Andrew’s Astronomy Blog

Saturday was clear and the forecast for the evening was good so I started looking at Cartes Du Ciel for possible targets for the 20″. Low in the East is generally best for this system and fitting the bill perfectly was a comet, C2009/P1 (Garradd). Brightness was shown as M8.8 which is fairly bright as well.

The plan was to take multiple LRGB sequences with the Atik 383, each exposure being 60 seconds.  Then stack on the comet and remove the stars from the image, stack on the stars and remove the comet and finally combine the images. Due to the comet’s motion across the sky, this complex procedure is required to avoid trailing of either the comet or stars.

There were some problems with the altitude drive which resulted in a fair few frames being rejected but, after a couple of runs through Photoshop trying different techniques, here is the result.

With a bright full moon in the sky Dan and I decided to spend the night trying to better understand the society’s 20″ reflector. Getting the best out of it is definitely an art rather than science and the longer you spend with it the better you get to know it’s strange quirks and foibles.

After some time with the Orion nebula I put the webcam on with Televue x2.5 and took some 10fps videos of Saturn. The final one looked the best on the laptop so I stacked 400 of the best frames in Registax and applied a lot of sharpening.

The rings have noticibly opened  since last year and as it climbs higher in the sky it should present a nice target later in the year.

A rare clear interval on Tuesday evening at the observatory and I put my modified webcam on the 20″ with a narrowband infra-red filter. The seeing wasn’t up to much but I got some pictures both with and without a x2 barlow.

The southern cloud band that so dramatically disappeared last year is back although in this image it does appear to have a gap in it where it’s still obscured by higher level clouds.

Tuesday morning was bright and clear (and minus 9C) when I left the house at 06:30 to walk to the top of the lane. As I setup the camera and tripod, the Earth’s shadow was just starting to take the first bite out of the lunar disk. Sticking mainly with the Canon 75-300 zoom I took pictures until the moon faded into the dawn sky as it reached totality. At 07:30 I took this wider field image.

Camera: Canon 350D

Lens: Canon 75-300 zoom @ 125mm f/4.5

ISO: 400, 1/3 sec

Once every year the Earth overtakes Jupiter on the inside track and as Jupiter is opposite to the Sun in the sky this is known as Opposition. As the planetary orbits are not circular, the inter-planetary distance varies each year and this year Jupiter is the closest it’s been since 1963. Additionally, for Northern hemisphere observers it’s also higher in the sky than it’s been for many years and this results in a clearer view as there’s less of our atmosphere in the way. To add additional interest this year, the southern equatorial cloud belt has disappeared although it’s just beginning to make a comeback.

Also in this picture, the moon Ganymede has just re-appeared from behind Jupiter.

This image was taken on Tuesday evening with the club 9.25″ Celestron SCT with a 2.5x PowerMate  and modified Phillips SPC900 camera. It’s a stack of about 1000 frames processed in Registax.

Friday evening at the Observatory was spent showing some visitors around. As it was clear we were able to look at Venus, Mars, Jupiter and Uranus as well as the Moon through the 20″. Although the planets were all very low and suffering from massive amounts of atmospheric dispersion they went away happy.

After that, it was down to the main business of the night, measuring periodic error on the 20″ drives. This shows that we have some more work to do to stop drift on the altitude drive and also that we have about 7 arc seconds  peak to peak periodic error on the azimuth axis.

By this time, Jupiter was high in the sky so we finished up putting my modified Philips webcam on with a 2.5x PowerMate for some video images. Jupiter is more favourably positioned for Northern hemisphere observers than it has been for many years and it was nice to see it at a decent altitude with lots of detail visible in the eyepiece.

Looking through the images I collected last night revealed 6 meteors, 2 aircraft & a lot of satellites. I’d taken 10 90 second images of the area around Cassiopeia which were stacked to provide the background. The images with meteors trails were then selected and using painted selection masks superimposed on the background using Photoshop.

Next time I will acquire the images slightly differently.  Downloading them to the laptop results in a considerable time lapse between images. Capturing jpegs directly to the camera flash card with the camera locked on repeat would minimise the chance of missing meteors.

Last night was the peak for this year’s Perseid meteor shower and the weather was reasonably kind with only occasional cloud until 2AM when it clouded over.

I’ve got a lot of photos to sort through but this image came from one of the longer exposures aimed at capturing the star background. A single 90 second exposure at ISO1600, f/3.5, 18mm.

Comet C/2009 R1 (McNaught) is currently travelling through Perseus, low down in the pre-dawn sky. I managed to get a single 60 second exposure from New Mexico on GRAS-14, a Takashashi FSQ 106ED with an SBIG STL-11000M-ABG camera. The comet is currently 177 million kilometres from Earth and makes it’s closest approach on 15th June at 170 million kilometres.

I’ve had to remove a substantial background gradient on this image as this was just before dawn and it’s binned 3×3 to reduce the image size.

Saturn is back in the evening sky. Having shot some three colour video sequences of Mars on the Celestron 9.25 I switched to Saturn which was just rising out of the murk at about 20 degrees elevation. The rings are just beginning to open out after last year’s edge on aspect and with the planet higher in the sky as it approaches opposition it should be favourable for imaging.

1500 frames each of red, green and blue video were stacked and combined for this image.