Monday, 13 April 2015
Sunday, 29 March 2015
When performing photometry on DSLR images, should dark frames be stacked and subtracted from the light frames? If so, how many dark frames should be used, and which stacking method should be employed? This experiment attempts to answer the first question by evaluating the signal-to-noise ratio (SNR) of stars on an image from which different numbers of dark frames have been subtracted.
Constellations, of course, aren’t “real” objects, but they are a handy way of slicing up the night sky into more manageable chunks.
Having the sky sub-divided in this way immediately suggests an observing project: carefully examine each chunk of sky for anything and everything interesting. This raises the question: when is a particular part of the sky well-placed for observing?
With the recent addition of “constellation place holders” to the DOCdb database, this is now easy to answer, using the DOCdb List Plan option. Here’s the step-by-step guide.
 News Notes
 Three in: Carina by Dave Blane & Auke Slotegraaf
 E3 — A curious globular cluster in Chamaeleon by Douglas Bullis
 Heartbeat of a Unicorn — Exploring the fascinating but often overlooked constellation of Monoceros by Carol Botha
 Birth of a Deep-Sky Marathon — A report from the 2014 Free State Star Party, with guidelines and recommendations for conducting a deep-sky observing marathon by Hannes & Pieter Pieterse
 At My Eyepiece — Veteran deep-sky observer Magda Streicher gives us a look at how she observes. by Magda Streicher
 Deep-Sky Projects
 Photo Gallery
 On The Cover
[appendix] Big 5 of the African Sky
Saturday, 28 March 2015
Sunday, 15 February 2015
Click to Enlarge.
The Boyden Observatory is not next to the light pollution from "next door neighbours" anymore. It is right in the glow. Not long before the Milky Way will be an image on the screen and not a magnificent object in the Boyden night sky.
"next door neighbours" - Maselspoort resort and all the owners on the banks of the Modder River.
Earth Observation Group (EOG)
The NGDC Earth Observation Group (EOG) specializes in nighttime observations of lights and combustion sources worldwide. The group started working with DMSP data in 1994 and has produced a time series of annual cloud-free composites of DMSP nighttime lights. EOG's current focus is on nighttime VIIRS data.
Monday, 26 January 2015
Click to Enlarge!
Hot bright news (26 January 2015) Chart date 26 January 2015, 20:30
from Bloemfontein, South Africa.
Source: Comet Chasing in January; Chart: Skytools 3
15P/Finlay is now a binocular object! It brightened by several magnitudes on January 16, on top of a similar episode in mid-December, apparently due to a series outbursts.
Coma Diameter: 3.9'
Earth Distance: 1.4 AU
Sun Distance: 1.1 AU
Tail Position Angle: 65°
Tail Forshortening: 30%
Actual Coma Diameter: 240000 km
Total motion: 3.06 "/min
RA: 2.71 "/min
Dec: 1.44 "/min
Tuesday, 13 January 2015
Click to see example map!
- Download and print Naked Eye Star Map for the Southern Hemisphere
(Select Southern hemisphere, the time and the type of map)
Sunday, 11 January 2015
Friday, 26 December 2014
UFOS: UNEXPLAINED FLAPPING OBJECTS
In SkyNews (January 2015)
On August 5, 2010, I was out with my telescope observing the night sky from my drive- way in southern Hamilton, Ontario, when I looked up toward the zenith and saw a triangular formation of three bright “orbs” of light moving incredibly fast toward the northern sky. By this time, I had already been observing the night sky for two years and quickly realized the lights were moving too fast and were larger in size and appearance than a satellite. They were also switching positions smoothly and swiftly. My next thought was a meteorite breakup, but there was no trail and no change in luminosity, and these objects persisted at a constant brightness for about 20 seconds before disappearing behind a tree. I could not come up with a plausible explanation.
About eight months later, while walking into The Hamilton Spectator building to attend a meeting of the Hamilton amateur astronomers, I briefly witnessed a similar event in the low eastern sky and still had no explanation. My answer finally came in June 2011. While outside on my driveway observing, I noticed five strange objects moving down the eastern sky. Luckily, I had binoculars with me this time. To my amazement—and embarrassment— I discovered that the strange “ufos” I had told numerous friends and fellow astronomers about were, in fact, Canada geese illuminated just enough by city lights from below to give the geese a strange, almost otherworldly glow, which made it very difficult to see any detail with the unaided eye. I could not hear them flying, and because they were moving about one another in formation, flapping their wings and flying at a fair speed, they gave an eerie appearance that had haunted me for almost a year.
Since then, I have seen Canada geese at night on numerous occasions. however, once I look through my binoculars, I laugh at myself and return to observing. if you witness what at first appears to be a strange triangular formation of alien craft, grab your binoculars, because I would wager that it’s some Canada geese happily on their way. and you can blame light pollution for the interruption.
(Het self al saans oor Bloemfontein hierdie wit voëls - soos bosluisvoëls gelyk - met my verkyker gesien. Wonder of hulle die stadsligte vir navigasie gebruik? - Hannes Pieterse)