Viewing Report – 6th May 2020 – IMT3

The plan for the night (to try using the Esprit120 as the guider for the OS 12″ if it is on the West side of the Mount) was scuppered as we couldn’t connect to GingerGeek’s SX814 camera. GingerGeek checked in device manager and COM7 is missing so we suspect the USB cable has dropped out again.

Following on the the news earlier in the day of the SN in M61, I slew to it and grabbed some 300s unguided subs ( which also proves that it is the guiding that is moving the mount unnecessarily … but we knew that already !). Thare was a suggesting on the evenings group Zoom call that the drift might be due to ‘Cone Error’, but I found several posts stating that ‘Cone error does not affect guiding’. After M61 dropped into the weeds I slewed to M3 and grabbed some Luminance frames shutting down very tired at around 4am.

Viewing Report – Cinco de Mayo 2020

Moon 96% Waning.

Our TOSA Manual needs updating now that we have replaced the HiTechAstro Deluxe Cloud Sensor with the Lunático AAG CloudWatcher cloud detector.

New Screens to get familiar with:







Initially I was unable to open the shutter of the dome. Thinking I’d forgotten to reset the HiTechAstro relay I soon realised I had to figure out why the AAG_Cloudwatcher software was reporting Unsafe. GingerGeek spotted that the Brightness level looked like a sawtooth and should settle after a few minutes, which it appeared to do and the dome shutter opened successfully.

Following on from my previous observing session on 1st May when clouds interrupted play just as I was completing a Guiding Assistant run in PHD2, I started tonight’s session with a quick look at Venus before it set below our horizon and then had another go at running the Guiding Assistant in PHD2 for the OS 12″ / Tak FS-102 combination, with the Tak as the guider for the Officina Stellare.

Venus in Ha (because it’s so bright).


As the Tak has an Alnitak Flip Flat attached to it I added it to the profile I’ve created for the OS12 and Tak combination so that the panel can be opened to allow light through to the camera 🙂

Guiding Assistant completed successfully and values applied for RA MnMo, Dec MnMo and Dec Backlash compensation.


Y scale = 2, Target Radius = 1.5

Sequence running for 2, 5, 7, 10, 12 and 15minutes.

2, 5,& 7 minutes exposures ok but trailing beginning to show at 10 minutes, quite evident at 12 minutes and very evident at 15 minutes.

Added 8 and 9 minutes to sequence, but both of these show signs of stars trailing.

Started a sequence of 24 x 5 minute exposures.

Aborted at frame 20 as the NGC3628 was now below the horizon.

The image has drifted and NGC 3628 has not remained fixed in the frame, so we still have issues with guiding as that is almost certainly the source of the drift.

02:22 Slew to M5, just off centre.

Slew to HIP 74975 to centre and focus.

De-selected guider.

02:57 Slewed to M5 and started a sequence of 24 x Lum and 8 x R,G,B 120s frames.

Sample Luminance frame:

04:08 SQM graph has started to droop. Was 18.2 before 4am, now down to 18

04:10 ASC image brightening quickly

04:15 SQM 17.54

04:24 Camera Warming Up

Disconnected Guider

Telescope Parked and disconnected.

Dome Parked (shutter closed) and disconnected

De-humidifier on.

Camera Power Off

04:30 I’m off to bed

Viewing Report 1st May 2020 – IMT3

On opening the dome I slewed to Venus hoping to catch it before it disappeared below the horizon. I took a 1s Frame and Focus image just to confirm it was in the centre of the FoV and was puzzled by the resulting image.

At first I thought the 12″ was still covered so called Dave to check. He didn’t think the cover was in place as the last thing he’d done was to take some Flats. Dave confirmed that the cover was not in place but reported that I might be trying to view Venus through the trellis on the fence so I abandoned Venus and slewed to NGC3628 in Leo as it had just crossed the Meridian and I wanted to try and setup a profile to use my Tak FS-102 as a guide scope for Dave’s OS12″.

Previous attempts at guiding the OS with the QHY5 and MiniGuideScope combination had proved worse than imaging with the mount unguided.

Although I suspected we knew the root cause we hadn’t our research 🙁 which soon became apparent. I found a couple of rules of thumb, the first stated that ‘image scale in arc-seconds x 400 = max exposure time is seconds when guiding with a separate guide scope’.

For the ZWO ASI1600MM (3.8um pixel size) on the OS 12″ (2500mm fl)

((3.8/2500) x 206.265) x 400 = 125s

We can do better than that unguided.

The second ‘rule of thumb’ I found stated that the ‘Guide to Main train pixel ratio should not exceed 10:1.

Unfortunately the QHY5 MiniGuideScope to OS12″ ratio is close to 17.8:1, not good.

The QHY5 + MiniGuideScope scale is (3.75/130) x 206.265 = 5.95 arc-sec / pixel.

The OS 12″ + ZWO ASI1600MM scale is (3.8/2500) x 206.265 = 0.31 arc-sec/pixel.

The Tak FS-102 with the QHY168C scale is (3.75/820) x 206.265 = 0.94 arc-sec/pixel

So if we try the OS 12″ with the Tak as the guide scope the ratio is closer to 2.8:1 which sounds like a better proposition.

to be continued …

Viewing Report – 26th April 2020 – IMT3

21:30 Slew to M85

Camera -23°C, focus point 74534, temperature 15.81℃

Frame & Focus / Plate Solved / Centred

21:38 Autofocus Run – Failed.

21:50 Integrating M85 Event 1 Frame 1 for 300 seconds
Lost guide Star

22:13 Switch Guider to SW Lodestar

Integrating M85 Event 1 frame 1 for 300 seconds. Aborted run as M85 approaching the meridian and guiding graph was not looking good. Guider not calibrated.

Meridian flip to Chertan in Leo, Tak FS-102 now on top of configuration, Esprit below the OS 12″ so will be the better to guide with the QHY5 MiniGuideScope attached to the FS-102.

22:51 Slewed to a star field near Chertan for Auto Focus run. Start focuser position 72885, final focuser position 72178 ….. nice graph.

22:56 Calibrated QHY5 MiniGuideScope guider

Review calibration

23:08 Calibration suceeded, guiding.

Stoped guider and slewed to M85 which had just crossed the meridian.

Frame & Focus / Plate Solved / Centred

23:21 Integrating M85 Event 1 Frame 1

23:44 Telescope connection lost due to poor communication

23:48 SGPro reported USB error – lost FLI Focuser. FLI connects Ok in The Sky X.

Fix is to click on the spanner in SGPro for the Focuser and Rescan, Focuser now reconnects.

00:01 Re-centered M85

PHD2 restarted as it appeared to have hung.

00:12 Integration new Luminance sequence Event 1: 180s, Event 2: 300 seconds.

Viewing Report 22nd April 2020 – IMT3

22:10 – 03:00

22:10 Bob – Took over operating IMT3 from Dave

The plan was to capture data of NGC 4565 with the OS RiDK 305mm after the testing I’d done the previous night attempting to determine how long we could go with unguided exposures. As NGC4565 was due to transit at 23:36 I thought I’d wait until I could slew to it without performing a meridian flip so went chasing Comet C/2019 Y4 ATLAS to see what remains of it. However, judging by the horizon it was about to disappear from view but I grabbed a few frames anyway. Unlike previous attempts where it was clearly visible in a 60 seconds exposure I was now exposing for 180 seconds to make out the fuzzy remains.

23:15 Slewing to NGC 4565 would still require a meridian flip so I went to NGC 2903 which I’d looked at recently. set a sequence going to get 30mins of data with 5 minute subs. Auto focus succeeded at the start of the run.

00:05 Slewed to NGC 4565.

Solve and Sync then slewed the framing to try and include NGC 4562 in the FoV.

Plate Solved result for the centre of this frame:

12h36m06.94s Angle 185
25° 57′ 42.16″ Scale 0.325

Started sequence to gather 12x 300 seconds Lum, 6x 300 seconds R, G, B and 6x 600 seconds Ha subs.

SGPro failed to start the Guider and aborted.

PHD2 started manually and 5 frames of Luminance gathered before the guide star was lost and the sequence aborted. Profile does not have ‘Recovery’ set. Need to discuss this with DSW and GingerGeek. While looking at the option found in Tools > Options > Sequence I also noticed that ‘Pause Guiding during autofocus’ is not set.

Mil Dave showed me a procedure he believes is documented in the manual to centre the telescope on a previous image, but this failed to move the mount as expected. I later realized it may have been because we did a ‘Solve and Sync’ followed by a ‘Centre Here’ ( which hasn’t worked for me before). I need to see if I had done a ‘Solve and Sync’ followed by a ‘Slew Here’ whether that would have had the desired effect. Using ‘Slew here’ I was able to reasonably match the coordinates of the original frames (after unsuccessfully trying to ‘Slew to coordinates’ in the Sky).

Update 23Apr20:

Having discussed the above with Dave, I believe we identified where I was going wrong but also discovered some points along the way.

We noticed that the RA and Dec I had recorded from the SGPro Plate solve of the image did not match the numbers recorded in the FITS header of the image and using the SkyX to Slew to the coordinates recorded was off because I hadn’t selected Epoch J2000.0 (used by SGPro) but had used the default Sky ‘Apparent (i.e. current)’ setting for the Equinox.

Additionally, after performing a ‘solve and Sync’ in SGPro, I should have gone to The SkyX and syncronized the Telescope.

Turned off the guided and finally resume a sequence

03:00 Of to bed for me, leaving the sequence to run for a further 1hr30.

Bob’s viewing report: 6th April 2020 – More Comet chasing

Chineham Scouts say ‘Thank you’ on Zoom session whilst viewing the Moon

After helping with a BAS Outreach event using Zoom to share images from IMT3 of Venus and the Moon with 1st Chineham Cub Scouts (to help them acheive their Astronomy Badge) I joined Dave and GingerGeek for a joint observing session chasing Comet C/2019 Y4 (ATLAS) with Dave’s 12″ OS.

Comet C/2019 Y4 ATLAS through 12″

I continued to observe after both Dave and GingerGeek called it a night, my aim was to get some data from the Esprit 120 of C/2019 Y4 (ATLAS) as the previous nights run had been terminated when the clouds rolled in.

Quick 10min Exposure through Esprit 120 Comet C/2019 Y4 ATLAS

I set up another Profile in SGPro for GingerGeeks Esprit 120, adding his Lodestar Guider. C/2019 Y4 (ATLAS) was too far from the equator for the Calibration of the guider in PHD2, so I slewed to Bogardus in Auriga, cleared the calibration data for the Lodestar and re-calibrated it. I was then able to get two 10 minute guided exposures with the mount tracking at Sidereal rate before the comet disappeared from view below the roof line of a neighbouring house.

Comet C/2017 T2 PANSTARRS 10min Exposure Esprit 120

Having lost Comet Atlas for the night, I checked Heavens-Above for other candidates and found C/2019 Y1 (ATLAS) was about to drop below the horizon, but C/2017 T2 PANSTARRS was reasonably well placed, albeit a bit low, and only a short slew from where the telescope was already pointing. After slewing to PANSTARRS and a 5arcminute JOG Up, Left, Down, Right and Down I had it reasonably centred in the FoV. The first 10 minute exposure had star trails, thought I was guiding but found the Mount was still tracking at ‘Custom rates’. The next 10 minute exposure also had stars trailing even though the PHD2 Graph looked fine. I then discovered that with the SGPro profile changes I’d made I hadn’t connected to the ASCOM Telescope Driver for TheSky. The next 10 minute exposure was not much better as by now I’m imaging down in the weeds 🙁 . Time to find a new target … as it is up and really bright drowning out most objects I slewed to the Moon for a few final shots of the evening.

Moon Esprit 120 Ha with SX814

Bob’s viewing Report: 5th April 2020 – C/2019 Y4 (ATLAS)

I started the evenings session grabbing some frames of Comet C/2019 Y4 (ATLAS) with my Takahashi FS-102 and QHY168C OSC Camera.

After successfully acquiring some data of various exposure times I decided to try and grab some data from GingerGeek’s Esprit 120, the weather station was reporting Haze and I could see wisps of clouds on the All Sky Camera so it wasn’t worth spending lots of time gathering data but worth using the opportunity to work out a procedure for chasing comets. As I hadn’t switched Dome profiles I found that the view through the Esprit was partially obscured so I switched to Dave’s 12″ OS only to find that the last thing he’d been doing was collecting Dark frames and the cover was still on the 12″.

I was in the process of switching back to GingerGeeks’s Esprit when Dave ping’d me on WhatsApp to say he’d woken up and remember that he cover was on and did I want it removed … perfect timing !
I managed to grab some frames for comparison with those I’d taken with the Tak earlier in the evening but aborted the sequence as clouds were messing up the results. So decided to try GingerGeek’s Esprit one more time as the clouds appeared to have passed by.

I found I had to create a new Profile for GingerGeek’s Esprit as the only profile available had the ASCOM Telescope Driver for TheSky selected and as Dave had mentioned to me previously, this was not needed when Tracking a Comet as that would be done by the Mount under direct control of TheSky X.

This does create a problem in that with these profiles you cannot Plate Solve and Centre the object as they is no Telescope for SGPro to work with, so we’ll need to figure out how to do that in TheSky X or start the session with the Telescope selected, centre and frame the comet, set the Tracking Rates to the comet then switch to a profile without a Telescope to run the SGPro sequence.

The weather deteriorated and the Wx Stn Auto closed the slit at 01:27 part way through a 15minute exposure.

Another night of good lessons learnt.

IMT3 Environmental Monitoring Pt.3

In this part we’ll look at the Node-RED flow that controls the Arduino with a 4-Relay Shield attached. As previously mentioned, these relays are used to allow us to remotely reset the All Sky Camera and HiTechAstro Wx STn, which we found had a tendency to hang and wouldn’t reset unless the USB connection was broken and remade. As we would not be in a position to unplug and re-plug the USB connections I came up with a solution. By modified some short USB extension cables and breaking into the +5v line I could then connect to the ‘Normally Closed’ contacts of one of the relays, picking the relay effectively turns off the USB device connected to that cable.

Relay Shield that attaches directly to an Arduino UNO

Modified USB extension cable
Snapshot of the flow to control the relays to reset ASC and Wx Stn

For this solution, we don’t write any code for the Arduino but do load it with Standard Firmata code that comes with the Arduino IDE.

Just open a new sketch, select the StandardFirmata from the Examples and upload to the Arduino.

Firmata is a generic protocol for communicating with microcontrollers from software on a host computer. It is intended to work with any host computer software package.

If not done already we need to go to npm and install the node-red-node-arduino nodes.

Originally I used a Dashboard Switch to select each relay, but it can get confusing when turning on the relay turns off the device attached, so I replaced the Switch with a Button node, pass the message to a Trigger node that will activate for 7 seconds (give the OS time to recognize the USB device has been disconnected), debounce the signal before passing onto the Arduino Output node which connects to the local Arduino and writes to the selected digital pin turning the relevant Relay On.

As there are only a few basic nodes in this flow, here are some snapshots of how each is set-up:

This button will appear on the Dashboard under the Reset Controls group

7 seconds seems long enough but can easily be changed.

Off Button

On Button

debounce the signal
debug options
Pin 7 drives the appropriate relay

So the above covers the two relays that are used to reset the All Sky Camera and HiTechAsto Wx Stn. The same building blocks are used to control a pair of battery power LED worklights to provide illumination for the Web Cameras we have dotted around the dome and on the mount. After inadvertently leaving the lights on, on one occasion, the batteries needed to be replaced after a single use. So now in addition to having switches control the lights, we also have Buttons to push for preset times on of 1, 3, 7 or 10 minutes, with an option to turn them off early.

LED lighting control

Unlit dome

Flip-Flat Closed
Just a couple of counter-weights
Will the last one out please turn off the lights

Wrapping up for today

Here’s the Node-RED flow for the Relay Shield

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IMT3 Environmental Monitoring Pt.2

Getting Started with Node-RED is as good as anywhere to get started. There are also plenty of YouTube clips to watch, so I won’t repeat too much here.

I chose to run Node-RED locally on my Windows 10 laptop so my first step was to download and install a supported prerequisite version of Node.js which will also include npm (Node Package Manager).

npm is the worlds largest Software Registry containing over 800,000 code packages. It is free to use and Open-source developers use npm to share their software.

npm includes a CLI (Command Line Client) that we will use to download and install software.

Having installed Node.js open Windows PowerShell to execute the npm cli command to install Node-RED

  npm install -g --unsafe-perm node-red

The command installs Node-RED as a global module along with its dependencies.

Once installed as a global module we can use the node-red command to start Node-RED in a terminal.  Ctrl-C or closing the terminal window will stop Node-RED.

You can then access the Node-RED editor by pointing your browser at http://localhost:1880/

To access the Node-RED Dashboard point your browser at http://localhost:1881/

By default, Projects are disabled 🙁 , so brush up on your Vi skills* as we need to go and edit settings.js file located in the .node-red directory. *other editors are available.

Just remember to press escape key, colon, w q bang when done!  … now where did I drag that up from, I hadn’t used Vi in years!

After an initial foray into Node-RED, I realised I would need to use Projects within Node-RED. A pre-req for this is Git. With that installed I was good to create my first Project.

I was surprised how quickly I was able get some meaningful results and was soon using npm to add nodes from the Node-RED library for the Dashboard, Arduino and much more. It wasn’t long before I had my first Dashboard displaying the output of the BME280 sensor which looked like the following:

My first Node-RED Dashboard display

An early comment from our dear friend Mil Dave asked “What’s the Dew Point“? … thanks Dave !

Google to the rescue, however the Dewpoint calculation formulae found on the web look pretty scary. Fortunately a search of the Node-RED library found a flow with a dewpoint function defined that I was able to adapt to my flow. A snapshot of the flow follows as it is now beginning to take shape and looks like this:

Node-RED Flow

The green debug nodes are useful to follow the message as they progress through the flow, the debug output can be displayed in the debug window, the system console or as node status appearing just below the debug node

The data from the Arduino arrives on the Serial node which is configured for the com port the Arduino is connected to. I’ve found it easier to determine the relevant com port from the Arduino IDE rather than via control panel and device manager. Also the ‘Get board info’ from the IDE has prove very useful when running Node-RED on MAC OS.

Double clicking any node will open up an Edit window to let you configure each node

Connected to the Serial node is a Split Node. This splits the incoming message into a sequence of messages and is setup to split the message when it finds a comma.

The message is passed to the next node which is a function node which contains some Javascript to give a variable name to each of the values received from the Arduino.

var newMsg = {};
var Sensor = {
    S1C: 0, 
    S1F: 0,
    S2C: 0,
    S2F: 0,
    BT: 0,
    BH: 0,
    BP: 0,

}; = || {};

    case 0: = parseFloat(msg.payload);
        msg = null;
    case 1: = parseFloat(msg.payload);
        msg = null;
    case 2: = parseFloat(msg.payload);
        msg = null;
    case 3: = parseFloat(msg.payload);
        msg = null;
   case 4: = parseFloat(msg.payload);
        msg = null;
    case 5: = parseFloat(msg.payload);
        msg = null;
    case 6: = parseFloat(msg.payload);
        msg = null;

AllData = &&


    Sensor =;
    newMsg = { payload:,
    topic: 'DS18B20' }; = null;
    return newMsg;
    return msg;

The next Function node Splits these seven values and presents them on a separate output of the node which can then be connected to individual Dashboard Gauges.

var msgS1C = {payload: (msg.payload.S1C).toFixed(2)};
var msgS1F = {payload: (msg.payload.S1F).toFixed(2)};
var msgS2C = {payload: (msg.payload.S2C).toFixed(2)};
var msgS2F = {payload: (msg.payload.S2F).toFixed(2)};
var msgBT = {payload: (msg.payload.BT-1.4).toFixed(1)};
var msgBH = {payload: (msg.payload.BH).toFixed(1)};
var msgBP = {payload: (msg.payload.BP).toFixed(0)};

return [msgS1C, msgS1F, msgS2C, msgS2F, msgBT, msgBH, msgBP];

Having split these values out, the Temperature and Humidity values need to be recombined by the Join node so they can be passed to the Dew Point function node.

var newMsg = {};
var parts = msg.payload.split(",");
var Th = parseFloat(parts[0]);
var Hu = parseFloat(parts[1]);

var temp = -1.0*Th; 
es = 6.112*Math.exp(-1.0*17.67*temp/(243.5 - temp)); 
ed = Hu/100.0*es; 
eln = Math.log(ed/6.112); 
td = -243.5*eln/(eln -17.67);

var Dp = td.toFixed(1);

newMsg = {payload: Dp,
     topic: "DewPoint"};

return newMsg;

The DewPoint is now passed to a Dashboard Gauge node and displayed. The Dashboard currently looks like this:

IMT3 Environmental Dashboard

In Pt.3 we’ll take a look at the flow that controls the Arduino with the 4-Relay Shield that allows us to remotely reset the All Sky Camera, HiTechAstro Wx Stn and control a pair of LED lights to illuminate the rig so we can use ManyCam to monitor the web cams installed in the observatory.

The following is the current Node-RED flow running on the IMT3 MAC Mini

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LEDs on Timer","tooltip":"","color":"","bgcolor":"","icon":"","payload":"true","payloadType":"bool","topic":"","x":135,"y":907,"wires":[["ce4ad2aa.33a02"]]},{"id":"7432b57b.2b4fac","type":"serial in","z":"4d3e5207.bd89ec","name":"","serial":"afd985bb.b6f418","x":65,"y":255,"wires":[["fbe3b723.be8138","d6674162.0d89a"]]},{"id":"d968c054.e6532","type":"function","z":"4d3e5207.bd89ec","name":"","func":"var newMsg = {};\nvar Sensor = {\n //   NData: 0, \n    Temp: 0,\n    Humid: 0,\n    Pressure_BME280 : 0,\n\n//    Time: new Date().toString()\n};\n\ = || {};\n\nswitch({\n    case 0:\n = parseFloat(msg.payload);\n        msg = null;\n        break;\n    case 1:\n = parseFloat(msg.payload);\n        msg = null;\n        break;\n    case 2:\n = parseFloat(msg.payload);\n        msg = null;\n        break;\n        \n    case 3:\n = parseFloat(msg.payload);\n        msg = null;\n        break;\n        \n\n}\n\n//AllData = &&\nAllData = &&\n &&\n;\n       \n        \n         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parseFloat(msg.payload);\n        msg = null;\n        break;\n    case 2:\n = parseFloat(msg.payload);\n        msg = null;\n        break;\n        \n    case 3:\n = parseFloat(msg.payload);\n        msg = null;\n        break;\n    \n   case 4:\n = parseFloat(msg.payload);\n      msg = null;\n      break;\n     \n    case 5:\n = parseFloat(msg.payload);\n        msg = null;\n        break;\n       \n    case 6:\n = parseFloat(msg.payload);\n        msg = null;\n        break;\n\n\n}\n\nAllData = &&\n &&\n &&\n &&\n &&\n &&\n;\n       \n        \n         //;\n\nif(AllData){\n    //var time = Date();\n   // = time.toString();\n    Sensor =;\n    newMsg = { payload:,\n    topic: 'DS18B20' };\n = null;\n    return newMsg;\n}\nelse\n    return msg;\n\n\n","outputs":1,"noerr":0,"x":400,"y":525,"wires":[["ea728815.3b1928","bf04c7ef.157d88"]]},{"id":"ea728815.3b1928","type":"debug","z":"4d3e5207.bd89ec","name":"","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"payload","targetType":"msg","x":655,"y":525,"wires":[]},{"id":"bf04c7ef.157d88","type":"function","z":"4d3e5207.bd89ec","name":"Split Data","func":"var msgS1C = {payload: (msg.payload.S1C).toFixed(2)};\nvar msgS1F = {payload: (msg.payload.S1F).toFixed(2)};\nvar msgS2C = {payload: (msg.payload.S2C).toFixed(2)};\nvar msgS2F = {payload: (msg.payload.S2F).toFixed(2)};\nvar msgBT = {payload: (msg.payload.BT).toFixed(2)};\nvar msgBH = {payload: (msg.payload.BH).toFixed(2)};\nvar msgBP = {payload: (msg.payload.BP).toFixed(2)};\n\n//var msgS1C = {payload: (msg.payload.S1C).toFixed(2)};\n//var msgS1F = {payload: (msg.payload.S1F).toFixed(2)};\n//var msgS2C = {payload: (msg.payload.S2C).toFixed(2)};\n//var msgS2F = {payload: (msg.payload.S2F).toFixed(2)};\n//var msgBT = {payload: (msg.payload.BT).toFixed(2)};\n//var msgBH = {payload: (msg.payload.BH).toFixed(2)};\n\n\n//var msgbme280_h = {payload: (msg.payload.bme280_h).toFixed(1)};\n//var msgbme280_p = {payload: (msg.payload.bme280_p).toFixed(1)};\n\nreturn [msgS1C, msgS1F, msgS2C, msgS2F, msgBT, msgBH, msgBP];\n//return [msgS1C, msgS1F, msgS2C, msgS2F, msgbme280_t, msgbme280_h, msgbme280_p];\n\n\n\n\n\n//var msgTemp = {payload: msg.payload.Temp};\n//var msgTemp = {payload: (msg.payload.Temp).toFixed(1)};\n//var msgHumid = {payload: msg.payload.Humid};\n//var msgHumid = {payload: (msg.payload.Humid).toFixed(1)};\n//var msgTemp_DS = {payload: msg.payload.Temp_DS};\n//var msgTemp_BMP = {payload: msg.payload.Temp_BMP};\n//var msgPressure_BME = {payload: (msg.payload.Pressure_BME280).toFixed(0)};\n//var msgPressure_BME = {payload: (msg.payload.Pressure_BME280/100000).toFixed(2)};\n//var msgAltitud_BMP = {payload: msg.payload.Altitud_BMP};\n\n//return [msgTemp_DHT11];\n//return [msgTemp, msgHumid, msgPressure_BME];\n//return [msgTemp_DHT11, msgHumid_DHT, msgTemp_DS, msgTemp_BMP, msgPressure_BMP, msgAltitud_BMP ];","outputs":7,"noerr":0,"x":255,"y":750,"wires":[["5a7a2a2.9de7ed4","74244174.a7498"],["1df94d4f.96f153","bc09270c.1c3d38"],["83e8c937.e86d18","b9e2e2e3.e5de6"],["4dc159a8.536488","b3d40b.af729bf8"],["7bf4618d.9e1e2","edca722d.9bc12"],["24655be.0e446a4","76e9dff9.ffc88"],["5e28cc59.1975a4","214f5175.b812fe"]]},{"id":"5a7a2a2.9de7ed4","type":"debug","z":"4d3e5207.bd89ec","name":"","active":true,"tosidebar":false,"console":false,"tostatus":true,"complete":"payload","targetType":"msg","x":550,"y":615,"wires":[]},{"id":"1df94d4f.96f153","type":"debug","z":"4d3e5207.bd89ec","name":"","active":true,"tosidebar":false,"console":false,"tostatus":true,"complete":"payload","targetType":"msg","x":535,"y":720,"wires":[]},{"id":"83e8c937.e86d18","type":"debug","z":"4d3e5207.bd89ec","name":"","active":true,"tosidebar":false,"console":false,"tostatus":true,"complete":"payload","targetType":"msg","x":535,"y":810,"wires":[]},{"id":"4dc159a8.536488","type":"debug","z":"4d3e5207.bd89ec","name":"","active":true,"tosidebar":false,"console":false,"tostatus":true,"complete":"payload","targetType":"msg","x":480,"y":930,"wires":[]},{"id":"74244174.a7498","type":"ui_gauge","z":"4d3e5207.bd89ec","name":"Mac 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Timer","tooltip":"","color":"","bgcolor":"","icon":"","payload":"true","payloadType":"bool","topic":"","x":140,"y":700,"wires":[["ec59f57e.ea8d18"]]}]

IMT3 Environmental Monitoring Pt.1

IMT3 Environmental Monitoring Pt.1
Bob Trevan – Aug2019

When Dave, Mark and I first started planning what equipment we were going to install in IMT3 we started with a block diagram of what we thought we were going to install so we could determine the number of USB ports we would need and the power requirements. This soon morphed into much more as we started adding kit to the project.

Although the Observatory is install in the UK and not Spain as was originally planned, we decided we would still need a fair bit of monitoring to allow remote sensing of the local conditions. In particular making sure it was safe to open the shutter for a remote observing session

During AstroFest in Feb 2019 we bought a HiTechAstro Deluxe Weather Station which can be used as an ASCOM safety device to autonomously close the Dome Shutter if rain or cloud is detected. Although we were lead to believe it would directly interface with the Pulsar Dome Controller, this was not the case and required a simple interface consisting of a SPST Relay to control the shutter. Once the Relay is picked the shutter closes and will stay closed until the operator manually resets the state of the relay via the weather station software. The software has a number of options to configure to determine when to close the shutter

Although the Shutter itself has a battery pack that has sufficient capacity to close the shutter in the event of a power outage we decided to add an APC UPS with PowerChute software so provide AC power resilience to critical components. The shutter battery is wirelessly charged when the dome is parked at the end of each observing session.

In addition to the Cloud and Rain sensor, we also have a Sky Quality Meter and All Sky camera mounted on the same pole. The cable run to the pole from the panel inside the dome to which we were mounting various components … MAC Mini, 10-port USB HUB, Power Bricks, etc … is about 10m. The cabling provided with the Weather Station was somewhat shorter than this which meant having to extend it with the challenges of making the external connections water tight.

The HiTechAstro Wx Stn is also a Cloud Sensor utilizing an IR sensor to measure the Sky Temperature and a Dallas DS18B20 to measure Ambient Temperature. The waterproof probe is attached to the underside of the mounting bracket.

For monitoring the Dome Internal conditions I started looking at what we could achieve using an Arduino (*1) with various sensors. Currently we have two Arduinos installed, the first utilizes an Arduino UNO R3 with a Bosch BME280 (*2) Temperature, Humidity and Pressure Sensor and a pair of Dallas DS18B20 (*3) temperature probes for monitoring the internal temperatures of the enclosures housing the MAC Mini and Intel NUC (*4) (more on the NUC later). The current version of code running on this Arduino is provided at the end of this part of the blog.

A second Arduino has a 4-relay shield attached. The relays are used to control two 380 lumens LED lights inside the dome and after modifying a couple of short USB extension leads, breaking into the +5v line, the remaining 2 relays are used to reset the All Sky Camera and HiTechAstro Deluxe Wx Stn, when the need arises (which is all too frequently). This Arduino is programmed to run Standard Firmata code allowing Node-RED to communicate via the serial port and control the relays.

*1   Arduino is an open-source electronics platform based on easy-to-use hardware and software. Arduino boards are able to read inputs – light on a sensor, a finger on a button, or a Twitter message – and turn it into an output – activating a motor, turning on an LED, publishing something online.

The Arduino integrated development environment (IDE) is a cross-platform application (for Windows, macOS, Linux) that is written in the programming language Java, C, C++. It is used to write and upload programs to Arduino compatible boards. User-written code only requires two basic functions, for starting the sketch and the main program loop. For more info see

*2   Bosch BME280
The BME280 is an integrated environmental sensor developed specifically for mobile applications where size and low power consumption are key design constraints. The unit combines individual high linearity, high accuracy sensors for pressure, humidity and temperature in an 8-pin metal-lid 2.5 x 2.5 x 0.93 mm³ LGA package, designed for low current consumption (3.6 μA @1Hz), long term stability and high EMC robustness.

*3   Dallas DS18B20
The DS18B20-PAR digital thermometer provides 9 to 12–bit centigrade temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points. The DS18B20-PAR communicates over a 1-Wire bus, which by definition requires only one data line (and ground) for communication with a central microprocessor. It has an operating temperature range of –55°C to +100°C and is accurate to ±0.5°C over a range of –10°C to +85°C.

*4   Next Unit of Computing (NUC) is a line of small-form-factor barebone computer kits designed by Intel. The NUC motherboard measures 4 × 4 inches (10.16 × 10.16 cm)

The Bosch BME280 Sensor uses the I2C bus and the Dallas DS18B20 probes use a One-Wire interface. Each of the DS18B20 has a unique internal 64-bit address created during the manufacturing process, so you can just keep adding as many as you need with relative ease.

Currently, every 20 seconds, the Arduino spits out 7 values separated by commas and terminated with a line feed, these are:

  1. DS18B20 Ext sensor Temperatue in °C
  2. DS18B20 Ext sensor Temperature in °F
  3. DS18B20 Int sensor Temperature in °C
  4. DS18B20 Int sensor Temperature in °F
  5. BME280 sensor Temperature in °C
  6. BME280 sensor Humidity in %
  7. BME280 sensor Pressure in mPa

e.g. 27.0000,80.6000,26.0000,78.8000,28.53,43.53,1008.28

Mark also donated a HiTechAstro Hub to the project which is used to control DC power to the Cameras, Focuser, Filter Wheels and potentially Dew Heaters, but with three rigs mounted on the SB Paramount ME-II we were quickly using all available USB Ports and Switched DC power ports available.

After several ‘Hangs’ of the NUC due the to the software packages tested with the All Sky Camera, we added a MAC mini to run the environment applications, leaving the Intel NUC to run the Main Applications to control the mount and Cameras. The Sky X, Sequence Generator Pro etc…

So we now have a number of PC / MAC applications, controlling and displaying various functions of IMT3. But how do we display the Arduino data ?

Working for IBM, Dave had been exposed to Node-RED. Originally developed by IBM, Node-RED is a flow based development tool for visual programming for wiring together hardware devices, APIs and online services as part of the Internet of Things.

Node-RED provides a web browser-based flow editor, which can be used to create Javascript fuctions. The runtime is built on Node.js. The flows created in Node-RED are stored using JSON. Since version 0.14 MQTT nodes can make properly configured TLS connections.

In 2016, IBM contributed Node-RED as an open source JS Foundation project.

One of the Node-RED projects is a dashboard UI for Node-RED, and this is how the Arduino sensor data is displayed, along with the flow that controls the 4 relays on the Arduino Relay Shield.

We have a new vocabulary to learn; IoT, MQTT, node.js, Node-RED, JSON, Arduino, Sketch, Flow and new languages to learn C, C++, Javascript and we haven’t even mentioned the BBC MicroBit or Raspbery Pi and Python 🙂

I’ll describe the Node-RED flows I currently have working and the Dashboard in Pt. 2.

Arduino Code:

* Arduino code used for monitoring the Internal Ambient Temperature,
* Humidity and Air Pressure of IMT3 Observatory using a Bosch BME280 sensor
* and two Dallas DS18B20 temperature probes to measure the temperatures of
* the MAC Mini and Intel NUC enclosures.
* I have commented out alot of the lines used during development, but left
* them in to help comment the code.
* Currently, every 20 seconds, the Arduino spits out 7 values separated by
* commas and terminated with a line feed, these are:
* DS18B20 Ext sensor Temperatue in °C
* DS18B20 Ext sensor Temperature in °F
* DS18B20 Int sensor Temperature in °C
* DS18B20 Int sensor Temperature in °F
* BME280 sensor Temperature in °C
* BME280 sensor Humidity in %
* BME280 sensor Pressure in mPa
* e.g. 27.0000,80.6000,26.0000,78.8000,28.53,43.53,1008.28
* The above will be displayed as Gauges on a Node-RED Dashboard.
* Bob Trevan August 2019
This is a library for the BME280 humidity, temperature & pressure sensor
Designed specifically to work with the Adafruit BME280 Breakout
 These sensors use I2C or SPI to communicate, 2 or 4 pins are required
to interface. The device's I2C address is either 0x76 or 0x77.
 Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing products from Adafruit! 
Written by Limor Fried & Kevin Townsend for Adafruit Industries.
BSD license, all text above must be included in any redistribution
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>
#include <OneWire.h>
#include <DallasTemperature.h>

#define BME_SCK 13
#define BME_MISO 12
#define BME_MOSI 11
#define BME_CS 10

Adafruit_BME280 bme; // I2C
char buffer[60];
// Onewire Reference and assign it to pin 5 on the Arduino
OneWire oneWire(5);
// declare as sensor reference by passing oneWire reference to Dallas Temperature.
DallasTemperature sensors(&oneWire);
// declare the device addresses
//Device 1: 0x28, 0x41, 0x0F, 0x84, 0x1F, 0x13, 0x01, 0x16
//Device 2: 0x28, 0x89, 0x25, 0x6E, 0x1F, 0x13, 0x01, 0x3F

//Device 3: 0x28, 0xAD, 0x43, 0xE2, 0x1B, 0x13, 0x01, 0x8D
//Device 4: 0x28, 0x0B, 0xA9, 0x63, 0x1F, 0x13, 0x01, 0xCC

//Device 5: 0x28, 0x52, 0xDA, 0x71, 0x1F, 0x13, 0x01, 0x68
//Device 6: 0x28, 0xAA, 0xBD, 0x68, 0x3C, 0x14, 0x01, 0x4E

// Select the pair of sensor used with this Arduino, these addresses have previously been read with a separate piece of Arduino code.
DeviceAddress ExtSensor = {0x28, 0xAA, 0xBD, 0x68, 0x3C, 0x14, 0x01, 0x4E};
DeviceAddress IntSensor = {0x28, 0x52, 0xDA, 0x71, 0x1F, 0x13, 0x01, 0x68};

// Variables to hold the temperatures
float ExtC; // originally had one sensor hanging out of my study window
float IntC; // and a second sensor by my desk.

void setup() {

// Serial.println(F("BME280 test"));
bool status;
status = bme.begin(0x76); // I2C Address
if (!status) {
Serial.println("Could not find a valid BME280 sensor, check wiring!");
while (1);

// Serial.println("-- Default Test --");


// set the resolution to 9 bit - Valid values are 9, 10, or 11 bit.
sensors.setResolution(ExtSensor, 9);

// confirm that we set that resolution by asking the DS18B20 to repeat it back
//Serial.print("Exterior Sensor Resolution: ");
//Serial.println(sensors.getResolution(ExtSensor), DEC);
// set the resolution to 9 bit - Valid values are 9, 10, or 11 bit.

sensors.setResolution(IntSensor, 9);

// confirm that we set that resolution by asking the DS18B20 to repeat it back
//Serial.print("Interior Sensor Resolution: ");
//Serial.println(sensors.getResolution(IntSensor), DEC);

void loop() {
// Tell the Ext sensor to Measure and Remember the Temperature it Measured
sensors.requestTemperaturesByAddress(ExtSensor); // Send the command to get temperatures
// Get the temperature that you told the sensor to measure

ExtC = sensors.getTempC(ExtSensor);

//Serial.print("Exterior Sensor: ");
//Serial.print("Temp C: ");

Serial.print(ExtC,4); // The four just increases the resolution that is printed

//Serial.print(" Temp F: ");
// The Dallas Temperature Control Libray has a conversion function... we'll use it


// Tell the INT sensor to Measure and Remember the Temperature it Measured sensors.requestTemperaturesByAddress(IntSensor); // Send the command to get temperatures
// Get the temperature that you told the sensor to measure

IntC = sensors.getTempC(IntSensor);

//Serial.print("Interior Sensor: ");
//Serial.print("Temp C: ");

Serial.print(IntC,4); // The four just increases the resolution that is printed

//Serial.print(" Temp F: ");
// The Dallas Temperature Control Libray has a conversion function... we'll use it


void printTemp() {

// Serial.print("Temperature = ");


// Serial.println(" *C");

void printHum() {

// Serial.print("Humidity = ");


// Serial.println(" %");

void printPa() {

// Serial.print("Pressure = ");


// Serial.println(" hPa");

double getTemp(void) {
double t;
t = bme.readTemperature();
return (t);

double getHum(void) {
double h;
h = bme.readHumidity();
return (h);

double getPa(void) {
double p;
p = (bme.readPressure() / 100.0F);
return (p);