A Pulsar Observatory 2.7m installation, operation and use.
Heptagonal base is prepared...........dome panels arrive.......................construction of the wall.................pier lifted into place ................nearly complete. Bay to be fitted
date: 2019 December - deposit
paid (£1019) to Pulsar Observatories. Steve Collingwood FRAS is the CEO
On the Order: Full height with accessory bay, dome and shutter drives including delivery and build by Pulsar. Colour: SAGE green.
Base construction: Covid-19 restrictions and other factors, prevented the base being laid in summer 2020.
Dome Storage: Pulsar very kindly kept the dome in storage until we were able to install it.
Equipment : An EQ8 head purchased Feb 2019 from MrOatley(1450), a Pulsar pier from Astronomia(250), a C11 from from MrDaniel (1150)
2020 September: Local builder found to do the base, but not until mid-January 2021.
Jan 18: Base is excavated and
shuttered: 3m x 3m with a 1x1x0.9m foundation for the pier. Two men + a mechanical
digger, 2" of hardcore added.
2021 Jan 18: We estimate 2cu m of concrete will be used.
2021 Jan 22: The concrete is mixed on site as per specifications and slopped in from wheelbarrows. A power conduit with a "pull through" is included.
Surface of the base: Zig-zag tamping gave a flat surface, but when dried there was a very slight depression in the centre where rainwater collected.
Snow and ice: It turned cold over the following days. The surface was covered with tarpaulins, although the drying process created warmth (snow melted).
2021 Jan 27: Tarpaulins are removed. The base is 6" thick at the edges, and 2-3" above ground.
Feb 23 : The base has been
wind-dried for a few days.
2021 Feb 23 : Pulsar to deliver and construct the dome. Pulsar no longer offer a construction service. This is one of their last jobs.
Floor Kit: I asked about a floor kit but Pulsar no longer supply 2cm thick rubber mats. One can get 1cm mats from Halfords etc .easily.
1cm thick Mats: I order 2 packs of 6 mats from Halfords for home delivery at £20. They can be fitted later.
Sealing the dome: Pulsar advise me that the sealant should be used when the base is "bone dry", but to apply Unibond PVA first (not supplied).
Feb 23 :
The Pulsar team arrive at 0930 after a long drive to start in sunshine, but
with a wind developing.
2021 Feb 23 : My Pulsar pier is bolted down. I bought this a while ago. An offset to the South of 1-2" was added. I had planed on 8". (Too much)
2021 Feb 23 : An 8" pier offset would have given me more operational space near the bay, but would have restricted the S horizon.
2021 Feb 23 : The dome top required 5 persons to lift. Steve C said it was 20% heavier for some reason. The dome sections are subcontracted.
2021 Feb 23 : Work is complete but the walls are not sealed at the base. The dome drive is calibrated and demonstrated.
2021 Feb 23 : The dome needs to "settle" and should not be used for "a while". The pier nuts were nipped up about 1/4 turn (not torqued) 2 days later.
Feb 25: An EQ8
adapter plate ( by Altair) was added along with six long M8
bolts for added height. The EQ8 was
offered up and aligned N-S.
2021 Feb 25: The azimuth bolts are on the South Side of the Head (unlike EQ6pro on the North) - I rotated the top plate and mounted the C11.
C11 on an EQ8 in the "home" position. An off-set counterweight was fitted by the previous owner. I have added a pier extension using 6x M8 100mm bolts.
Feb 26: Attempted to make first
observation but the EQMOD GOTO wasn't working. Incorrect encoder feedback. I
continued to Drift Align the polar alignment.
2021 Feb 26: The dome rotation stops in places. Operation can't continue until the dome movement is assisted by hand !
Feb 27: EQ8:
Advice from a user indicates i need to disable the EQ8 freedom-find encoders
in EQMOD setup. All is OK now on Windows 7 and 10.
2021 Feb 27: Dew is forming puddles on the dome lip inside. Air is damp (T = -1C). Investigated the use of a dehumidifier which i have borrowed.
Feb 28: Did some imaging to
test the polar alignment - looking good. The dome rotation is making a loud
clonking sound and sometimes the motor looses grip.
2021 Feb 28: Rain is expected next week, so i start to run sealant around the base on the outside. Several days have been dry. There a few big gaps to fill.
Mar 01: Tweaked the polar alignment
via drift over 20min. Did some Ha imaging 30s x14. Nearly zero drift on the
stack - good!
2021 Mar 02: Completed the external wall-to-base seal with a fat bead on the outside, and squirting in where the gap is wider. One 300ml tube used up.
2021 Mar 03: Rain in the afternoon, and heavy during the night.
Mar 04: Disappointed
to find a large puddle of water in the dome on the weather side (E). Inspection
indicated the wall joint seal was the cause.
2021 Mar 04: The wall joint was separated by 3 mm and rain trickles in. The white ground seal applied on the 2nd seems OK.
2021 Mar 05: Keeping the door open increases air circulation to dry out the floor. All four wall gaps were filled with clear bathroom silicone.
Mar 06: I investigated the
"dome rotation seizure" and motor noise.
2021 Mar 06: When the friction drive is released, I can push the dome around by hand. It is essentially free except where the dome joints bump over the wheels.
2021 Mar 06: Feeling with my finger, one of the dome sections is not aligned, and there is a 2mm lip between sections that wheel has to move over.
2021 Mar 06: The lips comes into contact with two wheels at the same moment because the sections and wheels are 90 deg apart. The motor doesn't like this.
2021 Mar 06: When the friction drive is disengaged, there is some side-to-side sliding of the dome of about 2cm. Take care not to damage the induction charger.
2021 Mar 06: The battery has not been fully charged since the extension lead to the house was removed. The power level meter indicated charging is in progress.
2021 Mar 06: Does a full charge result in a "white or dark" display icon? - I guess i will find out, but there is plenty of power to close the dome.
Mar 07: Examined the dome wheel
arrangement. Looks like i get access to problem areas from outside the dome
where is can be lifted onto wood.
2021 Mar 07: When moving the dome i can slacken off the friction driver and turn it carefully by hand. I can then engage the tracking motor.
2021 Mar 07: I have chipped the entrance doorway with my head (Ouch!). The doorway needs protection. I have ordered 2m of rubber to cover the edges.
2021 Mar 07: The interior would benefit from some sound insulation to stop the echo, and provide a minimal amount of insulation.
Mar 08: I asked Steve about
the dome motors. All three are driven, two on the outside and one on the inside.
The pressure on the inside is adjustable.
2021 Mar 08: Given the power of the combined motors I'm surprised the dome sticks.
Mar 09: Rain and wind overnight
from S/SE. The floor is wet again on the side facing E near the door, but
no puddle. I think the wall joint seal worked.
2021 Mar 09: I now suspect the door. It is not sealed to allow air to circulate. The door doesn't reveal a possible cause though.
Mar 11: Wind and rain from
the SW. The floor is soaked. Rain is coming in between the dome and the wall.
Not weather proof.
2021 Mar 11: I took a video from inside using my headlamp (internal power is not connected). Will send to Steve C. for comment.
2021 Mar 11: A prompt reply from SteveC expressing shock says he will contact a Pulsar Owner who is in a similar rain-swept location. He has a fix?
Rain water collecting on the inside...................flowing onto the floor which had been dry.
Mar 13: Received from Pulsar
an edging strip 8m x 35mm (x2) self adhesive to block rain blown in under the
dome. (KEPEAK Silicone Door Bottom...)
2021 Mar 13: After mopping up, air circulation in the dome dries the floor off. The edging strip will not be fitted yet.
Mar 16: Fitted a wooden panel (3/4" ply 1100 x 650mm)
above the power cable entry point. It will support 4 x double sockets.
2021 Mar 16: I made two supporting cross beams in wood and aluminium plate to support the panel between the wall joint and the accessory bay.
Mar 17: Fitted
some U-Channel rubber edging strip to the doorway to protect the fiberglass
finish from shoes and heads. ( 2 x 1m ).
2021 Mar 17: Described as U50 U Channel (1638) 3-6.5mm panel x19mm high x 1.5-4mm wall (Commodity code 4008290090) £10.30
2021 Mar 17: Levered up one side of the dome onto wooden blocks (1 x 3") to get finger access to the underside where the joints were uneven.
2021 Mar 17: I stuck some Black grip tape over the uneven areas where the free movement of the dome was inhibited. Hopefully this will help the motor.
Mar 19: Black grip tape over the dome joins (underside)
has smoothed out the "ride" but not fully - much better now i feel.
2021 Mar 19: The dome track that is gripped by the inside motor is shinny, where the paint is rubbed thin, particularly the areas where grip is lost.
2021 Mar 19: I have stuck some grip tape over these areas to reduced the loss of traction. I think it has worked - we will see.
2021 Mar 19: The measured thickness of the dome and wall is 3 to 4mm.
2021 Mar 19: The doorway area is much thicker at 5-6mm
2021 Mar 20: I discovered the shutter drive will close if the mains power is cut (loss of Blue-Tooth). A useful fail-safe.
Mar 21: There
are gray areas where the inside motor looses traction. Here is an example -
and areas where i have added some grip tape
2021 Mar 21: Increasing the pressure on the drive motor doesn't help. Its already quite tight.
2021 Mar 21: I connected a DIY battery replacement cable/plug to replace the AC/DC adaptor. I now have a choice of 12V or AC/DC for the dome motors
Rubbing point from the motor wheel...............Grip tape over rubbing points.................2A 12V AC-DC adaptor supplied...............Home made plug for 12 battery (for emergency!)
Mar 22 : An electrician has connected the power cable through the trunking
to the fuse board. I have 4x double sockets.
2021 Mar 22 : The wall to base seal on the East side doesn't fully seal. I added another layer of Bond It over a 2ft area. My first bead was thin.
2021 Mar 22 : Bond It (trade) GP200 White. Two were supplied by Pulsar. Here are the details of use. I may need another tube
Mar 30: The
weather strip sent by Pulsar, was added during a spell of warm weather. Should
keep out wind-blown rain.
2021 Mar 30: Power was installed earlier, and i have made a shelf in the accessory bay to hold the laptop and other bits.
Mar 31: There
was a difficulty with the Sidereal drive rate.The dome just accelerated and
the azimuth encoder was zero.
2021 Apr 01: Pulsar helped diagnose the problem - simple - the dome motion encoder was not in contact the dome !
2021 Apr 01: I simply flicked the sprung loaded mechanism with by finger and all was OK. Re calibration was suggested.
2021 Apr 01: The azimuth is only off by a degree or so. I've left the azimuth readout as-is for the time being.
Apr 12: In
mid April a made an annular shelf to sit on the pier veins near the top. Stuck
on the underside is an LED strip light.
2021 Apr 12: The LED strip is three small sections with 3 LEDS in each connected by wires and running off a 9v 1amp AC/DC adapter.
2021 Apr 12: I bought a long strip of V-TAC leds for lighting an office (warm white 3000K) with a 12v transformer. Just 10leds on 9v is enough for the Obs.
2021 Apr 12: The LED strip can be cut with scissors into sections (in units of 3) and reconnected by soldering on wires.
2021 Apr 12: A second strip of 6 LEDs illuminates the work-station. This is run from a 9v PP3 in a switched battery box - ignoring the V-TAC instructions!
2021 Apr 16: Orion Optics (UK) 30cm F/4 installed on the EQ8. The Lossmandy dovetail plate was bought from OO at AstroFest 2019.
2021 Apr 20: Bought some cable ducting from Screw Fix to tidy up wires across the floor.
Apr 26: The
OO 30cm mirror was removed from the OTA and washed. - soapy tap water, de-ionised
water, and then IPA.
2021 Apr 26: The mirror was first coated in 2006. Outwardly its good, but close inspection showed microscopic dust and crud on the surface.
2021 Apr 26: There was also a spider web in the tube near the mirror, and and some metal swarf from a hole i drilled - now removed.
30cm before washing in 2021- It was previously washed in about 2016. I didn't remove it from the cell.
Apr 29: Some rain for the first
time in weeks. Not heavy, but there is an unsealed hole somewhere near the door
area allowing water ingress.
2021 Apr 29: I have bought 3 x 300gm tubes of GP200 sealant, and im going to push this into all the underside rim gaps from the inside.
2021 Apr 29: My thinking is that a thick bead around the outside (dome wall to concrete) is not enough to keep out water totally.
Picture: Observatory looking West. The home position
for the dome aperture (shown here) is pointing North. In this position the induction-
2021 Apr 30: - charger is engaged and charging the battery. There is a single accessory bay. The entrance door is visible from the house.
2021 Apr 30: Usually the dome is rotated to a more southerly azimuth for use. Afterwards i sometimes keep the dome in the last position used..
2021 Apr 31: EQ8: Over the last few weeks i experienced intermittent loss of connection to the mount. I use a RJ45 EQDIRECT/USB cable, EQASCOM and SkyMapPro.
Apr 31: The difficulty was
I think caused by a bad USB plug - i re-arranged the cables a bit, and moved
a unrelated transformer further away. (Interference?)
2021 Apr 31: The problem persisted without dropping any USBs, in particular COM6 for EQMOD was in service (see Device Manager).
2021 Apr 31: Reading some blogs, suggests the RJ45 connection at the mount was a possibility - it would explain a lot, but the connection seemes OK.
2021 Apr 31: I plugged in the coiled SynScan cable, and connected the Lynx cable via an RJ45 strait connector. This seems to be successful. The joins are tight.
May 01: A spare
ADM Vixen clamp is now used to hold a pan-and-tilt head attached with a tripod
1/4 20 bolt. I can now piggy-back a camera.
2021 May 01: I have added provison to adjust the OTA ballence, by hanging some extra weights on it. I'll make a more permanent fixure later on..