Thornbury

Astronomy

- o O o -

CORONAVIRUS

The coronavirus outbreak means that the astronomy group cannot meet in the near future.

There will be no meetings in April and May. We will review the situation after that.

- o O o -

The group meets in the Buckingham Room of The Chantry, Thornbury. Meetings take place on the first Monday of each month except August, when we take a break. The meetings start informally around 10am with coffee, biscuits and chat, and we sit down for the more formal proceedings at 10.30am. We finish around noon. Each member is expected to make a donation of £1 at each meeting to cover the costs of hiring the room and providing the refreshments.

(click on a thumbnail to see a larger image)

The membership varies widely in background and very few of us are telescope-owning observers. We are mainly a talks and discussions group and cover astronomy in the widest sense: observations, cosmology, space missions, history, and so on. We do not explore the subject systematically – every meeting is a stand-alone meeting with a main talk covering one particular topic. We are particularly keen on covering the latest findings in Astronomy as soon as possible after they are announced.

If you wish to know a little more about the group’s activities, you can consult our Astronomy pages on the Thornbury U3A website. In particular, a few days before each meeting a poster is placed on these pages advertising the meeting’s main talk. The "Past Meetings" page contains a collection of these posters and anyone interested in joining us can examine these to get some idea of what we cover. The group welcomes new members.

Contact the Group Leader, Peter Jackson, on 418050 or by email to Astronomy.

If you have any comments about the web site, please sent an email to Webmaster.

Bill Beer's observation of Comet PANSTARRS

One of our members, Bill Beere. He has managed to image comet PANSTARRS.

In his image it is a dot with a blue halo on the right, a little over halfway up from the bottom. Here are the images. First is Bill's Skysafari image taken from his ipad marked up with a rectangle showing the extent of the image viewed through the camera. Second is the image recorded by Bill. Finally is an image showing the location of the comet.

(click on an icon to get a larger image)

Here is Bill's description of the observation:

"I had a go at imaging the comet Eddie has given us two updates on. I thought it may be of general interest.

"I used the most basic Skywatcher equatorial Go To mount and inexpensive Canon camera with a secondhand manual focus Nikon 180mm f2.8 lens. I used a Skysafari app on my iPad to find where the comet was in the sky and just where to point the camera. One of the figures attached shows what appears on the iPad screen. The rectangle gives the size of the image I should see on the camera given the sensor size and focal length of the lens.

"It has been a while since I used the system so I needed to practice in daylight as the mount has to be aligned with the north celestial pole and the tracking system has to be aligned with bright stars. It's surprising how many things can go wrong fiddling around in the dark. Much to my surprise, I found the comet in the first frame. In the end I took 64 frames at 30s f2.8 ISO 1600. The comet could be seen in each frame but at 1600 ISO there was quite a bit of noise.

"I spent most of the time watching from indoors but as I knew exactly where to look, I did have a go trying to see the comet with 10x40 binoculars. I'm still not sure if I did see it so it has to be a no.

"The images were processed by aligning the stars in each and then averaging all frames to reduce the noise using Photoshop. The background light pollution has also been subtracted as much as is possible. The result is attached. The overall picture is similar to what was expected from Skysafari except for the comet's tail. It would have been great to see a tail but a smudge was all I could manage. Still, I was pleased to find the comet at all and the setup worked well. The tracking was good enough to see faint stars well below magnitude 14 (the limit available in my copy of Skysafari). The red at one end of the image is part of IC 1805 The Heart Nebula. The Soul Nebula is alongside but I could not image both and the comet with a 180mm lens. These two make a nice image particularly when using an H-alpha filter to pick up only the emission line from ionized hydrogen.

"If any of our members have similar kit and want to discuss setting things up, I am happy to help providing it is done over the phone. I'm on Skype and whatsapp which can be very useful when sorting things out."

Notice Board

• A small "Jessop’s refractor and tripod" has been offered for sale. Details are on the "For Sale" page (see the link on the right of this page).

• The Lyrids meteor shower is named after its radiant in the constellation Lyra. It will be visible in the South in the morning of April 22nd 2020. The radiant will be highest in the sky about 05:00. However, with sunrise at 03:43 earlier viewing would be better! Between 01:00 and 02:00, the radiant should be due East about 45 degrees above the horizon. There is a new moon at the time so this should not affect viewing conditions. The Lyrids are one of the oldest recorded meteor showers—according to some historical Chinese texts, the shower was seen over 2,500 years ago. The fireballs in the meteor shower are created by debris from comet Thatcher, which takes about 415 years to orbit around the Sun. The comet is expected to be visible from Earth again in 2276.