the eastern edge, is a very small fuzzy oblong shape. SkyTools 3 Pro says this is LEDA 1400836.

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Wikipedia link: Messier 58.

captured M59 (Halifax)

I ordered the BGO robot to image Messier 59. Another single-view Messier. I first took in this bright elliptical galaxy in Virgo on 4 July 2010.

galaxy Messier 59 in luminance

Luminance only, 60 seconds subexposures, 10 stacked shots. FITS Liberator, Paint.NET. North is up; east is left.

M59 aka NGC 4621 is big and bright with a fantastically bright core. It is oriented north-west, twisted slightly to the west or clockwise in this image.

To the north, and slightly west, a good distance away is a very faint round lint ball. This is LEDA 1398556.

IC 3665 lies to the south-west, a large diffuse fuzzy.

To the north-west is an elongated patch, oriented north-south. I believe this is LEDA 1398085. SkyTools 3 Pro also shows PGC 42679 here but it is opposed, oriented east-west. I don't see another galaxy here.

Nearby, further west, is the bright round diffuse galaxy IC 809.

Due north of 809 is a faint oblong but large fuzzy: PGC 42634.

The glow at the bottom-left corner of the image is NGC 4638...

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Wikipedia link: Messier 59.

captured M91 (Halifax)

BGO gathered photons from Messier 91. I first viewed the galaxy in the Coma Berenices constellation on 3 May '13.

galaxy Messier 91 in luminance

Luminance only, 60 seconds subexposures, 10 stacked shots. FITS Liberator, Paint.NET. North is up; east is left.

A big propeller. This is an amazing barred spiral galaxy with a large and incredibly bright hub. There are two prominent arms in NGC 4548. It's difficult to see and I am having a hard time drawing it out but there's a large halo around the whole galaxy. We're face on.

To the north is a tiny fuzz ball: LEDA 169575.

PGC 41858 is far away to the west-north-west. Another tiny round fuzzy point.

Close to the big island universe, to the south, is LEDA 169578.

Almond-shaped PGC 41978 lies to the south-east. The canted galaxy is quite large and bright.

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Wikipedia link: Messier 91.

Sunday, January 27, 2019

considered physical layout

Needed to do some board layout work with the physical components of the new dew heater controller. Sort placement and spacing issues now that I had a working prototype.

Used ExpressPCB once again. Copied the Sayal 103 perforated board layout from a previous project. Adjusted for wanting a number of diodes and resistors in a vertical orientation. Happily I found the old TO-18 transistor package in the component manager. Tried to space things out away from the power transistors and their heat-sinks all while keeping the layout as compact as possible. It was clear I would need a lot of jumpers. This was feeling more complex than the barn door tracker build...

Something new this time: I printed the board layout I created to paper. I was pleasantly surprised to find it was scaled perfectly. I laid it atop the perf board and used a push-pin for the through-the-hole lead positions. It worked really well.

I stared at the schematic for a long while. I rigorously checked all the nets. Everything seemed OK. I was certain I had not wired it up wrong. The next stage was important!

[ed: I am not including the image of the PCB from the software is it had errors at this stage.]

On the generous project box, I considered where to place the knobs, switch, RCA plugs, LEDs. Oh, and the fuse. The found fuse holder was big... But it looked like there'd be room.

I examined photos of do-it-yourself projects and commercial units in the interest of mimicry. How did other people arrange things? I was drawn to symmetrical styles.

Then, for the first time ever, I dove into old 123D to look for physical collisions. Cool! This was rather profound in helping me ensure that the circuit board elements would fit while not interfering with the case components. The TIP31C transistors with their heat sinks literally needed some breathing room, the business-end of the 1 mega-ohm variable resistors were big, and the fuse holder was rather long. I made a rectangular prism to represent the PCB volume. Turning the case transparent in the three-dimensional software let me see what might happen.

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Later, when I removed the fuse holder from the project box, knowing that I could rely on the fuse in the CLA connector, I reworked the case.

planned box layout for the custom dew heater controller

Lots of room inside. And I could easily create a balanced look. And I think it's a smart layout with outputs on the left and right sides. If placed horizontally at the telescope, some heating elements will be at the front of the 'scope and some at the back.

Saturday, January 26, 2019

bittersweet discovery

Started more testing with my dew heating gear. I needed to know that the new circuit design was correct and could drive a dew strap band. It was strange that I wasn't feeling any heat off the Kendrick 2" dew strap. Tried a direct connection of a heater to battery. Nothing. What?

Tried the custom circuit again. Noticed the CLA LED was not lit. Opened up the Cigarette Lighter Adapter to find a blown fuse! OK. How did that happen? I have a million spares. I loaded in a 5A fast-acting. OK, power was good now. But no heat. Please, no...

Checked the resistance of the 2" heater. It was open. Damn it! Now I have a malfunctioning or dead dew strap. Did I somehow overload a circuit and blow up the 2" eyepiece heater?!

Tested the Kendrick 8" strap - OK! Whew. On the prototype, I found the power transistor, as expected, getting toasty warm. This was good news. Overall, the circuit was correct.

But I was dismayed. Setbacks, frustration, sadness. And there's a distinct possibility there's something wrong with 2" heater.

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Now I'm wondering... when did this happen? Was it a past issue? Back on 5 Jan '19 in the backyard the 2" heater did not seem to be working.

I dunno. Blown CLA fuse, blown multi-meter fuse... Sure looks like I did something wrong in the last day or two. Gah.

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Realised the old Micronta digital multi-meter wasn't working right. Opened it up and found a blown fuse! Whiskey tango foxtrot! Fortunately, there was a spare unit tucked away inside the battery compartment.

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There's maybe a lesson to be learned here: do not do early prototype testing with expensive dew straps...

a partial prototype

With the new parts from amazing digi-key and my coddled bits, I prototyped the dew heater controller circuit with the IC 556. Or one half of it anyway. That is, I set up one potentiometer for one of the channels. It seemed to be working with the LED flashing at different rates. The pot changed the duty cycle. Good, in general, all the parts were working! I saw volts on the heater net, flicking on and off with the duty cycle. Curiously, I did not observe amps registering. Weird. I stepped away.

Friday, January 25, 2019

gathered the parts

Checked my electronic parts inventory for the dew heater controller build. I was surprised by all the parts that I already had.

From my personal supplies: a single-pole single-throw switch, 2.2 kilo-ohm resistors (4), 1N4148 signal diodes (4), diffuse red 5mm LEDs (2), male CLA plug with in-line fuse, various fuses of different ratings and speeds, and a suitable perf board. Oh, and I had small 4-40 bolts and nuts.

From the supplies provided me by my friend Dietmar Kupke I was thrilled to find: a LM556 dual timer IC, 47KΩ resistors (2), 10 nano-farad capacitors (2), and 1μF electrolytics (2). I was pleased to find a good sized black plastic project box.

I was blown away to find 2N2222 transistors (2), in the TO-18 package no less, as called for in the schematic diagram. Seen these old things but never used 'em before.

I had lots of wire: fine 22 or 24 gauge solid for signals and heavier stranded for high-amperage pathways.

Didn't know if I would need or use them but I also collected up some grommets, a fuse holder, various wire terminal blocks, and 16-pin IC socket.

From digi-key, I found: variable 1MΩ pots (2), knobs for the pots, a Schottky diode, TIP31C NPN power transistors (2) in the TO-220 package, small heat sinks for said TIPs, and RCA female connectors (4).

As expected, way less money than buying a commercial unit. In fact, 1/5th the price!

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Added to the order parts to replace missing pieces from the electronic lab. Also found battery packs for some other astro-projects...

Thursday, January 24, 2019

batteries outside

Made a simple external battery pack for the ETX. From spare parts. Plugs into my previously-added dongle which means I don't have to take the heavy base plate off each time! Stoopid design. And—fringe benefit—I should be able to avoid blowing up batteries inside the unit!