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21st April: Re-processed to better show the colour of the fainter stars ...
Shimmering like a pearl to the naked eye, this open cluster of mostly young blue stars ( known as the "Pearl Cluster" ) is approximately 5500 light years from Earth and was discovered by Abbe Lacaille in 1752 from South Africa.
This HDR image is constructed from 11 sets of exposures ranging from 1/4 sec ( to capture the centre of the brighter stars ) through to 240 seconds ( for the fainter stars of the Milky Way ). Total exposure time was around 5 hours.
A Cluster of Pearls in the Southern Skies ( NGC 3766 " The Pearl Cluster" )
( please click / tap on image to see larger and sharper - a full size image can be found here )
12 April 2018
Field of view ..... 58' 49.8" x 39' 36.4"
Image center ...... RA: 11 36 03.890 Dec: -61 35 30.17
Resolution ........ 0.586 arcsec/px ( full size image )
Orientation: North is up
Telescope: Orion Optics CT12 Newtonian ( mirror 300mm, fl 1200mm, f4 ).
Corrector: ASA 2" Coma Corrector Quattro 1.175x.
Effective Focal Length / Aperture : 1470mm f4.7
Mount: Skywatcher EQ8
Guiding: TSOAG9 Off-Axis-Guider, Starlight Xpress Lodestar X2, PHD2
Nikon D5300 (unmodified) (sensor 23.5 x 15.6mm, 6016x4016 3.91um pixels)
Blue Mountains, Australia
Moderate light pollution ( pale green zone on darksitefinder.com map )
Capture ( 12 April 2018 ):
11 sets of sub-images with exposure duration for each set doubling ( 1/4s to 240s ) all at ISO250.
( 70 x 240sec + 10 each forthe other durations )
Calibration: master bias, master flat and master dark
Integration in 11 sets
Pixinsight April 2018
This is a 6" f/5.9 refractor (890mm focal length). It is constructed from high quality Japanese Ohara and German Schott glass with top quality coatings. This has the large 3" rotatable focuser. It can accept a 2" or a 1.25" diagonal.
It comes with a carrying handle and a vixen dovetail bar. As you can see there is some of the usual scuffing on the dovetail bar.
No doubt you have seen the reviews of this scope. We have gone a bit berzerk over the last few months and have run out of scope shelves, so this one needs to go. We bought it new around 18 months ago direct from Altair Astro. It has seen minimal use what with one thing or another.
£590 preferably by bank transfer. The box and packing material has gone the way of all things. As such, this would need to be collected. I don't mind driving to meet someone half-way if necessary.
Looks like my Lipo project so far may be working good, ran a trial last night with a 3200Mah 3 cell Lipo from my RC airplane, the battery is an 11.1V nominal charge (uncharged) but charges up to 12.6V (4.2V per cell fully charged). All Lipo batteries display nominal charge capacity, which can be misleading because when charged, they jump up in voltage past displayed voltage.
I wanted to see how long that went for before using one of my larger 5000Mah batts, didn’t take much more than $5 for a 2.5mm connector with 6ft cable included and a Deans connector on other end for the battery. I have a small voltage meter we RC guys use to monitor battery levels per cell and combined voltage, meter just keeps displaying levels constantly then emits a buzz when it drops to pre programmed level. The loud buzz I muffled to a pitiful hum by dropping some hot glue over the little speaker holes, last thing I need is an 80 decibel buzz at 2am in my yard.
I set buzz for 3.5V per cell which is lowest you want to drain a Lipo per cell, after slewing around manually more times than I can remember I still had enough juice to slew around for another hour if i wanted, I was mimicking a nights slewing around and I think after I slewed around on both axis simultaneously on and off for 40 min I pretty much covered a nights worth.
the test will be in the field, if this battery doesn’t cut it I’m sure the 5000Mah will do the trick. I was watching for any shenanigans from the scope as the level dropped but nothing, no glitches or twitching of the controller display, all remained solid.
The next morning i turned on the scope (without recharging battery) and again spent the better part of an hour until i was just bored slewing the scope around, i was afraid to burn out a motor with constant back and forth slewing with a short pause of course.
i am now convinced that this 3200mah battery not much bigger than the average candy bar will last a whole night out and more! fantastic to know that when i drag the scope out for short periods locally (won't need heat strip those times) that this battery will be fine.
i was dreading having to take my 50Lb deep cycle marine battery every time id like to go for a short local 2hr outreach session, on those long drive dark sky all night sessions yes i will need heat and my marine battery but those a few compared to
short local sessions. I can now fit my power supply into my pocket and that is just GOLD!!
Decided to put cooling fans on my newtonians a 200pds and a 130pds ,used a 120mm on the 200 and a 80mm on the 130pds ,i used, Be Quite silent Wings2 fans they use rifle bearings and are so quite German made, i did the 200 first and was impressed with this make so ordered the same make for the 130 pds it comes with a lead with four wires but only needed neg ang pos so snipped other two out , made a disc from plastic and cut out around collimation screws on primary then used velcro to attach to OTA fitted a 2.1mm dc socket on to the disc then bought a usb lead to 2.1mm barrel though i may fit another 2.1mm socket on my power box and use 12v either way it works ,i used a dimmer on the 200pds but it doesnt need it and wouldn't use it again but its fitted now so will leave in place.