Any addicted astrophotographer is always considering new equipment, and also debating the merits of several options. One of the most common questions for beginners is about the difference between Digital SLRs and astronomical CCD cameras. I love a good experiment so below is my answer.

Every March, the Astronomical Society of Victoria hosts a 'Messier Star Party' at its Leon Mow Dark Sky Site near Heathcote, to celebrate and observe the famous catalogue of deep sky objects that Charles Messier originally recorded as nuisance objects that confused him in his hunt for comets in 18th century Paris.

If you've never heard of a 'Star Party' before, this video will give you a better idea, music and all :-). I recommend enjoying it in full screen glory via philhart.smugmug.com.

These pictures of bioluminescence in the Gippsland Lakes in my gallery have proven quite popular, so it seems time to provide a story to accompany them. But this is not a short story, rather a convoluted one of fires and floods, of microscopic algae and the inspiring, remarkable and surprising beauty of nature.

At the end of a very enjoyable three days of astrophotography with a several other astronomers at the Leon Mow Dark Sky Site in Victoria (Australia), I caught a nice display of Geminid meteors. Over two or three hours, while also tending to cameras and telescopes, I spotted about 44 Geminid meteors as well as a number of other 'sporadics'. My camera also caught quite a few.

For two hours, I kept a Canon 5D mkII ticking over at ISO3200 with 8 second exposures through a 24mm f1.4 lens wide open, all on a Vixen GP-DX equatorial mount. I stacked that against a single 2 minute exposure to capture the surrounding stars and the milky way through Orion and up to Sirius and Canis Major at the top.

Click for larger size

It's been awhile since I started playing with night sky timelapse videos, but finding a way to share them online with better than YouTube quality has been a bit of a stretch. Enter SmugMug and their video galleries which do the job nicely.

Below are the first few videos I've put online. You can even get them in Full HD resolution via the SmugMug 'Stars in Motion' gallery.

I've spent the last week trapsing around NSW, starting at the Central West Astronomical Society's 2009 Astrofest in Parkes - home of 'The Dish' (better in HD!):

On Saturday I dragged Neil Creek, a long time and astronomically minded friend, to Heathcote. A contributing factor was that I knew we'd both enjoy pointing his brand new Canon 5DmkII at the heavens, and in particular towards Comet Lulin.

Am I jealous.. you bet :-)

This set of images compares the actual infrared satellite image for midday Saturday 13th September 2008 with forecasts made on the same day and up to 5 days ahead. The forecasts made up to 2-3 days ahead are quite accurate, so that a reasonable estimate of the astronomy prospects for a Saturday night could be made on the Thursday beforehand. While the general trends are still correct in the 5 day forecast, the details for a particular location become much less accurate.

Edit Oct 2009: Since I originally wrote this article, SkippySky has become available. It uses the same US GFS weather model data so the discussion about accuracy is still relevant, but SkippySky is a much more convenient way to access the cloud forecast data, with great maps for all of Australia among other places.

Check out Cloud Forecasts for Astronomers for the story behind some of this and how to generate your own cloud forecast maps using US GFS model data.

Also see Cloud Forecast Accuracy for comparisons of the forecast charts with actual satellite images.

Edit Oct 2009: Since I originally wrote this article, SkippySky has become available. It uses the same US GFS weather model data so the discussion about accuracy is still relevant, but SkippySky is a much more convenient way to access the cloud forecast data, with great maps for all of Australia among other places.

Astronomers want good weather forecasts. In particular, they need to know about cloud. When you're deciding whether to travel two hours to a dark sky site for the weekend, an accurate forecast is invaluable.

Saturday 13th September 2008

1 Day Ahead Forecast

The 'Clear Sky Clock' is available via the web to amateur astronomers across North America, and includes not only cloud forecasts but also estimates for transparency and seeing. For those of us in the rest of the world, there are several other options:

• Updated Oct 2009: SkippySky - The most convenient option now for Australia, New Zealand and Europe.
• Global Forecast System (GFS) Cloud Charts from US NCEP
• 7Timer Astroweather Panel (APanel) Forecasts by Quanzhi
• Astroforecast.org Cloud Forecasts by Jeff Bullard
• Air Force MM5 Model Cloud Top Temperature Charts