IC 2391, Caldwell 85, an open cluster in Vela
|Magnitude: +2.6||Diameter: 10 light years.|
|Apparent size: 60 arc min||Distance: 570 light years.|
Live Fast, Die Young
About 36 million years ago – 570 light years from the Solar System – a cloud of gas in the Milky Way, gravitationally collapsed inwards and became a stellar nursery. About thirty stars were born and today we see them as a loose group of hot young stars in the Vela constellation called the Omicron Velorum Cluster.
The cluster is named after the brightest star it contains, Omicron Velorum, which is a Class B star (meaning it is very big, very young and very hot). It is also a pulsating variable star with a period of 2.8 days.
Most of the other bright stars in the cluster are also B Class stars, between 10,000ºK and 30,000ºK. These stars live their lives in the fast lane and will all die young.
|Feature image date:||2021-03-25|
|Exposure:||25 minutes (7 subs @215.8 sec)|
|Field of View:||76.7 x 51.1 arcmin.|
I’ve been refining my telescope equipment and processes over the last nine months. Hardware additions have been an Ha/OIII duo-pass filter, an electronic focuser and a street lighting glare mitigation screen. I’ve improved my software by installing the ASCOM astronomy platform, EQMOD and Cartes du Ciel navigation & mount control systems, plate-solving and electronic focusing control.
The bottom line with the software upgrade is that my laptop now has full control of almost everything the telescope does, from polar aligning, focusing, target selection, navigation, sky quality measurement and exposure settings, guiding, imaging and stacking. This leaves six pieces of equipment now surplus to requirement:
To me the most revolutionary recent improvement in amateur astronomy has been the introduction of plate-solving software – a process which replaces the (time consuming and error prone) need to carry out a three star alignment of the telescope. Once the computerised polar alignment is done, all I need to do is select a target and command the telescope to slew to it. Once it does that, the software analyses the stars in the next image downloaded. It then (i) calculates the exact location which the image (and ‘scope) is actually centred on; (ii) compares it to the location where I intended it to be centred; (iii) calculates the targeting error; and (iv) automatically slews to correct that error and the next image will pop up accurately centred on the target..
Under the Moonlight
Thanks for reading this far down the page!
|SkyWatcher Esprit 120 mm apochromatic 3-element refractor; 840 mm f/l @ f/7.|
|Field flattener; ZWO Duo-band Hα (656nm) and [OIII] (500nm) filter.|
|SkyWatcher EQ6-R Pro mount; ZWO ASI120 guide camera.|
|Imaging camera: ZWO ASI 071 MC Pro (CMOS 28.4mm 16 Mpx).|
|Software: Telescope control: Cartes du Ciel, EQMOD, PHD2, Imaging: SharpCap, Gimp.|
|Observatory location: 34° South.|
Location of IC2391 in Vela
Location of Vela Constellation
Images courtesy of nova.astrometry.net
If the images do not appear it is because the Astrometry website is sometimes off line.
I’m a founder member of Macarthur Astronomical Society
Images © Roger Powell